 DEAS 1079 : 2021  
ICS 67.220  
 
© EAC 2021                                                                                                                              First Edition 2021  
 DRAFT EAST AFRICAN STANDARD  
Mustard seed  — Specification  
EAST AFRICAN COMMUNITY  DEAS 1079 : 2021  
ii © EAC 2021  – All rights reserved  
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 DEAS 1079 : 2021  
© EAC 2021  – All rights reserved  iii 
 Foreword  
Development of the East African Standards has been necessi tated by the need for harmonizing requirements 
governing quality of products and services in the East African Community. It is envisaged that through 
harmonized standardization, trade barriers that are encountered when goods and services are exchanged 
within the Community will be removed.  
The Community has established an East African Standards Committee  (EASC)  mandated to develop and 
issue East African Standards  (EAS) . The Committee is composed of representatives of the National 
Standards Bodies in Partner  States, together with the representatives from the public and private sector 
organizations  in the community .  
East African Standards are developed through  Technical Committees that are representative of key 
stakeholders including government, academia, con sumer groups, private sector and other interested parties. 
Draft East African Standards are circulated to stakeholders through the National Standards Bodies in the 
Partner States. The comments received are discussed and incorporated before finalization of standards, in 
accordance with the Principles and procedures for development of East African Standards.  
East African Standards are subject to review, to keep pace with technological advances. Users of the East 
African Standards are therefore expected to en sure that they always have the latest versions of the standards 
they are implementing .  
The committee responsible for this document is Technical Committee EASC/TC 006, Spices , condiments and 
culinary herbs . 
Attention is drawn to the possibility that some o f the elements of this document may be subject of patent 
rights. EAC shall not be held responsible for identifying any or all such patent rights.  
 
 DRAFT EAST AFRICAN STANDARD  DEAS 1079 : 2021  
 
© EAC 2021  – All rights reserved  1 
 Mustard seed  — Specification  
1 Scope   
This draft East African Standard specifies requirements, methods of s ampling and tests for seeds of white 
mustard ( Sinapis alba or Brassica hirta ), brown and yellow mustard ( Brassica juncea ) or black mustard 
(Brassica nigra )”. 
 
2 Normative references   
The following documents are referred to in the text in such a way that so me or all of their content constitutes 
requirements of this document.  For dated references, only the edition cited applies. For undated references, 
the latest edition of the referenced document (including any amendments) applies.  
Codex online guideline for  pesticide residues in food  
CODEX STAN 193, Codex g eneral  standard for contaminants and toxins in food and feed   
CODEX STAN 228, General method of analysis for contaminants  
EAS 38, Labelling of pre -packaged foods  — General requirements  
EAS 39, Hygiene in the food and drink manufacturing industry — Code of practice  
EAS 803, Nutrition labelling — Requirements  
EAS 804,  Claims — General requirements  
IS0 927, Spices and condiments — Determination  of ex traneous matter content  
IS0 928, Spices and condiments — Determination of total ash  
IS0 930, Spices and condiments — Determination of acid -insoluble ash  
IS0 948, Spices and condiments — Sampling  
IS0 1108, Spices and condiments — Determination of non -volatile ether extract  
   ISO 4833 -1, Microbiology of the food ch ain — Horizontal method for the enumeration of 
microorganisms — Part 1: Colony count at 30 oC by the pour plate technique  
     ISO 6579 (all parts), Microbiology of the food chain — Horizontal method for the detection, enum eration 
and serotyping of salmone lla   
     ISO 21527 -2, Microbiology of food and animal feeding stuffs — Horizontal method for the enumeration of  
yeasts and moulds — Part 2: Colony count technique  in products with water activity less than or equal to 0.95  DEAS 1079 : 2021  
2 © EAC 2021  – All rights reserved  
       ISO 16649 -2, Microbiology of food and animal feeding stuffs — Horizontal method for the enumeration of 
beta –glucuronidase -positive Escherichia coli — Part 2: Colony count technique at 44ºC using 5 -bromo -4-
chloro -3-indolyl beta –D-glucuronide  
3 Terms and definitions   
For the purpo ses of this document, the following terms and definitions apply.  
ISO and IEC maintain terminological databases for use in standardization at the following addresses:  
— ISO Online browsing platform: available at http:// www.iso.org/obp  
3.1 
immature or shriveled seed  
mustard seed that has indications of lack of maturity or full development   
3.2 
damaged seeds  
seeds that are damaged mechanically, or by mould or weevils, or those showing internal discoloration of 
seeds m aterially affecting the quality  
4 Requirements  
4.1 Description  
Mustard seed is the dried clean seed of one or more of the following plants : 
a) Sinapis alba or Brassica hirta  — White mustard ;  
b) Brassi ca nigra  — Black mustard;  
c) Brassica juncea  — Brown and yellow mu stard   
4.2 General requirements  
4.2.1 Odour and flavour  
The odour and flavour of the seeds when ground and moist ened shall be fresh and pungent, and free from 
rancidity and mustiness.  
4.2.2 Freedom from moulds, insects, etc.  
The seeds shall be free fro m living insects, mites and moulds, dead insects, insect fragments and rodent 
contami nation visible to the naked eye.  
4.3 Specific requirements  
The mustard seed shall comply with the requirements given in the table.  
Table — Requirements for mustard seed  
S/No.  Characteristics  Requirement  Test method  
i)  Loss in mass at 103 C, % (m/m) max.  10 Annex A  DEAS 1079 : 2021  
© EAC 2021  – All rights reserved  3 
 ii)  Total ash, % (m/m) on dry basis, max.  6.5 IS0 928  
iii)  Acid-insoluble ash, % (m/m) on dry 
basis, min.  1.0 IS0 930  
iv)  Non-volatile ether extract, % (m/m) on 
dry ba sis, min.  28 IS0 1108  
v)  Allyl isothiocyanate, % (m/m) on dry 
basis   
Annex B  a) in B. nigra, min. 1.0 
b) in B. juncea , min.  0.70 
vi)  p-hydroxybenzyl isothiocyanate, % 
(m/m) on dry basis in Sinapis alba , min.  2.3 Annex C or Annex D  
 
vii)  Extraneous matter, m/m 0.7 %  IS0 927  
viii)  Damaged or shrivelled seeds (m/m).  2 % 
5. Contaminants  
5.1 Pesticide residues  
Pesticide residues in mustard seed  shall not exceed maximum residue limits as established in the Codex 
online guideline for pesticide residues in food.  
5.2 Heavy metals  
Heavy metals in mustard seed  shall not exceed maximum heavy metal limits as stipulated in CODEX STAN 
193. 
6 Hygiene  
Mustard seed  shall be manufactured and handled in a hygienic manner in accordance with EAS 39 and shall 
comply with the microb iological limits stipulated in Table 2  when tested in accordance with the methods 
specified therein.  
Table 2 — Microbiological requirements  for mustard seed  
S/No  Characteristic  Requirement  Test method  
i.  Total plate count, cfu/g, max.  105 ISO 4833 -1 
ii.  Yeast  and moulds, cfu/g, max.  104 ISO 21527 -2 
iii.  Salmonella spp ., per 25 g   Absent  ISO 6579  
iv.  E coli , MPN/g, max.  Absent  ISO 16649 -2 
7 Packaging  
The mustard seed shall be packaged in food grade packaging material that secure s the integrity and the  safety 
of the product . 
8. Labelling  
In addition to the requirements of EAS 38, EAS 803 and EAS 804, each container shall be legibly and indelibly 
labelled with the following information:  DEAS 1079 : 2021  
4 © EAC 2021  – All rights reserved  
 a) name of the product as “mustard seed”;  
b) trade name or brand name if any;  
c) name, p hysical and postal address of manufacturer and / or packer;  
d) batch or code number;  
e) net weight in metric units;  
f) storage conditions;  
g) manufacturing  date;  
h) expiry date ; and  
i) instructions for use.  
8 Sampling and test  
8.1 Sampling  
Sample the mustard seed by the me thod specified in IS0 948.  
8.2 Methods of test  
8.2.1  The samples of mustard seed shall be tested for conformity with the requirements of - this International 
Standard by the methods of test referred to in 3.4 and the table.  
8.2.2 For the determination of t otal ash, use the method specified in IS0 928, with the following modifications _ 
to sub - clause 8.3.2.  
Leach the ash with hot water, filter through a medium -fine, ash less filter paper and wash thoroughly. Transfer 
the filter paper and contents to the di sh (6.11, dry and heat again in the muffle furnace (6.2) for 1 h. Cool and 
add 5 to 10 drops of analytical quality nitric acid, evaporate to dryness on the steam bath (6.4) and heat in the 
muffle furnace for 30 min. Repeat the addition of 5 to 10 drops of the nitric acid, again evaporate to dryness 
and heat in the muffle furnace for 1 h. Cool the dish, add the filtrate, and evaporate to dryness on the steam 
bath. Heat again in the muffle furnace for 1 h, cool and weigh. Repeat these operations until the dif ference 
between two successive weighing is less than 0.002 g. Record the lower mass.  
The total ash may be retained for the insoluble ash and acid -insoluble ash.  
 DEAS 1079 : 2021  
© EAC 2021  – All rights reserved  5 
 Annex  A 
(normative ) 
 
Determination  of loss in mass  at 103 C1) 
A.1 Apparatus  
A.1.1  Dish , of corrosion -resistant  metal,  with a suitable  tight-fitting  lid. 
A.1.2  Constant  temperature oven , controlled at 103 + 2 °C. 
A.1.3  Desiccator,  provided  with an efficient desiccant.  
A.1.4  Analytical  balance.  
A.2 Procedure  
A.2.1  Test  portion  
Weigh, to the nearest 0.001 g, about 2 g of the sample in the  tared  dish (A.1.1).  
A.2.2  Determination  
Heat the dish and contents, with the lid alongside the dish, in  the oven (A.1.21 at 103 + 2 °C for 3 h. Fit the lid, cool in the  
desiccator  (A.1.3) and  weigh. Heat  in the oven  for 1 h, cool in the desiccator and weigh again. Repeat the operations of  
heating for 1 h in the oven, cooling and weighing, until the  difference beWveen two successive weighings does not 
exceed 0,001  g. 
A.2.3  Number of determinations  
Carry  out two determi nations  on the same  sample.  
 
A.3 Expression or results  
A.3.1  Method of calculation and formula  
The loss in mass  at 103 °C, i-I, expressed  as a percentage  by mass  of the sample,  is equal  to : 
(m0 – m1) × 100 
m0 
where  
m0 is the initial  mass,  in grams,  of the test portion;  
m1 is the mass,  in grams,  of the test portion after heating  in the oven.  
 
Take as the result the arithmetic mean of the two determinations (A.2.3), provided that the requirement for 
repeatability  (see A.3.2)  is satisfied.  
 DEAS 1079 : 2021  
6 © EAC 2021  – All rights reserved  
 A.3.2  Repeatabili ty 
The differenc e between the results of the two  determinations  (A.2.3), carried out simultaneously or in rapid 
succession by  the same  analyst,  shall not exceed  1 % of the mean value.  
1) For the purpose of calculating the results of tests on the dry basis,  it is assumed that the loss in mass at 
103 °C. as determined by the method described in annex A, is equal to the moisture content.  
 
 DEAS 1079 : 2021  
© EAC 2021  – All rights reserved  7 
 Annex  B 
(normative)  
 
Determination  of allyl isothiocyanate  
 
B.1 Principle  
 
After two successive soakings of the sample, the first in water at a temperature of 70 °C and the second in 
alcoholic medium, distillation of the allyl isothiocyanate liberated into an alcoholic ammonium hydroxide 
solution, addition to the distillate of a s tandard volumetric silver nitrate solution, and titration of the excess 
silver nitrate with standard volumetric potassiurri, or ammonium, thiocyanate solution in the presence of 
ammonium iron(III) sulphate.  
B.2 Reagents  
 
All reagents shall be of recognized ana lytical quality. The water used shall be distilled water or water of at 
least equivalent purity.  
B.2.1  Ethanol , 95 % ( V/V). 
B.2.2  Amm onium hydroxide solution , e20 = 0. 925 g/ ml.  
 
B.2.3  Nitric acid , e 20 = 1. 40 g/ml.  
 
B.2.4  Silver nitrate , standard volumetric solution, c(AgNO 3) = 0.1 mol/I.  
 
B.2.5  Potassiu m thiocyanate or ammonium thio cyanate, standard volumetric solution, c(KCNS) or 
c(NH 4CNS) = 0. 1 mol/I.  
 
B.2.6  Ammonium iron(III) sulphate solution , saturated when cold.  
 
B.3 Apparatus  
Usual laboratory apparatus, and in particular  
B.3.1  Grinding mill.  
B.3.2  Entrainment distillation apparatus  (see the figure for a suitable example).  
 
B.3.3  Burette , graduated at 0. 05 ml intervals, complying with the requirements of ISO/ R 385, class A.  
 
B.3.4  Analytical balance . 
B.4 Procedure  
 
B.4.1  Preparation of the sampl e 
 
After very careful  mixing of the sample, take 15 to 20 g and grind it (see ISO 2825).  
B.4.2  Test portion  
 
Take about 2 g of the ground sample and weigh it to the nearest 0.001 g.  DEAS 1079 : 2021  
8 © EAC 2021  – All rights reserved  
  
B.4.3 Determination  
 
Transfer the test portion to the pe ar-shaped flask of the distilla tion ap paratus, add 80 ml of  water previously 
heated to 70 ± 2 °C, close the flask with its ground glass stopper and leave to stand for 15 min. Then add 20 
ml of the ethanol (B.2.1) and allow to soak for 45 min.  
After the soaking, connect the flask quickly to the  distillation apparatus. Distil, and collect the dis tillate in a 
conical flask con taining a mixture of 5 ml of the ammonium hydroxide solution (B.2.2) and 10 ml of the 
ethanol (B.2.1). (Entrainment distilla tion lasts, on average, for 5 min.) The quantity o f the distillate should be 
at least 100 ml.  
Add to the distillate 10 ml of the standard volumetric silver nitrate solution (B.2.4) and leave for 12 h at 
ambient temperature (the operation will be faster if the conical flask is placed for 1 h in a water bat h heated 
to 70 to 80 °C).  
Filter through a fine filter paper, rinse the flask and residue several times with hot water (approximately 90 
°C). 
To the bulked filtrate and washings add 10 ml of the nitric acid (B.2.3) and then titrate with the standard 
volume tric potassium, or ammonium, thiocyanate solution (B.2.5) using the ammonium iron(III) sulphate 
solution (B.2.6) as indicator, until a persistent pink colour is obtained.  
 
B.4.4 Number of determinations  
 
Carry out two determinations on the same prepared sa mple.  
B.5 Expression of results  
 
B.5.1  Method of calculation and formula  
The allyl isothiocyanate content, expressed as a percentage by mass on the dry basis, is equal to  
 
4.95   (10 – V) x 100 x  100 
  103        m      100 – H  
 
Where; 
m is the mass, in g rams, of the test portion;  
V is the volume, in millilitres, of the standard volumetric potassium, or ammonium, thiocyanate 
solution used in the titration;  
H is the moisture content of the sample, expressed as a percentage by mass, determined by the 
method specified in annex A.  
NOTE — If the standard vo lumetric solutions used are not of the exact concentrations indicated in clause B.2, 
a suitable correction factor should be used in calculating the result.  
Take as the result the arith metic mean of the two det ermina tions (B.4.4), provided that the requirement for 
repeatability (see B.5.2) is satisfied.  
B.5.2  Repeatability  
The difference between the results of the two determinations (B.4.4), carried out simultaneously or in rapid 
succession by the same analyst, shall not exceed 1 % of the mean value.  DEAS 1079 : 2021  
© EAC 2021  – All rights reserved  9 
 B.6 Notes on procedure  
 
B.6.1  During the analysis, all contact with copper or rubber shall be avoided, especially in the 
distillation apparatus. Use cork or, preferably, ground glass stoppers.  
 
B.6.2  The enzymic activity of the must ard seed diminishes with age; thus, it may be necessary to 
modify the analytical method in the case of old seed.  
 
After a preliminary determination giving particularly low figures for allyl isothiocyanate, add to the 
distillation residue 5 g of Sinapis alb a (take care to check that sulphur -containing volatile s ubstances are 
not present in it  and then proceed to a second determination.  
 
The addition of the two  results will give the real figure of allyl isothiocyanate that may be formed in the 
sample. However , the actual quality of the sample should be considered as very reduced and it is 
recommended that the two figures, found before and after the addition of Sinapis alba , should be given 
in the test report.  
 
B.6.3  The enzymic activity of the se eds increases during  certain periods of the year (particularly in spring); 
thus, identical results are not always found with a given lot of seed, according to the season in which 
the analysis is carried out.  
 
 
 
 DEAS 1079 : 2021  
10 © EAC 2021  – All rights reserved  
 Annex  C 
(normative)  
 
Determination  of ρ-hydroxybenzyl isothiocyanate  (Colorimetric  
method)  
 
C.1 Principle  
 
Decomposition,  by enzymatic  hydrolysis,  of the sinalbin  (glucoside of Sinapis al bal) into glucose, the 
hydrogen sulphate  of sinapin  and ρ-hydroxybenzyl  isothiocyanate,  the last mentioned  giving  ρ-
hydroxybenzyl  and thiocyanate.  CoIorimetric  determination  of the thiocyanate  so formed.  
 
C.2 Reagents  
 
All reagents shall be of recognized analytical quality. The water  used shall be distilled water or water of at 
least equivalent  purity.  
 
C.2.1  Calcium  carbonate,  pulverized.  
 
C.2.2  Mercury  (II) chloride,  50 g/I solution.  
 
C.2.3  Potassium  hexacyanoferrate  (II), 106 g/l solution.  
 
C.2.4  Zinc acetate  solution  
 
Dissolve 21. 9 g of zinc acetate [(CH3COO) 2Zn] in water, add   3 ml of glacial acetic acid (CH 3COOH) and 
dilute to 100 ml with  water.  
 
C.2.5  Nitric  acid , approximately  1 mol/I  solution.  
 
C.2.6  Sodium  hydroxide,  approximately  1 mol/I  solution.  
 
C.2.7  Ammonium  iron (III) sulphate , 200 g/l solution  in approximately  0.5 mol/I  sulphuric  acid 
solution.  
 
C.2.8  Potassium thiocyanate  or ammonium thio cyanate , standard  volumetric  solution,  c(KCNS)  or 
c(NH 4CNS)  = 0.1 mol/I,  i.e. containing  5.808 g of CNS - per litre. 
 
C.3 Apparatus  
 
Usual  laboratory  apparatus,  and in particular . 
 DEAS 1079 : 2021  
© EAC 2021  – All rights reserved  11 
 C.3.1  Grinding  mill 
 
C.3.2  One-mark volumetric flasks,  of capacities 50, 250  and 1 000 ml, complying with the 
requirements of ISO 1042,  class  A. 
 
C.3.3  Pipettes , delivering  2 ml and 5 ml,  complying  with the requirements  of ISO 648, class A, ISO/R 
835. 
C.3.4  Colorimeter,  suitable  for measurements at a  wavelength  of 450 nm. 
 
C.3.5  Analytical  balance  
 
C.4 Procedure  
 
C.4.1  Preparation  of test sample  
 
Carefully  render  the sample  homogeneous,  then take a portion  of 20 to 25 g of the mustard  seed  and 
grind  it (see ISO 2825).  
 
C.4.2  Test  portion  
 
Take approximately 5 g of the ground sample and weigh it to  the nearest  0.001 g. 
 
C.4.3  Hydrolysis  
 
Transfer  the test portion  to a 250 ml beaker.  
 
Add 100 ml of water at 70 ± 2 °C and at least 100 mg of the  calcium carbonate (C.2.1). Cover the 
beaker with a watch  glass. Leave to soak for 15 min at 70 °C, cool, add 20 ml of the  sodium  hydro xide 
solution  (C.2.6),  and leave  in contact  for 15 min. 
 
C.4.4  Clarification  
 
Add a sufficient quantity of the nitric acid solution (C.2.5), to  bring the contents  of the beaker  to a pH of 
about 6.0 to 6. 5. Pour the contents of the beaker into a 250 ml volumetric  flask  and, shaking  the flask,  
add 2 ml of the potassium  hexa -cyanoferrate(II)  solution  (C.2.3)  and then 2 ml  of the zinc acetate  
solution  (C.2.4).  
Dilute to 250 ml with water and add 2 ml of water by pipette  (C.3.3) (to take into account the volume of 
the precipitate).  Shake, and filter through a rapid filter shaded from bright light.  The filtrate  (F) should  be 
clear  and colourless.  
 
C.4.5  Determination  
 
Add to a 50 ml volumetric  flask:  
 
— 5 ml of the filtrate  (F), 
 
— . 5 ml of the ammonium  iron(III)  sulphate  soluti on (C.2.7).  
 DEAS 1079 : 2021  
12 © EAC 2021  – All rights reserved  
 Dilute to 50 ml with water, shake, and measure the absorbance  at a wavelength  of 450 nm by means  of the 
colorimeter  (C.3.4).  
 
C.4.6  Calibration  curve  
 
Transfer, by means of a pipette (C.3.3), 5 ml of the standard  volumetric  potassium,  or ammonium,  
thiocyanate solution  (C.2.8) to a 1 000 ml volumetric flask and dilute to the mark  with water.  
 
Into a series  of five 50 ml  volumetric  flasks,  transfer  the volumes of this diluted potassium, or ammonium, 
thiocyanate  solution  indicated  in the following  table : 
Volum e of diluted p otassium, or  ammonium,  
thiocyanate  solution  Corresponding mass  of thiocyanate  ion 
ml μg 
5 145.2  
10 290.4  
15 435.6  
20 580.8  
25 726 
 
Add to each flask, 5 ml of the ammonium iron  (III) sulphate  solution (C.2.7), dilute to the mark with water, shake, 
and measure  the absorbance  as indicated  in C.4.5.  
Plot a calibration curve, giving the a bsorbance as a function of  the number  of micrograms  of thiocyanate.  
 
C.4.7  Matching  test 
 
Carry out a matching test in the same conditions as the actual  test, but adding 2 drops of the mercury  (Ill chloride 
solution  (C.2.2) to correct for errors due to the react ion of phenols with  the iron(III)  salts.  
Note on the calibration curve the dif ference in absorbance be tween  the test solution,  containing  the 
thiocyanate  and phenols,  and the matching  test solution.  
C.4.8  Number  of determinations  
 
Carry  out two determinations  on the same  prepared  sample.  
C.5 Expression  of results  
 
C.5.1  Method  of calculation  and formula  
 
The ρ-hydroxybenzyl  isothiocyanate  content,  expressed  as a percentage by  mass  on the dry basis,  is equal  to 
 
 DEAS 1079 : 2021  
© EAC 2021  – All rights reserved  13 
 2.84 m 1 × 250 × 100 × 100 
           106     5      mo 100 – H  
where  
 
mo    is the mass,  in grams,  of the test portion;  
m1 is the mass, in micrograms, of thiocyanate read from  the calibration  curve;  
H is the moisture content of the sample, expressed as a  percentage by mass, determined by the method 
specified in  annex  A; 
2.84 is the conversion factor from thiocyanate ion (CNS -) to ρ-hydroxybenzyl  isothiocyanate.  
 
Take as the result the arithmetic mean of the two determinations (C.4.8), provided that the requirement for 
repeatability  (see C.5.2)  is satisfied.  
 
C.5.2  Repeatability  
The difference between the results of the two determin ations  (C.4.8), carried out simultaneously or in rapid 
succession by the  same  analyst,  shall not exceed  2 % of the mean  value.  
C.6 Note  on procedure  
 
The enzymic  activity  of the seeds  increases  during  certain  periods of the year (particularly in spring); thus,  
identical results  are not always  found  with a given  lot of seed,  according  to the season  in which  the analysis  is 
carried  out. 
 DEAS 1079 : 2021  
14 © EAC 2021  – All rights reserved  
 Annex  D 
(normative)  
 
Determination of ρ-hydroxybenzyl isothiocyanate  (Argentimetric  
method)  
 
D.0 Introduction  
 
Laboratories not in possession of a colorimeter may determine  thiocyanate  by argentimetry.  In this case it is 
necessary  either  
 
a) to carry  out a preliminary  check  for the absence of  CI—ions in the seed  (no reaction  with sil ver nitrate on 
the ash of the mustard  seed);  or 
 
b) to provide for correction by carrying out the determination  of CI—ions on an aliquot  portion  of the filtrate.  
 
This method may be substituted for the colorimetric method by  agreement  between  the parties  concerned.  
 
 
D.1 Principle  
 
Decomposition, by enzymic  hydrolysis,  of sinalbin  (glucoside  of Sinapis albas into glucose, the hydrogen 
sulphate of sinapin  and ρ-hydroxybenzyl isothiocyanate, the last -mentioned giving  ρ-hydroxybenzyl alcohol and 
thiocyanate. Determination of the  thiocyanate  thus formed,  by argentimetry  in nitric  acid medium; back titration 
of the excess of silver nitrate using stan dard volumetric  potassium thiocyanate solution in the presence  of 
ammonium  iron(III)  sulphate.  
D.2 Reagents  
 
All reagents shall be of recognized analytical quality. The water  used shall be distilled water or water of at 
least equivalent  purity.  
The reagents  necessary  for hydrolysis  and clarification  (see annex  C), together  with 
D .2.1 Nitric  acid , e 20 = 1.40 g/ ml. 
D.2.2  Silver nitrate, standard volumetric solution,  c(AgNO3) = 0.1 mol/I.  
 
D.2.3  Potassium  thiocyanate , standard  volumetric  solution,  c(KCNS)  0.1 mol/I.  
 
D.2.4  Ammonium  iron (III) sulphate  solution,  saturated  when  cold.  
 
D.3 Apparatus  
 
The apparatus necessary for the preparation of the sample hydrolysis and clarification (see annex C), 
together with  
 
D.3.1  One-mark  pipettes , of capacities  5 and 100 ml, complying  with the requirements  of ISO 648, class  
A. 
 DEAS 1079 : 2021  
© EAC 2021  – All rights reserved  15 
 D.3.2  Burette , graduated  at every  0.05 ml, complying  with the requirements  of ISO/ R 385, class  A. 
 
D.4 Procedure  
 
D.4.1  Preparation  of test sample,  test portion,  hydrolysis  and clarification  
 
Proceed  as specified  in C.4.1  to C.4.4  of annex  C. 
 
D.4.2  Titratio n 
 
Add to the beaker,  shaking  after each  addition:  
 
— 100 ml, by means of a pipette (D.3.1), of the filtrate (F)  (see C.4.4), and approximately equivalent to 2 g of 
mustard  seed;  
 
— 1 ml of the nitric  acid (D.2.1);  
 
— 5 ml, by means of a pipette (D.3.1), of  the standard  volumetric  silver  nitrate  solution  (D.2.2);  
 
— 2 ml of the ammonium  iron(III)  sulphate  solution  (D.2.4).  
 
Shake the flask to coagulate the precipitate, and bitrate with the  potassium thiocyanate solution (D.2.3) until a 
persistent faint  red colour  is obtained.  
 
D.4.3  Number  of determinations  
 
Carry  out two determinations  on the same  prepared  sample.  
 
D.5 Expression  of results  
 
D.5.1  Method  of calculation  and formula  
 
The ρ-hydroxybenzyl isothiocyanate content,  expressed  as a percentage  by mass  on the dry basis,  is 
equal to 
 
0.016 5 (5  V) × 250 100 × 100 
       100  m  100  H 
Where  
 
m is the mass, in grams, of the test portion (see annex  C, C.4.2);  
V is the volume, in millilitres, of the sta ndard volumetric potassium thiocyanate solution (D.2.3) used in the 
titration.  
H is the moisture content of the sample, expressed as a percentage by mass, determined by the method 
specified in annex A.  
 DEAS 1079 : 2021  
16 © EAC 2021  – All rights reserved  
 NOTE — If the standard volumetric solutions used are not of the exact  concentrations specified in clause D.2, a 
suitable corr ection factor  should  be used  in calculating  the result.  
Take as the result the arith metic mean of the two determina tions ( D.4.3),  provided  that the requirement  for 
repeatability  (see D.5.2)  is satisfied.  
 
D.5.2  Repeatability  
 
The differenc e between the results o f the two  determinations  (D.4.3), carried out simultaneously or in 
rapid succession by  the s ame analyst, shall not exceed 0.1 g of ρ-hydroxybenzyl  isothiocyanate per  100 
g of dry matter  in the sample.  DEAS 1079 : 2021  
© EAC 2021  – All rights reserved  17 
 Annex  E 
(informative)  
 
Recommendations relating to storage and transport  
 
E.1 The packs  of mustard  seed  should  be stored  in covered  prem ises well protected  from the sun, rain and 
excessive  heat.  
E.2 The store room should be dry, free from objectionable odours and proofed against entry of insects and vermin. 
The ventilation  should be controlled so as to give good ventilation under dry condi tions and no ventilation 
under damp conditions. In a storage  warehouse,  suitable  facilities  should  be available  for fumigation.  
E.3 The packs should be so handled and transported that they are protected from the rain, from the sun or other 
sources of ex cessive heat,  from objectionable  odours  and from cross -infestation,  especially  in the holds  of 
ships.  
 
 DEAS 1079 : 2021  
18 © EAC 2021  – All rights reserved  
 Bibliography  
[1] ISO 1237 : Mustard seed  
 
 . DEAS 1079 : 2021    
 
© EAC 2021  – All rights reserved  
  
  