AFDC 21 (39 3) CD3  
ICS 67.080.20  
0 
  
 
 
DRAFT TANZANIA STANDARD  
 
 
Orange fleshed sweet potato flour  — Specification  
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TANZANIA BUREAU OF STANDARDS  
 
 
 
 
 
 
 AFDC 21 (39 3) CD3  
ICS 67.080.20  
1 
 0. Foreword  
Orange fleshed sweet potato  (Ipomoea batatas L. ) flour is a product produced by grinding dried orange 
fleshe d sweet potato  into flour  to sustain the promising source of pro -vitamin A f rom the cultivars. The 
demand for this product is increasing thus the need to ensure the safety and quality of orange fleshed 
sweet potato flour  produced and/or marketed for local consumption and export market . 
 
In developing this standard assistance 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 
obse rved or calculated, is to be rounded off, it shall be done in accordance with TZS 4 (See clause 2).  
 
1 Scope  
 
This Tanzania standard  prescribes  requirements , sampling and test  methods  for orange fleshed sweet 
potato flour intended for human consumption.  
 
 
2 Normative references  
 
The following 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 am endments) applies.  
 
TZS 4, Rounding 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: Detecti on of Salmonella spp  
 
TZS 330 (EAS 900), Cereals and Pulses – Sampling  
 
TZS 538 (EAS 38),  Labelling of pre -packaged foods — General requirements  
 
TZS 731  (ISO 7251 )- Microbiology of food and animal feeding stuffs -  Horizontal method for the detection 
and e numeration of presumptive Escherichia coli - Most probable number technique  
 
TZS 961 (1st Ed), Starch – Determination of moisture content – Oven -drying method  
 
TZS 1581 -2, Determination of cadmium content – Method flame atomic absorption spectrometry  
TZS 20 44 (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  AFDC 21 (39 3) CD3  
ICS 67.080.20  
2 
  
FTZS 2473, Animal feeding stuffs - Determination of crude ash  
 
TZS 2565, Bio fortified sweet potato – Specification  
 
 
3 Terms and definitions  
 
For the purpose of this standard, the following term s and defini tions shall apply.  
 
3.1  
orange fleshed sweet potato   
storage roots biofortified with beta -carotene (provitamin A) obtained from a plant of the species ( Ipomoea 
batatas ( L.) Lam), prima rily used for human consumption  
 
3.2  
orange fleshed sweet potato  flour  
flour obtained from sweet potato as defined under 3.1  
 
3.3  
foreign matter  
inorganic matter such as sand, glass, metal, stones, clay , mud and organic matter such as chaff, straw, 
weed seeds , live insects , insect fragments  and rodent hairs  
 
3.4  
food grad e material  
material that will not transfer non -food chemicals into the food and contains no chemicals which would be 
hazardous to human health  
 
 
4 Requirements  
 
4.1 General requirements  
 
4.1.1 Orange fleshed sweet potato  flour shall be produced from orange  fleshed sweet potato  complying t o 
TZS 2565. 
4.1.2 Orange fleshed sweet potato flour shall be  
a) uniformly orange in colour,  
b) free from off-flavours and odours;  
c) practically free from any living insects and foreign matter s 
 
4.2 Specific  requirements  
 
4.2.1 Orange fleshed sweet potato  flour shall conform to the compositional quality requirements shown in 
Table 1.  
 
 Table 1 — Specific  requirements  for orange fleshed sweet potato 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/100g, min  
 3.2 Annex  A AFDC 21 (39 3) CD3  
ICS 67.080.20  
3 
 4.  Crude fibre, % by mass on dry 
weight basis, max  3 ISO 5498  
5.  Acid insoluble ash, % by mass, max.  0.15 TZS 2044  
 
4.2.2 For particle size, not le ss than 95 % of mass of orange fleshed sweet potato  flour shall pass through 
a sieve of 140 -μm mesh screen.  
 
 
5 Hygiene  
 
Orange fleshed sweet potato  flour shall be prepared and handled in a hygienic manner in accordance  
with TZS 10 9 and shall conform to mi crobiological limits specified in Table 2 .  
 
 
Table 2 — Microbiological limits for orange fleshed sweet potato  flour  
 
S/NO  Micro -organisms  Maximum limit  Method of Test  
1.  Escherichia coli,  cfu/g,  Absent  TZS 731  
2.  Salmonella  spp, per 25g Absent   TZS 122 -1 
3.  Yeast and mould, cfu/g,.  103 TZS 2426 -1 
 
 
6 Contaminants  
 
6.1 Heavy metals  contaminants  
Orange fleshed sweet potato flour shall not contain any metal contaminants in exces s of levels specified 
in Table 3 . 
 
Table 3 – Limit for heavy metals contaminants for orange fleshed sweet potato flour  
  
S/NO   
Characteristics   
Maximum (mg/kg)   
Method of Test  
1.  Lead ( Pb) 
 0.1 TZS 1502  
 
2.  Cadmium (Cd)  0.1 TZS 1581 -2 
 
 
6.2 Pesticide residues  
 
Orange fleshed sweet potato  flour shall conform to maximum residue limits fo r pesticide residues 
established by the Codex Alimentarius Commission for this commodity.  
 
6.3 Aflatoxin  
Orange fleshed sweet potato  flour shall not have more than 5 ppb for Aflatoxin B 1 and 10 ppb for total 
aflatoxin when tested according to TZS 799.  
 
 AFDC 21 (39 3) CD3  
ICS 67.080.20  
4 
 7 Pack ing, marking and labelling  
 
7.1 Packing  
Orange fleshed sweet potato  flour 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 requirements shall apply and sha ll 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  flour; 
 
b) the net weight the name and  physical address of the manufacturer / 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 te sts 
8.1 Sampling  
Sampling of orange fleshed sweet potato  flour shall be done according to TZS 330.  
 
8.2 Test s 
Testing of orange fleshed sweet potato  flour shall be done according to test methods prescribed in Table 
1,2,3 and Annex A of this  standard.  
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 3) CD3  
ICS 67.080.20  
5 
 ANNEX A (Normative)  
DETERMINATION OF BETA CAROTENE IN FOOD BY U V-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 filtrate 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 Sodium Sulphate   
c) β-Carotene sta ndard ≥93% (UV), powder . 
d) Petroleum Ether, Spectrophotometric 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 grains or pellets form and mak e 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 filter paper No. 1 to obtain cle ar 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 extra ct 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 t hrough 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 with petroleum ether into 10 0ml 
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 3) CD3  
ICS 67.080.20  
6 
 standard calibration curve, from th e 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 extract  
 M    = Slope of the  standard plot  
 Sp wt. = Amount of sample taken for analysis