i 
   
ICS 67.080               DMS 542:2022   
    Second  Edition  
 
 
 
 
 
 
DRAFT MALAWI STANDARD  
 
MALAWI STANDARD  
  
 
 
 
 
 
 
 
Sorghum grains  – Specification  
 
 
 
 
 
 
 
 
 
 
Note: This is a draft Malawi standard  and shall neither be regarded nor used as a Malawi standard  
 
 ICS 67.080         DMS 542 :2022  
                                                                                                                              Second Edition  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Sorghum  grains – Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Obtainable from the  
Malawi Bureau of Standards  
Ali Hassan Mwinyi  Road  
P O Box 946  
BLANTYRE  
 
 Tel: +265 1 870 488  
Fax: +265 1 870 756  
 E-mail: mbs@mbsmw.org  
Website: www.mbsmw.org  
 
Price based on 9 pages  
© Copyright reserved   
i TABLE OF CONTENTS  
 
Contents  ................................ ................................ ................................ ................................ .....................  Page  
Foreword  ................................ ................................ ................................ ................................ .............................  ii 
Technical Committee  ................................ ................................ ................................ ................................ ..........  ii 
Notice  ................................ ................................ ................................ ................................ ................................ .. ii 
Scope  ................................ ................................ ................................ ................................ ................................ . 1 
Normative references  ................................ ................................ ................................ ................................ ........  1 
Terms and definitions  ................................ ................................ ................................ ................................ ........  2 
Quality requirements  ................................ ................................ ..........................  Error! Bookmark not defined.  
Contaminants  ................................ ................................ ................................ ................................ .....................  3 
Hygiene  ................................ ................................ ................................ ................................ ..............................  4 
Packaging  ................................ ................................ ................................ ................................ ..........................  5 
Labelling  ................................ ................................ ................................ ............  Error! Bookmark not defined.  
Sampling  ................................ ................................ ................................ ................................ ............................  5 
Annex A: Determination of ergot  ................................ ................................ ................................ .......................  6 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
ii FOREWORD  
 
This draft Malawi standard  has been prepared by MBS/TC 16, the Technical Committee on Cereals, pulses, 
legumes and their products to provi de requirements for sorghum  grains.  
 
This draft Malawi standard  is a revision of MS 544:2010, and has been prepared with reference to th e following 
standards:  
 
African Standard ARS 462 2022 , Sorghum  grains – Specification ; and  
 
Codex Stan 168:1987(Rev.1:1995, Amended 2019, Standard for sorghum  grains.  
 
Acknowledgement is made for the use of the information.  
 
 
TECHNICAL COMMITTEE  
 
This draft Malawi standard  has been prepared by MBS/TC 16, the Technical Committee on Cereals, pulses, 
legumes and their products and the following companies, organizations and institutions were consulted:  
 
Agricultural Development and Marketing Corporation;  
Agricultural Commodity Exchange;  
Auction Holdings Limited Commodity Exchange;  
Export Trading Limited;  
Lilongwe University of Agriculture and Natural Resources;  
Ministry of Agriculture – Department of Crop Development;  
National Smallholder Farmers’ Association of Malawi;  
Rab Processors Limited; and  
University of Malawi.  
 
 
NOTICE  
 
This standard shall be reviewed every five years, or earlier when it is necessary, in order to keep abreast of 
progress. Comments are welcome and shall be considered when the standard is being reviewed.  
 
  
1 
                  DMS 544:2022  
 
DRAFT MALAWI STANDARD  
 
Sorghum  grains – Specification  
 
1 SCOPE  
 
This draft Malawi standard  specifies the quality and grading requirements and methods of sampling and  
test for sorghum grains of varieties (cultivars) grown from Sorghum bicolor (L.) Moench intended for  
human consumption, i.e., ready for its intended use as human food, presented in packaged form or  
sold loose from the package directly to the consumer. It does not apply to other products derived from  
sorghum grains.  
 
 
2 NORMATIVE REFERENCES  
 
The followi ng standards contain provisions, which through reference in this text, constitute provisions of this 
Malawi standard. All standards are subject to revision and, since any reference to a standard is deemed to be 
a reference to the latest edition of that sta ndard, parties to agreements based on this standard are encouraged 
to take steps to ensure the use of the most recent edition of the standard s indicated below. Information on 
current valid national and international standards can be obtained from the Malawi Bureau of Standards.  
 
MS 19: Labeling of prepacked foods – General standard;   
 
MS 21: Food and food processing units – Code of hygienic cond itions;  
 
MS145:  Cereals and cereal products — Sampling:  
 
MS 302: Contaminants and toxins in fo od and feed – General standard;  
 
MS 612:  Sorghum – Determination of tannin content;  
 
MS 1796 : Pulses — Determination of impurities, size, foreign odours, insects,  and species and variety — 
Test methods;  
 
AOAC Official Method 2001.04: Determination of Fumonisins B 1 and B 2 in corn and corn flakes — Liquid 
chromatography with immunoaffinity column cleanup.  
 
ISO 520: Cereals and pulses — Determination of the mass of 1000 grains;  
  
ISO 711: Cereals and cereal products — Determination of moisture content (Basic reference method)   
 
ISO 712: Cereals and cereal products — Determination of moisture content — Routine reference method;  
  
ISO 5498: Agricultural food products — Determination crude fibre content — General method;  
 
ISO 5984: Animal feeding stuffs — Determination of crude ash ;  
 
ISO 6561 -1: Fruits, vegetables and derived products — Determination of cadmium content — Part 1: Method 
using  graphite furnace atomic absorption spectrometry;   
 
ISO 6561 -2: Fruits, vegetables and derived products — Determination of cadmium content — Part 2: Method 
using flame atomic absorption spectrometry;  
  
ISO 6579: Microbiology of food and animal feeding stuf fs — Horizontal method for the detection of 
Salmonella spp;  
  
2 ISO 6637: Fruits, vegetables and derived products — Determination of mercury content — Flameless atomic 
absorption method ;  
 
ISO 6888 -1: Microbiology of food and animal feeding stuffs — Horizontal method for the enumeration of 
coagulase -positive staphylococci (Staphylococcus aureus and other species);  
 
ISO 7251:  Microbiology of food and animal feeding stuffs — Horizontal method for the detection and 
enumeration of presumptive Escherichia coli — Most probable number technique;  
  
ISO 7971: Cereals — Determination of bulk density, called mass per hectolitre — Part 2: Method of 
traceability for measuring instruments through reference to the international standard instrument;  
  
ISO 11085: Cereals, cereals -based products and animal feeding stuffs — Determination of crude fat and 
total fat content by the Randall extraction method ;  
 
ISO 16050:  Foodstuffs — Determination of aflatoxin B 1, and the total content of aflatoxin B 1, B 2, G 1  
and G 2 in cereals, nuts and derived products — High performance liquid chromatographic method;  
  
ISO 20483: Cereals and pulses — Determination of the nitrogen content and calculation of the crude protein 
content — Kjeldahl method;  
 
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;  and 
 
ISO 27085: Animal feeding stuffs – Determination of calcium, sodium, phosphorus, magnesium,  
potassium, iron, zinc, copper, manganese, cobalt, molybdenum, arsenic, lead and cadmium by ICP - 
AES. 
 
 
3 TERMS AND DEFINITIONS  
 
For the purpose of this Malawi standard, the following terms and definitions shall apply:  
 
3.1  
broken kernels  
pieces of sorghum grain which passes through a screen having round holes of 1.8 mm in diameter  
 
3.2 
damaged grains  
kernels, pieces of sorghum kernels, and other grains that are badly ground damaged, badly weather 
damaged, diseased, frost -damaged, germ -damaged, heat -damaged, insect -bored, mould -damaged, 
sprout -damaged, or otherwise materially damaged  
 
3.3 
decorticated grains  
grains from which the external casings and whole or parts of the germ have been removed in an 
appropriate manner, using mechanical treatment  
 
3.4  
foreign matter  
foreign matter is mineral or organic matter (dust, twigs, seed coats, seeds of other species, dead insects, 
fragments, or remains of insects, other impurities of animal origin)  
 
3.5  
immature and shrivelled grains  
grains that are not properly developed  
 
3.6  
poisonous, toxic and/or harmful seeds  
any seed which if present in quantities above permissible limit may have damaging or dangerous effect 
on health, organoleptic properties or technological performance such as Jimson weed — Datura ( D. 
fastuosa  Linn and D. stramonium  Linn.) corn cokle ( Agrostemma githago  L., Machai Lallium remulenum   
3 Linn.) Akra (Vicia species), Argemone mexicana , Khesari and other seeds that are commonly recognized 
as harmful to health  
 
3.7 
sorghum grain   
grain that, before the removal of dockage, consists of 50 % or more of whole kernels of sorghum (Sorghum 
bicolor (L.) Moench) excluding non -grain sorghum and not more than 10.0 % of other grains for which 
standards have been established.  
 
3.8  
sprouted  
sprouted grains are those with any visible evidence of root system beginning to emerge  
 
3.9  
test weight  
the density of a measured volume of grain expressed in kilograms per hectolitre  
  
 
4 QUALITY REQUIREMENTS  
 
4.1 General requirements   
 
4.1.1  Sorghum grains shall meet the following general requirements : 
 
a) The dried mature grains of Sorghum bicolor (L.) Moench ; 
 
b) Hard, clean, wholesome, uniform in size and shape;  
 
c) Free from abnormal flavours, musty, sour or other undesireable odour, obnoxious smell and 
discolouration;  
 
d) Safe and suitable for human consumption; and  
 
e) Free from micro -organisms and substances originating from micro -organisms, fungi or other 
poisonous or deleterious substances in amounts that may constitute a hazard to human health.  
 
4.1.2  Sorghum grains shall be in form of well -filled seeds of uniform colour.  
 
4.3 Grading  
 
Sorghum grains may be classified into three grades on the basis of the tolerable limits established in Table 1  
which shall be additional to the general requirements set out in this draft Malawi standard . 
 
4.4 Microbiological requirements  
 
Sorghum  shall comply with the microbiological limits given in Table 2.  
 
 
5 CONTAMINANTS  
 
5.1 Heavy metals  
 
Sorghum  grains shall be free from heavy metals in amounts which may represent a hazard to human health 
and shall comply with maximum limits indicated in MS 302.  
 
5.2 Pesticides residues  
 
Sorghum  shall conform to the Maximum Residue Limits for  pesticides  established by the Codex Alimentarius 
Commission.  
 
 
 
 
  
4 Table 1: Specif ic requirements for sorghum  
 
S/N 1 2 3 
1 Characteristic  Specification  Method       
of 
test Grade 1  Grade 2  Grade 3  
2 Moisture, max (%)  13.5 13.5 13.5 ISO 711/712  
3 Test weight, Min (kg/hl)  71 62 62 MS 1796  
4 Total admixture max (% by wt) 
(Total of foreign material, 
screenings  
and trash)  11.0 30.0 50.0 
5 Foreign material max (% by wt)  2.0 3.0 4.0 
6 Foreign matter, decorticated seed 
(% by wt)  0.5 0.5 0.5 
7 Screenings, max (%  by wt) (All 
matter passing through a 2.0 mm  
slotted screen - 40 shakes in the 
direction of the slots using an  
agitator)  11.0 25.0 50.0 
8 Trash, max (% by wt) (Chaff and 
other sorghum trash retained  
above a 2.0 mm slotted screen 
following the screening process)  5.0 15.0 15.0 
7 Crude protein, % by dry mass 
basis, min 7.0 7.0 7.0 ISO 20483  
8 Ergot affected grains, %m/m  0.05 Annex A  
9 Tannin content, %  
on dry mass basis,  
max.  Whole grains  0.5 0.5 0.5 MS 619  
Decorticated grains  0.3 0.3 0.3 
10 Defective   grains,  
max  (% by count,  
300 grain sample  Weather stained  5.0 20.0 20.0 MS 1796  
Field fungi  5.0 10.0 10.0 
Dry green  5.0 10.0 10.0 
Immature grain (fully 
green in colour)  5.0 10.0 10.0 
Split/broken  7.0 10.0 10.0 
Total defective  5.0 8.0 10.0 
11 Small foreign seeds (% by weight)  1.6 1.6 1.6 
12 Total aflatoxin (AFB1+AFB2+AFG1 
+AFG2)), ppb, max  10 ISO 16050  
13 Aflatoxin B1 only, ppb, max  5 
14 Fumonisin, ppm, max  2 AOAC Official  
Method  
2001.04  
 
Table 2: Microbiol ogical limits  for sorghum  
 
S/N 1 2 3 
1 Type of micro -organism  Limits  Test method  
2 Yeasts and moulds, cfu per g, max  105 ISO 21527 -2 
3 Staphylococcus aureus, cfu  per 25 g, max  Absent  ISO 6888  
4 E. coli , max. per g  Absent  ISO 7251  
5 Salmonella, max. per 25 g  Absent  ISO 6579  
 
 
6 HYGIENE  
 
6.1 Products covered by the provisions of this standard shall be prepared and handled in accordance with 
the appropriate clauses of MS 21.   
5  
6.2 To the extent possible in good manufacturing practice, the product shall be free from objectionable 
matter.  
 
 
7 PACKAGING  
 
7.1  Sorghum grains shall be packaged  in suitable packages which shall be clean, sound, free from 
insect, fungal infestation and the packing material shall be of food grade quality and shall be securely closed 
and sealed.  
 
7.2  Sorghum grains shall be packaged  in containers which will safeguard the hygienic, nutritional, 
technological and organoleptic qualities of the products.  
7.3  Each package shall contain sorghum grains of the same type and of the same grade 
designation.  
 
7.4  If  sorghum  grains  are  presented  in  bags,  the  bags  shall  also  be  free  of  pests  and 
contaminants.  
 
Note:  Maximum package weight of 50 kg where human loa ding and offloading is involved.  
 
 
8. LABELLING  
 
In addition to the requirements of MS 19, the following specific provisions shall apply:  
 
8.1 Product name as “Whole Sorghum Grains” ; 
 
8.2 Variety;  
 
8.3 Grade;  
 
8.4 Name, address and physical location of the producer/ packer/importer;  
  
8.5 Lot/batch/code number;  
 
8.6 Net weight in Kg;  
 
8.7 The declaration “Food for Human Consumption’’  
 
8.8 Storage instruction as “Store in a cool dry place away from any contaminants’’;  
 
8.9 Crop year;  
 
8.10 Packing date;  
 
8.11 Instructions on disposal of used  package;  
 
8.12 Country of origin; and  
 
8.13 A declarat ion on whether the sorghum was genetically modified or not.  
 
 
9 SAMPLING  
 
Sampling shall be done in accordance with the MS 145 . 
 
 
 
 
 
 
 
 
  
6 Annex A  
(Normative)  
 
DETERMINATION OF ERGOT  
 
A.1 Test for presence of ergot in food grains  
 
A.1.1  Reagents  
 
(a) Petroleum ether  40 – 60 °C  
 
(b) diethyl ether  
 
(c) Dilute Ammonia  10 % (v/ v)  
 
(d) Tartaric acid solution  — 1 % (freshly prepared)  
 
(e) p-dimethyl amino benzaldehyde (PDAB)  — Dissolve 0.125 gm of PDAB in a cold mixture of 65 ml 
of conc sulphuric acid and 35 ml of distilled water.  
 
Add 0.1 ml of 5 % Ferric chloride solution and let it stand for 24 hours before use.  
 
A.1.2  Apparatus  
 
(a) Grinding mill  
 
(b) Electric shaker  
 
A.1.3  Procedure  
 
Grind about 50 gm of sample in the grinding mill to a fine powder. Take 10 gm of powdered sample in a 
stoppered conical flask. Add sufficient petroleum ether and shake for half an hour in the electric shaker. Allow 
to settle and decant off  the petroleum ether. Dry the material in air. Add to the material 8 ml of dilute ammonia 
and sufficient quantity of solvent ether. Again shake for ½ hour. Filter ether portion in a beaker and concentrate 
to a small volume. Add 2 ml of tartaric acid soluti on to the beaker and shake thoroughly. Mix 1 ml of this tartaric 
acid – sample solution with 1 or 2 ml of p -dimethyl benzaldehyde solution.  
 
The appearance of blue colour indicates presence of ergot.  
 
A.2 Determination of quantity of ergot ( Claviceps purp urea  Tul.)  
 
A.2.1  Objective and field of application  
 
The method is used for both qualitative and quantitative determination of ergot in food and feed. The method 
is suitable for the examination of food and feed of different particle sizes. In pelleted feedingstuff only qualitative 
determination is possible.  
 
A.2.2  Principle  
 
Ergot in food and feed is determined by the macroscopic and microscopic identification of the ergot sclerotia 
and fragments. Quantification is done by weighing the amount of identif ied sclerotia and fragments with a 
particle size >0.5 mm.  
 
A.2.3  Reagents  
 
A.2.3.1 Chloral hydrate,  = 60%  
 
A.2.3.2 Sodium hydroxide (pelleted)  
 
A.2.3.3 Potassium hydroxide (pelleted)  
 
A.2.3.4 Ethanol,  = 50%  
  
7 A.2.3.5 Acetone  
 
The reagents listed can be replaced by others which produce comparable results.  
 
A.2.4  Equipment and accessories  
 
A.2.4.1  Optical equipment  
 
A.2.4.1.1 Stereo microscope (up to 70x magnification)  
 
A.2.4.1.2 Magnifier (up to 10x magnification)  
 
A.2.4.2  Mortar and pestle  
 
A.2.4.3  Sieve s fitted with wire nettings or perforations with different mesh sizes (e.g. 2.0 mm, 1.0 mm, 0.5 mm, 
0.25 mm) and collecting tray; recommended additional equipment: sieve towers, sieve shaker  
 
A.2.4.4  Analytical balance (accuracy 0.001 g)  
 
A.2.4.5 Oven (up to 130 °C)  
 
A.2.4.6 Laboratory glassware  
 
A.2.4.7 Filters (e.g. paper, gaze)  
 
A.2.4.8 Freeze dryer  
 
A.2.4.9 Hot plate or Bunsen burner  
 
A.2.4.10 Reference material  
 
A.2.5  Procedure  
 
The examination is performed in non -pelleted food and feed. Pelleted food and feed have to be depelleted 
before examination ( A.2.4.2 ; A.2.8.1 ). 
 
Qualitative determination of the sclerotia is performed macroscopically and microscopically considering ergot 
and its fragments in both the sieve fraction >0.5mm and < 0.5mm.  
 
Quantific ation is performed by selecting and weighing of ergot and its fragments with a particle size >0.5mm 
out of the laboratory sample or an aliquot of it.  
 
A.2.5.1 Preparation of the laboratory sample  
 
A.2.5.1.1 Whole kernel feeding stuff  (at least 250g) are we ighed ( A.2.4.4 ) and used directly for the investigation 
(A.2.5.2  and A.2.5.3 ). 
 
A.2.5.1.2 Non-pelleted feeding stuff (at least 10g) are weighed ( A.2.4.4 ) and fractionated bysieving. The 
obtained fractions > 0.5mm and  0.5mm are weighed ( A.2.4.4 ). 
 
A.2.5.2  Identification of ergot  
 
Ergot sclerotia are identified based on their characteristic features. The identification may be facilitated by 
comparison to reference material ( A.2.4.10 ) and existing descriptions.  
Morphology : Ergot sclerotia  Tul. are elongated with a length up to several centimetres, coloured dark violet to 
black. The shape is similar to cereal kernels. They only consist of fungal hyphae.  
 
Anatomy : Cross sections through the random parts of ergot sclerotia show very small, na rrow interconnected 
hyphae which yield a dense pseudoparenchymatic tissue. The cells contain lots of fat oil. The outer layers of 
the hyphae are coloured dark violet to black, whereas the inner parts are coloured light pink to violet.  
 
For the identificati on of ergot fragments in the sieve fractions <0.5mm the following colour reaction can be 
used. This staining procedure is only applicable to fresh sclerotia material.   
8  
A filter paper is soaked with a solution of 3ml ethanol ( A.2.3.4 ) and 2 sodium hydroxide  pellets ( A.2.3.2 ) or 2 
potassium hydroxide pellets ( A.2.3.3 ). The sample is distributed on the filter paper.  
 
After app. 5 min. a red -violet halo around the ergot fragments is observed.  
 
The dark violet colouring of the outer hyphae layers is dissolved al so in chloralhydrate ( A.2.3.1 ) and colours it 
violet.  
 
A.2.5.3 Quantification  
 
The quantification of ergot is performed using the sieve fractions > 0.5 mm.  
 
Material identified as ergot in each fraction is selected and weighed. An aliquot of the sieved fra ctions may be 
used if necessary. The ergot content of the fractions >0.5mm is summarized and expressed in mg/kg feeding 
stuff ( A.2.6.1 ). 
 
A.2.6  Calculation and report  
 
A.2.6.1  Calculation  
 
The amount of ergot fragments in mg/kg (ppm) feeding stuff (original sample) is calculated using the following 
formula:  
 
EBCC1000
 [mg/kg]  
 
C = amount of component in mg/kg feeding stuff (ppm)  
 
BC = selected fragments of component in the laboratory sample or an aliquot of it [mg]  
 
E = total weight of the laboratory sample or an examined aliquot of the laboratory sample [g]  
 
A.2.6.2 Report  
 
A.2.6.2.1 Negative result:  
 
As far as was discernible using a microscope, ergot was not found in the submitted sample.  
 
A.2.6.2.2 Positive result:  
 
As far as was discernible using a microscope xx mg ergot/kg feeding stuff were found in the submitted sample. 
For quantification ergot particles >0.5 mm are considered.  
 
A.2.6.2.3 Possible adding to the report:  
 
In pelleted feeding stuff only qualitative  determination of ergot is possible.  
A.2.7     Remarks  
 
A.2.7 .1 For the identification of ergot in pelleted feedstuffs, the sample is depleted using either of the 
following procedures:  
 
(a)  At least 10 g of the pressed material is mixed with at least three times as much water. The  
suspension is stirred up several times and left standing until the pellets disintegrate. Then the  
depelletised material is filtered ( A.2.4.7 ) and dried at room temperature or freeze -dried  
(A.2.4.8 ).  
(b)  For depelletising at high humidity pressed material (at least 10 g) is left standing in humid  
atmosphere at 70 °C ( A.2.4.5 ) until the pellets disintegrate. The material is crushed, sieved  
(A.2.4.3 ) and dried at room temperature immediately to prevent the particles from sticking  
together again.   
9 A.2.7 .2 Ergot are the permanent forms or sclerotia of ergot which mainly occur in rye, more seldom in wheat, 
triticale and barley.  
A.2.7 .3 This method also is suitable for the examination of raw material and food.   
 
 
ICS 67.060                  DMS 542 :2022  
                                                                                                                                  Second Edition  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
THE MALAWI  BUREAU OF STANDARDS              CERTIFICATION MARK SCHEME  
The Malawi Bureau of Standards is the 
standardizing body in Malawi under the aegis 
of the Ministry of Trade and Industry.  Set up in 
1972 by the Malawi Bureau of Standards Act 
(Cap: 51:02), the Bureau is a parastatal body 
whose activities aim at formulating and 
promoting the general adoption of standards 
relating to structures, commodities, materials, 
practices, operations and from time to time 
revise, alter and amend the same t o 
incorporate advanced technology.  To bring the advantages of standardization 
within the reach of the common consumer, the 
Bureau operates a Certification Mark Scheme. 
Under this scheme, manufacturers who 
produce goods that confor m to national 
standards are granted permits to use the 
Bureau’s “Mark of Quality” depicted below on 
their products.  This Mark gives confidence to 
the consumer of the commodity’s reliability. 
 2