ICS 67.230, 763.2012  
 
Reference number
DRS 150: 2023
© RSB 2023
  
 RWANDA 
STANDARD  DRS 
150 
 
Third edition  
yyyy-mm-dd  
Cooked packaged maize— Specification 
   
DRS 150: 2023 
©RSB 2023- All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition 
 
 
 
 
 
 
 
 
© RSB 2023 
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without 
prior written permission from RSB. 
Requests for permission to reproduce this document should be addressed to: 
Rwanda Standards Board 
P.O Box 7099 Kigali-Rwanda 
KK 15 Rd, 49 
Tel. +250 788303492 
Toll Free: 3250 
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw  DRS 150: 2023 
iii                ©RSB 2023- All rights reserved 
 Contents Page 
Foreword ............................................................................................................................................................. v 
1 Scope ................................................................................................................................................................ 1 
2 Normative references ...................................................................................................................................... 1 
AOAC 985.16, Tin in Canned Foods. Atomic absorption Spectrophotometric method  ............................... 1 
3 Terms and definitions ..................................................................................................................................... 2 
4 Requirements ................................................................................................................................................... 2 
4.1 Ingredients .................................................................................................................................................... 2 
4.1.1 Essential ingredients ................................................................................................................................ 2 
4.1.2 Optional ingredients.................................................................................................................................. 2 
4.2 General requirements .................................................................................................................................. 3 
4.3 Specific requirements .................................................................................................................................. 3 
4.4 Microbiological limits ................................................................................................................................... 3 
5 Food additives ................................................................................................................................................. 4 
6 Hygiene ............................................................................................................................................................. 4 
7 Contaminants ................................................................................................................................................... 4 
7.1 Pesticide residues and other contaminants .............................................................................................. 4 
7.2 Mycotoxins .................................................................................................................................................... 4 
7.3 Heavy metals ................................................................................................................................................. 4 
8 Packaging ......................................................................................................................................................... 5 
9 Labelling ........................................................................................................................................................... 5 
10 Sampling ........................................................................................................................................................ 5 
Annex A  (normative)  Determination of drained weight ................................................................................ 6 
A.1 Definition ...................................................................................................................................................... 6 
A.2 Apparatus ..................................................................................................................................................... 6 
A.3 Procedure ..................................................................................................................................................... 6 
A.4 Calculation .................................................................................................................................................... 6 
Annex B  (normative)  Determination of water capacity of containers ......................................................... 7 
B.1 Scope ............................................................................................................................................................ 7 
B.2 Definitions .................................................................................................................................................... 7 
B.3 Procedures ................................................................................................................................................... 7 
B.3.1 Metal containers ........................................................................................................................................ 7 
B.3.2 Glass containers ....................................................................................................................................... 7 
B.4 Calculation .................................................................................................................................................... 7 
B.4.1 Metal containers ........................................................................................................................................ 7 
B.4.2 Glass containers ....................................................................................................................................... 8 
Annex C  (normative)  Determination of Sodium chloride content ............................................................... 9 
C.1 Scope ............................................................................................................................................................ 9 
C.2 Definition ...................................................................................................................................................... 9 
C.3 Principle ........................................................................................................................................................ 9 
C.4 Reagents ....................................................................................................................................................... 9 DRS 150: 2023 
©RSB 2023- All rights reserved                  iv 
 C.5 Apparatus ......................................................................................................................................................9 
C.6 Procedure ................................................................................................................................................... 10 
C.7 Expression of results ................................................................................................................................ 10 
 DRS 150: 2023 
v                ©RSB 2023- All rights reserved 
 Foreword 
Rwanda Standards are prepared by Technical Committees and approved by Rwanda Standards Board (RSB) 
Board of Directors in accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards. 
The main task of technical committees is to prepare national standards. Final Draft Rwanda Standards 
adopted by Technical committees are ratified by members of RSB Board of Directors for publication and 
gazettment as Rwanda Standards. 
RS 150 was prepared by Technical Committee RSB/TC 003, Cereals, pulses, legumes and cereal products  
In the preparation of this standard, reference was made to the following standard (s): 
1) CODEX STAN 18, Canned Sweet Corn — Specification  
The assistance derived from the above source is hereby acknowledged with thanks. 
Thisthirdedition cancels and replaces the secondedition (RS 150: 2018)  which has been technically revised. 
Committee membership  
The following organizations were represented on the Technical Committee on Cereals, pulses, legumes and 
cereal products (RSB/TC 003) in the preparation of this standard. 
Enterprise URWIBUTSO/SINA GERARD 
MANOSALIWA Food Industries Ltd  
MINIMEX Ltd  
National Agricultural Export Development Board (NAEB) 
National Industrial Research and Development Agency (NIRDA) 
Nyarutarama Business Incubation Center 
One Acre Fund-Tubura 
Rwanda Food and Drugs Authority 
Zamura Feeds Ltd DRS 150: 2023 
©RSB 2023- All rights reserved                  vi 
 Rwanda Standards Board (RSB) – Secretariat 
 DRS 150: 2023 
1                ©RSB 2023- All rights reserved 
 Cooked packaged maize — Specification 
1 Scope 
This Draft Rwanda Standard specifies the requirements, sampling and test methods for cooked packaged 
maize (Zea mays indentata L. and/or Zea mays indurata L. or their hybrids) intended for human consumption. 
This standard does not include corn-on-the-cob. 
2 Normative references 
The following documents are referred to in the text in such a way that some 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. 
ISO 11289 , Heat-processed foods in hermetically sealed containers — Determination of pH 
AOAC 985.16, Tin in Canned Foods. Atomic absorption Spectrophotometric method  
RS CAC/RCP 1,  General principles of food hygiene 
RS CODEX STAN 192 ,General standard for food additives 
RS CODEX STAN 193, General Standard for Contaminants and Toxins in Food and Feed 
RS EAS 12 , Potable water — Specification 
RS EAS 2,  Maize Grains — Specification 
RS EAS 22,  Butter — Specification 
RS EAS 35,  Fortified edible salt — Specification 
RS EAS 38,  Labelling of pre- packaged foods — General requirements 
RS ISO 16050 , Foodstuffs — Determination of aflatoxin B1, and the total content of aflatoxins B1, B2, G1 and 
G2 in cereals, nuts and derived products — High-performance liquid chromatographic method 
RS 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 44 degrees C using 5-
bromo-4-chloro-3-indolyl beta-D-glucuronide 
RS 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 0,9  
©RSB 2023- All rights reserved                  2 
 RS ISO 24333 , Cereals and cereal products — Sampling 
RS ISO 6579-1,  Microbiology of the food chain — Horizontal method for the detection, enumeration and 
serotyping of Salmonella — Part 1: Detection of Salmonella spp 
3 Terms and definitions 
For the purposes of this standard, the following terms and definitions apply. 
3.1 
cooked packaged maize: 
maize which have been subjected to boiling or steaming and packed in food grade packaging materials 
3.2 
food gradepackaging material 
packaging material, made of substances which are safe and suitable for their intended use and which will not 
impart any toxic substance or undesirable odour or flavour to the product. 
3.3 
drained weight 
weight of the contents of the container after draining 
4 Requirements 
4.1 Ingredients 
4.1.1 Essential ingredients 
The following essential ingredients  shall be used in the preparation of cooked packaged maize and shall 
comply with relevant standards: 
a) maize grains complying with  RS EAS 2; and 
b) potable water complying with RS EAS 12. 
4.1.2 Optional ingredients 
The following optional ingredients including but not limited to the following may be used in cooked packaged 
maize  and shall comply with relevant standards:: 
a) sweetening ingredients such as sucrose, invert sugar, dextrose, glucose syrup; DRS 150: 2023 
3                ©RSB 2023- All rights reserved 
 b) herbs and spices; 
c) butter complying with RS EAS 22; 
d) salt complying with  RS EAS 35; 
e) pieces of green or red peppers or mixture of both, or other vegetables; and 
f) starches - natural (native), physically or enzymatically modified - in whole kernel style, only when used 
with butter. 
4.2 General requirements 
Cooked packaged maize shall: 
a) be free from extraneous matter; 
b) be free from off flavours and odours; 
c) be free from any insects and foreign matter; 
d) be safe and suitable for human consumption; and 
e) have colour characteristic of the variety. 
4.3 Specific requirements 
Cooked packaged maize shall comply with the requirements in Table 1 when tested in accordance with test 
methods specified therein. 
Table 1 — Specific requirements for cooked packaged maize 
S/N  Parameter  Requirements  Test method  
i.  Minimum drained weight, % of net weight  80 Annex A 
ii.  pH, 5-6  ISO 11289  
iii.  Salt content (as sodium chloride), % w/w max.  1.2  Annex C  
4.4 Microbiological limits 
Cooked packaged maize shall comply with the microbiological limits specified in Table 2 when tested in 
accordance with test methods specified therein. 
Table 2 — Microbiological limits for cooked packaged maize 
S/N  Micro-organism  Maximum limits  Test method   
©RSB 2023- All rights reserved                  4 
 i.  Total viable count, CFU/g,  103 RS ISO 4833-1 
ii.  E. coli, CFU/g Absent  RS ISO 16649-2  
iii.  Salmonella spp , in  25g  Absent  RS ISO 6579-1 
iv.  Yeasts and moulds, CFU/g 102 RS ISO 21527-2 
v.  Clostridium botulinum , CFU/g Absent  RS ISO 7937 
5 Food additives 
Food additives which may be used in the preparation of cooked packaged maize shall comply with RS 
CODEX STAN 192. 
6 Hygiene 
Cooked packaged maize shall be prepared and handled in accordance with RS CAC/RCP 1. 
7 Contaminants 
7.1 Pesticide residues and other contaminants 
Cooked packaged maize shall conform to maximum residue limits for pesticide residues established by the 
Codex Alimentarius Commission for this commodity and shall comply with the maximum levels of 
Contaminants and Toxins in Food stipulated in RS CODEX STAN 193. 
7.2 Mycotoxins 
Cooked packaged maize shall not exceed the maximum limits of mycotoxins specified in Table 3 when tested 
in accordance with test methods specified therein. 
Table 3 — Mycotoxin limits for Cooked packaged maize 
S/N Mycotoxin Maximum limit (µg/kg) Test method 
i.  Total aflatoxin  10 RS ISO 16050 
ii.  Aflatoxin B1 5 
iii.  Fumonisins 2000 AOAC 2001.04  
7.3 Heavy metals 
Cooked packaged maizeshall comply with the maximum heavy metal limits indicated in Table 4 when tested in 
accordance with test method specified therein. 
Table 4 — Maximum limits for heavy metal inCooked packaged maize 
S/N Heavy metal Maximum limits(mg/kg) Test method 
i.  Cadmium  0.1  AOAC 999.11  
ii.  Lead  0.1  DRS 150: 2023 
5                ©RSB 2023- All rights reserved 
 iii.  Tina  250 AOAC 985.16,  
a For canned cooked maize  
8 Packaging 
Cooked packaged maize shall be packaged in food grade packaging material that ensures the integrity and 
safety of the product 
9 Labelling 
9.1 In addition to the requirements of RS EAS 38, the following specific labelling requirements shall apply 
and shall be legibly and indelibly marked: 
a) name of the product “Cooked packaged maize”; 
b) name and address of the manufacturer/packer/distributor/ importer/exporter/vendor; 
c) date of manufacture; 
d) batch number; 
e) list of ingredients in descending order; 
f) expiry date; 
g) country of origin; 
h) the net content shall be declared in the metric system; 
i) instructions for use; 
j) the statement ‘Human Food’ shall appear on the package; 
k) storage instructions; and 
l) instructions on disposal of used package. 
9.2 When labelling non-retail packages, information for non-retail packages shall either be given on the 
packages or in accompanying documents, except that the name of the product, lot identification and the name 
and address of the manufacturer or packer shall appear on the packages. 
10 Sampling 
Sampling of Cooked packaged maize shall be done in accordance with RS ISO 24333.  
©RSB 2023- All rights reserved                  6 Annex A 
(normative)  
 
Determination of drained weight 
A.1 Definition 
Drained weight expresses percentage of solid content as determined by the procedure described below. 
A.2 Apparatus 
A sieve 20 cm (check) in diameter. The meshes of such sieves are made by so weaving wire as to form 
square openings of 2.8 mm by 2.8 mm. 
A.3 Procedure 
Carefully weigh the clean and dry sieve. Weigh the container plus the contents. Empty the contents of the 
container into the sieve taking care to distribute the beans evenly. Without shifting the product, incline the 
sieve at an angle of approximately 17 % to 20° to facilitate drainage. Drain the product for two minutes and 
then weigh the sieve plus the product. Weigh the dry empty container 
A.4 Calculation 
Drained weight, as per cent of net weight = 
 
Where, 
M=is the weight, in grams, of the sieve; 
M1=is the weight, in grams, of the sieve with the product; 
M2=is the weight, in grams, of the empty container; and 
M3=is the weight, in grams, of the container with the contents 
 
  
DRS 150: 2023 
7                ©RSB 2023- All rights reserved 
 Annex B 
(normative)  
 
Determination of water capacity of containers 
B.1 Scope 
This method applies to metals and glass containers. 
B.2 Definitions 
The water capacity of a container is the volume of water at room temperature which the sealed container will 
hold when completely filed. 
B.3 Procedures 
B.3.1 Metal containers 
B.3.1.1 Select a container which is undamaged in all respects 
B.3.1.2 Wash, dry and weigh the empty container after cutting out the lid without removing or altering the 
height of the double seam 
B.3.1.3 Fill the container with water at room temperature to 4.8 mm vertical distance below the top level 
of the container, and weigh the container thus filled. 
B.3.2 Glass containers 
B.3.2.1 Select a container which is undamaged in all aspects 
B.3.2.2 Fill the container with water at room temperature to the level of the top thereof, and weigh the 
container thus filled. 
B.4 Calculation 
B.4.1 Metal containers 
Subtract the weight found in B.3.1.2 from the weight found in B.3.1.3. The difference shall be considered to be 
the weight of water required to fill the container. Results are expressed as milliliters of water.  
©RSB 2023- All rights reserved                  8 
 B.4.2 Glass containers 
Subtract the weight found in B.3.2.2 from the weight found in B.3.2.3. The difference shall be considered to be 
the weight of water required to fill the container. Results are expressed as milliliters of water. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 DRS 150: 2023 
9                ©RSB 2023- All rights reserved 
 Annex C 
(normative) 
 
Determination of Sodium chloride content 
C.1 Scope 
This method determines the content of chlorides. 
C.2 Definition 
The chloride content corresponds to the sum of all anions (halides) calculated as sodium chloride precipitable 
with silver ions in a nitric acid solution. 
C.3 Principle 
Quantitative precipitation of the halides extracted from the ash in a nitric acid solution with AgNO3 in excess. 
Back titration of the surplus AgNO3 with ammonium thiocyanate, using ferric alum (ferric ammonium sulphate) 
as the indicator. 
C.4 Reagents 
C.4.1 Distilled or demineralized water 
C.4.2 AgNO3 solution, 0.1 N (16.9888 g AgNO3) 
C.4.3 NH4SCN solution, 0.1 N (7.6113 g NH4SCN). In practice a slightly higher weight is taken and the 
solution is adjusted by dilution against a 0.1 N AgNO3 solution 
C.4.4 Cold saturated NH4Fe (SO4) 2.12H2O solution (approximately 40 %). The ensuing brown colouring is 
eliminated by adding pure nitric acid drop wise 
C.4.5 HNO3 (approximately 30 %) 
C.4.6 Diethyl ether of nitrobenzene 
C.5 Apparatus 
C.5.1 Measuring flask, 100 ml 
C.5.2 Burette, 50 ml 
C.5.3 Erlenmeyer flask, 200 ml  
©RSB 2023- All rights reserved                  10 C.5.4 Pipettes 
C.5.5 Funnel, filtering paper 
C.6 Procedure 
The ash (residue after carbonization and incineration of the potato crisp at a maximum temperature of 550 °C 
in a muffle furnace) obtained from 1 g – 2 g dry matter is extracted by means of 80 ml – 90 ml hot distilled 
water acidified with a few drops of nitric acid. The washings are filtered off into a 100-ml measuring flask; after 
cooling distilled water is added until the mark is reached (stock solution). 
In proportion to the expected chloride content aliquot part of this solution, which should preferably contain 50 
mg – 100 mg NaCl, taken off, distilled water being added to obtain a quantity of approximately 100 ml  
Subsequently 5 ml ferric alum solution (see C.4.4), 20 ml 0.1 N AgNO3 solution (see C.4.2) and 5 ml – 10 ml 
ether or 1 ml nitrobenzene are added; titration is carried out by means of an ammonium thiocyanate 
solution0.1 N (see C.4.3), until the red coloring remains after stirring. 
C.7 Expression of results 
Report in percentage by weight to one decimal place. 
Chloride content = 
 
where, 
P = is the test portion, in mg, incinerated; 
V = is the ml of the stock solution derived from the ash; 
V1 = is the volume, in ml, stock solution used from titration; 
V2 = is the volume, in ml, AgNO3 added; and 
V3 = is the volume, in ml, NH4SCN necessary for back titration. 
 
 
DRS 150: 2023 
11                ©RSB 2023- All rights reserved 
 Bibliography 
[1] RS 150: 2018 Cooked packaged maize-Specification, Second edition 
 DRS 150: 2023 
 
Price based on 10pages  
©RSB 2023- All rights reserved