AFDC 21 (39 2) CD3  
ICS 67.080.20  
0 
  
 
 
DRAFT TANZANIA STANDARD  
 
 
Orange fleshed  sweet potato, sorghum and soya composite flour — 
Specification  
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TANZANIA BUREAU OF STANDARDS  
 
 
 
 
 
 AFDC 21 (39 2) CD3  
ICS 67.080.20  
1 
  
0. Foreword  
Orange  fleshed sweet potato, sorghum and soya composite flour is locally produced  and some is being  
imported. The demand for th ese products is improving thus necessitated the need to ensure the safety 
and quality of these products produced and / or marketed for local consumption and export market .  
 
In developing this standard assistan ce was drawn from stakeholders who provided necessary information 
and samples.  
 
In reporting the result of a test or analysis made in accordance with this standard, if the final value 
observed or calculated, is to be rounded off, it shall be done in accord ance with TZS 4 (See clause 2).  
 
1 Scope  
 
This Tanzania standard  prescribes  requirements , sampling and methods of test for composite flour made 
of orange fleshed sweet potato , sorghum and soya  intended for human consumption.  
 
 
2 Normative references  
 
The f ollowing referenced documents are indispensable for the application 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.  
 
TZS 4, Ro unding off numerical values  
TZS 109, Food Processing units - Code of h ygiene  
TZS 122 -1 (ISO 6579 -1), Microbiology of the food chain — Horizontal method for the detection, 
enumeration and serotyping of Salmonella - Part 1: Detection of Salmonella spp  
 
TZS 330  (EAS 900 ), Cereals  and Pulses – Sampling  
 
TZS 538:2015 (EAS 38:2014), Labelling of pre -packaged foods — General requirements  
 
TZS 731 ( ISO 7251 ), Microbiology of food and animal feeding stuffs -  Horizontal method for the detection 
and enumeration of pres umptive Escherichia coli - Most probable number technique  
 
TZS 9 61, Starch – Determination of moisture content – Oven -drying method  
 
TZS 765 , Sorghum flour – Specification  
TZS 799 /ISO 16050,  Foodstuffs – Determination of aflatoxin B 1, and the total content  of aflatoxins B 1, B2, 
G1 and G 2 in cereals, nuts and derived products – High-performance liquid chromatographic method  
 
TZS 1510 ( EAS 799), Edible full fat soya flour - specification  
TZS 1581 -2, Determination of cadmium content – Method flame atomic absorp tion spectrometry  AFDC 21 (39 2) CD3  
ICS 67.080.20  
2 
 TZS 2044 ( ISO 5985 ), Animal feeding stuffs – Determination of ash insoluble in hydrochloric  
TZS 2426  -1 (ISO 21527 -1), Microbiology of food and animal feeding stuffs - Horizontal method for the 
enumeration of yeasts and moulds - Part 1: Colony count technique in products with water activity greater 
than 0.95  
 
FTZS 2473,  Animal feeding stuffs - Determination of crude ash  
 
TZS 2565 , Bio fortified sweet potato – Specification  
 
ISO 9648, Sorghum — Determination of tannin  
 
 
3 Terms and definitions  
 
For the purpose of this standard, the following term s and definition s shall apply.  
 
3.1  
orange fleshed sweet potato, sorghum and soya composite flour   
composite flour obtained by blending flours from dried orange fleshed sweet potato or flour, sorghum 
grains or flour and soya  grains or flour  
 
3.2  
foreign matter  
inorganic matter such as sand, glass, metal, stones , clay and mud and organic matter such as chaff, 
straw, weed seeds , live insects , insects fragments, and rodent hairs  
 
3.3  
food grade material  
one that will not transfer non -food chemicals into the food and contains no chemicals which would be 
hazardous t o human health  
 
3.4  
practically free  
without defects in excess of those that can be expected to result from, and be consistent with good 
cultural and handling practices employed in the production and marketing of the composite flour  
 
 
4 Requirements  
 
4.1 General requirements  
 
4.1.1 Orange fleshed sweet potato, sorghum and soya composite flour  shall be produced from sweet 
potato , sorghum and soya complying  with TZS 2565 , TZS 765 and TZS 1510 , respectively.  
  
4.1.2  The composite flour shall be  
a) practically free fr om foreign matter;  
b) free of off -flavours and off -odours; and  
c) practically free from any living insects and filth;  
 
 AFDC 21 (39 2) CD3  
ICS 67.080.20  
3 
 4.2 Specific  requirements  
 
Orange fleshed sweet potato, sorghum and soya composite flour shall conform to the compositional 
quality require ments shown in Table 1.  
 
Table 1 —Quality requirements  of composite flour   
S/NO  Analytical characteristic  Limits  Method of test  
1.  Moisture, % by mass, max  12 TZS 961  
2.  Ash content, %, by mass, min.  2 FTZS 2473  
3.  Carotenoids, mg/100/g, min 
 0.5 Annex  A 
4.  Crude fibre, % by mass on dry weight basis, max  3 ISO 5498  
5.  Tannin  0.3 ISO 9648  
6.  Acid insoluble ash, % by mass, max.  0.15 TZS 2044  
 
 
5 Hygiene  
 
The product shall be prepared and handled in a hygienic manner in accordance  with TZS 109 and shall 
conform to  microbiological limits specified in Table 2 .  
 
 
Table 2 — Microbiological limits for the orange fleshed sweet potato, sorghum and soya 
composite flour  
 
S/NO  Micro -organisms  Maximum limit  Method of Test  
1.  Escherichia coli,  cfu/g,  Absent  TZS 731  
2.  Salmone lla spp, per 25g Absent   TZS 122 -1 
3.  Yeast and mould, cfu/g,.  103 TZS 2426 -1 
  
 
6 Contaminants  
 
6.1 Heavy metal  contaminants  
Orange fleshed sweet potato, sorghum and soya composite flour shall not contain any metal 
contaminants in exces s of levels specifi ed in Table 3 . 
 
Table 3  – Limit for heavy metals contaminants for orange fleshed sweet potato, sorghum and soya 
composite flour  
  
S/NO   
Characteristics   
Maximum (mg/kg)   
Method of Test  
1.  Lead ( Pb) 
 0.2 TZS 1502  
 
2.  Cadmium (Cd)  0.2 TZS 1581 -2 
 
 AFDC 21 (39 2) CD3  
ICS 67.080.20  
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 6.2 Pest icide residues  
 
The product shall  conform to maximum residue limits for pesticide residues established by the Codex 
Alimentarius Commission for this commodity.  
 
6.3 Aflatoxin  
 
The product shall not have more than 5 ppb for Aflatoxin B 1 and 10 ppb for total  aflatoxin when tested 
according to TZS 799.  
 
 
7 Pack ing, marking and labelling  
 
7.1 Pack ing 
The product  shall be pack ed in suitable food grade materials,  
7.2 Marking and labelling  
 
In addition to the requirements of TZS 538 ; the following labeling requi rements shall apply and shall be 
legibly and indelibly marked  
 
a) the common name of the food product  to be declared on the label shall be ‘ Orange fleshed sweet 
potato, sorghum and soya composite flour ; 
 
b) the net weight the name and  physical address of the man ufacturer / distributor;  
 
c) the country of origin;  
 
d) batch number ; 
 
e) date of manufacture and expiry  date 
 
f) storage conditions  
 
g) instructi ons on disposal of used package  
 
h) The language on the label shall be Swahili  and/or English”. Another language may be used 
depending on the designated market.  
 
 
8 Sampling and test s 
8.1 Sampling  
Sampling of the product shall be done according to TZS 330 . 
 
8.2 Test s  
Testing of the product shall be done according to test methods prescribed in Table 1 ,2, 3 and Annex A  of 
this stan dard.  
 
NOTE: The TBS Standards Mark of Quality may be used by the manufacturers only under license  from 
TBS. Particulars of conditions under which the license  are g ranted may be obtained from TBS  
 
 AFDC 21 (39 2) CD3  
ICS 67.080.20  
5 
 ANNEX A (Normative)  
DETERMINATION OF BETA CAROTENE IN FOOD BY UV -VIS 
SPECTROPHOTOMETRIC METHOD  
A. Principle  
This method is based on solvent extraction followed by UV -Vis spectrometric detection.  The sample is 
extracted using Acetone, filtered and  the filtr ate extracted using Petroleum ether,  then the concentration 
of β-carotene is determined  by reading the absorbance of standard  and sample extract using petroleum 
ether as blank at 450nm using UV -Visible spectrophotometer . 
B. Reagents and Apparatus  
a) Acetone, AR grade  99.5% purity  
b) Anhydrous Sodi um Sulphate   
c) β-Carotene standard ≥93% (UV), powder . 
d) Petroleum Ether, S pectrophotometric grade  
e) Distilled water  
f) UV-Visible spectrophotometer     
g) Blender  
h) 100 ml Volumetric flask  
i) 100ml Beaker  
j) 100 ml Measuring cylinder  
C. Extraction  
Grind sample if it is in gra ins or pellets form and make sure almost 95% the powder can pass through 
1mm sieve. Weigh 0.2 -1.0 g of homogenized test portion into blender, then Add 50mls of cold acetone 
and mix/mill to extract for about 10 minutes.  
Filter the sample using whatman filte r paper No. 1 to obtain clear filtrate. Wash the residue on the filter 
paper three times or more until the residuals are white (free from carotenoids).  
Transfer the carotenoids extract into separating funnels containing 50ml of petroleum ether and 25 ml of  
distilled water, and extract by shaking the funnel for about five minutes , then wash the extract using 
60mls portions of distilled water until it is free from acetone.  
Prepare volumetric flask and glass funnel containing anhydrous dry Sodium Sulphate , pass the 
carotenoids extract through anhydrous Sodium Sulphate to dry it. Rinse the separating flask, Sodium 
Sulphate and funnel using petroleum ether but taking care not to exceed the mark of the volumetric flask . 
D. Determination  
Prepare 100µg/ml working standard  solution from  stock β-carotene standard, then prepare calibration 
standards  by diluting  it serially to obtain 0, 2, 4, 8, 16, 32, 64µg/ml beta carotene by taking appropriate 
volume of working standard  solution into volumetric flask and diluting it w ith petroleum ether  into 100ml 
volumetric flask . 
Read the absorbance of standards and sample extract using petroleum ether as blank at 450nm using 
UV-Visible spectrophotometer. Use standard concentrations and the obtained absorbance to construct a AFDC 21 (39 2) CD3  
ICS 67.080.20  
6 
 standard  calibration curve, from the curve obtain equation and calculate the beta carotene concentration 
in the samples  
Calculation  
 
where      A     = Sample absorbance  
 K     = Y -intercept of the standard calibration curve  
 V1    = Total volume of the sample e xtract  
 M    = Slope of the standard plot  
 Sp wt. = Amount of sample taken for analysis