Edible s alt ─ Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Note: This is a draft Malawi standard and shall neither be used nor regarded as a Malawi Standard  
 
________  
Published by  
MALAWI STANDARDS BOARD  
 ICS 67.220.20                 DMS 188:2021  
              Third  edition  
 
 
 
DRAFT MALAWI STANDARD  
(COMESA /SADC HARMONISED)  
 
 
 
 ICS 67.220.20                  DMS 188:2021  
                                                                                          Third edition  
 
 
 
 
 
 
 
Edible salt ─ Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Obtainable from the  
Malawi Bureau of Standards  
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 1 3 pages  
© Copyright reserved   
 i TABLE OF CONTENTS  
 
Content  Page  
Foreword   ................................ ................................ ................................ ................................ ....................     i 
Technical committee   ................................ ................................ ................................ ................................ ..    i 
Scope   ................................ ................................ ................................ ................................ .........................     1 
Normative reference   ................................ ................................ ................................ ................................ ..    1 
Terms and Definitions   ................................ ................................ ................................ ................................     1 
Description    ................................ ................................ ................................ ................................ .................     2 
Essential composition and other quality factors   ................................ ................................ ........................     2 
Food additives   ................................ ................................ ................................ ................................ ...........     2 
Contaminants   ................................ ................................ ................................ ................................ .............     2 
Hygiene   ................................ ................................ ................................ ................................ ......................     4 
Packaging , transportation and storage    ................................ ................................ ................................ ......    4 
Labeling   ................................ ................................ ................................ ................................ .....................     4 
Methods of sampling and test   ................................ ................................ ................................ ....................     5 
Annex A: Methods of sampling edible salt  ................................ ................................ ................................ .    6 
Annex B: Determination of iodine in edible salt   ................................ ................................ .........................     7 
Annex C: Determination of chloride content in edible salt   ................................ ................................ .........     8 
Annex D:  Determination of alkalinity in edible salt   ................................ ................................ ....................     10 
Annex E: Examination for the presence of red halophilic organisms   ................................ ........................     11 
Annex F: Determination of moisture content in edible salt   ................................ ................................ ........     12 
Annex G:  Determination for insoluble matter and drier co ntent   ................................ ................................     13 
 
FOREWORD  
 
This draft Malawi standard  is a third  edition of MS 188:1988, Specification for salt which covers the 
requirements for all types of salt includi ng table salt.and this is the second  revision of th e Malawi Standard. .   
 
This standard is exactly the same as COMESA/SADC harmonised standards on food grade salt in all respects 
except for iodine content, alkalinity and limits for contaminants. The COMESA/SADC Harmonised Standard is 
an adoption of CODEX STAN 150 , Adopted  in 198 5; Revised in 1997; 2012; Amended in 1999; 2001; 2006  – 
Food Grade Salt . 
 
Acknowledgement is made for the use of the information.  
 
 
TECHNICAL COMMITTEE  
 
The following institutions, companies and organisations were represented on the Technical Committee 
MBS/TC 8  Spices, condiments and culinary herbs : 
Blantyre City Council;  
Consumers Association of Malawi;  
Lilongwe University of Natural Resources;  
Malawi Bureau of Standards;  
Malawi University of Business and Applied Science;  
Ministry of Health – Blantyre District Health Office;  
Nali Limited;   
 ii Peoples Trading Center;  
Rab Processors Limited;  
Rambo Packaging;  
Shoprite Trading; and  
Tajo Products.  
 
 
NOTICE  
 
This standard shall be reviewed every five years, or earlier when it is necessary, in order to keep abreas t of 
progress. Comments are welcome and shall be considered when the standard is being reviewed.  
  
 1 DMS 188: 2021  
DRAFT MALAWI STANDARD  
 
Edible salt − Specification  
 
 
1 SCOPE  
 
This draft Malawi standard  applies  to salt used as an ingredient of food, both for direct sale to the consumer 
and for food manufacture. It applies also to salt used as a carrier of f ood additives and/or nutrients. It does not 
apply to salt from origins other t han those mentioned in this draft Malawi standard , notably the salt which is a 
by-product of chemical industries.  
 
 
2 NORMATIVE REFERENCES  
 
The following standard contains provisions, which through reference in th is text, constitute provisions of this 
draft 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 standard, parties to agreements based on this Malawi standa rd 
are encouraged to take steps to ensure the use of the most recent edition of the standard 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 conditions;  
 
MS 237:  Food additives  ̶   General standard;  
 
MS 302:  Contaminants and toxins in food;  and 
 
ISO 2479: Sodiu m chloride for industrial use – Determination of matter insoluble in water or in acid and 
preparation of principal solutions for other determinations . 
 
 
3 TERMS AND DEFINITIONS  
 
For the purposes of this draft Malawi standard  the following  terms and definitions shall apply:  
 
3.1  
iodised coarse salt  
shall mean coarse salt product consisting predominantly of sodium chloride to which iodine has been added 
for human and livestock consumption. It is obtained from sea, underground rock  salt deposits or na tural brine  
 
3.2  
edible salt  
shall mean iodised common salt that is meant for human  and livestock  consumption. It is used as an ingredient 
of food, both for the direct sale to the consumer and for the manufacture of food. Edible salt i s synonymous to 
food grade salt  
 
3.3  
anti-caking agents  
shall mean substances added to the salt in finely powdered form to prevent caking, lumping or agglomeration 
to impart a free flowing property and retard moisture absorption. Anti -caking agents include magnesium 
carbonate, calcium car bonate and tricalcium phosphate  
 
3.4  
Iodine  
shall mean a substance added to salt as a fortifier in the form of iodate or iodide  
 
  
 2 3.5  
iodised table salt  
shall mean crushed and dried coarse salt to which iodine has been added.  Ninety -nine percent (99 % m/m) 
of the iodised table salt s hall pass through 1.00 mm sieve  
 
3.6  
free flowing iodised salt  
shall mean iodised table salt to which anti -caking agents have been added.  Ninety -nine percent (99 % m/m) 
of the free flowing iodised  salt s hall pass through 1.00 mm sieve  
 
3.7  
special purpose salt:  
shall mean non -iodised salt intended for the food industry and/or medical use for which addition of iodine can 
cause adverse reaction to health or deterio rate the quality of the product  
 
 
4 DESCRIPTION  
 
4.1  Food grade salt is a crystalline product consisting predominantly of sodium chloride. It is obtained from 
the sea, from underground rock salt deposits or from natural brine.  
 
4.2 Classification  
 
Edible  salt shall be of three types name ly: 
 
4.2.1 Iodised coarse salt;  
 
4.2.2 Iodised table salt; and  
 
4.2.3 Free flowing iodised table salt.  
 
 
5 ESSENTIAL COMPOSITION AND QUALITY FACTORS  
 
5.1 Colour  
 
Edible salt shall be white, crystalline and free from grit and any other foreign matter.  
 
5.2 Particle size  
 
Ninety -nine percent (99 % m/m) of the iodised table salt and free flowing iodised table salt shall pass through 
1.00 mm sieve.  
 
5.3 Specific requirements  
 
Edible salt shall have comply with the specific requirements  as stipulated in Table 1 . 
 
5.4 Microbiological requirements  
 
The salt shall not contain red halophilic organisms when tested according t o Annex D . 
 
 
6 FOOD ADDITIVES  
 
Only those food additives listed under this product in MS 237 shall be used and only within the limits specified.  
 
 
7 CONTAMINANTS  
 
7.1 The products  covered by this draft Malawi standard  shall comply with the maximum levels for h eavy 
metals as stated in MS 302 . 
  
 3 7.2 The remainder comprises natural secondary products, which are present in varying amounts 
depending on the origin and the method of production of the salt, and which are composed mainly of calcium, 
potassium, magnesium and sodium sulphates, carbonates, bromides, and of calcium, potassium, magnesium 
chlorides as well. Natural contaminants may also be present  in amounts varying with the origin and the method 
of production of the salt. Copper shall not exceed 2 mg/kg (expressed as Cu).  
 
 
 
 
 
Table 1 ─ Specific  requirements for edible salt  
 
Characteristic  Requirement  
Method of test  Iodised 
coarse 
salt Iodised table 
salt Free flowing 
iodised table 
salt 
Moisture, % (m/m), max.  5.0 3.0 0.5 Annex M  
Water insoluble matter % 
(m/m) max.  1.0 0.5 1.0 Annex N  
Acid insoluble matter, % (m/m), 
max.  - 0.5 0.5 ISO 2479  
Chloride content (as NaCl), % 
(m/m), min.  96 97 97 Annex C  
Alkalinity (as CO 3), % (m/m), 
max.  1.0 1.0 1.0 Annex E  
Iodine (as KIO 3) ppm, (Port of 
entry, iodisation salt plant and 
prepacking factory)  80 - 100 80 - 100 80 - 100 Annex B  
Iodine (as KIO 3) ppm, min. 
(Whole sale and retail)  50 50 50 Annex B  
 
 
 
8 HYGIENE  
 
It is recommended that the products covered by the provisions of this draft Malawi standard  shall be prepared 
and handled in accordance with the appropriate sections of MS 21, and other relevant Codex texts  
 
 
9 PACKAGING , TRANSPORTATION AND STORAGE  
 
In any salt iodisation program, it is important to ensure that salt contains the recommended amount of iodine 
at the time of consumption. The retention of iodine in salt depends on the iodine compound used, the typ e of 
packaging, the exposure of the package to prevailing climatic conditions and the period of time between 
iodisation and consumption. To ensure that iodized salt ultimately reaches the consumer with the specified 
level of iodine, the following precautio ns may be taken into consideration by countries where climatic and 
storage conditions could result in a large amount of iodine loss:  
 
9.1 Edible salt shall be packed in , air tight, clean and dry moisture proof containers made of material which 
does not aff ect the quality of the salt and which ensures the ventilation of the appropriate Iodine level at the 
time of consumption.   
 
9.2 Suitable packing material shall include  bags of either high density polyethylene (HDPE) or 
polypropylene (PP) (laminated or non-laminated) or LDPE -lined jute bags (Grade 1803 DW jute bags lined 
with 150 gauge polyethylene sheet)  or woven plastic bags.   
  
 4 9.3 Edible salt shall be packed in 20 kg consumer packages at point of entry into Malawi and wholesale 
outlets.  The packages  shall be securely closed or sealed ’.  
 
9.4 Iodized table salt and free flowing iodised table salt shall be packed in a suitable moisture proof 
consumer packages which do not affect the quality of the salt and which ensures the retention of the 
appropriate  iodine level at the time of consumption.  The product shall be packed in 1 kg, 0.5 kg, 0.25 kg or 
other suitable small consumer packages at retail outlets.  The package shall be securely closed and sealed.  
 
9.5 Bags that have already been used for packing  other articles such as fertilizers, cement, chemicals, 
etc. should not be reused for packing iodised salt.  
 
9.6 The distribution network should be streamlined so as to reduce the interval between iodisation and 
consumption of salt.  
 
9.7 Iodised salt shoul d not be exposed to rain, excessive humidity or direct sunlight at any stage of storage, 
transportation or sale.  
 
9.8 Bags of iodised salt shall be stored only in covered rooms or “godowns” that have adequate ventilation.  
 
9.9 The consumer should be simila rly advised to store iodised salt in such a manner as to protect it from 
direct exposure to moisture, heat and sunlight.  
 
 
10 LABELING  
 
In addition to the requirements of MS 19, the following s pecific provisions shall apply;  
 
10.1 Name of the product  
 
10.1.1  The name of the product, as declared on the label shall be “salt”.  
 
10.1.2  The name “salt” shall have in its close proximity a declaration of either “Edible salt” or “Cooking salt” 
or “Table salt”.  
 
10.1.3  Only when salt contains one or more ferrocy anide salts, added to the brine during the crystallization 
step, the term “dentritic” could be included accompanying the name.  
 
10.2 Where salt is used as a carrier for one or more nutrients, and sold as such for public health reasons, 
the name of the prod uct shall be declared properly on the label, for example “ iodated salt ,” “iodised salt ”, “salt 
fortified with iron” “salt fortified with vitamins” and so on, as appropriate.  
 
10.3 Date ma rking and storage instructions  
 
The expiry date shall be indicated and in addition conditions of storage shall be declared.  
 
10.4 An indication of either the origin, according to the description on Section 2, or the method of production 
may be declared on the label, provided such indication does not mislead or deceive the  consumer.  
 
10.5 Labelling  of non -retail containers.   
 
Information for non -retail containers shall either be given on the container or in accompanying documents, 
except that the name of product, lot identification and name and address of the manufacturer or a packer shall 
appear on the container. However, lot identification and the manufacturer or packer may be replaced by an 
identification mark, provided that such a mark is clearly identifiable with the accompanying documents.  
 
 
11 METHODS OF SAMPLING AND  TEST  
 
11.1 The methods of sampling shall be done as outlined in Annex A.  
 
11.2 Test methods for edible salt have  been outlined in Annexes B to G .
 
  
6 
 Annex A  
 
METHOD OF SAMPLING EDIBLE SALT  
 
A1 General requirements  
 
In drawing, stirring, preparing and handling test samples, the following precautions shall be observed:  
 
A1.1  Samples shall not be taken at a place exposed to weather;  
 
A1.2  Precautions shall be taken to protect the samples, the sampling instrument and the containers for 
samples from adventitious contamination;  
 
A1.3  To draw a representative sample, the contents of each container selected for sampling shall be mixed 
thoroughly by suitable means;  
 
A1.4  The sample shall be placed in clean, dry and air -tight glass or plastic containers which are suitable;  
 
A1.5  Each sample container shall be sealed air -tight after filling and marked with full details of sampling and 
the date of sampling and year of manufacture;  
 
A1.6  The number of packages (n) to be selected from a lot shall depend upon the size of the lot (N) and 
shall be in accordance with the Table A.  
 
 
Table A − Number of packages to be selected for sample  
 
Lot size ( N) Number of packages to be selected (n)  
5 to 100  4 
101 to 500  5 
501 to 1000  7 
1001 to above  10 
*A lot is a collection of packages of the same size, type and style, which have been manufactured and 
packaged under essentially the same conditions.  If the consignment is declared to consist of different 
batches, the batches shall be marked separately and the group of containers in each batch shall 
constitute separate lots.  
 
 
A1.7  All samples shall be randomly taken.  
 
A2 Preparation of test samples  
 
The contents of the packages selected as per A1 shall be thoroughly mixed and by a process of quartering 
the sample shall be reduced to about 500 g for testing.  The test sample shall be immediately transferred to a 
sample container for testing.  
 
 
 
 
 
 
 
 
 
 
  
7 
  
Annex B  
 
DETERMINATION OF IODINE IN EDIBLE SALT  
 
 
B1 Reagents. Sodium thiosulphate, conc. sulphuric acid (H 2SO 4), potassium iodide, soluble chemical 
starch, and boiled  double -distilled water (BDDW).  
 
Preparation of reagents  
 
Sodium thiosulphate solutions:  Add 1.24 g in 1 ℓ BDDW. Store in cool dark place.  
 
Sulphuric acid, 1M solution:  To 90 mℓ of BDDM add 5.56 mℓ concentrated sulphuric acid slowly. Add further 
water to the volume to 100 mℓ. Store in a cool, dark place.  
 
Potassium iodide (KI) solution:  Dissolve 10 g KI in 100 mℓ BDDW.  
 
Saturated sodium chloride:  Take 100 mℓ BDDW in a be aker and go on adding crystalline sodium chloride 
with continuous stirring until no more salt is soluble.  Heat the contents of the beaker until the excess salt 
dissolves, then cool (Nacℓ crystals will appear on the sides of the beaker).  When completely c ool, decant the 
supernatant into a clean bottle.  This can be stored for 3 to 4 weeks.  
 
Soluble chemical starch solution:  To be prepared freshly each day as follows:  Add 1 g to 10 mℓ of boiling 
double distilled water, continue to boil until the starch com pletely dissolves.  Add saturated Nac ℓ solution to 
make up to 100 mℓ.  
 
 
B2 Apparatus. Analytical balance, hot plate or gas burner, 50 mℓ measuring cylinder with stopper,               
500 mℓ wash bottle, glass stirring rod, conical flask, 100 mℓ with stopp er, glass or plastic funnel, 1 mℓ pipette, 
5 mℓ pipette, 10 mℓ burette and stand, stop watch or clock, and closed box, cupboard or drawer to keep the 
conical flask.  
 
B3 Procedure. Carefully weigh 10.0 g of the salt sample on a clean piece of paper boat. Tr ansfer 
completely into the 50 mℓ measuring cylinder. Slowly add BDDW from a wash bottle and shake to dissolve 
completely.  Add more of the water to make up to the 50 mℓ mark. Transfer completely the 50 mℓ salt solution 
into a conical flask with stopper. Pi pette out 1 mℓ of the sulphuric acid solution and add it to the salt solution 
pipette out 5 mℓ of the KI solution and to the conical flask. The solution will turn yellow. Stopper the flask and 
place in the closed box or in the dark for 10 minutes. Pour the  sodium thiosulphate into the burette and adjust 
the level to the “0” mark. After the 10 minutes, take the flask out of the dark and while shaking it, titrate with 
sodium thiosulphate a top titration as soon as the solution turns pale (becomes very light y ellow). Add a few 
drops (1 to 5 mℓ of the fresh starch solution. The colour turns to deep purple. Continue titration until the purple 
coloration disappears as the solution becomes colourless. Note the burette reading.  
 
B4 Calculations. Calculate the conten t of iodine using the following equivalence:  
 
1 mℓ of sodium thiosulphate = 10.6 mg/kg (ppm)  
 
Report the date of testing, sample number, source of iodine in mg/kg (ppm).  
 
To obtain value of potassium iodate (KIO 3) multiply the 1 mg/kg by 1.6864.  
 
 
 
 
 
 
 
 
 
 
  
8 
  
 
Annex C  
 
DETERMINATION OF CHLORIDE CONTENT IN EDIBLE SALT  
 
C1 Reagents  
 
C1.1  Potassium chromate solution.  
 
Preparation:  Dissolve 5 g of potassium chromate (K 2CrO 4) in 10 mℓ of water.  
 
C1.2  Standard 0.1 N silver nitrate solution.  
 
Preparation:  Dissolve 17 g of silver nitrate (AgNO 3) in 100 mℓ of water.  Store the solution in the dark.  
 
C1.3  Standardization:  Weigh accurately 5.8g of analytical reagent grade sodium chloride (NaCℓ), 
previously dried at 200 oC  50 oC, into a 1 ℓ volumetric flask and dissolve it in approximately 200 mℓ of water.  
Adjust the temperature of this solution to 20 oC and dilute it to 1 000 mℓ with water at the same temperature.   
 
Pipette 25 mℓ of the sodium chloride solution at 20 oC into 250 mℓ conical flask, add 1 mℓ of potassium chromate 
solution, and titrate with the 0.1 N silver nitrate solution until a faint reddish -brown colour p ersists after brisk 
shaking.  Carry out a blank titration using the same procedure and replacing the 25 mℓ of sodium chloride 
solution with 25 mℓ of water.  
 
Calculate the Normality of silver nitrate solution:  
 
 
 = 
cbA
42277.0  
 
where  
 
A =  weight of sodium chlorid e in 1000 m ℓ solutions in grams;  
 
b = volume of silver nitrate solution required to titrate 25 mℓ of sodium chloride solution, in millilitres; 
and  
 
c = volume of silver nitrate solution required to titrate the blank, in millilitres.  
 
C1.4  Procedure  
 
C1.4.1  Carry out the determination in triplicate on each of the test samples.  
 
C1.4.2  Pipette 50 mℓ of the filtrate at 20 oC, reserved in accordance with 7.5.1(b), into a 250 mℓ volumetric 
flask and dilute to 250 m ℓ with water at the same temperature.  Mix  well and pipette 25 m ℓ of this solution at 
20 oC into a 250 mℓ conical flask.  If the solution is acid to litmus, neutralize with sodium bicarbonate; if the 
solution is alkaline, add dilute nitric acid (1:10) drop by drop until the solution is acid to lit mus and then 
neutralize with sodium bicarbonate.  Add 1 m ℓ potassium chromate solution and titrate with the standard    0.1 
silver nitrate solution until a faint reddish -brown colour persist after brisk shaking.  
 
C1.5  Calculation  
 
(a) Chloride content calculated as Nac ℓ on a moisture free (and drier -free) basis,  
 
             per cent = 
BNa 11169  
 
where  
 
a = volume of silver nitrate solution used in the titration, in millilitres   
9 
  
B = weight of sample in 1000 mℓ solution, corrected for moisture content and where  relevant, the drier 
content, in grams; and  
 
N = Normality of the silver nitrate solution.  
 
(b) Report the chloride content of each test sample as the mean of  its triplicate determinations. 
10 
  
Annex D  
 
DETERMINATION OF ALKALINITY IN EDIBLE SALT  
 
 
D1 Reagents  
 
D1.1 Screened methyl orange indicator  
 
Dissolve 0.2 g of methyl orange and 0.28 g of xylene cyanol FF in 100 mℓ of ethyl alcohol (50 per cent).  
 
D1.2 Standard 0.1 N hydrochloric acid solution  
 
D1.2.1  Preparation  
 
Dilute 10 m ℓ of concentrated hydrochloric acid (sp.gr.1.16) to 1000 mℓ with water.  
 
D1.2.2  Standardization  
 
Dry about 0.25 g of anhydrous sodium carbonate in a weighing bottle at 260 to 270 ºC for 30 minutes.  Allow 
to cool in a desiccator and weigh accurately, transfer the contents into a 250 mℓ conical flask, and re -weigh 
the empty of sodium carbonate.  Add 50 mℓ of water to the flask, and swirl the flask until the sodium carbonate 
is completely dissolved.  Add two drops of screened methyl  orange indicator and titrate with the 0.1 N 
hydrochloric acid solution until the colour changes from green to grey.  
 
Normality of hydrochloric acid solution = 
bA 87.18  
 
where  
 
A = weight of anhydrous sodium carbonate taken, in grams, and  
 
b = volume of the hydr ochloric acid solution used in the titration, in millilitres.  
 
D2 Procedure  
 
Pipette 200 m ℓ of the filtrate into a 500 m ℓ conical flask, add two drops of screened methyl orange indicator 
and titrate with the standard 0.1 N hydrochloric acid solution until the colour changes from green to grey.  
 
 
D3 Calculation  
 
Alkalinity, calculated as CO 3-2 on a moisture free basis, per ce nt = 
BNa 15  
 
where  
 
a = volume of hydrochloric acid solution used in the titration, in millilitres  
 
B = weight of sample in 1000 m ℓ solution corrected for moisture content and where relevant, in grams, and 
normally or the hydrochloric acid solution  
 
 
 
 
 
 
 
 
  
 
11 Annex E  
 
EXAMINATION FOR THE PRESENCE OF RED HALOPHILIC ORGANISMS  
 
 
E1 Glassware  
 
Sterililize all glassware used in the microbiological examination of the salt by application of dry heat at 170 ºC 
for 1 hour.  
 
E2 Preparation of Modified Nutrient Brine Medium (Dussault and Lachance)  
 
Dissolve 5 g of magnesium sulphate, 1 g of magnesium nitrate, 0.025 g of ferric chloride, 5 g of proteose 
peptone, 10 g of glycerol and  200 g of the test sample in 100 m ℓ of distilled water, warming to dissolve if 
necessary. Adjust the pH value of the solution to 7.5.  Sterilize this nutrient brine by autoclaving at 121 ºC for 
15 minutes and then divide it into two equal portions.  To one  portion, A, add 10 % skim milk, and to the other, 
B, add 3 % of plain agar.  
 
Immediately before using the medium, melt portion B and warm portion A (which must be well mixed to ensure 
uniform suspension).  Then mix the two portions together in a flask and  dispense between 15 and           20 m ℓ 
of the medium into each of two Petri dishes.  
 
E3 Inoculation and Incubation  
 
Sprinkle 1 g of the test sample on the medium in each dish and incubate the Petri dishes at 37 ºC for 14 days.  
 
E4 Examination  
 
After incubation examine the Petri dishes for red colonies; such colonies indicate the presence of red halophilic 
organisms.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 12 Annex F  
 
DETERMINATION OF MOISTURE CONTENT IN EDIBLE SALT  
 
 
F1 Procedure  
 
F1.1 Carry out the determination in    triplicates on each of the test sample.  
 
F1.2 Weigh out accurately about 10 g of the test sample into a weighing bottle approximately 3 cm high 
and 6 cm in diameter.  Dry at 140 ºC for at least 12 hours and until constant weight is attained.  
 
 
F2 Calculation  
 
F2.1 Moisture content, per cent = 
ABA 100) (  
where  
 
A = weight of sample taken, in grams, and  
 
B = weight of sample after drying in grams.  
 
F2.2 Report the moisture content of each test sample as the mean of its triplicate determinations.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 13  
Annex G  
 
DETERMINATION FOR INSOLUBLE MATTER AND DRIER CONTENT IN EDIBLE SALT  
 
G1 Procedure  
 
G1.1 Carry out the determination in triplicates on each of the test samples.  
 
G1.2 Weigh out accurately about 50 g of the test sample into a one litre beaker.  Add 500 to 700 m ℓ of 
water and mix well until all the soluble matter has dissolved.  Filter the solution through a Gooch crucible 
containing a medium asbestos pad; wash the beaker and the residue five times with 20 m ℓ portions of 
boiling water.  And add these portions to t he filtrate.  
 
Where relevant, examine the residue for visible impurities.  Transfer the filtrate to a one -litre volumetric 
flask; adjust the temperature of the filtrate to 20 ºC and dilute to 1000 m ℓ with water at the same 
temperature.  Retain the filtrate  for the determination of alkalinity and the contents of chloride, calcium, 
magnesium, sulphate, and fluorine.  Dry the residue at 100 ºC until constant weight is attained  
 
G1.3 If the salt contains a drier, wash the residue in the Gooch crucible five time s with 20 m ℓ portions of 
boiling hydrochloric acid (1.1) and then five times with 20 m ℓ portions of boiling water.  Dry the residue at 
100 ºC until constant weight is attained.  
 
G2 Calculation  
 
G2.1 Drier content.  Calculated on a moisture -free basis, perc ent = 
CBA 100  
 
G2.2 Free -flow table salt.  Insoluble matter, calculated on a moisture -free (and drier -free) basis,  
 
                                                percent = 
DB100  
 
G2.3 Other salts.  Insoluble matter, calculated on moisture -free basis, per cent = 
CA100  
 
where  
 A = weight of total residue before extraction with acid, in grams;  
 
 B = weight of residue after extraction with acid, in grams;  
 
C = weight of sample taken, corrected for moisture content, in grams; and  
 
D = weight of sample taken, corrected for moisture and drier contents, in grams  
 
G2.4 Report the insoluble matter and where relevant, the drier content of each test sample as the mean 
of its triplicate determinations ICS 67.220.20                   DMS 188:2021  
                                                                                                                                   Third edition  
 
 
 
 
 
 
 
THE MALAWI BUREAU OF STANDARDS  
The Malawi Bureau of Standards is the 
standardizing body in Malawi under the aegis 
of the Ministry of Industry and Trade.  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 o f standards 
relating to structures, commodities, materials, 
practices, operations and from time to time 
revise, alter and amend the same to 
incorporate advanced technology.  CERTIFICATION MARK SCHEME  
To bring the advantages of standardization 
within the rea ch of the common consumer, 
the Bureau operates a Certification Mark 
Scheme. Under this scheme, 
manufacturers who produce goods that 
conform 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.