As mentioned earlier, the JAK‐STAT pathway was initially characterized for its role in develop‐ ment and hemocyte proliferation [77]. The JAK‐STAT pathway also gets activated in respond to bacterial infections leading to production of AMPs and other effector molecules [55, 174]. This pathway is activated in a paracrine fashion through the binding of secreted ligands. In the case of virus infections, a novel ligand for the JAK‐STAT pathway has recently been identified. In fruit flies, DCV and Sindbis virus (SINV) infections result in increased expression of mRNA for Vago, an 18 kDa cysteine‐rich protein with a single von Willebrand factor type C motif [175]. Vago was then shown to be secreted by West Nile virus (WNV)‐infected *Culex quinquefasciatus* (southern house mosquito) cells [173]. In addition, Vago mRNA expression was dependent on Dicer‐2 but no other RNAi pathway components [173]. Secreted Vago then goes and activates the JAK‐STAT pathway in other cells, but interestingly it does not bind the Dome receptor. A different unknown receptor must be responsible for activation of this signaling pathway (**Figure 9**). This creates a new level of complexity to our understanding of the JAK‐STAT pathway in insects [176]. The mechanism by which the JAK‐STAT pathway creates an antiviral state in the cells is also not known. Future research will help understanding this complex immune response in insects.

**Figure 9.** RNA interference (RNAi) pathway and JAK‐STAT pathway in viral infections. In a virus‐infected cell, an increased expression of mRNA for Vago is observed. The Vago mRNA expression is dependent on Dicer‐2. Secreted Vago then goes and activates the JAK‐STAT pathway in other cells, but interestingly it does not bind the Dome receptor. A different unknown receptor (?) must be responsible for activation of this signaling pathway to induce expression of viral response genes, including TotM, upd2, and upd3.

#### **5.3. The autophagy pathway**

Autophagy has also been proposed as another antiviral mechanism in insects that is independent of the Toll, Imd, or JAK‐STAT pathways [177, 178]. Autophagy is the process by which double‐ membrane vesicles named autophagosomes are formed inside cells. These vesicles are formed with newly synthesized membranes that incorporate large cytoplasmic components including damaged organelles or protein aggregates. Then, the autophagosome fuses with lysosomes and degrades its content. Autophagy is induced by several stress signals including nutrient starvation, infection, and cellular repair mechanisms. In this manner, the degradative process of autophagy helps recycle nutrients and maintains cellular homeostasis [179]. The signaling pathway to autophagy involves the phosphoinositide 3‐kinase (PI3K)‐Akt pathway, which aug‐ ments the level of TOR, a negative regulator of autophagy [180] (**Figure 10**). During growing conditions, TOR is active and phosphorylates Autophagy‐related (Atg) 13 protein at multiple sites. This prevents Atg13 to bind with Atg1, a central regulator for autophagy [180], leading to decreased Atg1 kinase activity and blocking autophagy (**Figure 10**). During starvation condi‐ tions, TOR activity is reduced and Atg13 is rapidly dephosphorylated and forms a complex with Atg1, thus activating it. Atg1 in turn binds to other Atg proteins for assembly of the preautopha‐ gosomal structure (PAS) leading to autophagy (**Figure 10**). Different Atg proteins accumulate at the PAS under normal growing conditions to generate cytoplasm to vacuole targeting (Cvt) vesicles, or under starvation conditions to generate autophagosomes [181].

dated. In contrast, the JAK‐STAT pathway response to viruses seems to be more relevant for preventing the spread of infection [172]. Recent reports also suggest that the JAK‐STAT path‐ way may function similarly to the mammalian interferon system [173]. Infected cells produce factors that activate this pathway in uninfected bystander cells inducing an antiviral state in

As mentioned earlier, the JAK‐STAT pathway was initially characterized for its role in develop‐ ment and hemocyte proliferation [77]. The JAK‐STAT pathway also gets activated in respond to bacterial infections leading to production of AMPs and other effector molecules [55, 174]. This pathway is activated in a paracrine fashion through the binding of secreted ligands. In the case of virus infections, a novel ligand for the JAK‐STAT pathway has recently been identified. In fruit flies, DCV and Sindbis virus (SINV) infections result in increased expression of mRNA for Vago, an 18 kDa cysteine‐rich protein with a single von Willebrand factor type C motif [175]. Vago was then shown to be secreted by West Nile virus (WNV)‐infected *Culex quinquefasciatus* (southern house mosquito) cells [173]. In addition, Vago mRNA expression was dependent on Dicer‐2 but no other RNAi pathway components [173]. Secreted Vago then goes and activates the JAK‐STAT pathway in other cells, but interestingly it does not bind the Dome receptor. A different unknown receptor must be responsible for activation of this signaling pathway (**Figure 9**). This creates a new level of complexity to our understanding of the JAK‐STAT pathway in insects [176]. The mechanism by which the JAK‐STAT pathway creates an antiviral state in the cells is also not known. Future research will help understanding this complex immune response in insects.

Autophagy has also been proposed as another antiviral mechanism in insects that is independent of the Toll, Imd, or JAK‐STAT pathways [177, 178]. Autophagy is the process by which double‐ membrane vesicles named autophagosomes are formed inside cells. These vesicles are formed with newly synthesized membranes that incorporate large cytoplasmic components including damaged organelles or protein aggregates. Then, the autophagosome fuses with lysosomes and degrades its content. Autophagy is induced by several stress signals including nutrient

**Figure 9.** RNA interference (RNAi) pathway and JAK‐STAT pathway in viral infections. In a virus‐infected cell, an increased expression of mRNA for Vago is observed. The Vago mRNA expression is dependent on Dicer‐2. Secreted Vago then goes and activates the JAK‐STAT pathway in other cells, but interestingly it does not bind the Dome receptor. A different unknown receptor (?) must be responsible for activation of this signaling pathway to induce expression of

those cells [172, 173].

196 Insect Physiology and Ecology

**5.3. The autophagy pathway**

viral response genes, including TotM, upd2, and upd3.

In an infection of *Drosophila* with vesicular stomatitis virus (VSV), the PI3K‐Akt‐TOR signal‐ ing pathway is inhibited. This activates autophagy and in turn decreases viral replication [178]. The viral surface glycoprotein, VSV‐G, was proposed to be the pathogen‐associated molecular pattern (PAMP) that initiated this cell response [178]. More recently, it was found that, the Drosophila TLR ortholog, Toll‐7, was responsible for sensing VSV on the cell sur‐ face (**Figure 10**). Toll‐7 signaling was activated upon VSV infection and knockdown of Toll‐7 resulted in a higher viral protein level *in vitro* and greater pathogenesis *in vivo* [177].

**Figure 10.** Autophagy response in viral infections. The signaling pathway to autophagy involves the phosphoinositide 3‐kinase (PI3K)‐Akt pathway, leading to activation of TOR. This kinase phosphorylates autophagy‐related (Atg) 13 protein at multiple sites. This prevents Atg13 binding to Atg1 and other Atg proteins like Atg17, for assembly of the preautophagosomal structure (PAS), which leads to autophagy. Different Atg proteins accumulate with Atg1 under normal growing conditions to generate cytoplasm to vacuole targeting (Cvt) vesicles. During an infection with vesicular stomatitis virus (VSV), the receptor Toll‐7 detects the virus, and the PI3K‐Akt‐TOR signaling pathway is inhibited. This activates autophagy and in turn decreases viral replication.

## **6. Conclusion**

Insects clearly possess powerful defense mechanisms for fighting infections. Cellular responses involve phagocytosis of bacteria, and encapsulation of parasites, while humoral responses involve secretion of antimicrobial peptides into the hemolymph. Recognition of foreign pathogens involves specific receptors such as peptidoglycan recognition proteins (PGRPs), β‐glucan recognition proteins (βGRPs), and Toll‐related proteins. These receptors activate signaling pathways such as the Toll, the Imd, and the JAK‐STAT pathways. The par‐ ticular pathway activated by each pathogen and the final outcome in each case are still not completely known. This is particularly true for viral infections. Thus, future research in the area of insect immunity promises to be full of surprises.

Another fascinating aspect of insect defense mechanisms against infections is the current view that insects depend only on its innate immune response to fight invading microorgan‐ isms. By definition, innate immunity lacks adaptive characteristics. However, there are some reports showing that in *Drosophila*, an initial sublethal exposure to *Streptococcus pneumoniae* can protect flies from a second lethal exposure to the same bacteria [182]. Although not all microbial challenges generate this specific primed response, the fungus *Beauveria bassiana*, a natural fly pathogen, can also induce specific protection against a second exposure to the fungus [182]. These results indicate that insect immune responses can indeed adapt and sug‐ gest that insect hemocytes may also present an activation response similar to the one known in mammalian leukocytes.

Finally, most of what we know about insect innate immunity comes from studies of *Drosophila*, where genetics analysis has been instrumental in elucidating the antimicrobial peptide response, as well as to open the door for the study of Toll‐like receptors, which are essential for the innate immune response of mammals. Similarly, future genetic screens will help identifying novel host antiviral genes and also the receptor molecules that sense viral infection. Yet, it is important to keep in mind that insect‐pathogen interactions have coevolved. Thus, it is important to confirm findings from *Drosophila* studies in other insect species [8, 128, 176].

## **Acknowledgements**

This work was supported by grant 254434 from Consejo Nacional de Ciencia y Tecnología, Mexico.

## **Author details**

Carlos Rosales

Address all correspondence to<EMAIL_ADDRESS>
Immunology Department, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico

## **References**

**6. Conclusion**

198 Insect Physiology and Ecology

in mammalian leukocytes.

species [8, 128, 176].

**Author details**

Address all correspondence to<EMAIL_ADDRESS>
Autónoma de México, Mexico City, Mexico

Carlos Rosales

Mexico.

**Acknowledgements**

Insects clearly possess powerful defense mechanisms for fighting infections. Cellular responses involve phagocytosis of bacteria, and encapsulation of parasites, while humoral responses involve secretion of antimicrobial peptides into the hemolymph. Recognition of foreign pathogens involves specific receptors such as peptidoglycan recognition proteins (PGRPs), β‐glucan recognition proteins (βGRPs), and Toll‐related proteins. These receptors activate signaling pathways such as the Toll, the Imd, and the JAK‐STAT pathways. The par‐ ticular pathway activated by each pathogen and the final outcome in each case are still not completely known. This is particularly true for viral infections. Thus, future research in the

Another fascinating aspect of insect defense mechanisms against infections is the current view that insects depend only on its innate immune response to fight invading microorgan‐ isms. By definition, innate immunity lacks adaptive characteristics. However, there are some reports showing that in *Drosophila*, an initial sublethal exposure to *Streptococcus pneumoniae* can protect flies from a second lethal exposure to the same bacteria [182]. Although not all microbial challenges generate this specific primed response, the fungus *Beauveria bassiana*, a natural fly pathogen, can also induce specific protection against a second exposure to the fungus [182]. These results indicate that insect immune responses can indeed adapt and sug‐ gest that insect hemocytes may also present an activation response similar to the one known

Finally, most of what we know about insect innate immunity comes from studies of *Drosophila*, where genetics analysis has been instrumental in elucidating the antimicrobial peptide response, as well as to open the door for the study of Toll‐like receptors, which are essential for the innate immune response of mammals. Similarly, future genetic screens will help identifying novel host antiviral genes and also the receptor molecules that sense viral infection. Yet, it is important to keep in mind that insect‐pathogen interactions have coevolved. Thus, it is important to confirm findings from *Drosophila* studies in other insect

This work was supported by grant 254434 from Consejo Nacional de Ciencia y Tecnología,

Immunology Department, Instituto de Investigaciones Biomédicas, Universidad Nacional

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**Provisional chapter**

## **Potential of Insect-Derived Ingredients for Food Applications Potential of Insect-Derived Ingredients for Food Applications**

Daylan Amelia Tzompa Sosa and Vincenzo Fogliano Fogliano

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

Daylan Amelia Tzompa Sosa and Vincenzo

http://dx.doi.org/10.5772/67318

*"The supreme irony is that billions are spent every year to save crops that contain no more than 14% of plant protein by killing another food source (insects) that may contain up to 75% of high quality animal protein". [1]*

#### **Abstract**

Insects are a sustainable and efficient protein and lipid source, compared with conventional livestock. Moreover, insect proteins and lipids are highly nutritional. Therefore, insect proteins and lipids can find its place as food ingredients. The use of insect proteins and lipids as food ingredients requires a deep understanding on the chemical and physical characteristics of these ingredients, as well as its functionality. Information on the chemical and physical characteristics of insect proteins and oils will help to assess the possibilities of its use on different food applications. In this chapter, we briefly review the nutritional aspects of insect proteins and lipids, insect processing, protein and lipid extraction as well as the perspectives of food applications of insect protein and lipids. Future studies should delve into extraction methods and into intrinsic properties of insect ingredients. This knowledge will be useful to introduce insect ingredients into various food preparations. Also valuable will be the study of other insect species with perspectives for its commercial rearing.

**Keywords:** fractionation, insect proteins, insect fats and oils, food ingredient, food applications

## **1. Introduction**

Sustainability is becoming increasingly important in the world. Alternative sources of proteins and oils have to be found to replace traditional less sustainable ingredients. One of

© 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.

the possible alternatives to replace traditional proteins and oils in food products is insects. About 1900 insect species are traditionally consumed as a whole or low processed by approximately two billion people worldwide [2]. In some cases, insects have been consumed as emergency food, in other circumstances as staple food, and in other cultures, they are even considered delicacies [3]. Insects are in general a healthy food source with a high content of protein, fat, vitamins, minerals and fibres. Furthermore, there is a wide range of edible insects which contributes to a high variation in terms of protein and fat profiles. Using insects as a source of protein and lipids can contribute to global food security through feed or as a direct food. Edible insects have been traditionally harvested from natural forests or in the fields, providing food in rural areas for self-consumption or local markets.

Despite the proven nutritional aspects of insects, in the western world, the acceptability of insects as food is low due to its association as pests and disease transmitters [4], which is often described as "dirty image." In other countries with entomophagy tradition, the consumption of insects has decreased due to the growing urban society. FAO has pointed out the need to examine modern food science practices to increase insect trade, consumption and acceptance. Food scientists and food technologists have been innovating and have been looking for alternative solutions for postharvest handling, to improve processing and increase shelf life of insect products to increase availability and consumer acceptance. One of the proposed solutions to increase consumer acceptance is isolation of insect proteins and fats to be used as food ingredient. This requires a deep understanding on the chemical and physical characteristics of insect proteins and lipids, its functionality as well as an assessment on the consumer's perception and motivations to accept this novel source. In this chapter we describe some nutritional aspects of insect proteins and lipids, insect processing, protein and lipid extraction as well as the perspectives of food applications of insect-derived ingredients. Since the use of insect-derived ingredients is still in its infancy, there are more questions than answers. In this chapter, we also point out the need of information on the chemical and physical characteristics of insect proteins and oils that will help to assess the possibilities of its use for different food applications.

#### **2. Insect proteins**

Food scientists need to tackle in the next future the challenge of food security: how to ensure enough protein production to the 2–3 billions of additional people that will populate the planet in the coming decades [5]. There are different possibilities that could be explored as alternative source to obtain a sustainable production of proteins in the future. In this vein, several studies have been done looking at the potentiality of protein from yeast [6], microscopic fungi [7] and microalgae [8].

Recently, insects have been proposed as one of the most promising alternative source of proteins to solve the global issue of protein shortage: the main advantage of insects over other protein sources is the low environmental costs of production, which becomes essential to satisfy the rise in the global protein demand [2, 9]. In **Table 1**, a short summary of the main

**Table 1.** Intrinsic advantage and disadvantage related to the use of different organisms for feed and food production.

advantage and disadvantages related to the use of insect proteins in comparison with other alternative protein sources is provided.

**Table 1** focuses on the intrinsic advantage and disadvantage of the different organisms; however, it is clear that new technological solutions as well as changes in consumer awareness can probably solve many of the present disadvantages. It is very likely that in the next few years, the scenario will be significantly different.

In particular, it is important to consider that the sustainability aspects are gaining more and more importance and for this reason, they are already shaping the production systems in many food chains. In this respect, insects and microalgae have now the competitive advantage that can be produced using nonsophisticated technological infrastructure. Moreover, the possibility to feed insect using by-products of food productions or organic municipality waste could represent the perfect solution to close the circle of food and feed production favouring the transition towards a zero waste system.

As for the sustainability and also food security standpoint, the best way to take advantage from the insect proteins is to use the whole insect eventually grinded to favour consumer acceptance. However, protein-rich ingredients, which can be used in various food preparations, are also very important, and their development would require a better knowledge of the intrinsic properties of these proteins and also to understand the behaviour of insect proteins during extraction and processing.

#### **2.1. Insect processing and protein extraction**

the possible alternatives to replace traditional proteins and oils in food products is insects. About 1900 insect species are traditionally consumed as a whole or low processed by approximately two billion people worldwide [2]. In some cases, insects have been consumed as emergency food, in other circumstances as staple food, and in other cultures, they are even considered delicacies [3]. Insects are in general a healthy food source with a high content of protein, fat, vitamins, minerals and fibres. Furthermore, there is a wide range of edible insects which contributes to a high variation in terms of protein and fat profiles. Using insects as a source of protein and lipids can contribute to global food security through feed or as a direct food. Edible insects have been traditionally harvested from natural forests or in the fields, providing food in rural areas for self-consumption or local

Despite the proven nutritional aspects of insects, in the western world, the acceptability of insects as food is low due to its association as pests and disease transmitters [4], which is often described as "dirty image." In other countries with entomophagy tradition, the consumption of insects has decreased due to the growing urban society. FAO has pointed out the need to examine modern food science practices to increase insect trade, consumption and acceptance. Food scientists and food technologists have been innovating and have been looking for alternative solutions for postharvest handling, to improve processing and increase shelf life of insect products to increase availability and consumer acceptance. One of the proposed solutions to increase consumer acceptance is isolation of insect proteins and fats to be used as food ingredient. This requires a deep understanding on the chemical and physical characteristics of insect proteins and lipids, its functionality as well as an assessment on the consumer's perception and motivations to accept this novel source. In this chapter we describe some nutritional aspects of insect proteins and lipids, insect processing, protein and lipid extraction as well as the perspectives of food applications of insect-derived ingredients. Since the use of insect-derived ingredients is still in its infancy, there are more questions than answers. In this chapter, we also point out the need of information on the chemical and physical characteristics of insect proteins and

oils that will help to assess the possibilities of its use for different food applications.

Food scientists need to tackle in the next future the challenge of food security: how to ensure enough protein production to the 2–3 billions of additional people that will populate the planet in the coming decades [5]. There are different possibilities that could be explored as alternative source to obtain a sustainable production of proteins in the future. In this vein, several studies have been done looking at the potentiality of protein from yeast [6], microscopic fungi [7] and

Recently, insects have been proposed as one of the most promising alternative source of proteins to solve the global issue of protein shortage: the main advantage of insects over other protein sources is the low environmental costs of production, which becomes essential to satisfy the rise in the global protein demand [2, 9]. In **Table 1**, a short summary of the main

markets.

216 Insect Physiology and Ecology

**2. Insect proteins**

microalgae [8].

Protein extraction and fractionation are necessary steps to produce insect protein-rich ingredients. The protein concentration in the various insect species is usually very high (typically 50–70% of the dry matter), and this facilitates the isolation process.

Grinding of fresh insect is mechanically complicated, and it would result in the production of a slurry, which could be difficult to store and be further processed. Therefore, the first necessary processing step immediately after the insect harvesting is their drying. The conditions of the biomass preliminary treatment are critical: time/temperature can be adjusted according to the species and their initial water content. The damage of the tissue should be limited to avoid the contact of proteolytic and browning enzymes with their substrates. These enzymes are confined in specific organelles surrounded by membranes. The main objective of the drying step is to reduce the water content up to 5–10%. In this condition, the microbiological growth is ruled out, and the quality of the starting material can be better preserved. Fat oxidation is another main factor that could bring to quality decay during this step and during the following storage. In production, plants dedicated to insect protein production, drying and defatting conditions can be adjusted according to the need of the following steps.

In fact, for many purposes and especially to produce insect protein-rich ingredients, extraction of fats and grinding into small particles are essential prerequisite. Also when protein extraction is not the ultimate goal, it must be considered that the particle size of the final powder has a big impact on the technological properties of the insect-based ingredients. In particular grinding conditions will influence the:

Therefore, a careful selection of the grinding conditions according to the species should be performed particularly when adult insect (such as crickets or grasshoppers) rich in chitins and with a structured exoskeleton must be processed.

Up to now mainly wet fractionation processes have been proposed in the literature, although in principle dry fractionation could potentially lead to a better quality, and it is also intrinsically more sustainable because you do not need to eliminate water after extractions.

Data on the amount of proteins that can be extracted by grinded insect powder in aqueous solutions showed an enormous variability [11]. Factors like solid/water ratio as well as the pH of the media and the temperature play an important role. Using alkaline pHs (i.e. far from the protein isoelectric point), higher extraction yield was obtained [12]. Also ionic strength, i.e. the presence of sodium chloride in the solution, can increase the solubility, and as above mentioned, the finer the granulometry, the higher the extraction yield. However, the most important factor affecting protein extractability is the thermal treatment insects undergo before extraction. When the biomass is heated before extraction, the yield of soluble protein extraction drops dramatically moving from about 50% of the total proteins below the 20%. **Figure 1** suggests that the denaturation of insect proteins decreases their water solubility in a similar way observed for meat proteins.

There are some good reasons to perform a thermal treatment before extraction. First of all, the higher the temperature, the faster is the drying step. Secondly, a treatment at high temperature can be used to prevent enzymatic browning. Enzymatic browning catalysed by polyphenol oxidases (PPOs) is a major phenomenon taking place during insect protein extraction on aqueous solutions [12]. The browning reaction has negative effects on proteins by affecting the solubility and other technological functionalities. Moreover, brown colour is generally not well accepted by consumers, and consequently brown ingredients are always more difficult to use in several food preparations. Browning can be prevented also with not thermal treatment adding chemical agent such as sodium bisulphite or ascorbic acid in the extraction buffer [12].

The design of an insect protein extraction and fractionation process could often result in a trade-off between yield and purity. A higher yield of the extraction always comes with a lower purity of the final product and *vice versa*. For instance, an aqueous extraction followed by an acidic precipitation step could bring to a fraction containing more than 85% of proteins, which is a remarkably high purity, but this comes at the expenses of a final yield below 20% [13].

In such a condition, it is useful to follow an approach driven by the ingredient final destination of use, i.e. when the final goal is to get the maximum nutrient value, it is logical to prioritise the protein yield. On the other hand, when specific techno-functionality of proteins is desired, such as gelling or foaming properties, it is better to elaborate strategies that allow to obtain more purified preparation also at the expenses of a low yield.

#### **2.2. Insect protein techno-functional properties and their food applications**

Unfortunately, due to lack of standardised fractionation procedure, studies about the technological functionality of insect proteins are still at their infancy. Looking at what happened first with the dairy proteins and later on with legumes proteins (soybean, pea, lupine), the capability to fractionate them in defined preparations opened many possibilities of use as ingredients. We can assume that also for insect proteins, their use in different foods will be mainly driven by the added value they can bring to specific food preparations.

The main techno-functional properties that should be considered for insect proteins are:

Grinding of fresh insect is mechanically complicated, and it would result in the production of a slurry, which could be difficult to store and be further processed. Therefore, the first necessary processing step immediately after the insect harvesting is their drying. The conditions of the biomass preliminary treatment are critical: time/temperature can be adjusted according to the species and their initial water content. The damage of the tissue should be limited to avoid the contact of proteolytic and browning enzymes with their substrates. These enzymes are confined in specific organelles surrounded by membranes. The main objective of the drying step is to reduce the water content up to 5–10%. In this condition, the microbiological growth is ruled out, and the quality of the starting material can be better preserved. Fat oxidation is another main factor that could bring to quality decay during this step and during the following storage. In production, plants dedicated to insect protein production, drying and defatting conditions can be adjusted according to the need of the

In fact, for many purposes and especially to produce insect protein-rich ingredients, extraction of fats and grinding into small particles are essential prerequisite. Also when protein extraction is not the ultimate goal, it must be considered that the particle size of the final powder has a big impact on the technological properties of the insect-based ingredients. In

Therefore, a careful selection of the grinding conditions according to the species should be performed particularly when adult insect (such as crickets or grasshoppers) rich in chitins

Up to now mainly wet fractionation processes have been proposed in the literature, although in principle dry fractionation could potentially lead to a better quality, and it is also intrinsically more sustainable because you do not need to eliminate water after

Data on the amount of proteins that can be extracted by grinded insect powder in aqueous solutions showed an enormous variability [11]. Factors like solid/water ratio as well as the pH of the media and the temperature play an important role. Using alkaline pHs (i.e. far from the protein isoelectric point), higher extraction yield was obtained [12]. Also ionic strength, i.e. the presence of sodium chloride in the solution, can increase the solubility, and as above mentioned, the finer the granulometry, the higher the extraction yield. However, the most important factor affecting protein extractability is the thermal treatment insects undergo before extraction. When the biomass is heated before extraction, the yield of soluble protein extraction drops dramatically moving from about 50% of the total proteins below the 20%. **Figure 1** suggests that the denaturation of insect proteins decreases their water solubility in a

following steps.

218 Insect Physiology and Ecology

extractions.

particular grinding conditions will influence the:

• Rheological performance when rehydrated

similar way observed for meat proteins.

and with a structured exoskeleton must be processed.

• Dispersibility and solubility

• Water and lipid holding capacity

Interestingly, all these properties depend on the nature of the starting material (for instance, the species and maturity stage of the insects); however, they can be also modulated by the extraction and fractionation process especially by heating and the consequent protein denaturation.

Looking at the properties that can be influenced by the hydration of the proteins (i.e. the water holding and the thickening capacities), they can be particularly useful to improve the quality of meat and bakery products or even to modify the sensory properties of thick beverages such as the electrolyte-rich solutions for sportsman or the satiating products. As far as the emulsification and foaming capacities, they are particularly interesting for drinkable dairy products, desserts and salad dressing, while the gelation and structuring capacities are relevant for products such as cheese and tofu.

These potential applications of various insect protein fractions in real food product should also take into account the potential negative effects associated to their use. Although the increase of protein concentration is often desired parameters, insect proteins are often brown or even dark. The colour change in the final products caused by protein addition could be perceived as a very negative sensory attribute especially in dairy products. On the other hand, in many bakery products or when insect proteins will be used as meat replacers, this is not expected to be a significant problem.

#### **2.3. Nutritional and healthy properties**

A large part of the literature focused on the nutritional quality and the benefit related to the whole insect consumption. The attention is focused on proteins and the most important parameter is their total concentration. When measured on fresh weight basis, the insect protein concentration is within the range of that of the other animals, i.e. between 10 and 30%. So the real nutritional advantage of using insect proteins can be only understood when looking at the bigger picture as it was done by the consortium of the SUSFAN project. What makes the insect proteins particularly interesting from the nutritional point of view is not only their high concentration and the favourable amino acid composition but also their potential to meet all the so-called sustainable, healthy, affordable, reliable, palatable (SHARP) principles [14]. To have a 360 degree evaluation of the potentiality, the protein sources of the future should confront with these five criteria. In this respect, insects will perform very well.

In the previous paragraph, the reasons highlighting the sustainability, affordability, reliability and palatability of insect proteins have been discussed. Regarding the healthiness which includes also the nutritional properties, it is essential to say that insect proteins are rich in all essential amino acids. A diet based on insect proteins can perfectly sustain the harmonious growth of laboratory and husbandry animals also indicated that there are no major limiting or anti-nutritional factors affecting the growth of mice, fish and poultry [15].

Interestingly, insect proteins can be a good vehicle to increase mineral bioavailability. Insect contain much more iron, zinc and calcium than beef, pork and chicken [16]. As observed for the casein-calcium system in milk, it can be hypothesised that thanks to the interaction with specific peptides formed during insect protein digestion, these minerals can be more bioavailable than in protein-free food matrix.

Recent papers also confirmed that insect proteins are well digested during gastroduodenal digestion: in vitro data showed that the extent of the digestion depends also on the fraction of the insect proteins considered. In particular, the water soluble proteins are digested more efficiently than those remaining in the insoluble moiety [13]. No consisting data have been still published about the effect of browning and thermal treatment on the insect protein digestibility. Both phenomena can have opposite effects: on one hand they determine protein aggregation and crosslinking which decrease protein digestibility; on the other they favour protein denaturation, thus improving their degradation.

In addition to their use as nutrients, proteins from different sources have emerged as precursors of specific peptides, which are now known to be bioactive. A wide range of biological properties have been demonstrated with protein-derived bioactive peptides including antihypertensive, immunomodulatory, antimicrobial and antioxidant. These effects can be relevant in human and animal health promotion and can also be applied in food preservation for extended shelf life. The production of bioactive peptides has relied heavily on the use of food proteins, which further contributes to the depletion of their primary food sources. Edible insects can also be sustainable sources of proteins for bioactive peptide production. The availability of the gene sequence of major proteins in several insects such as *Tenebrio molitor* or *Hermetia illucens* allows the theoretical calculations of the linear structure, conformation and biological significance of peptide motifs released by specific proteinases used in industrial food processing. Open-access web-based tools can be used to verify the presence of these potential bioactive peptides, and enzymatic and microbiological methodology can be used to generate these peptides from the different insect biomasses.

We could image that the same variety of products and applications now available for dairy or soybean proteins will be soon available also for insects.

## **3. Insect lipids**

Looking at the properties that can be influenced by the hydration of the proteins (i.e. the water holding and the thickening capacities), they can be particularly useful to improve the quality of meat and bakery products or even to modify the sensory properties of thick beverages such as the electrolyte-rich solutions for sportsman or the satiating products. As far as the emulsification and foaming capacities, they are particularly interesting for drinkable dairy products, desserts and salad dressing, while the gelation and structuring capacities are relevant for

These potential applications of various insect protein fractions in real food product should also take into account the potential negative effects associated to their use. Although the increase of protein concentration is often desired parameters, insect proteins are often brown or even dark. The colour change in the final products caused by protein addition could be perceived as a very negative sensory attribute especially in dairy products. On the other hand, in many bakery products or when insect proteins will be used as meat replacers, this is not

A large part of the literature focused on the nutritional quality and the benefit related to the whole insect consumption. The attention is focused on proteins and the most important parameter is their total concentration. When measured on fresh weight basis, the insect protein concentration is within the range of that of the other animals, i.e. between 10 and 30%. So the real nutritional advantage of using insect proteins can be only understood when looking at the bigger picture as it was done by the consortium of the SUSFAN project. What makes the insect proteins particularly interesting from the nutritional point of view is not only their high concentration and the favourable amino acid composition but also their potential to meet all the so-called sustainable, healthy, affordable, reliable, palatable (SHARP) principles [14]. To have a 360 degree evaluation of the potentiality, the protein sources of the future should

In the previous paragraph, the reasons highlighting the sustainability, affordability, reliability and palatability of insect proteins have been discussed. Regarding the healthiness which includes also the nutritional properties, it is essential to say that insect proteins are rich in all essential amino acids. A diet based on insect proteins can perfectly sustain the harmonious growth of laboratory and husbandry animals also indicated that there are no major limiting

Interestingly, insect proteins can be a good vehicle to increase mineral bioavailability. Insect contain much more iron, zinc and calcium than beef, pork and chicken [16]. As observed for the casein-calcium system in milk, it can be hypothesised that thanks to the interaction with specific peptides formed during insect protein digestion, these minerals can be more bioavail-

Recent papers also confirmed that insect proteins are well digested during gastroduodenal digestion: in vitro data showed that the extent of the digestion depends also on the fraction of the insect proteins considered. In particular, the water soluble proteins are digested more efficiently than those remaining in the insoluble moiety [13]. No consisting data have

confront with these five criteria. In this respect, insects will perform very well.

or anti-nutritional factors affecting the growth of mice, fish and poultry [15].

products such as cheese and tofu.

220 Insect Physiology and Ecology

expected to be a significant problem.

**2.3. Nutritional and healthy properties**

able than in protein-free food matrix.

Lipids in insects are either obtained from the diet or de novo synthesised. These lipids are stored in the insects in the fat body, where lipids are stored, degraded, transformed and further transported to the site of utilisation [17, 18]. Lipids are used by insects for several physiological functions, among them for reproduction, development, flight, buoyancy, integumental waterproofing, communication via pheromones, structure of cell membranes, etc. [17, 19]. Insects are rich in lipids; its content ranges from 10 to up to 50% in dry basis [20]. The fat content and the fatty acid (FA) composition of insect are related to its species, sex, life stage, diet, environmental temperature, diapause and migratory flight [17, 21, 22]. Therefore, it is not strange to find a wide variability of FA profiles among insects.

Insect lipids are composed mainly of triacylglycerols. Other types of lipids present in minor amounts include cholesterol, partial glycerides, free fatty acids (FFA), phospholipids and wax esters [18, 23]. When insect lipids are extracted for its consumption as edible oils, the main types of lipids are triacylglycerols, which reflect the original composition of the lipids in the insect. The presence of other minor compounds in the lipid extraction greatly depends on the extraction process.

The extraction of insect lipids aiming its use as edible oils has been investigated using Soxhlet extraction, an aqueous method and supercritical CO2 extraction [24, 25]. The lipid extraction process does not have a major impact in the FA composition of the extract, but it strongly influences the lipid extraction yield and the types of lipids extracted. For instance, when aqueous extraction is used, only triacylglycerols are extracted. In contrast, when organic solvents are used, phospholipids, partial glycerides and triacylglycerols are extracted [25]. Partial glycerides, FFA and phospholipids are undesired in edible oils and fats. To eliminate these undesired compounds, the fats and oils undergo refining processes, which increases the cost of the oils and fats. Insect lipid aqueous extraction provides a high oil quality similar to that of virgin oils. However the yield is lower than that obtained using organic solvents or supercritical CO2 extraction in which more than 95% of the lipids are extracted [24, 25]. Therefore, the extraction process should be carefully selected according to desired application and the costs of each extraction process. Other method for insect lipid extraction with industrial potential is extrusion and expelling, which is a method commonly used in oil extraction of seeds. However, this method remains unexplored in the scientific literature.

Most insect lipids are liquid at room temperature (20°C); thus, they are called "insect oils." Insect oils are rich in unsaturated fatty acids (UFA > 60% of total FA), being the most abundant C18:1 cis 9 (>30% of total FA) and C18:2 cis 9,12 (>20% of total FA). The most abundant saturated fatty acid (SFA) found in these oils is C16:0 (20–30% of total FA) [10, 26]. In general, insect oils are rich in essential fatty acids such as C18:2 cis 9,12 (LA) and contain other FA associated to health benefits such as C18:3 cis9,12,15 (ALA) and ω-3 FA, which further points its nutritional value. The concentration of these FA varies among species [21], and it is strongly influenced by the insect diet. Studies showed that the insects caught in the wild are richer in ω-3 than those commercially reared.

There are a few known insect lipids that are solid at room temperature, such as the lipids extracted from black soldier fly larvae (*H*. *illucens*). In this case, they are called "insect fats." The solid state of this insect fat reflects its high content in saturated FA, which ranges from 57 to 75% of total FA.  This insect fat is especially interesting for food and feed applications since it is rich in C12:0, with a concentration similar to that of coconut oil. C12:0 is more water soluble and is readily digestible than long-chain FAs. Moreover, after digestion C12:0 is transported to the liver and is immediately converted to energy; thus, it is not stored as fat [28]. Other properties related to lauric acid and monolaurin are antimicrobial activity against gram-positive bacteria and a number of fungi and viruses [28, 29]. Therefore, the fat from black soldier fly larvae could be used as a functional ingredient in food applications.

In **Figure 1**, we show the spatial arrangement of vegetable oils and fats, animal fats and insect oils. This plot was obtained using the FA composition of different fats and oils and was analysed using principal component analysis. When the FA of insect oils are compared with that of vegetable oils, vegetable fats and animal fats, it appears that insect oils have a FA profile similar to that of vegetable oils and animal fats. This is due to the increase content of SFA, namely, C16:0 and C18:0, and at the same time a high content of mono- and polyunsaturated FA, namely, unsaturated C18 FA. Saturated C18 and C16 FA are increased in most animal fats, whereas unsaturated C18 FA are typical of vegetable oils.

**Figure 1.** The first and second principal components of the principal component analysis. The amount of explained variance is provided in parenthesis in each axis. Fatty acids per group; LC SFA, long-chain saturated fatty acids; SFA, saturated fatty acids; MC SFA, middle-chain saturated fatty acids; SC FA, short-chain fatty acids; MUFA monounsaturated fatty acids; VLC SFA, very-long-chain saturated fatty acids; PUFA, polyunsaturated fatty acids; and UFA, unsaturated fatty acids. Source: Refs. [25, 30, 31] and the authors.

#### **3.1. Potential food uses of insect oils**

but it strongly influences the lipid extraction yield and the types of lipids extracted. For instance, when aqueous extraction is used, only triacylglycerols are extracted. In contrast, when organic solvents are used, phospholipids, partial glycerides and triacylglycerols are extracted [25]. Partial glycerides, FFA and phospholipids are undesired in edible oils and fats. To eliminate these undesired compounds, the fats and oils undergo refining processes, which increases the cost of the oils and fats. Insect lipid aqueous extraction provides a high oil quality similar to that of virgin oils. However the yield is lower than that obtained using

extracted [24, 25]. Therefore, the extraction process should be carefully selected according to desired application and the costs of each extraction process. Other method for insect lipid extraction with industrial potential is extrusion and expelling, which is a method commonly used in oil extraction of seeds. However, this method remains unexplored in the

Most insect lipids are liquid at room temperature (20°C); thus, they are called "insect oils." Insect oils are rich in unsaturated fatty acids (UFA > 60% of total FA), being the most abundant C18:1 cis 9 (>30% of total FA) and C18:2 cis 9,12 (>20% of total FA). The most abundant saturated fatty acid (SFA) found in these oils is C16:0 (20–30% of total FA) [10, 26]. In general, insect oils are rich in essential fatty acids such as C18:2 cis 9,12 (LA) and contain other FA associated to health benefits such as C18:3 cis9,12,15 (ALA) and ω-3 FA, which further points its nutritional value. The concentration of these FA varies among species [21], and it is strongly influenced by the insect diet. Studies showed that the insects caught in the wild are richer in

There are a few known insect lipids that are solid at room temperature, such as the lipids extracted from black soldier fly larvae (*H*. *illucens*). In this case, they are called "insect fats." The solid state of this insect fat reflects its high content in saturated FA, which ranges from 57 to 75% of total FA.  This insect fat is especially interesting for food and feed applications since it is rich in C12:0, with a concentration similar to that of coconut oil. C12:0 is more water soluble and is readily digestible than long-chain FAs. Moreover, after digestion C12:0 is transported to the liver and is immediately converted to energy; thus, it is not stored as fat [28]. Other properties related to lauric acid and monolaurin are antimicrobial activity against gram-positive bacteria and a number of fungi and viruses [28, 29]. Therefore, the fat from black soldier fly larvae could be used as a functional ingredi-

In **Figure 1**, we show the spatial arrangement of vegetable oils and fats, animal fats and insect oils. This plot was obtained using the FA composition of different fats and oils and was analysed using principal component analysis. When the FA of insect oils are compared with that of vegetable oils, vegetable fats and animal fats, it appears that insect oils have a FA profile similar to that of vegetable oils and animal fats. This is due to the increase content of SFA, namely, C16:0 and C18:0, and at the same time a high content of mono- and polyunsaturated FA, namely, unsaturated C18 FA. Saturated C18 and C16 FA are increased in most animal fats,

extraction in which more than 95% of the lipids are

organic solvents or supercritical CO2

ω-3 than those commercially reared.

ent in food applications.

whereas unsaturated C18 FA are typical of vegetable oils.

scientific literature.

222 Insect Physiology and Ecology

The liquid nature of insect oils makes them ideal for its use in mayonnaise, in vinaigrettes, as frying oils and as food grade lubricants, among others. Applications such as bakery, spreads, or confectionery are ideal for insect fats, such as the fat extracted from black soldier fly larvae, because these applications require a certain percentage of solid fat. In order to evaluate the specific applications of these oils, a detailed chemical and physical characterisation of the oils is necessary. Ekpo et al. [32] performed detailed chemical analysis in the extracted oil of four insect species consumed in Nigeria. They concluded that these insect oils had potential used in the pharmaceutical industry due to their low melting point, specific gravity (<0.89) and refractive index (<1.3) [32]. Other insect application oils remain unexplored in the scientific literature.

Traditionally, insect oils and fats have only being characterised in terms of its FA composition, mainly because this determines the nutritional value of fats and oils. However, other chemical and physical analyses are required in order to evaluate its potential applications as food ingredient. For instance, crystallisation, texture analysis and solid fat content at different temperatures are required to evaluate the use of a fat as a spread, in confectionary or its use as an ingredient in bakery. Rheological properties help to determine spreadability, ease of cutting and stand-up in margarines. Volatile compound analysis and sensory evaluations are required to assess its taste, mouth feel and aroma. Detailed triacylglycerol profiling and thermal behaviour analysis are required to evaluate the possibilities of fractionation of an insect fat or oil. Profiling of minor lipid compounds such as phospholipids and sterols help to fully assess its nutritional value. Currently, none of these information is available. However, information on the physical and chemical characteristics of insect fats and oils will become available as the attention of the consumers and the food industry for insect lipids increases.

#### **3.2. Fractionation of an insect oil**

Dry fractionation is a thermal procedure use to separate oils and fats into two or more components with different melting points. The aim of this separation is to extend the range of applications of the original oil or fat as well as to increase its commercial value. Fractionation is applied mainly to palm oil but also to coconut, palm kernel, butter oil and beef tallow, among others. Dry fractionation can be applied to insect oils showing different melting fractions. To show the possibilities of this process in insect oils, we applied dry fractionation to oil extracted from yellow mealworm (*T*. *molitor*). Then we performed physical and chemical analysis to the original oil and its fractions.

The first step of this study included a thermal analysis of the original oil. This analysis was performed to study the possibilities for fractionation of the yellow mealworm oil. In this analysis, the oil was heated to 70°C to eliminate all the crystals present in the oil; then the oil was cooled at a rate of 5°C/min from 70 to −60°C. In this step, the oil is crystallised and the crystallisation points of the fat are obtained. Then, the fat was melted again at 5°C/min from −60 to 70°C. In this step, all the formed crystals are melted and the melting points are obtained. The results of yellow mealworm oil showed four crystallisation points and three melting points (**Figure 2**). Each peak indicates the crystallisation or melting of crystals formed by triacylglycerols with similar structure. Therefore, when more than one crystallisation/melting point is obtained, it indicates that the triacylglycerols in the oil are crystallising/melting independently. This is because the structure and/or FA within the triacylglycerols are different and they cannot cocrystallise into one single crystal lattice. The results from this first thermal analysis showed that the yellow mealworm oil can be fractionated because several crystallisation and melting peaks were obtained and these peaks were clearly separated from each other.

In the second step of this study, we aimed to fractionate yellow mealworm oil into a high melting fraction (or stearin) and a low melting fraction (or olein). We applied two cooling temperatures, namely, 2 and 4°C, and then the solid and the liquid fractions were separated. These temperatures were selected because in the previous analysis, it was shown that the highest crystallisation point was 3.6°C. The first step of dry fractionation was to melt the fat at 60°C for 30 min to eliminate the crystals present. Then, the oil was placed in a water bath, at the crystallisation temperature (2, or 4°C) for 24 h. During this crystallisation process, only triacylglycerols capable of crystallising at this temperature nucleate and grow into crystals (solid fat); the rest of the triacylglycerols having lower crystallisation temperatures will remain liquid (liquid fat). Finally, the liquid fraction was separated from the solid fraction by centrifugation at 4800 g for 20 min at the cooling temperature. Both fractions were placed in a separated tube and weighted to obtain the fractionation yield. The physical (thermal analysis and colour) and chemical characteristics (FA composition) of the original oil and the obtained solid and liquid fractions were performed to assess the effect of fractionation in the oil.

**Figure 2.** Non-isothermal crystallisation and melting of unfractionated yellow mealworm oil. Cooled from 70 to −60°C at 5°C/min and heated from −60 to 70°C at the same rate.

#### *3.2.1. Physical characteristics of the yellow mealworm oil and its fractions*

thermal behaviour analysis are required to evaluate the possibilities of fractionation of an insect fat or oil. Profiling of minor lipid compounds such as phospholipids and sterols help to fully assess its nutritional value. Currently, none of these information is available. However, information on the physical and chemical characteristics of insect fats and oils will become available as the attention of the consumers and the food industry for insect lipids increases.

Dry fractionation is a thermal procedure use to separate oils and fats into two or more components with different melting points. The aim of this separation is to extend the range of applications of the original oil or fat as well as to increase its commercial value. Fractionation is applied mainly to palm oil but also to coconut, palm kernel, butter oil and beef tallow, among others. Dry fractionation can be applied to insect oils showing different melting fractions. To show the possibilities of this process in insect oils, we applied dry fractionation to oil extracted from yellow mealworm (*T*. *molitor*). Then we performed physical and chemical

The first step of this study included a thermal analysis of the original oil. This analysis was performed to study the possibilities for fractionation of the yellow mealworm oil. In this analysis, the oil was heated to 70°C to eliminate all the crystals present in the oil; then the oil was cooled at a rate of 5°C/min from 70 to −60°C. In this step, the oil is crystallised and the crystallisation points of the fat are obtained. Then, the fat was melted again at 5°C/min from −60 to 70°C. In this step, all the formed crystals are melted and the melting points are obtained. The results of yellow mealworm oil showed four crystallisation points and three melting points (**Figure 2**). Each peak indicates the crystallisation or melting of crystals formed by triacylglycerols with similar structure. Therefore, when more than one crystallisation/melting point is obtained, it indicates that the triacylglycerols in the oil are crystallising/melting independently. This is because the structure and/or FA within the triacylglycerols are different and they cannot cocrystallise into one single crystal lattice. The results from this first thermal analysis showed that the yellow mealworm oil can be fractionated because several crystallisation and melting

peaks were obtained and these peaks were clearly separated from each other.

In the second step of this study, we aimed to fractionate yellow mealworm oil into a high melting fraction (or stearin) and a low melting fraction (or olein). We applied two cooling temperatures, namely, 2 and 4°C, and then the solid and the liquid fractions were separated. These temperatures were selected because in the previous analysis, it was shown that the highest crystallisation point was 3.6°C. The first step of dry fractionation was to melt the fat at 60°C for 30 min to eliminate the crystals present. Then, the oil was placed in a water bath, at the crystallisation temperature (2, or 4°C) for 24 h. During this crystallisation process, only triacylglycerols capable of crystallising at this temperature nucleate and grow into crystals (solid fat); the rest of the triacylglycerols having lower crystallisation temperatures will remain liquid (liquid fat). Finally, the liquid fraction was separated from the solid fraction by centrifugation at 4800 g for 20 min at the cooling temperature. Both fractions were placed in a separated tube and weighted to obtain the fractionation yield. The physical (thermal analysis and colour) and chemical characteristics (FA composition) of the original oil and the obtained solid and liquid fractions were performed to assess the effect of fractionation in the oil.

**3.2. Fractionation of an insect oil**

224 Insect Physiology and Ecology

analysis to the original oil and its fractions.

Separation into solid and liquid fat was possible at 2 and 4°C. Fractionation changed the colour of the liquid and solid fractions as compared with the unfractionated oil as analysed by Hunter Lab colorimeter in L\*a\*b\* scale (**Table 2**). In general, the solid fractions had a more red-yellow colour when compared with the liquid fractions. The liquid fraction had a bright appearance, and the red and yellow tones were lower in the liquid oil fractionated at 2°C than oil separated at 4°C (**Figure 3**). As expected, the amount of liquid fat fraction increased as the crystallisation temperature increased (**Table 3**).

**Table 2.** Colour of unfractionated and fractionated yellow mealworm oil measured at 20°C.

**Figure 3.** Unfractionated and fractionated yellow meal worm oil (*Tenebrio molitor*). This picture was taken after stabilising the oil for 2 h at 24°C.

The unfractionated oil of yellow mealworm showed four crystallisation points at −45.4, −19.9, −5 and 3.6°C and three melting points at −24.7, −17.4 and 16.7°C (**Table 3**). The liquid fractions lack the two highest crystallisation points at −5 and at 3.6°C, and the last melting point was reduced from 16.7 to 1.7 and 3.2°C (L4 and L2, respectively). The solid fractions lack the crystallisation point at −5°C and showed an increase in the highest crystallisation points from 3.6 to up to 10.7°C (S4 and S2, respectively). The final melting point of the solid fractions was increased from 16.7 to 21.5 and 27.1°C (S2 and S4, respectively).

Non-isothermal analysis cooled from 70 to −60°C and then heated from −60 to 70°C at 5°C/min.

YMW: original yellow meal worm oil extracted by Soxhlet using petroleum ether

S4, solid fraction at 4 °C; S2, solid fraction at 2 °C; L4, liquid fraction at 4 °C; and L2, Liquid fraction at 2 °C Adapted from Ref. [33]

**Table 3.** Yield, crystallisation and melting points of unfractionated and fractionated yellow meal worm oil (N = 2).

After fractionation the solid and the liquid fraction did show differences in their physical properties, as shown by the change in colour and by the changes in crystallisation and melting points. The liquid fractions obtained after fractionation had bright and transparent appearance and were liquid even at refrigeration temperatures (4°C). Therefore, these liquid fractions can be used for sauces, dressings, vinaigrettes, mayonnaise, etc. Regarding the solid fractions obtained, the solid fraction obtained after fractionation at 4°C was solid when it was kept at room temperature (24°C). This solid fraction can be potentially used as margarine. Further studies on crystal form (α, β′ and β) are necessary to fully assess the use of this solid fraction as a margarine. To produce high-quality spreads, such as margarines, the crystals should be in the β′ form because these crystals are relatively small and can incorporate large volumes of oil; moreover, β′ crystals give the product a glossy surface and a smooth lustre [34, 35]. In contrast, β crystals are less desirable in spreads because they grow into large needle-like crystals producing a sandy mouthfeel and are less able to incorporate liquid [36].

#### *3.2.2. Chemical characteristics of the yellow mealworm oil and its fractions*

The unfractionated oil of yellow mealworm showed four crystallisation points at −45.4, −19.9, −5 and 3.6°C and three melting points at −24.7, −17.4 and 16.7°C (**Table 3**). The liquid fractions lack the two highest crystallisation points at −5 and at 3.6°C, and the last melting point was reduced from 16.7 to 1.7 and 3.2°C (L4 and L2, respectively). The solid fractions lack the crystallisation point at −5°C and showed an increase in the highest crystallisation points from 3.6 to up to 10.7°C (S4 and S2, respectively). The final melting point of the solid fractions was

**Figure 3.** Unfractionated and fractionated yellow meal worm oil (*Tenebrio molitor*). This picture was taken after stabilising

increased from 16.7 to 21.5 and 27.1°C (S2 and S4, respectively).

**Sample Yield (%) Crystallisation points (°C) Melting points (°C)**

Non-isothermal analysis cooled from 70 to −60°C and then heated from −60 to 70°C at 5°C/min.

S4, solid fraction at 4 °C; S2, solid fraction at 2 °C; L4, liquid fraction at 4 °C; and L2, Liquid fraction at 2 °C

**Table 3.** Yield, crystallisation and melting points of unfractionated and fractionated yellow meal worm oil (N = 2).

YMW: original yellow meal worm oil extracted by Soxhlet using petroleum ether

YMW −45.4 −19.9 −5.0 3.6 −24.7 −17.4 16.7 S4 54 −46.3 −19.3 10.7 – −24.4 −18.0 27.1 S2 81 −46.3 −19.8 2.7 – −24.4 −16.9 21.5 L4 46 −49.4 −19.7 – – −25.5 −18.3 1.7 L2 19 −44.7 −19.5 – – −24.3 −17.4 3.2

the oil for 2 h at 24°C.

226 Insect Physiology and Ecology

Adapted from Ref. [33]

The FA composition of the unfractionated oil and its fraction was determined by GC-FID. Similar FA composition of the unfractionated oil was found in previous studies done in our laboratory [25]. It is interesting that the FA composition between the unfractionated oil and its fractions did not change (**Table 4**). The solid fat separated at 4°C was highly unsaturated (74% of FA). In theory, this fraction should have remained liquid. However the experimental results showed a different behaviour. Several possibilities exist to explain this behaviour. It is likely that the arrangement of FA within the triacylglycerol molecule is different in the liquid than in the solid fat, if the arrangement differs, so will the physical properties of the triacylglycerol. The second possibility is that the solid fraction contains a compound that is structuring the oil and turning it into a solid-like material. It is known that natural waxes and partial glycerides are used to structure highly unsaturated oils, forming oleogels [37]. Waxes and partial glycerides are present in insect tissues and in the oil fraction [18, 25] and could remain in the solid fraction after fractionation. Therefore, it can be suggested that these two components can be structuring the solid fraction of the yellow mealworm oil and turning it into a solid-like material or oleogel.

The differences seen in physical properties of the fractions cannot be explained by its FA composition. To understand the differences in physical properties seen in this study, it will be necessary to analyse the profile and structure of the triacylglycerols as well as to analyse the concentration of other minor compounds such as waxes.

The fractionation process presented in the present study succeeded in changing the physical properties of yellow mealworm oil. This fractionation can broaden the applications of this oil as a food ingredient. However, further physical, chemical and sensory analyses are necessary to fully assess the potential use of yellow mealworm oil as a food ingredient.

**Table 4.** Fatty acid composition (g/100 g of fat) of unfractionated and fractionated yellow meal worm oil (N = 2).

## **4. Concluding remarks**

Insects represent a viable source of proteins and fats since they have a low environmental cost of production. However, its effective inclusion in food preparations or as a food ingredient relies on several factors including consumer's acceptance, rearing facilities and technological functionalities. A lot of work is needed regarding protein and fat extraction methods as well as on technological functionality of insect proteins and fats. Understanding the behaviour of insect proteins and fats during extraction and processing as well as better knowledge of the intrinsic properties of insect ingredients is required for the development of various food preparations. It is very likely that in the next few years, the scenario will be significantly different as there is an increase attention of the consumers and the food industry for the use of insects as food.

## **Author details**

Daylan Amelia Tzompa Sosa\* and Vincenzo Fogliano

\*Address all correspondence to<EMAIL_ADDRESS>
Food Quality and Design Group, Wageningen University, Wageningen, the Netherlands

## **References**

[1] Premalatha, M., T. Abbasi, and S.A. Abbasi, Energy-efficient food production to reduce global warming and ecodegradation: The use of edible insects. Renewable and Sustainable Energy Reviews, 2011. **15**(9): pp. 4357-4360. DOI: 10.1016/j.rser.2011.07.115.

**4. Concluding remarks**

Adapted from Ref. [33]

228 Insect Physiology and Ecology

**FA Unfractionated oil Fractionated**

**Author details**

**References**

Daylan Amelia Tzompa Sosa\* and Vincenzo Fogliano

\*Address all correspondence to<EMAIL_ADDRESS>
Insects represent a viable source of proteins and fats since they have a low environmental cost of production. However, its effective inclusion in food preparations or as a food ingredient relies on several factors including consumer's acceptance, rearing facilities and technological functionalities. A lot of work is needed regarding protein and fat extraction methods as well as on technological functionality of insect proteins and fats. Understanding the behaviour of insect proteins and fats during extraction and processing as well as better knowledge of the intrinsic properties of insect ingredients is required for the development of various food preparations. It is very likely that in the next few years, the scenario will be significantly different as there is an increase attention of the consumers and the food industry for the use of insects as food.

**Table 4.** Fatty acid composition (g/100 g of fat) of unfractionated and fractionated yellow meal worm oil (N = 2).

Total CLA <0.10 <0.10 0.13 0.14 <0.10 Total ω-3 1.68 1.66 1.65 1.69 1.71 Total ω-6 30.96 30.63 30.75 31.19 31.18 ω-6/ω-3 Ratio 18.43 18.45 18.64 18.46 18.23 Total SFA 21.35 21.05 21.80 21.85 21.00 Total UFA 73.98 73.36 73.28 74.72 74.70 Total MUFA 41.23 40.87 40.70 41.73 41.70 Total PUFA 32.71 32.45 32.54 32.94 32.96

**Solid 2 °C Solid 4 °C Liquid 2 °C Liquid 4 °C**

Food Quality and Design Group, Wageningen University, Wageningen, the Netherlands

[1] Premalatha, M., T. Abbasi, and S.A. Abbasi, Energy-efficient food production to reduce global warming and ecodegradation: The use of edible insects. Renewable and Sustainable Energy Reviews, 2011. **15**(9): pp. 4357-4360. DOI: 10.1016/j.rser.2011.07.115.

SUSFANS project. *Agricultural Systems, 2016. In press*. DOI: http://dx.doi.org/10.1016/j. agsy.2016.10.014

[26] Yang, L.F., S. Siriamornpun, and D. Li, Polyunsaturated fatty acid content of edible insects in Thailand. Journal of Food Lipids, 2006. **13**(3): pp. 277-285. DOI: 10.1111/j. 1745-4522.2006.00051.x.

SUSFANS project. *Agricultural Systems, 2016. In press*. DOI: http://dx.doi.org/10.1016/j.

[15] Józefiak, D., A. Józefiak, B. Kierończyk, M. Rawski, S. Świątkiewicz, J. Długosz, and R.M. Engberg, Insects—A natural nutrient source for poultry—A review. Annals of Animal

[16] Zielińska, E., B. Baraniak, M. Karaś, K. Rybczyńska, and A. Jakubczyk, Selected species of edible insects as a source of nutrient composition. Food Research International, 2015.

[17] Beenakkers, A.M.T., D.J. Vanderhorst, and W.J.A. Vanmarrewijk, Insect lipids and lipoproteins, and their role in physiological processes. Progress in Lipid Research, 1985.

[18] Fast, P.G., Insect lipids. Progress in the Chemistry of Fats and other Lipids, 1971. **11**: pp.

[19] Lease, H.M. and B.O. Wolf, Lipid content of terrestrial arthropods in relation to body size, phylogeny, ontogeny and sex. Physiological Entomology, 2011. **36**(1): pp. 29-38.

[20] Xiaoming, C., F. Ying, Z. Hong, and C. Zhiyong, Review of the nutritive value of edible insects, in Forest insects as food: humans bite back, P.B. Durst, et al., Editors. 2010, FAO:

[21] Fontaneto, D., M. Tommaseo-Ponzetta, C. Galli, P. Rise, R.H. Glew, and M.G. Paoletti, Differences in fatty acid composition between aquatic and terrestrial insects used as food in human nutrition. Ecology of Food and Nutrition, 2011. **50**(4): pp. 351-367. DOI:

[22] Oonincx, D.G.A.B., S. van Broekhoven, A. van Huis, and J.J.A. van Loon, Feed conversion, survival and development, and composition of four insect species on diets composed of food by-products. PLoS One, 2015. **10**(12). ARTN e0144601. DOI: 10.1371/

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[24] Purschke, B., T. Stegmann, M. Schreiner, and H. Jäger, Pilot-scale supercritical CO2 extraction of edible insect oil from *Tenebrio molitor* L. larvae—Influence of extraction conditions on kinetics, defatting performance and compositional properties. European Journal of Lipid Science and Technology, 2016. in press. DOI: 10.1002/ejlt.201600134.

[25] Tzompa-Sosa, D.A., L. Yi, H.J.F. van Valenberg, M.A.J.S. van Boekel, and C.M.M. Lakemond, Insect lipid profile: Aqueous versus organic solvent-based extraction methods. Food Research International, 2014. **62**: pp. 1087-1094. DOI: 10.1016/j.

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230 Insect Physiology and Ecology

#### **Chapter 10 Provisional chapter**

## **Entomophagy: Insects as Food Entomophagy: Insects as Food**

Tiencheu Bernard and Hilaire Macaire Womeni Hilaire Macaire Womeni

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

http://dx.doi.org/10.5772/67384

Tiencheu Bernard and

#### **Abstract**

Due to the increasing cost of animal proteins, food and feed insecurity, population growth, and increasing need for protein-rich food in the developed and less developed countries, alternative sources of protein-rich food are highly needed. Scientific research has shown that edible insects are a very rich source of proteins and other nutrients. Hence, insect consumption might help revolutionaries' food and feed insecurity and thus replace the conventional animal source. This work assesses the potential of insects as food for humans and feed for animals and gathers existing information and research on edible insects. The assessment is based on the most recent and complete data available from various sources and experts around the world, because lack of a complete data on edible insects reduces consumer confidence and limits integration of edible insect consumption with other food sources. Considering the nutritional, economic, and ecological advantages of edible insects over conventional livestock, much attention should therefore be given to their method of collection as this will help improve their availability. This could be achieved by improved conservation or by raising them as a minilivestock. Considering the economic, nutritional, and ecological advantages of this traditional food source, its promotion deserves more attention both from national governments and assistance programs.

**Keywords:** edible insects, entomophagy, minilivestock, food and feed security, conservation

### **1. Introduction**

Entomophagy, the consumption of insects, is rooted in human evolutionary history [1]. Insects have played an important part in the history of human nutrition in Africa, Europe, Asia, and Latin America. Over 1900 species of insects are known worldwide to be part of human diets;

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

© 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.

some important groups include grasshoppers, caterpillars, beetle grubs, wringed termites, bees, worms, ant brood, cicadas, and a variety of aquatic insects [2]. It is interesting to know that more than two billion people consume insects on a regular basis, and insect eating provides a significant proportion of the animal proteins consumed in some regions [3]. Because entomophagy is widely practiced, and because it compares favorably with nutrient and environmental aspects of conventional livestock rearing, it has the potential to contribute substantially to reducing undernutrition among an expanding global population [3].

## **2. Diversity of edible insect species in the world**

Insects have been in existence for at least 400 million years, making them among the earliest land animals. They diverged as members of one of the largest subphyla in arthropods more than 390 million years ago experiencing a rapid evolution and radiation that is considered faster than any other group [4]. The class insects are the largest animal group on earth and constitute as much as 80% of the animal kingdom. Because of the nutritional importance of edible insects and their huge availability, this has attracted their consumption by more than two billion people on a daily basis [5].

Over 1900 species of edible insects in 300 ethnic groups in 113 countries worldwide have been recorded by various authors to be part of human diet (**Table 1**) [6]. According to Van Huis et al. [3], 246 species of edible insects have been reported in 27 countries in Africa. Another study

**Table 1.** Diversity and location of the most consumed edible insects in the world.

some important groups include grasshoppers, caterpillars, beetle grubs, wringed termites, bees, worms, ant brood, cicadas, and a variety of aquatic insects [2]. It is interesting to know that more than two billion people consume insects on a regular basis, and insect eating provides a significant proportion of the animal proteins consumed in some regions [3]. Because entomophagy is widely practiced, and because it compares favorably with nutrient and environmental aspects of conventional livestock rearing, it has the potential to contribute substan-

Insects have been in existence for at least 400 million years, making them among the earliest land animals. They diverged as members of one of the largest subphyla in arthropods more than 390 million years ago experiencing a rapid evolution and radiation that is considered faster than any other group [4]. The class insects are the largest animal group on earth and constitute as much as 80% of the animal kingdom. Because of the nutritional importance of edible insects and their huge availability, this has attracted their consumption by more than

Over 1900 species of edible insects in 300 ethnic groups in 113 countries worldwide have been recorded by various authors to be part of human diet (**Table 1**) [6]. According to Van Huis et al. [3], 246 species of edible insects have been reported in 27 countries in Africa. Another study

Zimbabwe, Nigeria, Tanzania

Nigeria, Mozambique, Namibia, Ghana, Togo, Chad

Nigeria, Mozambique, Namibia, Ghana, Togo, Chad

Nigeria, Mozambique, Namibia, Ghana, Togo, Chad

Republic, Zimbabwe, Burkina Faso, Malawi, Mali

Guinea, Liberia, Guinea Bissau DRC, Congo, Botswana

Kenya, Uganda, Tanzania, Malawi

Coast, Sao Tomé, Guinea, Ghana, Liberia

*Cirina forda* (Westwood) DRC, Zambia, South Africa, Botswana, Burkina Faso,

*Dactyloceras lucina* (Drury) DRC, Zambia, South Africa, Botswana, Burkina Faso,

*Gynanisa ata* Strand DRC, Zambia, South Africa, Botswana, Burkina Faso *Anaphe venata* Butler Zambia, Nigeria, Ivory Coast, Sierra Leone, Guinea, Liberia, Guinea Bissau

*Ruspolia differens* (Serville) DRC, Zambia, South Africa, Cameroon, Congo, CA

*Zonocerus variegatus* Linnaeus) DRC, Zambia, South Africa, Cameroon, Zimbabwe,

*Rhynchophorus phoenicis* (Fabricius) Thailand, Australia, Nigeria, Ivory Coast, Sierra Leone,

Lepidoptera *Anaphe panda* (Boisduval) DRC, Zambia, Cameroon, Congo, CA Republic,

Orthoptera *Acanthacris ruficornis* (Fabricius) DRC, Zambia, South Africa, Botswana, Burkina Faso,

Coleoptera *Oryctes boas* (Fabricius) DRC, Cameroon, Congo, CA Republic, Nigeria, Ivory

tially to reducing undernutrition among an expanding global population [3].

**2. Diversity of edible insect species in the world**

two billion people on a daily basis [5].

234 Insect Physiology and Ecology

**Order Species Location**

carried out 2 years later by Ramos-Elorduy noted that Africa is one of the most important hot spots of edible insect biodiversity in the world with 524 species recorded from 34 African countries [7]. These species are mostly of the orders Orthoptera, Lepidoptera, Coleoptera, Hymenoptera, and Isoptera. Below is a checklist of the most consumed edible insect species in the world and their orders and locations (**Figure 1**).

**Figure 1.** Recorded number of edible insect species, by country. Source: Centre for Geo Information, Wageningen University, based on data compiled by Jongema, 2012 [21]. Banjo et al, [8]; Igwe et al, [9]; Opera et al, [10]; Kelemu et al, [11].

## **3. Why eat insects?**

Hunger and malnutrition is a serious problem in the ever-expanding human population. With the high rate at which the world population is growing, the world food supply should grow at the same rate, if not faster. Therefore, the search for new food sources including the identification and development of localized ethnic ones continues [3].

In most part of the world, particularly in Africa and Latin America, food resources are becoming increasingly scarce and the importing of foods is becoming more expensive. It is thus imperative to identify and develop indigenous food resources. To effectively respond not just to rapid population growth but also to other pressing challenges, researchers have turned their attention to insects not only because of their abundance, enormous biomass, and highquality protein but also because of the time-honored practice among many culturally diverse peoples of Africa and Latin America of consuming live, roasted, and fried insects, providing them with a nutritious protein of good quality and high digestibility [12, 13]. The choice of insects as food is further strengthened by the fact that they also constituted rich sources of fat, vitamins, and minerals, especially iron and zinc [14].

## **4. Edible insects as food for humans and feed for animals**

Insects are the most abundant and most diverse multicellular organisms on planet earth and are thought to account for about 80% of all species [15]. Numerous crops rely on them for pollination, and their importance extends into their other agricultural and human health benefit [16].

Over 1900 species of insects are known to be part of human diets, more than 2 billion people consume insects on a regular basis, and insect eating provides a significant proportion of the animal protein consumed in some regions [3, 17]. In fact, in many developing countries and among various cultures scattered throughout the world, insects remain a vital and preferred food and an essential source of protein, fat, minerals, and vitamins [18]. This is because some edible insects have been shown to have nutritional value that can be compared with meat and fish, while others have higher proportion of proteins, fat, and energy value [19]. This has become especially important as the need for alternative protein sources increases due to rapid urbanization in developing countries and the shifts in the composition of global food demand. Among the most important orders of insects consumed in the world are the Coleoptera, Hymenoptera, Isoptera, Lepidoptera, Odonata, and Orthoptera, and they are highly priced (**Figure 2**) [20]. Notable examples of these are the locusts, termites, worms, grasshoppers, caterpillars, palm weevils, and beetle grubs, among others.

Although insects were mainly recognized as pests affecting humans, plants, and animal health, insects play an essential role in minimizing food insecurity in addition to provide ecosystem services (such as pollination, waste degradation, and biological control). Insects also represent an important food source for a wide variety of animal species. Van Huis et al. outlined the important role of insects in assuring food and feed security. Below is a list of pictures showing the various edible insects consumed around the world (**Figure 3**) [3].

**Figure 2.** Number of insect species, by order, consumed worldwide. Source: Jongema [21].

**Figure 3.** Examples of edible insects.

**3. Why eat insects?**

236 Insect Physiology and Ecology

Hunger and malnutrition is a serious problem in the ever-expanding human population. With the high rate at which the world population is growing, the world food supply should grow at the same rate, if not faster. Therefore, the search for new food sources including the

In most part of the world, particularly in Africa and Latin America, food resources are becoming increasingly scarce and the importing of foods is becoming more expensive. It is thus imperative to identify and develop indigenous food resources. To effectively respond not just to rapid population growth but also to other pressing challenges, researchers have turned their attention to insects not only because of their abundance, enormous biomass, and highquality protein but also because of the time-honored practice among many culturally diverse peoples of Africa and Latin America of consuming live, roasted, and fried insects, providing them with a nutritious protein of good quality and high digestibility [12, 13]. The choice of insects as food is further strengthened by the fact that they also constituted rich sources of fat,

Insects are the most abundant and most diverse multicellular organisms on planet earth and are thought to account for about 80% of all species [15]. Numerous crops rely on them for pollination, and their importance extends into their other agricultural and human health benefit [16]. Over 1900 species of insects are known to be part of human diets, more than 2 billion people consume insects on a regular basis, and insect eating provides a significant proportion of the animal protein consumed in some regions [3, 17]. In fact, in many developing countries and among various cultures scattered throughout the world, insects remain a vital and preferred food and an essential source of protein, fat, minerals, and vitamins [18]. This is because some edible insects have been shown to have nutritional value that can be compared with meat and fish, while others have higher proportion of proteins, fat, and energy value [19]. This has become especially important as the need for alternative protein sources increases due to rapid urbanization in developing countries and the shifts in the composition of global food demand. Among the most important orders of insects consumed in the world are the Coleoptera, Hymenoptera, Isoptera, Lepidoptera, Odonata, and Orthoptera, and they are highly priced (**Figure 2**) [20]. Notable examples of these are the locusts, termites, worms,

Although insects were mainly recognized as pests affecting humans, plants, and animal health, insects play an essential role in minimizing food insecurity in addition to provide ecosystem services (such as pollination, waste degradation, and biological control). Insects also represent an important food source for a wide variety of animal species. Van Huis et al. outlined the important role of insects in assuring food and feed security. Below is a list of pic-

tures showing the various edible insects consumed around the world (**Figure 3**) [3].

identification and development of localized ethnic ones continues [3].

**4. Edible insects as food for humans and feed for animals**

grasshoppers, caterpillars, palm weevils, and beetle grubs, among others.

vitamins, and minerals, especially iron and zinc [14].

## **5. Medicinal value of edible insects**

Scientific validation of traditional wisdom in bioprospecting has assured greater significance. Edible insects have long been a significant dietary factor and remedy for illnesses in many regions of the world [22]. Traditional healers have used insects as medicine to treat various diseases in human beings and animals successfully. Some of these diseases include common fever, scabies, epilepsy, violent headaches, bronchitis, hemorrhage, and dog bite. Insects are also used to treat wound, to prevent gangrene, and to increase milk flow in lactating women, among others [23]. This treatment is finding modern usage in many hospitals. Also, chemicals produced by edible insects against self-defense have also been exploited by many researchers for the production of antibacterial and anticancer drugs. For instance, pierisin, a protein purified from pupa of cabbage butterfly, exhibits cytotoxic effects against human gastric cancer. Cecropin has also been reported to be cytotoxic against mammalian lymphoma and leukemia cells [22]. Despite the fact that edible insects have a high nutritional, economic, and medicinal value, they are often neglected. It is high time that scientists recognize this fact and begin to build on it given the benefits of these creatures to the environment and to human health.

## **6. Market value of edible insects**

Many rural communities like those in Africa, Asia, and South America know that eating insects provides a valuable source of protein, minerals, and vitamins as well as a tasty snack and therefore must be in high demand. Crickets, grasshoppers, and locusts, for example, are a seasonal delicacy, while the giant water beetles are used in salads [22].

Considering the popularity of edible insects, it is not surprising that scores of species have been and are prominent items of commerce in the town and village markets of Africa and tropical and semitropical regions of the world [24]. In several areas in Africa, particularly in Zimbabwe, Nigeria, South Africa, Ivory Coast, and Zambia, many families make fairly good living from selling insects [25, 26]. These insects are mostly gathered from bushes and farmland by women and children (**Figure 4**), processed, and eaten or sold in school premises and

**Figure 4.** A picture showing women and children selling edible insects in local markets.

local and urban markets. Some of these insects are also processed and exported to shops and restaurants in cities in and out of the country [20, 27]. The commercialization of edible insects therefore provides significant income to many households in Africa. However, poorly understood and poorly organized market chains severely limit agribusiness in Africa. The market constraints encountered by farmers when attempting to diversify the production of edible insect business should therefore be documented.

## **7. Nutritional value of edible insects**

**5. Medicinal value of edible insects**

238 Insect Physiology and Ecology

**6. Market value of edible insects**

Scientific validation of traditional wisdom in bioprospecting has assured greater significance. Edible insects have long been a significant dietary factor and remedy for illnesses in many regions of the world [22]. Traditional healers have used insects as medicine to treat various diseases in human beings and animals successfully. Some of these diseases include common fever, scabies, epilepsy, violent headaches, bronchitis, hemorrhage, and dog bite. Insects are also used to treat wound, to prevent gangrene, and to increase milk flow in lactating women, among others [23]. This treatment is finding modern usage in many hospitals. Also, chemicals produced by edible insects against self-defense have also been exploited by many researchers for the production of antibacterial and anticancer drugs. For instance, pierisin, a protein purified from pupa of cabbage butterfly, exhibits cytotoxic effects against human gastric cancer. Cecropin has also been reported to be cytotoxic against mammalian lymphoma and leukemia cells [22]. Despite the fact that edible insects have a high nutritional, economic, and medicinal value, they are often neglected. It is high time that scientists recognize this fact and begin to build on it given the benefits of these creatures to the environment and to human health.

Many rural communities like those in Africa, Asia, and South America know that eating insects provides a valuable source of protein, minerals, and vitamins as well as a tasty snack and therefore must be in high demand. Crickets, grasshoppers, and locusts, for example, are

Considering the popularity of edible insects, it is not surprising that scores of species have been and are prominent items of commerce in the town and village markets of Africa and tropical and semitropical regions of the world [24]. In several areas in Africa, particularly in Zimbabwe, Nigeria, South Africa, Ivory Coast, and Zambia, many families make fairly good living from selling insects [25, 26]. These insects are mostly gathered from bushes and farmland by women and children (**Figure 4**), processed, and eaten or sold in school premises and

a seasonal delicacy, while the giant water beetles are used in salads [22].

**Figure 4.** A picture showing women and children selling edible insects in local markets.

The part played by insects in human nutrition cannot be underestimated [28]. Substantial evidence suggests that insects are a highly nutritious and healthy food source with high content of nutrients such as fats, proteins, amino acids, carbohydrates, vitamins, fibers, and minerals required by humans and animals [3]. However, the nutritional compositions of edible insects between and within species are highly variable depending upon the metamorphic stage, habitat, and diet of the insect as well as the preparation and processing methods applied before consumption [29]. Although the nutritional composition of some edible insects has previously been investigated in a number of countries, for example, India, the USA, Mexico, and Thailand, very few authors have reported a compiled nutritional composition of edible insects in the world. The lack of nutritional data on most edible insects may result in a reduction in consumer confidence and limits integration of insect consumption with other food sources. Hence, this work seeks to compile nutritional data of edible insects consumed in the world.

#### **7.1. Dietary energy content of edible insects**

With the growing world population, there are now more than 3.7 billion people suffering from malnutrition, mainly due to lack of protein and energy from food [30]. Also, new agricultural land is scarce to produce food for humans, and as such a greater proportion of people are eating resource-intensive animal protein than ever before. Livestock production is very expensive because it requires a large input of energy compared to the energy output [31]. These livestock also compete for nutrients and energy with humans.

Utilization of insects as a protein source could benefit insect conservation through habitat protection [32]. Insects are essential agents because they are able to exploit all organic sources in nature and are able to recycle organic waste and provide nutrients to farm animals and humans [33, 34]. Furthermore, edible insects have high quantities of polyunsaturated fat which provides majority of the energy for sustaining life. The energy contents of edible insects vary according to the species and region found and have also been found to be significantly higher than those of livestock and vegetables [19, 35]. Hence, edible insects may efficiently provide the necessary energy for the vital functions and survival of organisms.

Ramos Elorduy et al. [36] analyzed 78 insects from Oaxaca State, Mexico, and determined that caloric content was 293–762 kcal per 100 g of dry matter as shown in **Table 2**.

Source: FAO [37].

**Table 2.** Examples of energy content of different processed insect species, by regions.

#### **7.2. Protein and amino acid composition of edible insects**

Proteins are organic compounds consisting amino acids which are the building blocks and could be either essential or nonessential. Protein is the basis of all organism activity and constitutes many important materials such as enzyme, hormones, and hemoglobin. Proteins are the most abundant biological macromolecules, occurring in all cells and all parts of cells. Proteins also occur in great variety; thousands of different kinds, ranging in size from relatively small peptides to huge polymers with molecular weights in the millions, may be found in a single cell. Moreover, proteins exhibit enormous diversity of biological function and are the most important final products of the information pathways. Proteins are the molecular instruments through which genetic information is expressed. Therefore, ensuring a steady source of protein is very important in providing energy for humans and animals.

Insects are potentially an important energy efficient source of protein in humans (**Table 3**), either through a direct consumption or as food supplements for stock [17]. Many local communities in the world, particularly in the Amazon region, attain about 8–70% of their dietary protein from insects [39]. The highest amount of crude protein is found in insects in the order Lepidoptera followed by Coleoptera, while the order Hymenoptera has the least. The high protein content is an indication that edible insects can be of value to man and animal ration and can eventually replace higher animal protein usually absent in the diet of rural dwellers in developing countries [8].

**7.2. Protein and amino acid composition of edible insects**

**Table 2.** Examples of energy content of different processed insect species, by regions.

Australia Australia plague locust, raw

240 Insect Physiology and Ecology

Canada, Quebec Red-legged grasshopper,

The USA, Illinois Yellow mealworm, larva, raw

The USA, Illinois Yellow mealworm, adult, raw

Ivory Coast Termite, adult, dewinged,

Thailand Domestic silkworm, pupa, raw

The Netherlands Migratory locust, adult, raw

Source: FAO [37].

whole, raw

dried, flour

Proteins are organic compounds consisting amino acids which are the building blocks and could be either essential or nonessential. Protein is the basis of all organism activity and constitutes many important materials such as enzyme, hormones, and hemoglobin. Proteins are the most abundant biological macromolecules, occurring in all cells and all parts of cells. Proteins also occur in great variety; thousands of different kinds, ranging in size from relatively small peptides to huge polymers with molecular weights in the millions, may be found in a single cell. Moreover, proteins exhibit enormous diversity of biological function and are the most important final products of the information pathways. Proteins are the molecular instruments through which genetic information is expressed. Therefore, ensuring a steady source of protein is very important in providing energy for humans and animals.

**Location Common name Scientific name Energy content kcal/100 g fresh**

Australia Green (weaver) ant, raw *Oecophylla smaragdina* 1272

Mexico Veracruz State Leaf-cutter ant, adult, raw *Atta mexicana* 404 Mexico Hidalgo State Honey ant, adult, raw *Myrmecocystus melliger* 116 Thailand Field cricket, raw *Gryllus bimaculatus* 120 Thailand Giant water bug, raw *Lethocerus indicus* 165 Thailand Rice grasshopper, raw *Oxya japonica* 149 Thailand Grasshopper, raw *Cyrtacanthacris tatarica* 89

*Chortoicetes terminifera* 499

*Melanoplus femurrubrum* 160

*Tenebrio molitor* 206

*Tenebrio molitor* 138

*Macrotermes subhyalinus* 535

*Bombyx mori* 94

*Locusta migratoria* 179

**weight**

Insects are potentially an important energy efficient source of protein in humans (**Table 3**), either through a direct consumption or as food supplements for stock [17]. Many local communities in Xiaoming et al. [40] evaluated the protein content of 100 species from a number of insect orders. He showed that protein content was high and in the range of 13–77% of dry matter and that there was a large variation between and within the insect orders.

Edible insects have also been shown to have higher protein content, on a mass basis, than other animal and plant foods such as beef, chicken, fish, soybeans, and maize [41]. FAO compared protein content of insects, reptiles, cattle, and fish (**Table 4**) [42]. Results showed that the protein content of the selected insect species had higher protein contents than the fish and mammals. This strongly suggests that insects are an important source of protein and as such their consumption should be encouraged.

Many studies have also shown that edible insects are important source of amino acids (tryptophan and lysine). The inclusion of these insect species in diets could be of immense benefit in complementing lysine-poor staple cereals [43–45], and a host of others were able to demonstrate that an insect species *Tenebrio molitor* had a significant amount of essential and nonessential amino acids compared to beef (**Table 5**).

#### **7.3. Fat and carbohydrate composition of edible insects**

Fats and carbohydrates are important nutritive elements in the human body. They are the main energy source in the body, can reduce consumption of proteins, and help for detoxification [38].

Edible insects are also a good source of carbohydrates. In fact, the carbohydrate content of edible insects ranged from 6.71% in sting bug to 15.98% in cicada [47]. Carbohydrates in insects are formed mainly by chitin. Chitin is a macromolecular compound that has a high nutritional and health value. This chitin reduces serum cholesterol [48]. Also, recent report showed that considerable amounts of polysaccharide in edible insects might improve immune functioning of human body [49].

Sources: FAO [37, 42].

**Table 4.** Comparison of average protein content among insects, fish, reptiles, and cattle.

Fat is the most energy-dense macronutrient in food. It consists of triglycerides and three fatty acid molecules which are the backbone. Fatty acid can either be saturated, unsaturated, or essential. Dietary intervention and epidemiological studies showed that fatty acid intake

**Table 5.** Average amino acid content in *Tenebrio molitor* and beef in g/kg dry matter.

are formed mainly by chitin. Chitin is a macromolecular compound that has a high nutritional and health value. This chitin reduces serum cholesterol [48]. Also, recent report showed that considerable amounts of polysaccharide in edible insects might improve immune functioning

**Animal group Species and common name Edible product Protein content (g/100 g fresh**

Silkworm (*Bombyx mori*) Caterpillar 10–17

Crickets Adult 8–25 Termites Adult 13–28

**weight)**

Larva 14–18

Adult 13–28

Adult 35–48

Larva 7–36

Larva 14–25

Flesh 25–27 Intestine 18 Liver 11 Heart 17–23 Liver 12–27

Mackerel 16–28 Catfish 17–28

Prawn (Malaysia) 16–19 Shrimp 13–27

Fat is the most energy-dense macronutrient in food. It consists of triglycerides and three fatty acid molecules which are the backbone. Fatty acid can either be saturated, unsaturated, or essential. Dietary intervention and epidemiological studies showed that fatty acid intake

Crustaceans Lobster 17–19

Mollusks Cuttlefish 15–18

of human body [49].

242 Insect Physiology and Ecology

Insect (raw) Locusts and grasshoppers:

*Locusta migratoria, Anacridium melanorhodon*, *Ruspolia differens*

Locusts and grasshoppers: *Locusta migrator*ia, *Anacridium melanorhodon*, *Ruspolia differens*

*Sphenarium purpurascens* (chapulines, Mexico)

Palm worm beetles: *Rhynchophorus palmarum*, *R. phoenicis*, *Callipogon barbatu*s

*molitor*)

*Chelonia depressa*

Cattles Turtles: *Chelodina rugosa*,

Sources: FAO [37, 42].

Yellow mealworm (*Tenebrio*

Fish (raw) Finfish Tilapia 16–19

**Table 4.** Comparison of average protein content among insects, fish, reptiles, and cattle.

played a key role in human health. Reduction in dietary saturated fatty acids can decrease factor VII coagulant activity, which was implicated as a risk factor of cardiovascular disease [50]. Scientific literature has shown that consumption of PUFAs has several health benefits to humans such as reduction of glucose tolerance, thus reducing risk of diabetes and blood pressure [51], and prevention of insulin resistance [52], decreasing thrombotic tendency by inhibition of thromboxane A2 formation [53] and lowering blood pressure [51, 54]. Womeni et al. [55] investigated the content and composition of fat extracted from several insects (**Table 6**). They showed that their oils are rich in polyunsaturated fatty acids and frequently contain the essential linoleic and α-linolenic acids. The nutritional importance of these two essential fatty acids is well recognized, mainly for the healthy development of children and infants [56].

Many recent studies have shown that edible insects are a rich source of fatty acids, particularly polyunsaturated fat [19, 57]. These fatty acids differ and depend on many factors such as species reproduction stages [58, 59] and season or life stage [59].

Source: Womeni et al. [55].

**Table 6.** Fat content and randomly selected fatty acids of several edible insect species consumed in Cameroon.

#### **7.4. Mineral composition of edible insects**

Minerals are known to play important metabolic and physiologic roles in the living system. Iron, zinc, copper, and manganese strengthen the immune system as antioxidant and cofactors of enzyme [60]. Similarly, magnesium, zinc, and selenium prevent cardiomyopathy, muscle degeneration, growth retardation, impaired spermatogenesis, immunologic dysfunction, and bleeding disorder [61]. Iron deficiency is a major problem in women's diets in the developing world, particularly among pregnant women, and especially in Africa [62]. Magnesium is needed for more than 300 biochemical reactions in the body. It helps to maintain normal muscle and nerve function, keeps the heart rhythm steady, and regulates blood sugar levels [63].