ICS 67.220.10  
 
Reference number
DRS 359: 2023
© RSB 2023
  
 RWANDA 
STANDARD  DRS 
359 
 
Second edition  
YYY-mm-dd  
 
Spirulina — Specification   
DRS 359: 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 2022 
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 359: 2023 
iii                ©RSB 2023 - All rights reserved 
 Contents Page 
1 Scope ...................................................................................................................................................... 1  
2 Normative references ............................................................................................................................ 1  
3 Terms and definitions ........................................................................................................................... 1  
4 Product presentation ............................................................................................................................ 2  
5 Requirements ......................................................................................................................................... 2  
5.1 General requirements ........................................................................................................................... 2  
5.2 Specific requirements ........................................................................................................................... 2  
5.3 Particle size ............................................................................................................................................ 2  
6 Contaminants ......................................................................................................................................... 2  
6.1 Heavy metals .......................................................................................................................................... 2  
6.2 Pesticide residues ................................................................................................................................. 3  
6.3 Microbiological requirements .............................................................................................................. 3  
7 Hygiene ................................................................................................................................................... 3  
8 Packaging ............................................................................................................................................... 3  
9 Labelling ................................................................................................................................................. 3  
10 Sampling ................................................................................................................................................ 4  
A.1.1 Liquid or strained honey....................................................................................................................... 6  
A.1.2 Comb honey ........................................................................................................................................... 6  
A.2 Procedure ............................................................................................................................................... 6  
A.2.1 Preparation of test sample ................................................................................................................... 6  
A.2.2 Gravimetric determination .................................................................................................................... 6  
A.2.3 Expression of results ............................................................................................................................ 6  
C.1 Reagent ................................................................................................................................................ 10  
C.1.1 Resorcinol solution ............................................................................................................................. 10  
C.2 Procedure ............................................................................................................................................. 10  
C.3 Expression of results .......................................................................................................................... 10  
 DRS 359: 2023 
©RSB 2023 - All rights reserved                  iv 
 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 359 was prepared by Technical Committee RSB/TC 019, Spices, condiments and food additives. 
This second edition cancels and replaces the first edition (RS 359: 2017) which has been technically revised. 
Committee membership  
The following organizations were represented on the Technical Committee on Spices, condiments and food 
additives (RSB/TC 019) in the preparation of this standard. 
Rwanda Standards Board (RSB) – Secretariat 
 DRS 359: 2023 
1                ©RSB 2023- All rights reserved 
 Spirulina — Specification 
1 Scope 
This Rwanda Standard specifies the requirements, sampling and test methods for spirulina. 
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. 
RS EAS 82,  Determination of Acid insoluble ash 
RS ISO 5498,  Agricultural food products — Determination of crude fibre content — General method 
ISO 16634-2, Food products — Determination of the total nitrogen content by combustion according to the Dumas 
principle and calculation of the crude protein content — Part 2: Cereals, pulses and milled cereal products  
RS ISO 7305, Milled cereal products — Determination of fat acidity.  
3 Terms and definitions 
For the purposes of this standard, the following terms and definitions apply. 
3.1 
spirulina 
blue-green algae (cyanobacterium) of the Genus Spirulina: processed as a valuable source of proteins and other 
nutrients such as vitamins and minerals 
3.2 
foreign matter 
organic and inorganic materials (such as sand, soil, glass) other than spirulina 
3.3 
filth 
impurities of animal origin, including dead insects. DRS 359: 2023 
©RSB 2023- All rights reserved                  2 
 4 Product presentation 
Spirulina may be presented in different form such as pellet, powder, flake form, dried and freeze-dried. 
5 Requirements 
5.1 General requirements 
Spirulina shall:  
a) be free from filth; 
b) be practically free of any visible foreign matter; 
c) be safe and suitable for human consumption; and 
d) have characteristic colour, odour and flavour of spirulina 
5.2 Specific requirements 
Spirulina shall comply with the requirements in Table 1. 
Table 1 — Specific requirements 
S/N Characteristics Requirement Test method 
i. Protein content %, min, m/m  50 ISO 16634-2 
ii. Moisture content, %, max, m/m 10 RS ISO 712 
iii. Lipids %, max, m/m 7 ISO 7305 
iv. Fiber content, %, max, m/m  7 RS ISO 5498 
v. Total ash, %, max, m/m 13 
RS EAS 82 vi. Acid insoluble ash %, max, m/m 0.35 
vii. pH 7 - 9 
5.3 Particle size 
When presented in powder form, not less than 90 % of particles of the product shall pass through a 0.60-mm sieve. 
6 Contaminants 
6.1 Heavy metals 
The product shall be free from heavy metals in amounts set in Table 2 when tested in accordance with test methods 
specified therein. DRS 359: 2023 
3                ©RSB 2023- All rights reserved 
 Table 2 — Limits for metal contaminants 
S/N Heavy metals Maximum Limits 
mg/kg Test method 
i. Lead 0.1 RS ISO 6633 
ii. Arsenic 1 RS ISO 6634 
iii. Mercury 0.1 RS ISO 6637 
iv. cadmium 2.0 RS ISO 6561-2 
6.2 Pesticide residues 
Spirulina shall conform to those maximum residue limits established by the Codex Alimentarius Commission for the 
ingredients used in the preparation of this product. 
6.3 Microbiological requirements 
Spirulina shall conform to microbiological maximum limits in Table 3 when tested in accordance with test methods 
specified therein. 
Table 3 — Microbiological limits 
Microorganisms Maximum limit Test method 
Total viable count, CFU/g 104 RS ISO 4833-1 
Escherichia. coli, CFU/g absent RS ISO 16649-1 
Salmonella, spp in 25 g absent RS ISO 6579-1 
Staphylococcus aureus, CFU/g absent RS ISO 6888-1 
Yeast and moulds, CFU/g 102 RS ISO 21527-2 
7 Hygiene 
Spirulina shall be processed, packaged, stored and distributed under hygienic conditions prescribed in RS CAC/RCP 
1. 
8 Packaging 
Spirulina shall be packaged in food grade packaging materials that shall not affect the safety and the quality of the 
product. 
9 Labelling 
In addition to the requirements of RS EAS 38, the labelling shall include the following: DRS 359: 2023 
©RSB 2023- All rights reserved                  4 
 a) the name of the product as “Spirulina”, 
b) form in which the product is presented (powder, pellet, flaked), 
c) net content, 
d) name, location and address of the manufacturer, 
e) country of origin, 
f) lot or batch number, 
g) manufacture date, 
h) expiry date, 
i) storage instructions, and 
j) instruction for use. 
10 Sampling 
Sampling shall be done in accordance with CAC/GL 50. 
. 
. 
 
 
 
 
 
 
 
 
 DRS 359: 2023 
5                ©RSB 2023- All rights reserved 
  
 DRS 359: 2023 
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 Annex A 
(normative ) 
 
Gravimetric determination of water-insoluble solids content (Type II method) 
A.1 Sampling 
A.1.1 Liquid or strained honey 
If sample is free from granulation, mix thoroughly by stirring or shaking; if granulated, place closed container in 
water-bath without submerging, and heat 30 min at 60 °C; then, if necessary, heat at 65 °C until liquefied. 
Occasional shaking is essential. Mix thoroughly and cool rapidly as soon as sample liquefies. Do not heat honey 
intended for Hydroxymethylfurfural or diastatic determination. If foreign matter, such as wax, sticks, bee’s particles or 
comb, etc., is present, heat sample at 40 °C in water-bath and strain through cheesecloth in hot-water-funnel before 
sampling 
A.1.2 Comb honey 
Cut across top of comb, if sealed, and separate completely from comb by straining through a sieve the meshes of 
which are made by so weaving wire as to form square opening of 0.500 mm by 0.500 mm when portions of comb or 
wax pass-through sieve, heat sample as in A.1.1 and strain through cheesecloth. If honey is granulated in comb, 
heat until wax is liquefied; stir, cool and remove wax. 
A.2 Procedure 
A.2.1 Preparation of test sample 
Weigh 20 g of honey and dissolve in a suitable quantity of distilled water at 80 °C and mix well.  
A.2.2 Gravimetric determination 
The test sample is filtered through a previously dried and weighed fine sintered glass crucible (pore size 15.40) and 
washed thoroughly with hot water (80 °C) until free from sugars (Mohr test). The crucible is dried for one hour at 135 
°C, cooled and weighed to 0.1 mg.  
A.2.3 Expression of results 
The result is expressed as percent water insoluble solids (m/m). 
 
 
 DRS 359: 2023 
7                ©RSB 2023- All rights reserved 
 Annex B 
(normative)  
 
Determination of fructose-glucose ratio 
B.1 Principle of the method 
The glucose portion of the invert sugar content of honey is determined by reacting it with iodine. The fructose 
content is calculated by subtraction.  
B.2 Apparatus 
B.2.1 0.05 N iodine solution  
B.2.2 0.01 N sodium hydroxide solution  
B.2.3 0.05 N standard sodium thiosulphate solution 
B.3 Procedure 
Pipette 50 ml of honey solution in a 250-ml stoppered flask. Add iodine solution and 25 ml of sodium hydroxide 
solution. Stopper the flask and keep in dark for 20 min. Acidify with 5 ml of sulphuric acid and titrate quickly the 
excess of iodine against standard thiosulphate solution. Conduct a blank using 50 ml of water instead of honey 
solution.  
B.4 Calculation and expression of results 
B.4.1 Approximate glucose, percent by mass (g of glucose per 100 g honey):  
𝑤=(𝐵−𝑆)×0.004502×100
𝑎 
where 
B is the volume, in millilitres, of sodium thiosulphate solution required for the blank.  
S is the volume, in millilitres, of sodium thiosulphate solution required for the sample, and  
a is the mass, in grams, of honey taken for the test.  
B.4.2 Approximate fructose, per cent by mass (g fructose per 100 g honey): DRS 359: 2023 
©RSB 2023- All rights reserved                  8 
 𝑥=𝑇𝑜𝑡𝑎𝑙 𝑟𝑒𝑑𝑢𝑐𝑖𝑛𝑔𝑠𝑢𝑔𝑎𝑟𝑠 (𝑐)−𝑎𝑝𝑝𝑟𝑜𝑥𝑖𝑚𝑎𝑡𝑒𝑔𝑙𝑢𝑐𝑜𝑠𝑒𝑐𝑜𝑛𝑡𝑒𝑛𝑡  (𝑤)
0.925 
B.4.3 Actual glucose content (g per 100 g honey), per cent (Y)= W-0.012X and  
𝐹𝑟𝑢𝑐𝑡𝑜𝑠𝑒𝑐𝑜𝑛𝑡𝑒𝑛𝑡 (𝑔𝑝𝑒𝑟 100𝑔 ℎ𝑜𝑛𝑒𝑦),𝑝𝑒𝑟𝑐𝑒𝑛𝑡 (𝑧) =𝑇𝑜𝑡𝑎𝑙 𝑟𝑒𝑑𝑢𝑐𝑖𝑛𝑔𝑠𝑢𝑔𝑎𝑟𝑠 −𝑦 𝑎𝑐𝑡𝑢𝑎𝑙
0.925 
 
B.4.4   Fructose-glucose ratio  
𝐹𝑟𝑢𝑐𝑡𝑜𝑠𝑒 −𝑔𝑙𝑢𝑐𝑜𝑠 𝑟𝑎𝑡𝑖𝑜=𝐴𝑐𝑡𝑢𝑎𝑙 𝑓𝑟𝑢𝑐𝑡𝑜𝑠𝑒𝑐𝑜𝑛𝑡𝑒𝑛𝑡  (𝑧)
𝐴𝑐𝑡𝑢𝑎𝑙 𝑔𝑙𝑢𝑐𝑜𝑠𝑒𝑐𝑜𝑛𝑡𝑒𝑛𝑡  (𝑦) 
 
. 
 
 
 
 
 
 
 
 
 
 
 
 
 DRS 359: 2023 
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  DRS 359: 2023 
©RSB 2023- All rights reserved                  10 
 Annex C 
(normative ) 
 
Fiehe's test 
C.1 Reagent 
C.1.1 Resorcinol solution 
Dissolve 1 g of resublimed resorcinol in 100 ml of hydrochloric acid (specific gravity 1.18 or 1.19).  
C.2 Procedure 
Dissolve 2 g of honey in 10 ml of water and extract with 30 ml ether. A continuous extractor is preferable. Remove 
ether in a separating funnel and concentrate the layer at 5 ml. Add 2 ml of freshly prepared resorcinol solution, 
shake and note the colour.  
C.3 Expression of results 
A cherry red colour appearing in a minute indicates the presence of commercial invert sugar.DRS 359: 2023 
 
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