The present topic is characterized by a large natural population of indigenous and underutilized fruits which despite growing in popularity are on the verge of being extinct as they are not cultivated in large acreages. Several of these crops were consumed as the main fruits by earlier inhabitants in the Caribbean. However, most of them have lost their popularity due to changes in the taste patterns in favor of temperate fruits such as grapes, apples, pears, peaches, and plums. With the growing demand for some of these commodities and possible export potential, there are considerable market development opportunities within the Caribbean for these fruits. The low production of these fruits and the limited information on the postharvest physiology and disease characteristics of these fruits have made large-scale production and packing/processing difficult. The magnitude of postharvest losses of many of these fruits can exceed 50% depending on the commodity as many of them are highly perishable due to high moisture content under tropical conditions [1].

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Many of these fruits are harvested, handled, and sometimes processed using local indigenous knowledge at the household level. The main ripe fruits that fall in this category are the edible fresh fruits and include pommerac *(Syzygium malaccense)*, sapodilla (*Manilkara zapota)*, balata (*Manilkara bidentata)*, carambola (*Averrhoa carambola)*, guinep (*Melicoccus bijugatus*), and cashew (*Anacardium occidentale*)*.* The fruits that are harvested mature but do require to be ripened and need to be cooked include breadfruit *(Artocarpus altilis)* and chataigne (*Artocarpus camansi)* and also the palm fruit peewah (*Bactris gasipaes).* There are two edible fresh fruits that are made into frappes or sherbets and ice cream, sweet sop (*Annona squamosa*) and barbadine (*Passiflora quadrangularis*)*.* There is also a very popular root tuber in the Caribbean Latin American countries called topi tamboor leren *(Calathea allouia)*. **Table 1** shows some of the most common indigenous and underutilized fruits in Trinidad and Tobago, their utilization, harvest and postharvest practices.

**Crop Utilization Harvesting and postharvest handling**

• The fruits are ready for harvesting when the skin becomes translucent and glossy and is beginning to turn yellowish at the

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167

• Very careful handling and packing are

• Fruit stalks must be cut to a length of 1.5 cm and the latex must be drained in

• Full green fruits are usually plucked by

• Fruits can be wrapped in polyethylene and stored at 12°C last about 20 days • Lower temperature causes chilling injury ad higher temperature will allow it to ripen

apex

Postharvest Handling of Indigenous and Underutilized Fruits in Trinidad and Tobago

essential • Highly perishable

the field.

hand or by a rod.

more quickly.

shriveling

delivery

the consumer

when ripe.

life

• Fruits are picked by hand

avoid rubbing injury • Plastic wraps can also be used

• The fruit ripens in 3–7 days

• The ideal relative humidity is 90–95% to prevent water and weight loss and

• The storage time between packing and delivery to the market should be as short as possible to ensure that the fruit still has a reasonable shelf life when it reaches

• Fruit should be firm and crisp with shiny golden-yellow, orange, or yellow skin

• Fruits can be wrapped in tissue paper to

• Can be cooled after harvest to extend shelf

• Waxing has been reported to be helpful in

• Can be stored up to 5 weeks at 5°C • Moisture loss can occur during storage and

can lead to skin browning

reducing desiccation

• Well-ventilated cartons should be used and fruits packed in a single layer and separated from adjacent fruits by separators to prevent bruising during transport • Fruit for the local market should also be graded and packed in sturdy crates for

• It is clipped from the vine

• Fresh fruit can be made into sherbet or used in desserts • Can also be cooked and used as a vegetable

• Fruit is usually cooked before eating • Ripe fruit can be eaten as a dessert • Fruit can be boiled, dried, and made into flour, and slices can be fried or stored in

brine

• The cooked fruit can also be stored • The collected latex can be used as a caulk, glue, and chewing gum

• Fruits can be eaten when fully ripe • Sliced fruits can be added to salads • Can be made into jams, preserves, pickles, candy, juice, and liquor

*Passiflora quadrangularis* (barbadine)

*Artocarpus altilis* (breadfruit)

*Averrhoa carambola* (carambola)

Plate 6

Plate 4

Plate 5

Many of these fruits are harvested, handled, and sometimes processed using local indigenous knowledge at the household level. The main ripe fruits that fall in this category are the edible fresh fruits and include pommerac *(Syzygium malaccense)*, sapodilla (*Manilkara zapota)*, balata (*Manilkara bidentata)*, carambola (*Averrhoa carambola)*, guinep (*Melicoccus bijugatus*), and cashew (*Anacardium occidentale*)*.* The fruits that are harvested mature but do require to be ripened and need to be cooked include breadfruit *(Artocarpus altilis)* and chataigne (*Artocarpus camansi)* and also the palm fruit peewah (*Bactris gasipaes).* There are two edible fresh fruits that are made into frappes or sherbets and ice cream, sweet sop (*Annona squamosa*) and barbadine (*Passiflora quadrangularis*)*.* There is also a very popular root tuber in the Caribbean Latin American countries called topi tamboor leren *(Calathea allouia)*. **Table 1** shows some of the most common indigenous and underutilized fruits in Trinidad and Tobago, their utilization, harvest and postharvest practices.

**Crop Utilization Harvesting and postharvest handling**

• Tastes similar to water chestnut and can be used as a substitute • Retains its crispness when cooked • Can be used to make

• Harvested after 9 months by using fork to

• Tubers can be stored at room temperatures

• Harvested using coco-knife, sharp chisel, or a sharp luchette attached to picking rods • Can be stored at room temperatures for up

• Usually harvested in the green to orange stage by picking rods or shaking of trees • Fruits usually have latex which should be

• Fruit can be stored up to 1 week at 15°C • Spoilage may occur when left in plastic bags at room temperature

pull up tubers

temperature

to 1 month

temperature

allowed to drain

• Does not tolerate refrigeration • Spoilage in plastic bags at room

for up to 3 months • Does not tolerate refrigeration • Spoilage in plastic bags at room

• Eaten boiled as an appetizer

flours

• Can be boiled with salt and other spices and eaten as an appetizer

• Can also be preserved

in brine

• Edible fresh fruit • Latex is used industrially for products such

as chicle

*Calathea allouia* (Aubl.) Lindl.

*Bactris gasipaes* (peewah)

*Manilkara bidentata* (balata)

Plate 2

Plate 3

(topi tambo) Plate 1

166 Postharvest Handling

**Crop Utilization Harvesting and postharvest handling**

• When ripe, the fleshy pulp may be eaten or used to make custard and ice cream called "chicle," and it was this—with the addition of massive amounts of sugar chewing gum

• Can be eaten raw in fruit salads jellies or

ice cream

• Edible fresh fruit • Fruit can be pureed and used to prepare iced drink or mixed with other juices, or it can be made into sherbets and gelatin

dishes

• Fruits should be harvested when the brown scaly external material from the fruit sheds

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169

• Fruit becomes corky brown in color • Ensure that latex does not flow when the fruit is scratched with the finger nail • Maturity usually judged by size and

• Harvest with the use of appropriate harvesting tools and ensure that fruit does not

• Should be carefully handled as fruit can be readily damaged by abrasion and impact • Mature frit ripens in 3–7 days at 25°C and

• Lower storage temperatures lead to chilling

• Fruit marketability lessened by low "shelf life" and difficulty of grading for similar

• Harvest by hand and avoid the fruit touch-

• Low temperatures required during handling and sensitive to chilling injury • Controlled and/or modified atmosphere packaging extends its storage life

• Harvest the fruit by hand when it is fully

• The color of the fruit peel changes from

• The fruit is still firm when pressed with the

• Can be held after harvest for up to 4–7 days at room temperature before softening occurs • The skin of ripening fruit usually turns dark brown to black, but flesh is unspoiled • Harvested fruits must be transferred to cushioned boxes or crates in order to avoid

• Individual fruit should be wrapped in soft packing material and transported in well-

mechanical damage or bruising • Harvested fruit should not be exposed to direct sunlight, but should be kept under

ventilated cardboard boxes • Can be kept for up to 7–10 days at 17°C • Pre-cooling is essential to help extend shelf

developed and still firm

dark green to pale green

thumb or finger

shade

life

off

Postharvest Handling of Indigenous and Underutilized Fruits in Trinidad and Tobago

appearance

maturity

ing the ground • Perishable during transport

touch the ground

stored at 15°C for 14 days

injury and a failure to soften

*Manilkara zapota* (sapodilla)

*Mammea americana* L (mamey apple)

*Annona squamosa* (sweet sop)

Plate 10

Plate 11

Plate 12

**Crop Utilization Harvesting and postharvest handling**

• The ripe fruit can be eaten fresh or processed into juices

• Harvested either mature-green, semiripe, or ripe • It can be eaten fresh or processed into juices or preservatives • The skin is thin and delicate and can be

• Fruits are harvested when the skin has nearly full color and the fruit is firm either

• Harvested fruit should be sorted, sized, and packed in a single layer in trays with

• Extra care is required when harvesting and

easily damaged

by hand or rod

padding to limit injury • Paper can be used to wrap fruits • The fruit is non-climacteric and is chill

wrapped pack at 12°C

• Fruit can last 4–6 days at ambient

• Water loss and sugar content usually declines if fruits are left in polyethylene-

• Fruits are harvested when full and light green to yellow by hand or rod

• Fruit must be harvested using the appro-

• Fruits must not be detached from the trees

• Rough handling of harvested fruit must be avoided in order to prevent bruising,

• Fruit must not be exposed to direct sunlight. They should be kept under shade • Harvested fruits must be transferred to clean and dry plastic crates

• Defective fruits, i.e., those that are diseased, mechanically damaged, and otherwise not marketable, must be separated out • Fruit must be cleaned by washing in water containing 100–120 ppm sodium hypochlo-

• Fruits can be packed into fiberboard waxed

• Ambient conditions. For temporary storage under ambient conditions, store in a cool, dry place with adequate ventilation, away

handling

sensitive

temperature

• Fruit is climacteric

priate harvesting tools

or fall to the ground

cracking, and wounding

rite and 0.05% thiabendazole • Surface moisture must be removed by spreading fruit on racks under shade with

adequate ventilation

from sources of ethylene • Cool storage. Transport and store at 13–15°C and 85–90% relative humidity

cartons

*Syzygium malaccense* (pommerac)

*Syzygium aqueum* (wax apple)

*Spondias cytherea* (pommecythere)

Plate 7

168 Postharvest Handling

Plate 8

Plate 9

• Pre-cooling is essential to help extend shelf life

observed that although tropical fruit crops are cultivated under higher ambient temperatures, they usually have poor postharvest practices, which further affects their shelf life [3]. It was recommended that storage in different packaging materials, viz., micro-perforated polypropylene bags (MPB), micro-perforated polypropylene bags with ethylene absorbent (MPB+K), macro-perforated polypropylene bags coated with antimist coating (PP), fruit waxing, gib-

Postharvest Handling of Indigenous and Underutilized Fruits in Trinidad and Tobago

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171

Many scientific research have been focused on the crop production but little on postharvest issues. However, postharvest quality and shelf life of the fruit in part will depend on some postharvest handling practices and treatments carried out after harvest [4]. Handling practices like harvesting, pre-cooling, cleaning and disinfecting, sorting and grading, packaging, storing, and transportation all play an important role in maintaining quality and extending shelf life. The use of improved postharvest techniques such as refrigeration, heat treatment, modified atmosphere packaging (MAP), and 1-methylcyclopropene (1-MCP) and calcium

This chapter will review and evaluate the applicability and appropriateness of some of these postharvest handling practices and treatment techniques in extending the shelf life and quality and reduction of the losses in some selected indigenous fruits of Trinidad and Tobago.

**2. Harvest and postharvest practices and operations for indigenous fruits**

Almost all minor tropical fruits are harvested manually, but this physical handling can have a drastic effect on the postharvest quality and shelf life. Most tree ripened fruits are susceptible to rough handling during and after harvesting due to mechanical injuries which reduces postharvest quality and shelf life [5]. The more common handling practices by small farmers include picking, pre-cooling and washing, sorting and grading, wrapping or packaging,

Small-scale producers throughout the Caribbean usually harvest most of their fruits very early, when fruits are sometimes green to avoid the incidence of praedial larceny (farm theft) [6]. This often results in underripe fruits which have not yet developed their full flavor.

The maturation of fruit ready for harvest varies depending on the fruit type which may be harvested in either the matured green, partially ripe, or ripe state [7]. The physiological stages of fruit maturity are the maturation, ripening, and senescence, and they influence the postharvest quality and shelf life. The climacteric fruits are usually harvested at the matured green and then placed in special conditions that ensure their continuation into ripening and senescence. There is little fruit loss during this phase except with physical damage or fruit-fly infested fruits.

The fully ripened fruits are more susceptible to mechanical injuries during harvesting and should be harvested during a cool period of the day to avoid excessive field heat accumulation. The use of sharp tools or containers with edges is discouraged as these bruise and punc-

Mechanical damage during harvest is therefore not often a serious problem.

berellic acid (GA3), and indole butyric acid (IBA) applications [3].

) has been suggested [4].

chloride (CaCl2

transport, and storage.

ture the fruits (**Table 1**).

**Table 1.** Some of the most common indigenous and underutilized fruits in Trinidad and Tobago, their utilization, harvest, and postharvest practices.

All these tropical fruits offer many diverse aromas, textures, tastes, and shapes and include many different bioactive compounds. These exotic indigenous tropical fruits and root vegetable products are seasonal crops to a great extent and form part of the diaspora niche markets in Europe and North America. However, because of the poor storage qualities and high rate of spoilage due to the poor postharvest handling, the export potential is not realized. There is a gap in the information for the minor exotic crops and fruits for export which have to be transported over a longer period than the local market.

The commercial success of these tropical fruits depends on the development of postharvest technologies and handling techniques both for marketing locally and export. There are many advances in techniques for harvesting, packing, selection and grading, quality evaluation, transportation, and refrigerated storage conditions and management of postharvest physiological symptoms, insect pest, and microbial decay which must be considered.

It has been reported that the major causes of postharvest losses in tropical fruits were due to fungal pathogens particularly *Colletotrichum* spp. [2]*.* However, the etiology, biology, and environmental and horticultural factors that contribute to the high infection and development of decay are critical in improving fruit quality and must be clearly defined. It has been observed that although tropical fruit crops are cultivated under higher ambient temperatures, they usually have poor postharvest practices, which further affects their shelf life [3]. It was recommended that storage in different packaging materials, viz., micro-perforated polypropylene bags (MPB), micro-perforated polypropylene bags with ethylene absorbent (MPB+K), macro-perforated polypropylene bags coated with antimist coating (PP), fruit waxing, gibberellic acid (GA3), and indole butyric acid (IBA) applications [3].

Many scientific research have been focused on the crop production but little on postharvest issues. However, postharvest quality and shelf life of the fruit in part will depend on some postharvest handling practices and treatments carried out after harvest [4]. Handling practices like harvesting, pre-cooling, cleaning and disinfecting, sorting and grading, packaging, storing, and transportation all play an important role in maintaining quality and extending shelf life. The use of improved postharvest techniques such as refrigeration, heat treatment, modified atmosphere packaging (MAP), and 1-methylcyclopropene (1-MCP) and calcium chloride (CaCl2 ) has been suggested [4].

This chapter will review and evaluate the applicability and appropriateness of some of these postharvest handling practices and treatment techniques in extending the shelf life and quality and reduction of the losses in some selected indigenous fruits of Trinidad and Tobago.

### **2. Harvest and postharvest practices and operations for indigenous fruits**

Almost all minor tropical fruits are harvested manually, but this physical handling can have a drastic effect on the postharvest quality and shelf life. Most tree ripened fruits are susceptible to rough handling during and after harvesting due to mechanical injuries which reduces postharvest quality and shelf life [5]. The more common handling practices by small farmers include picking, pre-cooling and washing, sorting and grading, wrapping or packaging, transport, and storage.

All these tropical fruits offer many diverse aromas, textures, tastes, and shapes and include many different bioactive compounds. These exotic indigenous tropical fruits and root vegetable products are seasonal crops to a great extent and form part of the diaspora niche markets in Europe and North America. However, because of the poor storage qualities and high rate of spoilage due to the poor postharvest handling, the export potential is not realized. There is a gap in the information for the minor exotic crops and fruits for export which have to be

**Table 1.** Some of the most common indigenous and underutilized fruits in Trinidad and Tobago, their utilization,

**Crop Utilization Harvesting and postharvest handling**

• Edible fresh fruit or processed to make ice

• The fruit can be eaten when ripe • Puree can be used to make juice, cakes, sauces, jams, and jellies and ice cream

• Light green to yellow fruits should be

• Can be stored for up to 1–5 days before

• Cannot withstand low temperatures and

• Fruit should be handpicked and not allowed to touch the ground • The fruit is usually grown for processing

held for 2–3 weeks at 8–10°C • Ripe, soft fruit can be held about 1 week

• RH of 90–95% is recommended [23] • Shelf life is about 7 days when stored at

• Susceptibility to physical damage, chilling injury, diseases, and insect pests • Mature green and partially ripe fruit can be

should not be refrigerated

handpicked • Highly perishable

spoilage occurs

• Highly perishable

at 5–8°C

20°C

cream

*Musa* spp. (silk fig)

170 Postharvest Handling

*Psidium guajava* (L.) (guava)

Photo credits: Terry Sampson

harvest, and postharvest practices.

Plate 13

Plate 14

The commercial success of these tropical fruits depends on the development of postharvest technologies and handling techniques both for marketing locally and export. There are many advances in techniques for harvesting, packing, selection and grading, quality evaluation, transportation, and refrigerated storage conditions and management of postharvest physi-

It has been reported that the major causes of postharvest losses in tropical fruits were due to fungal pathogens particularly *Colletotrichum* spp. [2]*.* However, the etiology, biology, and environmental and horticultural factors that contribute to the high infection and development of decay are critical in improving fruit quality and must be clearly defined. It has been

ological symptoms, insect pest, and microbial decay which must be considered.

transported over a longer period than the local market.

Small-scale producers throughout the Caribbean usually harvest most of their fruits very early, when fruits are sometimes green to avoid the incidence of praedial larceny (farm theft) [6]. This often results in underripe fruits which have not yet developed their full flavor. Mechanical damage during harvest is therefore not often a serious problem.

The maturation of fruit ready for harvest varies depending on the fruit type which may be harvested in either the matured green, partially ripe, or ripe state [7]. The physiological stages of fruit maturity are the maturation, ripening, and senescence, and they influence the postharvest quality and shelf life. The climacteric fruits are usually harvested at the matured green and then placed in special conditions that ensure their continuation into ripening and senescence. There is little fruit loss during this phase except with physical damage or fruit-fly infested fruits.

The fully ripened fruits are more susceptible to mechanical injuries during harvesting and should be harvested during a cool period of the day to avoid excessive field heat accumulation. The use of sharp tools or containers with edges is discouraged as these bruise and puncture the fruits (**Table 1**).

### **3. Recommended best practice postharvest treatments**

### **3.1. Pre-cooling and field heat reduction after harvest**

There is usually a high build of field heat in the afternoon which is undesirable during the harvesting stage. This increases the metabolic activity that should be reduced immediately after harvest. Pre-cooling minimizes the effect of microbial activity, metabolic activity, respiration rate, and ethylene production [8, 9].

induce mechanical injuries which will increase ethylene production, thus reducing posthar-

Postharvest Handling of Indigenous and Underutilized Fruits in Trinidad and Tobago

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173

Tropical fruits usually have a very high moisture content and are very difficult to store at ambient temperatures for extended periods without refrigeration. It is critical that storage is extended so that processing operations can provide continuity of product supply throughout the seasons. Most fruits can be stored for short terms at ambient temperature (10–15°C) and relative humidity (85–95%) [16], provided that ventilation is adequate to prevent heat built from respiration and reduce poor ripening and chilling injuries. However, these conditions in tropical countries are difficult to achieve due to high day temperatures and high relative humidity [17]. On the contrary, very low storage temperature is also detrimental to the shelf life and quality of many tropical fruits and will reduce its flavor, total soluble solids (TSS), and pH of

It is essential that the correct temperature management is predetermined during storage so as to extend the shelf life of the fruit while maintaining fruit qualities. Storage for short to

Farms are usually located away from the marketing centers, processing plants, and inaccessible roads. The lack of proper transportation, like refrigerated vehicles, is a big challenge for both producers and distributors in Small Island Developing States (SIDS). This causes unnecessary delays in getting the produce to the pack houses or market, and such delays can result in losses up to about 20%. During transportation, the produce should be immobilized by proper packaging and stacking to avoid excessive movement or vibration or heat buildup, if transport is not refrigerated. Refrigerated trucks are not only convenient but also effective in preserving the quality of fruits. But it has a high initial investment which is usually unaf-

After harvesting, fruits remain living, and all the metabolic process and functions of living tissue continue. However, the postharvest quality of the fruits at or after harvest cannot be enhanced by any postharvest technology, except fruit color, but can be maintained or

Refrigeration is one of the most common effective methods of preserving the quality of many fruits for several days. Low fruits placed at storage temperature can protect quality attributes

intermediate time by using evaporative cooling system is recommended.

**4. Selected postharvest treatment techniques**

vest quality of the fruits [5].

**3.5. Storage**

the fruit [18].

**3.6. Transportation**

fordable in SIDS.

prolonged.

**4.1. Refrigeration storage**

Pre-cooling treatments can reduce the ripening rate, water loss, and decay, thereby preserving quality and extending shelf life of most fruits. It is critical to determine the specific temperature range usually between 13 and 20°C for specific fruits. Pre-cooling can be done by hydro-cooling or dipping fruits in cold water with disinfectants such as thiabendazole and sodium hypochlorite to reduce microbial infections [10].

### **3.2. Sanitization**

Proper hygiene can prevent postharvest diseases and transmission of food-borne pathogens such as *Salmonella*, *Cryptosporidium*, *Cyclospora*, and hepatitis A virus particularly where water is a constraint or likely to be contaminated. Care should be taken to ensure that harvested fruits do not come into contact with the ground to avoid any source of contamination. Disinfection or sanitization in conjunction with hydro-cooling is recommended using sodium hypochlorite solution to reduce the incidence of fungal infection before any postharvest process [11]. Thiabendazole [12] and anolyte water dips [13] have been shown to reduce the microbial infection and maintain superior fruit quality during storage.

### **3.3. Grading and sorting**

Sorting and removal of damaged, infected, or diseased fruits can prevent the production of ethylene in substantial amounts which is capable of affecting the adjacent fruits. When sorting is followed immediately by grading and categorizing of fruits based on color, size, stage of maturity, or degree of ripening, cross contamination and the spread of infectious microbes from discarded fruits to healthy fruits during postharvest handling are reduced. Additionally, through removal, overripen fruits reduce ethylene production and reduce "forced" ripening of the other fruits.

### **3.4. Packaging**

Packaging is done to improve handling, storage, and transport. It involves enclosing the product to protect it from mechanical injuries, tampering, and contamination from physical, chemical, and biological sources [14]. The materials used vary from wooden and plastic crates, cardboard and styrofoam boxes, woven palm baskets to nylon, jute sacks, and polythene bags. However, not all materials give full protection to the fruits [15].

Improper or inadequate aeration within the packaged commodity can result in a buildup of heat as a result of respiration. Similarly, crates or baskets with rough surfaces and edges can induce mechanical injuries which will increase ethylene production, thus reducing postharvest quality of the fruits [5].

### **3.5. Storage**

**3. Recommended best practice postharvest treatments**

There is usually a high build of field heat in the afternoon which is undesirable during the harvesting stage. This increases the metabolic activity that should be reduced immediately after harvest. Pre-cooling minimizes the effect of microbial activity, metabolic activity, respi-

Pre-cooling treatments can reduce the ripening rate, water loss, and decay, thereby preserving quality and extending shelf life of most fruits. It is critical to determine the specific temperature range usually between 13 and 20°C for specific fruits. Pre-cooling can be done by hydro-cooling or dipping fruits in cold water with disinfectants such as thiabendazole and

Proper hygiene can prevent postharvest diseases and transmission of food-borne pathogens such as *Salmonella*, *Cryptosporidium*, *Cyclospora*, and hepatitis A virus particularly where water is a constraint or likely to be contaminated. Care should be taken to ensure that harvested fruits do not come into contact with the ground to avoid any source of contamination. Disinfection or sanitization in conjunction with hydro-cooling is recommended using sodium hypochlorite solution to reduce the incidence of fungal infection before any postharvest process [11]. Thiabendazole [12] and anolyte water dips [13] have been shown to reduce the microbial

Sorting and removal of damaged, infected, or diseased fruits can prevent the production of ethylene in substantial amounts which is capable of affecting the adjacent fruits. When sorting is followed immediately by grading and categorizing of fruits based on color, size, stage of maturity, or degree of ripening, cross contamination and the spread of infectious microbes from discarded fruits to healthy fruits during postharvest handling are reduced. Additionally, through removal, overripen fruits reduce ethylene production and reduce "forced" ripening of the other fruits.

Packaging is done to improve handling, storage, and transport. It involves enclosing the product to protect it from mechanical injuries, tampering, and contamination from physical, chemical, and biological sources [14]. The materials used vary from wooden and plastic crates, cardboard and styrofoam boxes, woven palm baskets to nylon, jute sacks, and poly-

Improper or inadequate aeration within the packaged commodity can result in a buildup of heat as a result of respiration. Similarly, crates or baskets with rough surfaces and edges can

thene bags. However, not all materials give full protection to the fruits [15].

**3.1. Pre-cooling and field heat reduction after harvest**

sodium hypochlorite to reduce microbial infections [10].

infection and maintain superior fruit quality during storage.

ration rate, and ethylene production [8, 9].

**3.2. Sanitization**

172 Postharvest Handling

**3.3. Grading and sorting**

**3.4. Packaging**

Tropical fruits usually have a very high moisture content and are very difficult to store at ambient temperatures for extended periods without refrigeration. It is critical that storage is extended so that processing operations can provide continuity of product supply throughout the seasons.

Most fruits can be stored for short terms at ambient temperature (10–15°C) and relative humidity (85–95%) [16], provided that ventilation is adequate to prevent heat built from respiration and reduce poor ripening and chilling injuries. However, these conditions in tropical countries are difficult to achieve due to high day temperatures and high relative humidity [17]. On the contrary, very low storage temperature is also detrimental to the shelf life and quality of many tropical fruits and will reduce its flavor, total soluble solids (TSS), and pH of the fruit [18].

It is essential that the correct temperature management is predetermined during storage so as to extend the shelf life of the fruit while maintaining fruit qualities. Storage for short to intermediate time by using evaporative cooling system is recommended.

### **3.6. Transportation**

Farms are usually located away from the marketing centers, processing plants, and inaccessible roads. The lack of proper transportation, like refrigerated vehicles, is a big challenge for both producers and distributors in Small Island Developing States (SIDS). This causes unnecessary delays in getting the produce to the pack houses or market, and such delays can result in losses up to about 20%. During transportation, the produce should be immobilized by proper packaging and stacking to avoid excessive movement or vibration or heat buildup, if transport is not refrigerated. Refrigerated trucks are not only convenient but also effective in preserving the quality of fruits. But it has a high initial investment which is usually unaffordable in SIDS.

### **4. Selected postharvest treatment techniques**

After harvesting, fruits remain living, and all the metabolic process and functions of living tissue continue. However, the postharvest quality of the fruits at or after harvest cannot be enhanced by any postharvest technology, except fruit color, but can be maintained or prolonged.

### **4.1. Refrigeration storage**

Refrigeration is one of the most common effective methods of preserving the quality of many fruits for several days. Low fruits placed at storage temperature can protect quality attributes like texture, nutrition, aroma, and flavor in many harvested fruits and extend shelf life. However, some fruits are sensitive to chilling injury when they are stored below their critical temperature (10°C) for even short durations and may result in pitting, uneven ripening, and fungal infestation of stored fruits.

**4.5. Calcium chloride (CaCl<sup>2</sup>**

ness levels during storage. CaCl2

**Author details**

**References**

Puran Bridgemohan<sup>1</sup>

Tobago, Trinidad and Tobago

**) application**

ration, maintaining firmness, and reducing physiological disorders [27, 28].

shelf life and quality of many fruits [26] by delaying ripening and senescence, reducing respi-

It has also been shown to reduce fungal and other microbial infections and maintain the structural integrity of cell walls, delaying softening and extending shelf life by 4–5 weeks [29]. It also aids in maintaining the quality of fruits by reducing the physiological disorders, increasing the fruit firmness, delaying ripening process, and prolonging the shelf life [30]. Fruit color loss is also delayed, and ethylene production is reduced by 92% [26] while maintaining higher firm-

\*

1 Faculty of Biosciences, Agriculture and Food Technologies, The University of Trinidad and

2 Department of Food Production, Faculty of Food and Agriculture, The University of the

[1] Muhammad RH, Bamisheyi E, Olayemi FF. The effect of stage of ripening on the shelf life of tomatoes (*Lycopersicon esculentum*) stored in the evaporative cooling system (E.C.S).

[2] Yahia EM, De Jesus Ornelas-Paz J, Gonzalez-Aguilar GA. Nutritional and Health promoting Properties of Tropical and Subtropical Fruits. In: Postharvest Biology and Technology of Tropical and Subtropical Fruits. Edited by Yahia EM: Woodhead Publishing; 2011. pp.

[3] Droby S, Wisniewski ME, Benkeblia N. Postharvest pathology of tropical and subtropical fruit and strategies for decay control. In: Yahia E, editor. Post-harvest Biology and Technology of Tropical and Sub-tropical Fruits. Vol. 1. Cambridge, UK: Woodhead

[4] Arah IK, Ahorbo GK, Anku EK, Kumh EK, Amaglo H. Postharvest Handling Practices and Treatment Methods for Tomato Handlers in Developing Countries: A Mini Review, Advances in Agriculture, vol. 2016, Article ID 6436945, 8 pages, 2016.

Journal of Dairying, Foods & Home Sciences. 2011;30(4):299-301

21-78. ISBN<PHONE_NUMBER>334. https://doi.org/10.1533/9780857093622.21

dissolved easily and used in the pre-cooling or cleaning of the fruits after harvesting.

and Wendy-Ann P. Isaac2

\*Address all correspondence to<EMAIL_ADDRESS>
West Indies, St. Augustine, Trinidad and Tobago

Publishing Limited; 2011. pp. 194-223

DOI:10.1155/2016/6436945

is a very cheap and cost-effective soluble salt which can be

Postharvest Handling of Indigenous and Underutilized Fruits in Trinidad and Tobago

) has been shown to improve

175

http://dx.doi.org/10.5772/intechopen.70424

The pre- and postharvest treatment of calcium chloride (CaCl2

The required optimum temperatures (10–15°C at 85–95% relative humidity) can be achieved by using less expensive methods of cooling such as an evaporative cooling system [19]. Where, air temperatures can be decreased (16°C, 91% relative humidity) without significant deterioration due physiological weight loss.

### **4.2. Postharvest heat treatment**

Postharvest heat treatments using hot air and heated water have been reported to reduce chilling injuries in fruits like mangoes and oranges. Heat treating (37–42°C) prior to cold storage can slow down ripening while increasing pathogenic resistance enhanced or caused no change in some quality traits particularly in modified atmosphere storage system. Heat treatment before cold storage at 14°C can also increase TSS and titratable acids (TA) when fruits ripened as compared to the untreated fruits.

### **4.3. Modified atmosphere packaging (MAP)**

Modified atmosphere packaging (MAP) is a packaging technique of using packaging materials with predetermined composition of gases (O2 and CO2 ) after which there is no active effort of modifying the storage space. The materials allow for diffusion of gases through them until a stable equilibrium is reached between the external gases and those inside the package.

MAP materials used include polyethylene terephthalate (PET), low-density polyethylene (LDP), high-density polyethylene (HDP), polyvinyl chloride (PVC), polypropylene [20], and polystyrene [21, 22].

MAP provides a modified atmosphere to control ripening, reducing water loss in stored products reducing mechanical injuries, and reduces the spread of food-borne diseases [23]. The water loss and subsequent shriveling of fruits in tropical regions are two of the causes of their deterioration. However, maintaining excessively high levels of relative humidity inside the package can result in moisture condensation on the commodity, which will in turn create a conducive environment favorable for pathogenic activities, thus increasing the risk of fruit deterioration.

### **4.4. Methylcyclopropene (1-MCP)**

Treatments of 1-methylcyclopropene (1-MCP) can suppress the action of and reduce the rate of ethylene production in harvested climacteric fruit [24].  The reduced metabolic activities are closely associated with the ripening process such as color change, cell wall breakdown, and respiration rates and are advantageous to extending storage life [24] and the prevention of abscission in fruits [25].

#### **4.5. Calcium chloride (CaCl<sup>2</sup> ) application**

The pre- and postharvest treatment of calcium chloride (CaCl2 ) has been shown to improve shelf life and quality of many fruits [26] by delaying ripening and senescence, reducing respiration, maintaining firmness, and reducing physiological disorders [27, 28].

It has also been shown to reduce fungal and other microbial infections and maintain the structural integrity of cell walls, delaying softening and extending shelf life by 4–5 weeks [29]. It also aids in maintaining the quality of fruits by reducing the physiological disorders, increasing the fruit firmness, delaying ripening process, and prolonging the shelf life [30]. Fruit color loss is also delayed, and ethylene production is reduced by 92% [26] while maintaining higher firmness levels during storage. CaCl2 is a very cheap and cost-effective soluble salt which can be dissolved easily and used in the pre-cooling or cleaning of the fruits after harvesting.

### **Author details**

like texture, nutrition, aroma, and flavor in many harvested fruits and extend shelf life. However, some fruits are sensitive to chilling injury when they are stored below their critical temperature (10°C) for even short durations and may result in pitting, uneven ripening, and

The required optimum temperatures (10–15°C at 85–95% relative humidity) can be achieved by using less expensive methods of cooling such as an evaporative cooling system [19]. Where, air temperatures can be decreased (16°C, 91% relative humidity) without significant

Postharvest heat treatments using hot air and heated water have been reported to reduce chilling injuries in fruits like mangoes and oranges. Heat treating (37–42°C) prior to cold storage can slow down ripening while increasing pathogenic resistance enhanced or caused no change in some quality traits particularly in modified atmosphere storage system. Heat treatment before cold storage at 14°C can also increase TSS and titratable acids (TA) when fruits

Modified atmosphere packaging (MAP) is a packaging technique of using packaging materi-

of modifying the storage space. The materials allow for diffusion of gases through them until a stable equilibrium is reached between the external gases and those inside the package.

MAP materials used include polyethylene terephthalate (PET), low-density polyethylene (LDP), high-density polyethylene (HDP), polyvinyl chloride (PVC), polypropylene [20], and

MAP provides a modified atmosphere to control ripening, reducing water loss in stored products reducing mechanical injuries, and reduces the spread of food-borne diseases [23]. The water loss and subsequent shriveling of fruits in tropical regions are two of the causes of their deterioration. However, maintaining excessively high levels of relative humidity inside the package can result in moisture condensation on the commodity, which will in turn create a conducive environment favorable for pathogenic activities, thus increasing the risk of fruit

Treatments of 1-methylcyclopropene (1-MCP) can suppress the action of and reduce the rate of ethylene production in harvested climacteric fruit [24].  The reduced metabolic activities are closely associated with the ripening process such as color change, cell wall breakdown, and respiration rates and are advantageous to

extending storage life [24] and the prevention of abscission in fruits [25].

and CO2

) after which there is no active effort

fungal infestation of stored fruits.

174 Postharvest Handling

**4.2. Postharvest heat treatment**

polystyrene [21, 22].

deterioration.

**4.4. Methylcyclopropene (1-MCP)**

deterioration due physiological weight loss.

ripened as compared to the untreated fruits.

**4.3. Modified atmosphere packaging (MAP)**

als with predetermined composition of gases (O2

Puran Bridgemohan<sup>1</sup> and Wendy-Ann P. Isaac2 \*

\*Address all correspondence to<EMAIL_ADDRESS>
1 Faculty of Biosciences, Agriculture and Food Technologies, The University of Trinidad and Tobago, Trinidad and Tobago

2 Department of Food Production, Faculty of Food and Agriculture, The University of the West Indies, St. Augustine, Trinidad and Tobago

### **References**

[5] Arah IK, Amaglo H, Kumah EK, Ofori H, Preharvest and Postharvest Factors Affecting the Quality and Shelf Life of Harvested Tomatoes: A Mini Review. International Journal of Agronomy, vol. 2015, Article ID 478041, 6 pages, 2015. DOI:10.1155/2015/478041

[18] Moretti CL, Sargent SA, Huber DJ, Calbo AG, Puschmann R. Chemical composition and physical properties of pericarp, locule and placental tissue of tomatoes with internal bruising. Journal of the American Society for Horticultural Science. 1998;123(4):

Postharvest Handling of Indigenous and Underutilized Fruits in Trinidad and Tobago

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[19] Workneh TS, Woldetsadik K. Forced ventilation evaporative cooling: A case study on banana, papaya, orange, mandarin, and lemon. Tropical Agriculture. 2004;81(1):1-6 [20] de Wild HPJ, Otma EC, Peppelenbos HW. Carbon dioxide action on ethylene biosynthesis of preclimacteric and climacteric pear fruit. Journal of Experimental Botany.

[21] Artés F, Gómez P, Artés-Hernández F. Modified atmosphere packaging of fruits and

[22] Sandhya. Modified atmosphere packaging of fresh produce: Current status and future

[23] Kader AA, Watkins CB. Modified atmosphere packaging – Towards 2000 and beyond.

[24] Watkins CB. Overview of 1-methylcyclopropene trials and uses for edible horticultural

[25] Passam HC, Karapanos IC, Bebeli PJ, Savvas D. A review of recent research on tomato nutrition, breeding and post-harvest technology with reference to fruit quality. The

[26] Senevirathna PAWANK, Daundasekera WAM. Effect of post-harvest calcium chloride vacuum infiltration on the shelf life and quality of tomato (cv. 'Thilina'). Ceylon Journal

[27] Hong MN, Lee BC, Mendonca S, Grossmann MVE, Verhe R. Effect of infiltrated calcium

[28] Akhtar A, Abbasi AA, Hussain A. Effect of calcium chloride treatments on quality characteristics of loquat fruit during storage. Pakistan Journal of Botany. 2010;42(1):181-188

[29] Lara I, García P, Vendrell M. Modifications in cell wall composition after cold storage of calcium-treated strawberry (Fragaria×ananassa Duch.) fruit. Postharvest Biology and

[30] Abbasi AA, Zafar L, Khan HA, Qureshi AA. Effects of naphthalene acetic acid and calcium chloride application on nutrient uptake, growth, yield and postharvest perfor-

mance of tomato fruit. Pakistani Journal of Botany. 2013;45(5):1581-1587

vegetables. Stewart Postharvest Review. 2006;5:1-13

of Science (Biological Sciences). 2010;39(1):35-44

Hort Technology. 2000;10(3):483-486

crops. HortScience. 2008;43:86-94

Technology. 2004;34:331-339

needs. LTW-Food Science and Technology. 2010;43:381-392

European Journal of Plant Science and Biotechnology. 2007;1:1-21

on ripening of tomato fruits. LWT Journal of Food Science. 1999;33:2-8

656-660

2003;54:1537-1544

[18] Moretti CL, Sargent SA, Huber DJ, Calbo AG, Puschmann R. Chemical composition and physical properties of pericarp, locule and placental tissue of tomatoes with internal bruising. Journal of the American Society for Horticultural Science. 1998;123(4): 656-660

[5] Arah IK, Amaglo H, Kumah EK, Ofori H, Preharvest and Postharvest Factors Affecting the Quality and Shelf Life of Harvested Tomatoes: A Mini Review. International Journal of Agronomy, vol. 2015, Article ID 478041, 6 pages, 2015. DOI:10.1155/2015/478041 [6] Isaac WAI, Ganpat W, Joseph M. Farm security for food security: Dealing with farm theft in the Caribbean Region. In: Ganpat W, Dyer R, Isaac Wendy-Ann P., editors. Agricultural Development and Food Security in Developing Nations. Pennsylvania

[7] Moneruzzaman KM, Hossain ABMS, Sani W, Saifuddin M, Alenazi M. Effect of harvesting and storage conditions on the postharvest quality of tomato (*Lycopersicon esculentum*

[8] Akbudak B, Akbudak N, Seniz V, Eris A. Effect of pre-harvest harpin and modified atmosphere packaging on quality of cherry tomato cultivars "Alona" and "Cluster". British

[9] Shahi NC, Lohani UC, Chand K, Singh A. Effect of pre-cooling treatments on shelf life of tomato in ambient condition. International Journal of Food, Agriculture and Veterinary

[10] Ferreira MD, Brecht JK, Sargent SA, Aracena JJ. Physiological responses of strawberry to film wrapping and precooling methods. Proceedings of Florida State Horticulture

[11] Genanew T. Effect of postharvest treatments on storage behaviour and quality of tomato

[12] Batu A, Thompson AK. Effects of modified atmosphere packaging on post harvest quali-

[13] Arjenaki OO, Moghaddam PA, Motlagh AM. Online tomato sorting based on shape, maturity, size, and surface defects using machine vision. Turkish Journal of Agriculture

[14] Prasad P, Kochhar A. Active packaging in food industry: A review. IOSR Journal of

[15] Idah PA, Ajisegiri ESA, Yisa MG. An assessment of impact damage to fresh tomato fruits.

[16] Žnidarčič D, Trdan S, Zlatič E. Impact of various growing methods on tomato (*Lycopersicon esculentum* Mill.) yield and sensory quality. Research Reports Biotechnical

[17] Parker R, Maalekuu BK. The effect of harvesting stage on fruit quality and shelf-life of four cultivars (*Lycopersicon esculentum* Mill). Agriculture and Biological Journal of North

ties of pink tomatoes. Journal of Agriculture and Forestry. 1998;22:365-372

Environmental Science, Toxicology and Food Technology. 2014;8(5):01-07

fruits. World Journal of Agricultural Sciences. 2013;9(1):29-37

Australian Journal of Technology. 2007;10(4):271-275

Faculty, University of Ljubljana, Agriculture. 2003;81(2):341-348

Food Journal. 2012;114(2):180-196. https://doi.org/10.1108/00070701211202377

USA: IGI Publications; 2017. (ISBN 978-152-250-942-4). pp. 300-319

Science. 2012;2(3):50-56

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Society. 1994;107:265-269

and Forestry. 2013;37:62-68

America. 2013;4(3):252-259

Mill) cv. Roma VF. Australian Journal of Crop Science. 2009;3(2):112-121

**Chapter 10**

**Provisional chapter**

**Post-Harvest Handling of Freshwater Crayfish:**

**Post-Harvest Handling of Freshwater Crayfish:**

DOI: 10.5772/intechopen.69842

Development of post-harvest handling practices of crayfish in Fennoscandia has largely been based on their high value and has historical rationale. Crayfish were transported from Finland to St. Petersburg and Central European markets already in the early mid-1800s using rather sophisticated methods. Crayfish require cool and moist environment for stress minimisation and may easily be transported and stored to live out of water if these principles are followed. During post-harvest process, it is important to minimise handling of crayfish from the point traps which are pulled until crayfish are processed for food. Crayfish should be protected against the elements and stored in cool containers during on board and land transport, after initial sorting of the catch. In the holding depot, crayfish are normally sorted for the second time and then placed in holding facilities waiting for the transport to markets. Holding facilities could be tanks or more developed and cost-effective systems, such as CrayShower. This storage system is based on crayfish being stored out of water in moist environment. The main principles during post-harvest handling are to keep physical disturbances to the minimum and to provide cool and

> © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

© 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

**1.1. Crayfisheries and catch in the Fennoscandian countries: history and present time**

Freshwater crayfish have since ages formed a crucial part in the Fennoscandian culture both economically and culturally [1–4]. Finnish tenant farmers used crayfish to fulfil their obligations

**Techniques, Challenges and Opportunities**

**Techniques, Challenges and Opportunities**

Japo Jussila, Ravi Fotedar and Lennart Edsman

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

Japo Jussila, Ravi Fotedar and Lennart

http://dx.doi.org/10.5772/intechopen.69842

moist environment for crayfish.

**Keywords:** catch, stress, survival, mortality

**Abstract**

**1. Introduction**

Edsman

**Provisional chapter**

### **Post-Harvest Handling of Freshwater Crayfish: Techniques, Challenges and Opportunities Techniques, Challenges and Opportunities**

**Post-Harvest Handling of Freshwater Crayfish:**

DOI: 10.5772/intechopen.69842

Japo Jussila, Ravi Fotedar and Lennart Edsman

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

Japo Jussila, Ravi Fotedar and Lennart

http://dx.doi.org/10.5772/intechopen.69842

### **Abstract**

Edsman

Development of post-harvest handling practices of crayfish in Fennoscandia has largely been based on their high value and has historical rationale. Crayfish were transported from Finland to St. Petersburg and Central European markets already in the early mid-1800s using rather sophisticated methods. Crayfish require cool and moist environment for stress minimisation and may easily be transported and stored to live out of water if these principles are followed. During post-harvest process, it is important to minimise handling of crayfish from the point traps which are pulled until crayfish are processed for food. Crayfish should be protected against the elements and stored in cool containers during on board and land transport, after initial sorting of the catch. In the holding depot, crayfish are normally sorted for the second time and then placed in holding facilities waiting for the transport to markets. Holding facilities could be tanks or more developed and cost-effective systems, such as CrayShower. This storage system is based on crayfish being stored out of water in moist environment. The main principles during post-harvest handling are to keep physical disturbances to the minimum and to provide cool and moist environment for crayfish.

**Keywords:** catch, stress, survival, mortality

### **1. Introduction**

### **1.1. Crayfisheries and catch in the Fennoscandian countries: history and present time**

Freshwater crayfish have since ages formed a crucial part in the Fennoscandian culture both economically and culturally [1–4]. Finnish tenant farmers used crayfish to fulfil their obligations

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

with their landlords, as part of their annual work quota which could be substituted by providing crayfish instead of labour [5]. This greatly helped since the kids could easily contribute to the well-being of the family by trapping the required crayfish. Since then, the productive wild stock of crayfish has allowed the purchase of the first work horses, bikes, mopeds, cars and even elevation of the standard of living in the Fennoscandian countryside [5–7].

could easily earn equal to industrial worker's pay during crayfish trapping season. Later, for example, during the 1980s and 1990s, the monetary value of the freshwater crayfish in Finland was roughly a minimum of 10 FIM each, and the beach price has been during the 2000s roughly from 1.50 to 2 € per 10 cm TL noble crayfish [1]. As the trade is based on very basic capitalistic principle, the price has varied somewhat depending on supply and demand in addition to various sociological issues. In Sweden, the price is based on weight, not on individual crayfish. The beach price has ranged between 290 and 530 Swedish krona per kilo (i.e., about 30 and 55 €) for noble crayfish and between 105 and 220 Swedish krona (i.e., about 11 and 23 €) for signal crayfish. Thus, crayfish have traditionally been considered as delicacy, especially when catch has been low. The scenario has somewhat changed due to the introduction of signal crayfish into the wild in Fennoscandia, and the price for the signal crayfish has been lower than for the noble crayfish. Even with the lowered price for the signal crayfish, crayfish are still considered

Post-Harvest Handling of Freshwater Crayfish: Techniques, Challenges and Opportunities

http://dx.doi.org/10.5772/intechopen.69842

181

It was a common knowledge right from the start of crayfish trade in Finland that crayfish survive out of water under certain conditions [6]. This allowed a lively trade of crayfish, as they could be transported for long distances. Crayfish were thus highly valued, as the rural population could exploit this natural resource, supply even Central European market, and

Traditionally, crayfish have been transported both on board and on land for long distances in Fennoscandia, with some of the crayfish been trapped in Häme County (Finland) and Stockholm County (Sweden) transported for markets of St. Petersburg, Hamburg and even Paris as early as 1910 [10, 11]. Even a narrow railroad track was built from Lake Erken to the coast for the sole purpose of transporting crayfish catch to be shipped further by boat to other cities in Sweden and the continent [11, 12]. It was discovered that crayfish can survive lengthy periods out of water, if kept under proper conditions and processed as soon as they reached their destination. Crayfish were also placed in submerged cages during the transport, if overnighting was required. This eased their transportation stress but also allowed a rapid spreading of the diseases [6] and also crayfish, as they sometimes escaped from the cages.

Crayfish have traditionally been first stored in wooden cages around the shores of the water bodies where they have been trapped [6]. The wholesalers have then been collecting the catch from crayfish trappers and transported them either to the local markets or further to export markets in baskets made from wood splints lined with moist moss. During transport, conditions might have worsened, especially temperature could have risen, and caused stress resulting in increased mortality. Until recently, crayfish have been stored under similar conditions during transport, i.e., open cardboard or plastic boxes or crates have been used with crayfish been covered with moist cloth or layer of the tree, for example, alder and branches [10].

Crayfish have been collected by the wholesalers to be marketed and held first in cages along the shoreline of the lakes and later in holding depot's tanks [6]. Due to aggression [13, 14], this communal holding could have resulted in losses, as crayfish might have been moulting in

addition to aggressive behaviour caused by crowding.

gourmet food for festivities [9].

greatly improve their living standards.

**1.3. Past aspects of freshwater crayfish post-harvest handling**

During the turn of the 1900s, crayfish exports from Finland to St. Petersburg region peaked around 16 million individual crayfish [1, 6], and this trade has been claimed to have been a corner stone for even initiation of industrial-scale enterprises in Finland. There was also a trade of crayfish to both directions between Finland and Sweden, and this trade is claimed to have introduced crayfish plague (i.e., *Aphanomyces astaci*, the disease agent) into Sweden [4, 8]. Because of the nature of the Finnish and Swedish aquatic ecosystems, there have traditionally been only a limited number of Finns and Swedes not being aware of the noble crayfish and tradition of crayfish trapping. Well, the situation has changed dramatically recently.

Crayfish plague epidemics ended the golden age of the noble crayfish fishery and trade in Fennoscandia around 1910, after the first epidemics were observed in 1893 in Lake Saimaa in Finland and some 14 years later around Stockholm in Sweden [4–6]. Regardless, the tradition of trapping crayfish and selling them to be enjoyed during autumn crayfish parties is still strong. Catches are lower and prices are higher [1, 2], but there is still a strong demand for delicious freshwater crayfish in Finland and Sweden. Thus, the development of better means to ensure maximum catch is required, and post-harvest handling methods have improved.

Crayfish trapping and post-harvest handling of the catch are closely connected to conservation of valuable native crayfish stocks [3]. For crayfish trapper, it is of utmost importance to remember that crayfish, once taken out of the water and transported away from the trapping site, should never be put back to natural water bodies again. This is to ensure that crayfish would not be accidentally introduced to new water bodies and, more importantly, the diseases accompanying crayfish would not spread.  Value of crayfish**

Freshwater crayfish have traditionally had a high commercial value in Europe [5, 6], which has encouraged trapping and trade of the valuable natural resource. Crayfish have even been used as an alternative for currency, which was greatly improving the standard of living especially in the countryside and among rural population in Finland and wider in Fennoscandia, too [6, 8]. The need to develop post-harvest handling practices surfaced early with holding of crayfish along water bodies in cages and transport over short or long distances in special crates. Especially in Finland, reaching the Russian and European markets [6] required gentle post-harvest handling of crayfish. These inventive systems could be afforded and applied due to value of crayfish catch.

As an example, during the turn of the twentieth century, crayfisherman could be payed from 1 to 2 Finnish penni for a crayfish, while an industrial workers' pay was from 3 to 4 Finnish markka per day [6]. Thus, a crayfisherman having access to a productive noble crayfish stock could easily earn equal to industrial worker's pay during crayfish trapping season. Later, for example, during the 1980s and 1990s, the monetary value of the freshwater crayfish in Finland was roughly a minimum of 10 FIM each, and the beach price has been during the 2000s roughly from 1.50 to 2 € per 10 cm TL noble crayfish [1]. As the trade is based on very basic capitalistic principle, the price has varied somewhat depending on supply and demand in addition to various sociological issues. In Sweden, the price is based on weight, not on individual crayfish. The beach price has ranged between 290 and 530 Swedish krona per kilo (i.e., about 30 and 55 €) for noble crayfish and between 105 and 220 Swedish krona (i.e., about 11 and 23 €) for signal crayfish. Thus, crayfish have traditionally been considered as delicacy, especially when catch has been low. The scenario has somewhat changed due to the introduction of signal crayfish into the wild in Fennoscandia, and the price for the signal crayfish has been lower than for the noble crayfish. Even with the lowered price for the signal crayfish, crayfish are still considered gourmet food for festivities [9].

### **1.3. Past aspects of freshwater crayfish post-harvest handling**

with their landlords, as part of their annual work quota which could be substituted by providing crayfish instead of labour [5]. This greatly helped since the kids could easily contribute to the well-being of the family by trapping the required crayfish. Since then, the productive wild stock of crayfish has allowed the purchase of the first work horses, bikes, mopeds, cars and even

During the turn of the 1900s, crayfish exports from Finland to St. Petersburg region peaked around 16 million individual crayfish [1, 6], and this trade has been claimed to have been a corner stone for even initiation of industrial-scale enterprises in Finland. There was also a trade of crayfish to both directions between Finland and Sweden, and this trade is claimed to have introduced crayfish plague (i.e., *Aphanomyces astaci*, the disease agent) into Sweden [4, 8]. Because of the nature of the Finnish and Swedish aquatic ecosystems, there have traditionally been only a limited number of Finns and Swedes not being aware of the noble crayfish and

Crayfish plague epidemics ended the golden age of the noble crayfish fishery and trade in Fennoscandia around 1910, after the first epidemics were observed in 1893 in Lake Saimaa in Finland and some 14 years later around Stockholm in Sweden [4–6]. Regardless, the tradition of trapping crayfish and selling them to be enjoyed during autumn crayfish parties is still strong. Catches are lower and prices are higher [1, 2], but there is still a strong demand for delicious freshwater crayfish in Finland and Sweden. Thus, the development of better means to ensure maximum catch is required, and post-harvest handling methods have improved.

Crayfish trapping and post-harvest handling of the catch are closely connected to conservation of valuable native crayfish stocks [3]. For crayfish trapper, it is of utmost importance to remember that crayfish, once taken out of the water and transported away from the trapping site, should never be put back to natural water bodies again. This is to ensure that crayfish would not be accidentally introduced to new water bodies and, more importantly, the diseases accompanying crayfish would not spread. The crayfish plague has been proven a big

Freshwater crayfish have traditionally had a high commercial value in Europe [5, 6], which has encouraged trapping and trade of the valuable natural resource. Crayfish have even been used as an alternative for currency, which was greatly improving the standard of living especially in the countryside and among rural population in Finland and wider in Fennoscandia, too [6, 8]. The need to develop post-harvest handling practices surfaced early with holding of crayfish along water bodies in cages and transport over short or long distances in special crates. Especially in Finland, reaching the Russian and European markets [6] required gentle post-harvest handling of crayfish. These inventive systems could be afforded and applied due

As an example, during the turn of the twentieth century, crayfisherman could be payed from 1 to 2 Finnish penni for a crayfish, while an industrial workers' pay was from 3 to 4 Finnish markka per day [6].  Value of crayfish**

to value of crayfish catch.

tradition of crayfish trapping. Well, the situation has changed dramatically recently.

elevation of the standard of living in the Fennoscandian countryside [5–7].

It was a common knowledge right from the start of crayfish trade in Finland that crayfish survive out of water under certain conditions [6]. This allowed a lively trade of crayfish, as they could be transported for long distances. Crayfish were thus highly valued, as the rural population could exploit this natural resource, supply even Central European market, and greatly improve their living standards.

Traditionally, crayfish have been transported both on board and on land for long distances in Fennoscandia, with some of the crayfish been trapped in Häme County (Finland) and Stockholm County (Sweden) transported for markets of St. Petersburg, Hamburg and even Paris as early as 1910 [10, 11]. Even a narrow railroad track was built from Lake Erken to the coast for the sole purpose of transporting crayfish catch to be shipped further by boat to other cities in Sweden and the continent [11, 12]. It was discovered that crayfish can survive lengthy periods out of water, if kept under proper conditions and processed as soon as they reached their destination. Crayfish were also placed in submerged cages during the transport, if overnighting was required. This eased their transportation stress but also allowed a rapid spreading of the diseases [6] and also crayfish, as they sometimes escaped from the cages.

Crayfish have traditionally been first stored in wooden cages around the shores of the water bodies where they have been trapped [6]. The wholesalers have then been collecting the catch from crayfish trappers and transported them either to the local markets or further to export markets in baskets made from wood splints lined with moist moss. During transport, conditions might have worsened, especially temperature could have risen, and caused stress resulting in increased mortality. Until recently, crayfish have been stored under similar conditions during transport, i.e., open cardboard or plastic boxes or crates have been used with crayfish been covered with moist cloth or layer of the tree, for example, alder and branches [10].

Crayfish have been collected by the wholesalers to be marketed and held first in cages along the shoreline of the lakes and later in holding depot's tanks [6]. Due to aggression [13, 14], this communal holding could have resulted in losses, as crayfish might have been moulting in addition to aggressive behaviour caused by crowding.

The increased mortality has traditionally been largely accepted as part of the risks included in the transport of crayfish catch with little or no development of more suitable applications for transport. One of the reasons for the lack of development has been the fact that large proportion of crayfish catch in Fennoscandia has been trapped by recreational trappers working with small-scale catches and respecting traditional aspects of crayfish trapping [1].

and significant changes within the upper optimum limit, could be causing stress and require resources from crayfish [24]. The catch has to be protected against direct sunlight, as there are multiple effects of temperature elevation, evaporation and intensive light causing stress and

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Air exposure during transport could cause severe dehydration, even though weight loss between 3.9 and 4.5% during transportation without any specific negative effects has been reported [23, 25]. Some of the water is lost from gill chambers, but also haemolymph has been suggested to dehydrate. The slight dehydration does not seem to cause elevated mortality, especially if the

Moulting causes a drop in the catch and affects the well-being of crayfish via physiological changes during post-harvest handling processes (e.g., Refs. [14, 26]), since crayfish would be more susceptible to stress close to a moult. Normally, there are at least two periods of moulting during trapping season in Fennoscandia, when commercial catch declines and the survival of crayfish declines, too. Both of these factors affect the economics of the trapping, and special care should be taken during the moult-related changes in the condition of crayfish. While handling, crayfish can be detected as newly moulted or approaching moult by the texture and hardness of the carapace. Dead or moribund crayfish could worsen the conditions for the surviving crayfish if held communally, due to possible damage of tissues and release of microorganisms. Post-harvest handling and transport of those crayfish close to the moult

Crayfish require shelter during both transport and holding. The availability of shelter pacifies crayfish and thus reduces stress [27]. Shelter also provides refugee during communal holding, when crayfish are held in tanks in the holding depots. Shelters can be designed to allow easy collection of crayfish from the tanks, since they tend to spend most of their time in shelters to avoid aggressive interactions with co-species and exposure to ambient conditions, such as light. Shelter during transport, on the other hand, is prone to reduce stress, as crayfish will be

Predatory pressure during communal holding can result in both excess mortality and aggressive behaviour [13]. During the growth season and if there are odd moulting events in the holding tanks, the mortality can be elevated and decaying crayfish affect the water quality in the tanks negatively. This can be avoided by storing crayfish in low densities, sorting of the catch by size and providing adequate shelter in the tanks. All of these methods may be costly and thus recommended only if the tank holding of crayfish is the only option available. On the other hand, sorting of the catch for commercial purposes, for example, by size, could later decrease the need for handling prior to transit to markets and thus would be a benefit.

Harvesting practices should be planned in order to minimise stress of the market quality crayfish [16], as well as those to be returned back to water as belonging to side catch. The commercial proportion of the catch has to be transported to markets in premium condition, and this part of the catch should experience minimal stress. Crayfish from the side catch should not be excessively stressed by the process being caused by pulling of traps and sorting of catch, thus increasing their chances to survive and grow to commercial size. Practices on board and during

offered escape from light, dry conditions and elevated temperature.

worsening post-harvest handling conditions.

transported crayfish are later submerged.

should thus be avoided.

### **2. Factors affecting post-harvest handling procedure**

Stress is an individual's response to challenge, and if the condition is prolonged, it can affect the well-being of the individual crustacean [15, 16]. Any diversion from the optimum conditions can cause stress [17], and the avoidance of stress is essential for the best practices during post-harvest handling of crayfish, as stress causes losses among the catch both as elevated mortality and as quality of the individual crayfish. In addition to the normal maintenance of the well-being of animals, crayfisherman and wholesaler have to focus on maximum costeffectiveness during trapping and post-harvest handling processes. The elevated individual mortality among the catch as such is a loss for crayfisherman, but it also is prone to create circumstances under which the overall well-being of the whole catch might be declining due to worsening of transport and holding conditions. Moribund and dead crayfish cause water quality problems especially when crayfish are held communally and they share the same water body. Furthermore, the price of crayfish, and thus crayfishermen's income, relies on the quality of the catch, which is largely based on the capability of crayfish to survive through the marketing chain to the consumers in prime condition.

Freshwater crayfish can survive out of water for long periods, even days [10, 18], which allows several options for both transport of the catch and holding for commercial purposes. The optimisation of the post-harvest handling conditions is essential in order to minimise handling stress and mortalities [19–22]. Crayfish should be handled as briefly and gently as possible, kept moist and cool all the time [16, 18].

Crayfish should remain in wet and cool transportation and handling environment throughout the post-harvest handling chain [10, 16]. The gill structure allows gas exchange as long as the surface layer of the gills remains moist, because, contrary to fish, the gill filaments do not collapse when not supported by the ambient water, thus allowing close to normal function even out of water. Cool conditions on the other hand minimise evaporation and lower metabolic rate, thus enabling resource allocation to prevent detrimental effects of the post-harvest handling stress.

The moisture level should be as close as possible to 100% humidity during every part of the post-harvest handling chain (e.g., Refs. [10, 23]). This enables gas exchange through gills and lowers stress, as crayfish would not be experiencing water loss through surface tissues. During the post-harvest handling, the ambient temperature should remain below 20°C, preferably even closer to 10°C, to slow down the metabolism of crayfish and to pacify them, as the transport mortality is prone to decrease with the lowering temperature. In addition, the temperature fluctuation should be kept minimal, since the temperature changes, especially rapid and significant changes within the upper optimum limit, could be causing stress and require resources from crayfish [24]. The catch has to be protected against direct sunlight, as there are multiple effects of temperature elevation, evaporation and intensive light causing stress and worsening post-harvest handling conditions.

The increased mortality has traditionally been largely accepted as part of the risks included in the transport of crayfish catch with little or no development of more suitable applications for transport. One of the reasons for the lack of development has been the fact that large proportion of crayfish catch in Fennoscandia has been trapped by recreational trappers working

Stress is an individual's response to challenge, and if the condition is prolonged, it can affect the well-being of the individual crustacean [15, 16]. Any diversion from the optimum conditions can cause stress [17], and the avoidance of stress is essential for the best practices during post-harvest handling of crayfish, as stress causes losses among the catch both as elevated mortality and as quality of the individual crayfish. In addition to the normal maintenance of the well-being of animals, crayfisherman and wholesaler have to focus on maximum costeffectiveness during trapping and post-harvest handling processes. The elevated individual mortality among the catch as such is a loss for crayfisherman, but it also is prone to create circumstances under which the overall well-being of the whole catch might be declining due to worsening of transport and holding conditions. Moribund and dead crayfish cause water quality problems especially when crayfish are held communally and they share the same water body. Furthermore, the price of crayfish, and thus crayfishermen's income, relies on the quality of the catch, which is largely based on the capability of crayfish to survive through

Freshwater crayfish can survive out of water for long periods, even days [10, 18], which allows several options for both transport of the catch and holding for commercial purposes. The optimisation of the post-harvest handling conditions is essential in order to minimise handling stress and mortalities [19–22]. Crayfish should be handled as briefly and gently as possible,

Crayfish should remain in wet and cool transportation and handling environment throughout the post-harvest handling chain [10, 16]. The gill structure allows gas exchange as long as the surface layer of the gills remains moist, because, contrary to fish, the gill filaments do not collapse when not supported by the ambient water, thus allowing close to normal function even out of water. Cool conditions on the other hand minimise evaporation and lower metabolic rate, thus enabling resource allocation to prevent detrimental effects of the post-harvest

The moisture level should be as close as possible to 100% humidity during every part of the post-harvest handling chain (e.g., Refs. [10, 23]). This enables gas exchange through gills and lowers stress, as crayfish would not be experiencing water loss through surface tissues. During the post-harvest handling, the ambient temperature should remain below 20°C, preferably even closer to 10°C, to slow down the metabolism of crayfish and to pacify them, as the transport mortality is prone to decrease with the lowering temperature. In addition, the temperature fluctuation should be kept minimal, since the temperature changes, especially rapid

with small-scale catches and respecting traditional aspects of crayfish trapping [1].

**2. Factors affecting post-harvest handling procedure**

the marketing chain to the consumers in prime condition.

kept moist and cool all the time [16, 18].

handling stress.

182 Postharvest Handling

Air exposure during transport could cause severe dehydration, even though weight loss between 3.9 and 4.5% during transportation without any specific negative effects has been reported [23, 25]. Some of the water is lost from gill chambers, but also haemolymph has been suggested to dehydrate. The slight dehydration does not seem to cause elevated mortality, especially if the transported crayfish are later submerged.

Moulting causes a drop in the catch and affects the well-being of crayfish via physiological changes during post-harvest handling processes (e.g., Refs. [14, 26]), since crayfish would be more susceptible to stress close to a moult. Normally, there are at least two periods of moulting during trapping season in Fennoscandia, when commercial catch declines and the survival of crayfish declines, too. Both of these factors affect the economics of the trapping, and special care should be taken during the moult-related changes in the condition of crayfish. While handling, crayfish can be detected as newly moulted or approaching moult by the texture and hardness of the carapace. Dead or moribund crayfish could worsen the conditions for the surviving crayfish if held communally, due to possible damage of tissues and release of microorganisms. Post-harvest handling and transport of those crayfish close to the moult should thus be avoided.

Crayfish require shelter during both transport and holding. The availability of shelter pacifies crayfish and thus reduces stress [27]. Shelter also provides refugee during communal holding, when crayfish are held in tanks in the holding depots. Shelters can be designed to allow easy collection of crayfish from the tanks, since they tend to spend most of their time in shelters to avoid aggressive interactions with co-species and exposure to ambient conditions, such as light. Shelter during transport, on the other hand, is prone to reduce stress, as crayfish will be offered escape from light, dry conditions and elevated temperature.

Predatory pressure during communal holding can result in both excess mortality and aggressive behaviour [13]. During the growth season and if there are odd moulting events in the holding tanks, the mortality can be elevated and decaying crayfish affect the water quality in the tanks negatively. This can be avoided by storing crayfish in low densities, sorting of the catch by size and providing adequate shelter in the tanks. All of these methods may be costly and thus recommended only if the tank holding of crayfish is the only option available. On the other hand, sorting of the catch for commercial purposes, for example, by size, could later decrease the need for handling prior to transit to markets and thus would be a benefit.

Harvesting practices should be planned in order to minimise stress of the market quality crayfish [16], as well as those to be returned back to water as belonging to side catch. The commercial proportion of the catch has to be transported to markets in premium condition, and this part of the catch should experience minimal stress. Crayfish from the side catch should not be excessively stressed by the process being caused by pulling of traps and sorting of catch, thus increasing their chances to survive and grow to commercial size. Practices on board and during transport dictate the fate of the commercial catch, as stress is prone to cumulate and initiation of the stress can be a point of no return resulting in increased mortality during post-harvest handling. Thus, commercial part of the catch is the main priority and should be handled first, while crayfishermen should remember that side catch crayfish are future commercial catch.

Exposure to adverse elements, causing stress, is the main cause of losses during post-harvest handling of crayfish. There are several individual factors stressing crayfish, in addition to the main ones discussed here. Furthermore, the combination of different stressors can be detrimental. Thus, focusing on minimisation of stress of any kind and combination is crucial.

### **3. Boat transfer: from the traps to the shore**

### **3.1. General handling of crayfish after traps have been pulled**

The general rule is that the handling of crayfish should be kept to the minimum after the traps have been pulled. Crayfish should also experience minimum exposure to the elements while on board, as both of these cause stress to crayfish and can result in losses during boat transport and afterwards. The moment when the traps are pulled is crucial, because handling of crayfish at this point of time reflects to their future stamina and thus also survival (e.g., Ref. [16]). The process of handling and transport is prone to cause stress regardless of crayfish trappers' handling and management practices, but the level of disturbance can be controlled and stress minimised by following best practice of post-harvest handling. This point of stress initiation is thus crucial, and it cannot be overly emphasised that the fate of the catch is set at this point of time.

Crayfish catch can be sorted by size, by appearance, by sex and sometimes even by species [29]. Quite often, if the catch is sorted on board, only a rough sorting to potential commercial catch and those crayfish to be released is carried out. In Sweden, specific grid systems for automatic sorting of crayfish catch by size have been utilised (**Figure 2**). The sorting is happening after a

**Figure 2.** Sorting of crayfish catch on board by size. A system of a grid with expanding distances of metal bars allows

crayfish to be sorted by size as they slide on the grids. Photo by MSc Fredrik Engdalh (SLU Aqua, Sweden).

**Figure 1.** Sorting of crayfish catch on board according to commercial and side catch criteria. White crates with partial lids

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for the commercial catch and grey crate for temporary holding of the side catch.

Crayfish should be sorted and stored according to the marketing criteria right after the traps have been pulled. Normally, the catch is sorted according to the size and general appearance. Those crayfish targeted for the further post-harvest handling and finally the commercial market should be stored according to standards aimed for the minimisation of stress immediately after sorting [28].

If the catch has to be stored any lengths of time exposed to sun, wind or dry air, crayfish have to be kept moist and as cool as the conditions on board allow [16]. Conditions on board should allow storing crayfish in the final transport conditions immediately. Crayfish can be sprayed with water, if kept in open containers, as the sprayed water improves holding conditions and could decrease temperature for the catch.

The key principle of crayfish handling after the traps have been pulled is to minimise handling time in order to avoid stress.

### **3.2. Sorting of crayfish on board**

Sorting of the catch on board has become a routine among some of the commercial crayfish trappers in Fennoscandia (**Figure 1**). This allows for minimising handling-related stress for the commercial catch. In the optimum case, crayfish could then be handled next time in the holding depot during a more detailed, additional sorting.

Post-Harvest Handling of Freshwater Crayfish: Techniques, Challenges and Opportunities http://dx.doi.org/10.5772/intechopen.69842 185

transport dictate the fate of the commercial catch, as stress is prone to cumulate and initiation of the stress can be a point of no return resulting in increased mortality during post-harvest handling. Thus, commercial part of the catch is the main priority and should be handled first, while crayfishermen should remember that side catch crayfish are future commercial catch.

Exposure to adverse elements, causing stress, is the main cause of losses during post-harvest handling of crayfish. There are several individual factors stressing crayfish, in addition to the main ones discussed here. Furthermore, the combination of different stressors can be detrimental. Thus, focusing on minimisation of stress of any kind and combination is crucial.

The general rule is that the handling of crayfish should be kept to the minimum after the traps have been pulled. Crayfish should also experience minimum exposure to the elements while on board, as both of these cause stress to crayfish and can result in losses during boat transport and afterwards. The moment when the traps are pulled is crucial, because handling of crayfish at this point of time reflects to their future stamina and thus also survival (e.g., Ref. [16]). The process of handling and transport is prone to cause stress regardless of crayfish trappers' handling and management practices, but the level of disturbance can be controlled and stress minimised by following best practice of post-harvest handling. This point of stress initiation is thus crucial, and it cannot be overly emphasised that the fate of the catch is set at this point of time. Crayfish should be sorted and stored according to the marketing criteria right after the traps have been pulled. Normally, the catch is sorted according to the size and general appearance. Those crayfish targeted for the further post-harvest handling and finally the commercial market should be stored according to standards aimed for the minimisation of stress immediately

If the catch has to be stored any lengths of time exposed to sun, wind or dry air, crayfish have to be kept moist and as cool as the conditions on board allow [16]. Conditions on board should allow storing crayfish in the final transport conditions immediately. Crayfish can be sprayed with water, if kept in open containers, as the sprayed water improves holding condi-

The key principle of crayfish handling after the traps have been pulled is to minimise han-

Sorting of the catch on board has become a routine among some of the commercial crayfish trappers in Fennoscandia (**Figure 1**). This allows for minimising handling-related stress for the commercial catch. In the optimum case, crayfish could then be handled next time in the

**3. Boat transfer: from the traps to the shore**

tions and could decrease temperature for the catch.

holding depot during a more detailed, additional sorting.

dling time in order to avoid stress.

**3.2. Sorting of crayfish on board**

after sorting [28].

184 Postharvest Handling

**3.1. General handling of crayfish after traps have been pulled**

**Figure 1.** Sorting of crayfish catch on board according to commercial and side catch criteria. White crates with partial lids for the commercial catch and grey crate for temporary holding of the side catch.

Crayfish catch can be sorted by size, by appearance, by sex and sometimes even by species [29]. Quite often, if the catch is sorted on board, only a rough sorting to potential commercial catch and those crayfish to be released is carried out. In Sweden, specific grid systems for automatic sorting of crayfish catch by size have been utilised (**Figure 2**). The sorting is happening after a

**Figure 2.** Sorting of crayfish catch on board by size. A system of a grid with expanding distances of metal bars allows crayfish to be sorted by size as they slide on the grids. Photo by MSc Fredrik Engdalh (SLU Aqua, Sweden).

set of traps is pulled, depending on crayfish trapping practice of individual crayfishermen. An advanced commercial crayfish trapper could have from 10 to 20 traps in one set of traps, joined by a long line. This set of traps is then pulled and emptied, rebaited and set back, before crayfisherman sorts the catch. With a deckhand, sorting could happen when the traps are pulled, and thus the time the catch is exposed to the elements is minimised; such practice would also minimise the stress. The sorted catch is then stored appropriately to allow stress-free on board transport.

The foam boxes are inexpensive, provide efficient insulation and are easy to handle. Cooling units are placed on the bottom of the foam box, then a plastic or rubber grid is placed on the cooling units to prevent crayfish from frostbites and crayfish are placed inside a plastic bag to ensure proper moisture level and to prevent evaporation and sun exposure during handling on the catch (**Figure 4**). This method has been shown to minimise mortality during transport

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Ventilation of the transport boxes and containers is not needed [30], since there is plenty of oxygen in the air and gas exchange does not elevate the metabolic gas levels to those causing stress to crayfish. The ventilation holes could actually worsen the conditions inside the transport containers, as ventilation could increase the temperature inside the box and lower moisture

Crayfish can be transported on board in plain plastic containers, while this normally does not allow proper cooling and exposes crayfish to the elements. For short on board transport distances and weather conditions not challenging crayfish, this very basic method could be sufficient. A moist fabric on top of crayfish would then allow for shade, some cooling and moisture. These rather hardy plastic containers are sold in local supermarkets, and they can

An on board CrayShower application has also been tried by the Lake Saimaa crayfishermen (**Figure 5**). The system is based on constant watering of the catch using fresh surface water from the lake. The CrayShower application requires outside energy source for pumping of the water and is dependent of the surface water temperature. The system works efficiently providing that at least the water temperature remains low, below 20°C, although during hot

**Figure 4.** A simple and cost-efficient method for transporting crayfish on board and on land [10] with explanation on

different parts inside the cooling box (an additional large plastic bag needed for protection of crayfish).

[10] with cool and passive crayfish being easy to handle later, too, if needed.

periods in summer, the sprayed water does not provide sufficient cooling.

level, too.

be durable, thus their popularity.

### **3.3. Holding conditions during boat transport**

It is essential to provide cool, moist and shady conditions for the boat-transported crayfish, with special care to avoid exposure to sun [17]. As crayfish will be experiencing some form of unavoidable physical disturbance, i.e., shaking of the boat due to waves and general movement around a lake or river, other forms of stress have to be minimised.

Crayfish tend to go passive with lowering of the temperature. It is preferential to provide stable conditions during transport, and for this purpose, a simple environment within cooled foam container, i.e., esky or foam box for fish, has shown to be optimal [10, 23] and is commonly used both in Sweden and Finland (**Figure 3**). The instant cooling of crayfish under conditions, which also provide immobilisation and moisture, has shown to decrease stress [16, 28] and minimise mortalities even during prolonged transport.

**Figure 3.** Crayfish transported on board in foam boxes with cooling and moisture provided.

The foam boxes are inexpensive, provide efficient insulation and are easy to handle. Cooling units are placed on the bottom of the foam box, then a plastic or rubber grid is placed on the cooling units to prevent crayfish from frostbites and crayfish are placed inside a plastic bag to ensure proper moisture level and to prevent evaporation and sun exposure during handling on the catch (**Figure 4**). This method has been shown to minimise mortality during transport [10] with cool and passive crayfish being easy to handle later, too, if needed.

set of traps is pulled, depending on crayfish trapping practice of individual crayfishermen. An advanced commercial crayfish trapper could have from 10 to 20 traps in one set of traps, joined by a long line. This set of traps is then pulled and emptied, rebaited and set back, before crayfisherman sorts the catch. With a deckhand, sorting could happen when the traps are pulled, and thus the time the catch is exposed to the elements is minimised; such practice would also minimise the stress. The sorted catch is then stored appropriately to allow stress-free on board transport.

It is essential to provide cool, moist and shady conditions for the boat-transported crayfish, with special care to avoid exposure to sun [17]. As crayfish will be experiencing some form of unavoidable physical disturbance, i.e., shaking of the boat due to waves and general move-

Crayfish tend to go passive with lowering of the temperature. It is preferential to provide stable conditions during transport, and for this purpose, a simple environment within cooled foam container, i.e., esky or foam box for fish, has shown to be optimal [10, 23] and is commonly used both in Sweden and Finland (**Figure 3**). The instant cooling of crayfish under conditions, which also provide immobilisation and moisture, has shown to decrease stress [16, 28] and minimise

ment around a lake or river, other forms of stress have to be minimised.

**Figure 3.** Crayfish transported on board in foam boxes with cooling and moisture provided.

**3.3. Holding conditions during boat transport**

186 Postharvest Handling

mortalities even during prolonged transport.

Ventilation of the transport boxes and containers is not needed [30], since there is plenty of oxygen in the air and gas exchange does not elevate the metabolic gas levels to those causing stress to crayfish. The ventilation holes could actually worsen the conditions inside the transport containers, as ventilation could increase the temperature inside the box and lower moisture level, too.

Crayfish can be transported on board in plain plastic containers, while this normally does not allow proper cooling and exposes crayfish to the elements. For short on board transport distances and weather conditions not challenging crayfish, this very basic method could be sufficient. A moist fabric on top of crayfish would then allow for shade, some cooling and moisture. These rather hardy plastic containers are sold in local supermarkets, and they can be durable, thus their popularity.

An on board CrayShower application has also been tried by the Lake Saimaa crayfishermen (**Figure 5**). The system is based on constant watering of the catch using fresh surface water from the lake. The CrayShower application requires outside energy source for pumping of the water and is dependent of the surface water temperature. The system works efficiently providing that at least the water temperature remains low, below 20°C, although during hot periods in summer, the sprayed water does not provide sufficient cooling.

**Figure 4.** A simple and cost-efficient method for transporting crayfish on board and on land [10] with explanation on different parts inside the cooling box (an additional large plastic bag needed for protection of crayfish).

at this point, the catch should be handled gently to avoid activating individual crayfish, which

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Conditions at holding depot have to be planned to minimise handling of crayfish and thus to minimise stress at this point, too. Once again, the less crayfish have to be handled, the better. The attempt is to explore the markets to ensure that the catch can be sorted and stored under conditions, which allow minimal handling when preparing crayfish for transport to markets

Normally, the catch has to be sorted according to the market demand at the holding depot. The standard criteria for sorting include variables such as size, intact claws and visible trauma [29]. The first sorting on board or during trap pulling rids the most obvious substandard crayfish, but depending on the conditions and handling routine, another sorting may be required. The sorted crayfish will then be stored in separate, graded as per different orders or quality standards. Again, the sorting has to be carried out with minimal stress for crayfish, since they

Crayfish have traditionally been held in tanks in the holding depot with basic freshwater crayfish aquaculture principles applied regarding conditions [14]. The communal holding of crayfish requires good conditions, as the method itself is prone to cause stress [32]. The water quality has to be optimal and water temperature low to minimise mortality during holding,

Normally, the tanks are simple, and no hides are provided to allow proper water flow in all parts of the tank and to enable efficient cleaning of wastes [14, 16]. Quite often tanks are covered to allow shade for crayfish. Water level can be low, less than 20 cm, but the water exchange has to be high to ensure optimum water quality. Due to the aggressive nature of crayfish, cannibal-

During the growth season, mortalities in the holding depots can be high due to problems caused by the physiological changes related to moulting. Normally, there are periods during crayfish season, when crayfish do not survive stressful conditions of holding due to proximity of moult, either premoult or post-moult [14]. These losses could cause problems in addition to holding conditions, i.e., lowered water quality in tanks or aggressive behaviour of other crayfish may elevate mortality of the most vulnerable crayfish. Crayfish in this physiological

A novel method for holding of crayfish for longer periods of time, called CrayShower, was first developed on Western Australia by Marron Farmer's Association during the 1990s. The method is based on combination of minimum water usage and cool temperature. Crayfish are held out water in misty air and cool temperature conditions in plastic containers for periods from days to several weeks. The method has been recently further developed in Finland and

is currently used by some commercial crayfish trappers and traders (**Figure 6**) [33].

due to the risk of worsening conditions resulting in elevated or mass mortalities.

may cause aggressive behaviour and harm to the less aggressive crayfish in the catch.

**5. Holding of crayfish: simple is beautiful**

have already experienced stressful conditions during transport.

ism is commonplace even if crayfish are being fed.

stage should not be taken into holding facilities.

or next level of wholesalers.

**Figure 5.** CrayShower on board transport application. This system uses lake surface water, thus not suitable during warmest summer days.

### **4. Land transfer: from the shore to the holding depot**

The transport on land should also be planned to minimise stressful conditions and rough handling of the catch. Especially during warm summer months, it could easily happen that the conditions get worse, i.e., warmer, during the land transport. Again, it would be beneficial if the number of different handling phases of the transported crayfish could be kept to a minimum and thus disturbance from handling of the catch, too. Crucial for stress minimisation is that crayfish are immobilised and thus do not react easily to gentle handling.

It would be beneficial to use the same containers on board of the boat and during land transport. This would be in line with the demand for minimal handling. It would also be beneficial if specific containers with cooling and immobilisation of the catch have been used on board.

During land transport, the catch has to be protected against heat, evaporation and excess light. Normally, the catch is taken from the boat directly to the transport vehicle, which could be a trailer or a truck. The trailer should have a cover to allow for proper protection. A truck could also be equipped with cooling system [16, 31], which would further improve transport conditions. Regardless of the transport method on land, the containers where the catch is held have to be secured to prevent excess shaking.

It would be preferential to allow the catch to remain in their original containers, untouched, until the holding depot is reached and further processing of the catch is taking place [10]. Even at this point, the catch should be handled gently to avoid activating individual crayfish, which may cause aggressive behaviour and harm to the less aggressive crayfish in the catch.

### **5. Holding of crayfish: simple is beautiful**

**4. Land transfer: from the shore to the holding depot**

on board.

warmest summer days.

188 Postharvest Handling

have to be secured to prevent excess shaking.

that crayfish are immobilised and thus do not react easily to gentle handling.

The transport on land should also be planned to minimise stressful conditions and rough handling of the catch. Especially during warm summer months, it could easily happen that the conditions get worse, i.e., warmer, during the land transport. Again, it would be beneficial if the number of different handling phases of the transported crayfish could be kept to a minimum and thus disturbance from handling of the catch, too. Crucial for stress minimisation is

**Figure 5.** CrayShower on board transport application. This system uses lake surface water, thus not suitable during

It would be beneficial to use the same containers on board of the boat and during land transport. This would be in line with the demand for minimal handling. It would also be beneficial if specific containers with cooling and immobilisation of the catch have been used

During land transport, the catch has to be protected against heat, evaporation and excess light. Normally, the catch is taken from the boat directly to the transport vehicle, which could be a trailer or a truck. The trailer should have a cover to allow for proper protection. A truck could also be equipped with cooling system [16, 31], which would further improve transport conditions. Regardless of the transport method on land, the containers where the catch is held

It would be preferential to allow the catch to remain in their original containers, untouched, until the holding depot is reached and further processing of the catch is taking place [10]. Even Conditions at holding depot have to be planned to minimise handling of crayfish and thus to minimise stress at this point, too. Once again, the less crayfish have to be handled, the better. The attempt is to explore the markets to ensure that the catch can be sorted and stored under conditions, which allow minimal handling when preparing crayfish for transport to markets or next level of wholesalers.

Normally, the catch has to be sorted according to the market demand at the holding depot. The standard criteria for sorting include variables such as size, intact claws and visible trauma [29]. The first sorting on board or during trap pulling rids the most obvious substandard crayfish, but depending on the conditions and handling routine, another sorting may be required. The sorted crayfish will then be stored in separate, graded as per different orders or quality standards. Again, the sorting has to be carried out with minimal stress for crayfish, since they have already experienced stressful conditions during transport.

Crayfish have traditionally been held in tanks in the holding depot with basic freshwater crayfish aquaculture principles applied regarding conditions [14]. The communal holding of crayfish requires good conditions, as the method itself is prone to cause stress [32]. The water quality has to be optimal and water temperature low to minimise mortality during holding, due to the risk of worsening conditions resulting in elevated or mass mortalities.

Normally, the tanks are simple, and no hides are provided to allow proper water flow in all parts of the tank and to enable efficient cleaning of wastes [14, 16]. Quite often tanks are covered to allow shade for crayfish. Water level can be low, less than 20 cm, but the water exchange has to be high to ensure optimum water quality. Due to the aggressive nature of crayfish, cannibalism is commonplace even if crayfish are being fed.

During the growth season, mortalities in the holding depots can be high due to problems caused by the physiological changes related to moulting. Normally, there are periods during crayfish season, when crayfish do not survive stressful conditions of holding due to proximity of moult, either premoult or post-moult [14]. These losses could cause problems in addition to holding conditions, i.e., lowered water quality in tanks or aggressive behaviour of other crayfish may elevate mortality of the most vulnerable crayfish. Crayfish in this physiological stage should not be taken into holding facilities.

A novel method for holding of crayfish for longer periods of time, called CrayShower, was first developed on Western Australia by Marron Farmer's Association during the 1990s. The method is based on combination of minimum water usage and cool temperature. Crayfish are held out water in misty air and cool temperature conditions in plastic containers for periods from days to several weeks. The method has been recently further developed in Finland and is currently used by some commercial crayfish trappers and traders (**Figure 6**) [33].

of the moult cycle especially late in the trapping season or when water temperatures remain low and moulting is infrequent. During warm summers or generally warm conditions with frequent moulting, on the other hand, crayfish are normally clean and, when cooked, display a

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Crayfish should be gently packed in specific foam boxes for the transport to the markets [23]. There should not be more than two layers of crayfish with moisture and cooling provided inside the foam box. Quite often, shallow foam boxes with less than 15 cm in height, which are routinely used in fish transport, are convenient as they can be stacked easily or can be equipped with lids (**Figure 7**). No more than two layers of crayfish inside the box ensures that crayfish can be moving around, if needed, and the pressure from crayfish would not create circumstances which would suffocate those crayfish on the bottom. Cooling can be provided in the form of ice on the bottom of the foam boxes or cooling units [10], as long as it is ensured that crayfish would not be in direct contact with frozen solid items. It should be taken care of that the water level inside the foam box is low so that crayfish are not submerged and thus capable of gas exchange during transport. There is no need for ventilation holes in the foam box, as there is always enough oxygen in the air for crayfish and the content of metabolic gases created by gas exchange does not reach levels harmful for crayfish. The ventilation actually worsens the conditions during the transport, because it may cause elevation of the

We will present here a synopsis of the post-harvest handling code of practice for freshwater crayfish. This is based on this short overview with detailed background information given in the above chapters. These basic principles allow for maximum number of crayfish reaching markets. These principles can easily be applied to recreational trapping practices, too. We will not go into exhausting details here in order to allow for imaginative application of the recommendations. The following basic actions should ensure minimum stress for the catch

**Figure 7.** An example of the foam boxes suitable for the transport of crayfish on land. The corrugated bottom structure

temperature due to loss of insulation and it may result in loss of moisture.

nicely even red colour with no discoloration.

**6. Code of practice: a case study**

allows for maintaining moist conditions without crayfish being submerged.

and maximum benefit for crayfish trapper:

**Figure 6.** CrayShower with stacked plastic containers for holding of crayfish and a close-up of the water sprinkler system (small picture).

Crayfish can be held under these conditions for several months without significant losses in the number or quality of crayfish. Tasting tests indicated that crayfish held for 9 months in the CrayShower were of equal quality (test and texture of flesh) compared to those been held in tanks and given food for the same period. The survival among the CrayShower-held crayfish was significantly higher and stable throughout the holding period than tank-held crayfish. Thus, the CrayShower system, being slightly more expensive to build, would be more economical to utilise than the conventional holding in tanks. The benefits of the CrayShower would be less water utilised, higher survival of crayfish and decrease in workload.

The commercial value of crayfish benefits from purging [14], which normally means gut evacuation and maybe general cleaning of the carapace from loose debris and solid particles. During communal holding in tanks, with the catch fully submerged, gut evacuation happens normally within 24 hours, depending on the water temperature in the holding tanks [34]. This excrete also affects water quality, and holding tanks require constant water exchange. In CrayShower, the gut evacuation can take up to 2 weeks [35]. Gut evacuation improves crayfish survival during further transport to markets, and it makes crayfish more desirable gourmet food when processed and served, for obvious reasons.

Some crayfish wholesalers or processers demand clean crayfish, i.e., free of solid particle matter or discoloration, which might require cleaning of crayfish or sorting the catch by cleanliness. Normally, crayfish collect dirt on the carapace and become exceedingly dirty towards the end of the moult cycle especially late in the trapping season or when water temperatures remain low and moulting is infrequent. During warm summers or generally warm conditions with frequent moulting, on the other hand, crayfish are normally clean and, when cooked, display a nicely even red colour with no discoloration.

Crayfish should be gently packed in specific foam boxes for the transport to the markets [23]. There should not be more than two layers of crayfish with moisture and cooling provided inside the foam box. Quite often, shallow foam boxes with less than 15 cm in height, which are routinely used in fish transport, are convenient as they can be stacked easily or can be equipped with lids (**Figure 7**). No more than two layers of crayfish inside the box ensures that crayfish can be moving around, if needed, and the pressure from crayfish would not create circumstances which would suffocate those crayfish on the bottom. Cooling can be provided in the form of ice on the bottom of the foam boxes or cooling units [10], as long as it is ensured that crayfish would not be in direct contact with frozen solid items. It should be taken care of that the water level inside the foam box is low so that crayfish are not submerged and thus capable of gas exchange during transport. There is no need for ventilation holes in the foam box, as there is always enough oxygen in the air for crayfish and the content of metabolic gases created by gas exchange does not reach levels harmful for crayfish. The ventilation actually worsens the conditions during the transport, because it may cause elevation of the temperature due to loss of insulation and it may result in loss of moisture.

**Figure 7.** An example of the foam boxes suitable for the transport of crayfish on land. The corrugated bottom structure allows for maintaining moist conditions without crayfish being submerged.

### **6. Code of practice: a case study**

Crayfish can be held under these conditions for several months without significant losses in the number or quality of crayfish. Tasting tests indicated that crayfish held for 9 months in the CrayShower were of equal quality (test and texture of flesh) compared to those been held in tanks and given food for the same period. The survival among the CrayShower-held crayfish was significantly higher and stable throughout the holding period than tank-held crayfish. Thus, the CrayShower system, being slightly more expensive to build, would be more economical to utilise than the conventional holding in tanks. The benefits of the CrayShower

**Figure 6.** CrayShower with stacked plastic containers for holding of crayfish and a close-up of the water sprinkler system

The commercial value of crayfish benefits from purging [14], which normally means gut evacuation and maybe general cleaning of the carapace from loose debris and solid particles. During communal holding in tanks, with the catch fully submerged, gut evacuation happens normally within 24 hours, depending on the water temperature in the holding tanks [34]. This excrete also affects water quality, and holding tanks require constant water exchange. In CrayShower, the gut evacuation can take up to 2 weeks [35]. Gut evacuation improves crayfish survival during further transport to markets, and it makes crayfish more desirable gourmet food when

Some crayfish wholesalers or processers demand clean crayfish, i.e., free of solid particle matter or discoloration, which might require cleaning of crayfish or sorting the catch by cleanliness. Normally, crayfish collect dirt on the carapace and become exceedingly dirty towards the end

would be less water utilised, higher survival of crayfish and decrease in workload.

processed and served, for obvious reasons.

(small picture).

190 Postharvest Handling

We will present here a synopsis of the post-harvest handling code of practice for freshwater crayfish. This is based on this short overview with detailed background information given in the above chapters. These basic principles allow for maximum number of crayfish reaching markets. These principles can easily be applied to recreational trapping practices, too. We will not go into exhausting details here in order to allow for imaginative application of the recommendations. The following basic actions should ensure minimum stress for the catch and maximum benefit for crayfish trapper:

1. Sort crayfish on board according to the commercial requirements, and store them in cool environment, away from the elements, as soon as the traps have been pulled.

**References**

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[2] Jussila J, Tiitinen V, Fotedar R, Kokko H. A simple and efficient cooling method for postharvest transport of the commercial crayfish catch. Freshwater Crayfish. 2013;**19**(1):15-19.

[3] Jussila J, Mannonen A. Crayfisheries in Finland, a short overview. Bulletin Français de la

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[7] Edsman L. Flodkräftan – värd att vårda. In: Blank S, Svensson M, editors. Artinriktad

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	- a. Provide either cool water tanks with shade or specific holding conditions, such as CrayShower or similar. If stored for longer periods in tanks, provide hides and ensure sufficient water exchange.
	- b. Sort crayfish according to the market requirements before putting them into the storage systems to avoid repeated handling.

### **Acknowledgements**

Thanks to the crayfishermen, including Vesa Tiitinen, Esko Toikka and Timo Myllynen, trapping in Lake Saimaa (Finland), for showing their stamina against the elements of the Finnish summer and challenges of trapping crayfish. They inspired our development of post-harvest handling practices for Fennoscandian conditions.

### **Author details**

Japo Jussila1 \*, Ravi Fotedar<sup>2</sup> and Lennart Edsman3

\*Address all correspondence to<EMAIL_ADDRESS>
1 Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland

2 Department of Environment and Agriculture, Curtin University, Bentley Campus, Western Australia, Australia

3 Department of Aquatic Resources, Swedish University of Agricultural Sciences, Sweden

### **References**

1. Sort crayfish on board according to the commercial requirements, and store them in cool

2. Aim for minimal handling of crayfish both initially and throughout the post-harvest

3. Allow the crayfish transport conditions with a steady moist and cool environment and

4. During the boat and road transport, ensure minimum changes in the ambient conditions

a. Provide either cool water tanks with shade or specific holding conditions, such as CrayShower or similar. If stored for longer periods in tanks, provide hides and en-

b. Sort crayfish according to the market requirements before putting them into the stor-

6. Pack crayfish in shallow foam boxes for transport to markets, with cooling and moisture

7. Throughout all stages of the post-harvest handling, remove weak, moribund and dead

Thanks to the crayfishermen, including Vesa Tiitinen, Esko Toikka and Timo Myllynen, trapping in Lake Saimaa (Finland), for showing their stamina against the elements of the Finnish summer and challenges of trapping crayfish. They inspired our development of post-harvest

1 Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio,

2 Department of Environment and Agriculture, Curtin University, Bentley Campus, Western

3 Department of Aquatic Resources, Swedish University of Agricultural Sciences, Sweden

and Lennart Edsman3

environment, away from the elements, as soon as the traps have been pulled.

processes.

192 Postharvest Handling

provided.

**Acknowledgements**

**Author details**

Australia, Australia

Japo Jussila1

Finland

5. In the holding depots:

total isolation from the outside elements.

and a low level of physical disturbance.

sure sufficient water exchange.

crayfish from the stock immediately.

handling practices for Fennoscandian conditions.

\*Address all correspondence to<EMAIL_ADDRESS>
\*, Ravi Fotedar<sup>2</sup>

age systems to avoid repeated handling.

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