KENYA STANDARD                                                       KS 2839 -4:2023  
ICS 67.060  
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Blended flour — Specification  
 
Part 4 : 
 
Wheat and Sweet Potato  blend  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
© KEBS 2023   
 
 
  APPROVED  
2018 -10-04 KS 2839 -4:2023  
 
ii  © KEBS 2023  — All rights reserved  TECHNICAL COMMITTEE REPRES ENTATION  
 
The following organizations were represented on the Technical Committee:  
 
Agriculture and Food Authority (AFA)  
Agriculture Sector Development Support Programme (ASDSP)  
Farm Concern International.  
Zeelandia EAST Africa Ltd.  
Kenya Agriculture and Livestock Research Organization (KALRO)  
Kenya Industrial Research and Development Institute (KIRDI)  
Ministry of Agriculture, Livestock, Fisheries and Irrigation (MOALF&I)  
Ministry of Health — Food Safety Unit  
Ministry of Health — Nutrition and Dietetic  
National Cereals and Produce Board (NCPB)  
University of Nairobi  
World Food Programme (WFP)  
Kenya Medical Research Institute (KEMRI)  
National Public Health Labs (NPHL)  
Government Chemist  
Mennonite Economic Development Associates (MEDA)  
Kenya Bureau of Standards — Secretariat  
 
 
 
 
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improvements to published standards, addressed to the Managing Director, Kenya Bureau of Standards, are 
welcome.  
 
 
 
 
 
© Kenya Bureau of Standards, 2023  
 
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of Kenya, copyright subsists in all Kenya Standards and except as provided under Section 25 of this Act, no 
Keny a Standard produced by Kenya Bureau of Standards may be reproduced, stored in a retrieval system in 
any form or transmitted by any means without prior permission in writing from the Managing Director.  
  KENYA STANDARD                                                                  KS 2839 -4:2023  
ICS 67.060  
© KEBS 2023 — All rights reserved    iii  
 
 
 
Blended flour — Specification  
 
Part 4 : 
 
Wheat an d Sweet potato  blend  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
KENYA BUREAU OF STANDARDS (KEBS)  
 
Head Office: P.O. Box 549 74, Nairobi -00200, Tel.: (+254 020) 6 05490, 602350, Fax: (+254 020) 604031  
E-Mail: info@kebs.org, Web:http://www.kebs.org  
 
Coast Region     Lake Region       Rift Valley Region  
P.O. Box 99376, Mombasa -80100   P.O. Box 2949, Kisumu -40100        P.O. Box 2138, Nakuru -
20100  
Tel.: (+254  041) 229563, 230939/40  Tel.: (+254 057) 23549, 22396        Tel.: (+254 051) 210553, 210555  
Fax: (+254  041) 229448    Fax: (+254 057) 21814  
 
  KS 2839 -4:2023  
 
iv  © KEBS 2023  — All rights reserved  Foreword  
 
This Kenya Standard  was prepared by the Joint Technical Committee comprising of key stakeholders under the 
guidance of the Standards Projects Committee, and it is in accordance with the procedures of the Kenya Bureau 
of Standards.  
 
Flour blending initiative is aimed at contr ibuting towards food security, improved nutrition and increased 
employment opportunities in Kenya through flour blending based on under -utilized high value foods. This multi -
sectoral approach has been designed through a consultative process that targets a high-impact approach aimed 
at integrating Arid and Semi Arid Lands (ASALs) as food and nutrition secure regions to contribute to the national 
food basket.  
 
This Kenya Standard  forms part of a series of standards aimed at blending traditional sources of fl ours mainly 
maize and wheat with the underutilized foods. This will reduce over reliance on maize and wheat as well as 
improve both food security and nutritional qualities  of the products.  
 
In the preparation of this Workshop Agreement, reference was made  to the following documents:  
 
KS EAS 1, Wheat flour — Specification.  
 
KS EAS 51, Wheat grain — Specification.  
 
KS EAS 773, Sweet  potato flour — Specification.  
 
KS EAS 772, Dried sweet  potato chips — Specification.  
 
Acknowledgement is hereby made for the a ssistance derived from these sources.  
 
 
  
KENYA STANDARD                                                               KS 2839 -4:2023  
 
 
© KEBS 2023  — All rights reserved    1  
Blended flour — Specification  
 
Part 4 : 
 
Wheat and S weet  Potato blend  
 
1 Scope  
 
This Kenya Standard  specifies the requirements, methods of sampling and test for blended wheat and sweet  
potato flours prepared from the grains of common wheat ( Triticum aestivum L.) and sweet  potato chips ( Ipoemea 
batatas .) or a mix ture of their flour thereof intended for human consumption.  
 
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 t he edition cited applies. For undated references, the 
latest edition of the referenced document (including any amendments) applies.  
 
AOAC 2001.06, Total fumonisins in corn. Competitive direct enzyme -linked immunosorbent assay  
 
AOAC 2013.06, Arsenic, Cadmium, Mercury and Lead in foods  
 
KS CODEX STAN 192, General standard for food additives  
 
KS CODEX STAN 193,  Codex general standard for contaminants and toxins in food and feed  
 
KS EAS 1, Wheat flour — Specification  
 
KS EAS 51, Wheat grains — Specification  
 
KS EAS 38 , Labelling of pre -packaged foods — Specification  
 
KS EAS 39 , Hygiene in the food and drink manufacturing industry  — Code of practice  
 
KS EAS 772, Dried sweet potato chips — Specification  
 
KS EAS 773, Sweet potato flour — Specification  
 
KS EAS 767, Fortified wheat flour  — Specification  
 
KS EAS 803, Nutrition labelling — Requirements  
 
KS EAS 804, Claims on food — General requirements  
 
KS EAS 805, Use of nutrition and health claims — Requirements  
 KS 2839 -4:2023  
 
2  © KEBS 2023  — All rights reserved  KS ISO 712, Cereals and cereal products — Determination of moisture content — Reference method  
 
KS ISO 2171 , Cereals, pulses and by -products — Determination of ash yield by incineration  
 
KS ISO 5498 , Agricultural food products — Determination crude fibre Content -General method  
 
KS ISO 5985, Animal feeding stuffs — Determination of ash insoluble in hydrochloric acid  
 
KS ISO 6579 -1, Microbiology of the food chain — Horizontal method for the detection, enumeration and 
serotyping of Salmonella — Part 1: Detection of Salmonella spp.  
 
KS ISO 7305, Milled cereal products — Determination of fat acidity  
 
KS 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  
 
KS 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  
 
KS 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 
 
KS ISO 24333, Cereals and cereal products — Sampling  
 
3 Terms and definitions  
 
For the purposes of this document, the following terms and definitions apply.  
 
  
3.1 blended flour  
a mixture of two different milled food crop produce. This can be obtained by mixing the food crop produce before 
milling or their flours thereof  
 
 
3.1.1 food grade packaging material  
material which will safeguard the hygienic, nutritional, technological and organoleptic qualities of the product  
 
3.1.2 wholesome  
free from disease and physiological deterioration (such as but not limited to decay, breakdown, freezing damage) 
or adulteration/contamination, that appreciably affects their appearance, edibility, the keeping quality of the 
produce or market value  
 
 
3.1.3 foreign matter  
organic and inorganic materials (such as sand, soil, glass) other than extraneous matter in the flour  
 
 
3.2 musty odour  KS 2839 -4:2023  
 
© KEBS 2023 — All rights reserved    3 stale, mouldy or dump smell  
 
3.2.1 foreign matter  
all organic and inorganic material  
 
3.2.2 inorganic  matter   
stones, glass, pieces of soil and other mineral matter  
 
3.2.3 organic matter   
any animal or plant matter (seed coats, straws, weeds) other than wheat grain, damaged wheat grain, other 
grains, inorganic extraneous matter and harmful/toxic seeds  
 
3.3 Extraneous matter  
Extraneous matter are all organic and inorganic materials other than wheat and sweet potato, broken wheat 
kernels, other grains and filth.  
 
3.3.1 Milled wheat flour . 
Wheat flour is the product prepared from grain of common wheat, Triticu m aestivum L., or club wheat, Triticum 
compactum Host., or mixtures thereof, by grinding or milling processes.  
 
3.3.2 Sweet potato flour  
product prepared from dried sweetpotato chips or paste by a pounding, grinding or milling process, followed by 
sifting to separate the fibre from the flour.  
 
 
4 Requirements  
 
4.1 Raw materials  
 
Blended wheat and sweet  potato flour shall be prepared by blending wheat flour complying with KS EAS 1 or 
wheat grains complying with KS EAS 51 and sweet potato flour complying with  KS EAS 773 or dried sweet 
potato chips complying with KS EAS 772.  
 
4.2 General requirements  
 
Blended wheat and sweetpotato flour shall be:  
 
a) of characteristic colour of wheat grains/flour and sweet potato chips /flour from which they were 
prepared;  
 
b) free from foreign matter such as insects, fungi or dirt;  
  
c) free from musty or other objectionable odour; and  
 
d) wholesome and fit for human consumption.  
 
4.3 Specific requiremen ts 
 
4.3.1  The minimum content of sweet  potato flour in the blended product shall be 10 %.  
 KS 2839 -4:2023  
 
4  © KEBS 2023  — All rights reserved  4.3.2  Blended wheat and sweet  potato flour shall comply with the requirements given in Table 1 when tested 
in accordance with test method specified therein.  
 
Table 1  — Compositional requirements for blended wheat and sweet  potato flour  
 
S/N Parameter  Limit  Test method  
i) Crude fibre, % by m/m, maxa. 5 KS ISO 5498  
ii) Moisture, % , m/m, max.  14 KS ISO 712  
iii) Total ash, %, max.a  3 KS ISO 2171  
iv) Fat acidity, mg KOH per 100 g 
of product, m/m, max.  50 KS ISO 7305  
v) Acid insoluble ash, % by m/m, 
max.  0.4 KS ISO 5985  
a % mass on dry matter basis.  
 
 
 
5 Fortification requirements  
 
5.1 Levels of micronutrients  
 
Fortified Blended wheat and sweet potato flour  shall comply with the levels of micronutrients  provided in Annex 
A.  
 
 
6 Food additives  
 
Only the food additives permitted by KS CODEX STAN 192 may be used without exceeding the stated limits.  
 
7 Hygiene  
 
7.1 Blended wheat and sweet  potato flour shall be produced, prepared and handled in accordance with KS 
EAS 39.  
 
7.2 The product shall comply with microbiological limits given in Table 5 when tested in accordance with the 
test methods specified therein.  
 
Table 2 — Microbiological limi ts for blended wheat and sweet  potato flour  
 
S/N Micro -organism  Maximum limit  Test method  
i) E. coli , Cfu/g  102 KS ISO 16649 -2 
ii) Salmonella spp in  25 g Absent  KS ISO 6579 -1 
iii) Yeast and moulds, Cfu/g  104 KS ISO 21527 -2 
 KS 2839 -4:2023  
 
© KEBS 2023 — All rights reserved    5 8  Contaminants  
 
8.1  Heavy metals  
 
Blended wheat and sweetpotato flour shall comply with KS CODEX STAN 193 for respective flours. In addition, 
the products shall comply with Table 3 when tested in accordance with test methods specified therein.  
Table 3 — Heavy metals limits for blended wheat and sweet  potato flour  
 
S/N Heavy metal  Limit , 
mg/k g Test method  
i) Arsenic (As)  0.1 
AOAC 2013.06  ii) Lead (Pb)  0.2 
iii) Cadmium (Cd)  0.1 
 
8.2  Pesticide residues  
 
Blended wheat and sweet  potato flour shall comply with the maximum residue limits established by the Codex 
Alimentarius Commission for this commodity.  
 
8.3  Mycotoxins  
 
Blended wheat and sweet  potato flour shall comply with mycotoxin limits specified in Table 4 when tested in 
accordance with test methods specified therein.  
 
Table 4 — Mycotoxin limits for blended wheat and sweet  potato flour  
 
S/N Mycotoxin  Maximum limit,  
µg/kg  Test method  
i) Total aflatoxins  10 KS ISO 16050  ii) Aflatoxins B 1 5 
iii) Fumonisins  2 000  AOAC 2001.06  
 
9 Packaging  
 
9.1 Blended wheat and sweet  potato flour shall be packaged in food grade packaging materials.  
 
9.2 When the product is packaged in sacks, these shall be clean, sturdy and strongly sewn or sealed.  
 
 
10 Labelling  
 
10.1 General labelling  
 
In addition to the requirements in KS EAS 38, each package shall be legibly and indelibly marked with the 
following:  
 
a) name of product such as "Blended W heat and Sweet  potato" Flour or "Blended Sweet  potato and Wheat 
Flour". The first name shall be that of the dominant flour in the blend;  
 KS 2839 -4:2023  
 
6  © KEBS 2023  — All rights reserved  b) name and address of the manufacturer/packer/importer;  
 
c) brand name/registered trade mark, if any;  
 
d) lot or batch number in code or in clear format;  
 
e) net weight in metric units;  
 
f) the statement "Store in a cool dry place and away from contaminants";  
 
g) the statement " for human consumption "; 
 
h) country of origin;  
 
i) date of manufacture;  
 
j) expiry date; and  
 
k) instructions for disposal of used package.  
 
10.2 Nutrition labelling  
 
The amount of nutrients in the blended wheat and sweet  potato flour shall be declared on the label in accordance  
with KS EAS 803 . 
 
10.3 Nutrition and health claims  
 
Blended wheat and sweet  potato flour  may have claims on - nutrition and health. Such claims when declared  
shall be in compliance with KS EAS 804 and KS EAS 805.  
 
11 Sampling  
 
Sampling shall be done in accordance  with KS ISO 24333 . 
 
 
 
 
 
 
 
 
 
 
 
 
 
 KS 2839 -4:2023  
 
© KEBS 2023 — All rights reserved    7  
 
Annex  A 
Requirements for levels of micronutrients in fortified composite flour.  
 
 
 
Nutrient   
Fortificant  Limits  
mg/kg   
Test method  
Min. Max.  
Vitamin  Aa Vitamin A (Retinyl) palmitate, spray - 
dried or equivalent, 75 000 μg RE/gb 
(7.5 % retinol),  min. 0.5 1.4  
AOAC  2001.13  
Vitamin  B1a Thiamin  Mononitrate,  81 %, min. 4.6 NAc AOAC  953.17  
Vitamin  B2a Riboflavin,  100 %, min. 3.3 NA AOAC  970.65  
Niacina Niacinamide,  99 %, min.  30 NA AOAC  975.41  
Vitamin  B6a Pyridoxine  hydrochloride,  82 %, min. 3 NA AOAC  961.15  
Folate  Folic  acid,  90.5 %,  min. 1.1 3.2 AOAC  2004.05  
Vitamin  B12 Vitamin   B12    (Water  soluble),   0.1 
%,min.  0.01 NA ISO 20634  
Zinc Zinc oxide,  80 %, min. 40 80 AOAC  2011.14  
Total  iron Total  iron 20 NA AOAC  944.02  
a The addition  of these  micronutrients  is optional  in Tanzania.  
b 1μg RE = 3.33 IU, RE = Retinol  equivalent.  
c    NA-Not Applicable. The maximum limits for these nutrients are not necessary because the upper tolerance limits of  these  
nutrients  are very  high.  
NOTE 1    Any other fortificants listed by either British Pharmacopoeia (BP); Food Chemical Codex (FCC); Merck Index  (MI); 
United States National Formulary (NF); European Pharmacopoeia (Ph Eur); United States Pharmacopoeia (USP); or  FAO 
WHO  Codex  Alimentarius  Commission  may be used.  
 
NOTE 2  Only NaFeEDTA, 12.5 % Fe, min or Ferrous fumara te, 32 %, min shall be used as a source of iron so as to  provide  
iron at 20 -40 mg/kg  and 30-50 mg/kg  respectively for wheat  flour fortification.