AFDC 04(1460 )DTZS  
                                                                                                               
                                                                                                                 
  
 
 
 
 
 
       DRAFT  TANZANIA STANDARD  
 
                        Edible Walnut  oil – Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                   TANZANIA BUREAU OF STANDARDS  
 
    ©TBS 2022  – All rights reserved  
                                                                                                              
                                                                                                             AFDC 04(1460 )DTZS  
                                                                                                               
                                                                                                                 
 Edible Walnut oil – Specification  
 
0 Foreword  
 
Edible w alnut oil is extracted from walnut  fruitt, Juglans regia  L. The oil contains polyunsaturated fatty 
acids, monounsaturated fatty acids, and saturated fats .  Edible w alnut oil is used in the food industry 
as a cooking oil or  as an ingredients in salad dressing. It is one of traded edible vegetable oils in 
Tanzania . 
 
This Tanzania Standard  has been prepared to ensure the safety and quality of edible walnut  oil 
produced domestically , exported  or imported into the country.  
 
In preparation of this  Tanzan ia standard considerable help was derived from : 
 
CODEX STAN 210 -1999 ( Revised  2019 ), Codex standard for named vegetable oil s published by the 
Codex Alimentarius Commission . 
 
In reporting the results of a test or analysis made in accordance with this Tanza nia Standard, if the 
final value observed or calculated is to be rounded off, it shall be done in accordance with TZS 4.  
 
1 Scope  
 
This Tanzania s tandard specifies  the requiremen ts, sampling  and testing methods  for walnut oil 
derived from the kernel of walnut fruit ( Juglans regia  L.) intended  for human consumption . 
 
2 Normative r eference s 
 
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 amendments) applies ; 
 
Codex s tan 192, General standards for food additives               
TZS 4 ,  Rounding off numerical values  
TZS 54 , Animal and Vegetable fats and oils – Sampling  
TZS 76 ,  Methods for determination of arsenic  
TZS 109, Food processing units – Code of hygiene — General  
TZS 268 , General atomic absorption – Spectro – Photometric method for determination of lead in 
food stuffs  
TZS 538  , Packaging and labeling of foods  
TZS 799 , Foodstuffs – Determination of aflatoxin B1, and the total content of aflatoxins B 1, B2, G1 and 
G2 in cereals, nuts and derived products – Highperformance liquid chromatographic method  
TZS 1313 , Fortified edible oils and fats — Specification  
TZS 1322,  Oils an d fats Sampling and test methods – Purity test TZS 1324 , Animal and vegetable 
fats and oils – Determination of peroxide value -Iodometric (visual) end point determination  
TZS 1325 ,  Animal and vegetable fats and oils - Determination of saponification value   
TZS 1326 ,  Animal and vegetable fats and oils – Determination of moisture and volatile matter  
TZS 1327 ,  Animal and vegetable fats and oils – Determination of iodine value  
TZS 1328 ,  Essential oils – Determination of relative density at 20  °C – Referen ce method                                                                                                                
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 TZS 1329 ,  Animal and vegetable fats and oils – Determination of refractive index  
TZS 1331 ,  Animal and vegetable fats and oils – Determination of acid value and acidity  
TZS 1332 ,  Animal and vegetable fats and oils – Determination of unsaponi fiable matter -method using 
diethyl ether extraction  
TZS 1335 ,  Animal and vegetable fats and oils – Determination of copper, iron and nickel content -
graphite furnace atomic absorption  
TZS 1336 ,  Animal and vegetable fats and oils – Determination of insol uble impurities content  
 
3 Term s and definitions  
 
For the purpose of this Tanzania Standard the definition s below shall apply;   
 
3.1 edible w alnut  oil  
 
oil derived from the kernel of walnut fruit ( Juglans regia  L.) intended for human consumption . 
 
3.2 virgin walnut oil 
 
edible walnut oil obtained, without altering the nature of the oil, by mechanical procedures, such as 
expelling or pressing, and the application of heat only. It may have been purified by washing with 
water, settling, filtering and centrifu ging only.  
 
3.3 c old pressed  walnut oil  
 
edible walnut oil obtained, without altering the oil, by mechanical procedures only, such as . expelling 
or pressing, without the application of heat. They may have been purified by washing with water, 
settling, fi ltering and centrifuging only.  
 
3.4 refined /non -virgin  walnut oil  
 
edible walnut oil obtained, by mechanical procedures and/or solvent extraction and subjected to 
refining processes.  
 
4.Requirements  
 
4.1 General requirements  
 
Edible walnut oil shall  
a) be free from  foreign and  rancid odour and taste;  
 
b) be clear and free from adulterants,  sediment s, suspended or foreign matter and water . 
 
4.2 Specific requirements  
Edible walnut oil shall comply with  specific requirements  given in Table 1 when tested in 
accor dance with the methods specified therein ; 
   
 
 
                                                                                                               
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 Table  1- Specific   require ments for edible walnut oil 
S. No.  Parameter  
 Requirement  Test method   
i.  Relative density  (at 25 oC/water at 25  oC) 0.923  - 0.925  TZS 1328  
  
ii.  Refractive index at  40 o C  
 
Refractive  index at 25˚C;  
 1.469  - 1.471  
 
1.472  - 1.475  
 TZS 1329  
 
iii.  Saponification value, mg KOH/g oil  189 - 198 TZS 1325  
 
iv.  Iodine value  (g I 2/100g)  132 - 162 TZS 1327  
v.  Unsaponifiable matter, g/kg, max.  20 TZS 1332  
vi.  Moisture and matter volatile at 105 o C, % 
m/m, max.  0.2 TZS 1326  
vii.  Insoluble impurities, % m/m, max.  0.05 TZS 1336  
viii.  Soap content, % m/m, max.  0.005  TZS 1322  
ix.  Iron (Fe) mg/kg ,max.  Cold pressed and 
virgin oil:          5  
 
Refined  oil:     1.5  
 TZS 1335  
x.  Copper (Cu) mg/kg ,max.  Cold pressed and 
virgin oil:         0.4  
 
Refined  oil:     0.1 
  TZS 1335  
xi.  Acid value , mg KOH/g Oil , max.  Refined  oil:    0.6  
 
Cold pressed and 
virgin oil:        4 
 TZS 1331  
xii.  Peroxide value, mEq/kg, max  Refined  oil :10  
 
Cold pressed and 
virgin oil: 15 
 TZS 1324  
 
5  Food additives  
 
Refined walnut oil may contain food additives in accordance with Codex Stan 192. In addition , food 
additives shall not be used  in virgin or cold pressed walnut oil . 
 
6.  Fortification  
 
Edible walnut oil may be fortified in accordance with TZS 1313.  
 
7  Hygiene                                                                                                                
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Edible walnut oil shall be processed, handled and stored in accordance with TZS 109  . 
 
8  Contaminants  
 
8.1 Aflatoxin  
 
Aflatoxin level for edible walnut oil shall not exceed maximum limits as given in Table 2 when tested in 
accordan ce with test method specified therein:  
 
                         Table 2 - Aflatoxin limits for edible walnut oil  
S/N Aflatoxin  Maximum limit  
 ( µg/kg)  Method of test  
i) Total aflatoxin  10 TZS 799  
 ii) Aflatoxin B 1 5 
 
8.2 Pesticide residues  
Edible walnut oil shall comply with relevant maximum pesticide residue limits established by the  Codex 
Alimentarius Commission  online data base . 
8.2. Heavy metal  contaminants  
Edible walnut oil shall comply with the maximum  heavy metal limits as specified in Table 3 . 
Table 3– Maximum Limits for heavy metal contaminants in edible walnut oil  
 
S/No  Contaminant  Maximum limit  Test Method  
i Lead (Pb) mg/kg  
 0.08 TZS 268  
ii Arsenic (As) mg/ kg  
 0.1 TZS 76  
 
9  Packing, Marking and Labelling  
 
Edible walnut oil shall be pac ked, marked and label led in accordance with TZS 538.  
 
9.1  Pack ing 
 
Edible walnut oil shall be pack ed in food grade materials  and properly sealed to ensure safety and 
quality requirements of the product  are main tained throughout the shelf life . 
 
9.2    Ma rking and label ling 
 
9.2.1 In addition each c ontainer of  edible walnut oil shall be legibly and indelibly marked with the 
following information:  
 
a) Name of the product  shall be " walnut oil "; 
b) The words virgin or refined shall be declared on the label to in dicate the type of oil  
c) Name, physical address of the manufacturer and/or packer;  
d) Batch or lot number;                                                                                                                
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 e) Date of manufacturer;  
f) Expiry date;  
g) Net weight in Metric unit;  
h) Country of origin;  
i) Storage conditions;  
j) List of ingredients in descending order, including t he specific name of additives;  
 
9.2.2 The containers may  also be marked with the TBS Standards Mark of Quality.  
 
NOTE – The TBS Standards Mark of Quality shall be used by the manufacturers only under licence from TBS. 
Particulars of conditions under whi ch the licences are granted, may be obtained from TBS.  
 
10 Sampling and Tests  
 
10.1 Sampling  
 
Edible walnut oil shall be sampled in accordance with  TZS 54.  
 
10.2 Tests  
 
Edible walnut oil shall be tested in accordance with the test methods given in this T anzania standard .