TBS/AFDC 23(364 ) CD3 
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 Draft Tanzania Standard  
 
 
Bivalve molluscs  – Specification  
TANZANIA BUREAU OF STANDARDS  
  
  
 
                                                                                                                                    TBS/AFDC 23(364 ) CD3 
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 Bivalve molluscs - Specification  
 
0. Foreword  
Bivalve molluscs are harvested alive from a harvesting area either approved for direct human 
consumption or further processing , e.g. relaying or depuration  prior to human consumption , thus the need 
to ensure its safety and quality.   
In preparation of this Tanzania sta ndard assistance was drawn from Standard for live and raw bivalve 
molluscs published by Codex Aliment arius Commission.  
In reporting the result of a test or an  analy sis made in accordance with this standard, if the final value 
observed or calculated, is to be rounded off, it shall be done in accordance with TZS 4 (See clause 2).  
1 Scope  
This Tanzania stand ard specifies requirements, m ethods of sampling and test for live and raw bivalve 
molluscs that  have been shucked and/or frozen, and/or processed . 
2 Normative References  
The following referenced documents are indispensable for the application of this docum ent. For dated 
references, only the edition cited applies. For undated references, the latest edition of the referenced 
document (including any amendments) applies.  
TZS 4 - Rounding off numerical values  
TZS 109 - Food processing uni ts - Code of hygiene - General  
TZS 447:2015, Fish and fishery products - determination of histamine  
TZS 538 Packaging and labelling of foods  
CAC/GL 50, General guidelines on sampling  
CAC/RCP 52, Code of practice for fish and fishery products  
TZS 731:2007 / ISO 7251:2005, Microbiol ogy of food and feeding stuffs – Horizontal method for detection 
and enumeration of presumptive  Escherichia Coli – Most Probable Number Technique   
AOAC 959.08 , Paralytic Shellfish Poison Biological Metho d 
AOAC 2011.27, Paralytic Shel lfish Toxins(PSTs) in S hellfish  
CXS-192-1995, General standard for food additives  
 
 
3 Terms and definitions  
For the purpose of this standard the following terms and definitions shall apply;                                                                                                                                     TBS/AFDC 23(364 ) CD3 
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 3.1  
live bivalve molluscs   
products that are alive imm ediately prior to consumption whos e presentation includes the shell  
 
3.2  
raw bivalve molluscs  
products that were alive immediately prior to the commencement of processing  
 
  
3.3  
food grade material  
material that will not transfer non -food chemicals into the food and contains no chemical s which would be 
hazardous to human health  
3.4 d epuration of seafood  
process by which marine or freshwater animals are placed into a clean water environment for a period of 
time to allow purging of biological contaminants (such as Escherichia coli) and ph ysical impurities (such 
as sand and silt)  
 
4 Requirements  
4.1 General requirements  
4.1.1  The bivalve molluscs  shall be free from any foreign material that compromise safety and quality . 
4.1.2  The bivalve molluscs  shall possess  organoleptic characteristics associated with fr eshness.   
4.1.3  The bivalve molluscs  shall be f ree off  distinct objectionable odours or flavours indicative of 
decomposition or rancidity.  
4.1.4  During storage or transportation,  live bivalve molluscs shall be kept at a temperature  that does 
not adversely affect its s afety or viability . 
4.1.5  Live bivalve mo lluscs shall not be re -immersed in or spread with water they have been packaged 
for retail sale  
4.2 Specific requirements  
The bivalve molluscs  shall conform to the compositional quality requirements shown in Table 1.  
Table 1  — Compositional requirements of bivalve molluscs   
Provision  Requirements  Method of test  
Histamine , mg per 100 g , max  40  TZS 447  
Dead or damaged bivalve 
molluscs, % ,max  5  Annex A  
Deep Dehydration, % , max 
 10  Annex B                                                                                                                                      TBS/AFDC 23(364 ) CD3 
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 8 Food additives  
Food additiv es are permitted only in raw bivalve molluscs in which the additive used shall comply 
with the limits established in the Codex General Standard for Food Additives (CXS 192 -1995).  
5  Contaminants  
 5.1 Live bivalve molluscs shall comply with the  following  biotoxins  provisions  measured in the whole 
body or any edible part separately as indicated  in Table 2 . 
Table 2—Bioxin limits of live bivalve molluscs  
Name of biotoxin 
groups  Maximum level mg/kg of mollusc s flesh  Methods of test  
Saxitoxin (STX)  0.8    
AOAC 959.08/   
AOAC 2011.27  Okadaic acid (OA)  0.16  
Domoic acid (DA)  20  
Brevetoxin (BTX)   200 
Azaspiracid (AZP)  0.16 
 
5.2 Pesticide residues  
 
Bivalve  molluscs products shall conform to maximum residue limits for pesticide residues established by 
the Codex Alimentarius Commission for this commodity.  
6 Hygiene  
6.1 Bivalve molluscs shall be produced and handled in a hygienic manner in accordance with TZS 
109 and CAC/RCP 52.  
6.3 When tested in accordance with TZS 731, E. coli shall not exceed 700 MPN/g . 
7 Sampling and test  
7.1 Sampling  
Sampling of bivalve molluscs  shall be done according to  the Codex general guideline on sampling 
(CAC/GL 50).  
 
7.2 Test  
Testing of bivalve molluscs  shall be done according to test methods prescribed in Table 1, 2 and in other 
parts of this standard.  
 
9 Weights and Measures  
 
Bivalve molluscs  shall be packaged in accordance with Weights and Measures requirements of the 
destination country.  
10 Packing, marking and labeling                                                                                                                                     TBS/AFDC 23(364 ) CD3 
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 10.1Packing  
Bivalve molluscs  shall be packed in suitab le food grade materials.   
10.2 Marking and labeling  
In addition to the requirements of TZS 538; the following labeling requirements shall apply and shall be 
legibly and indelibly marked  
a) name of the product as " bivalve molluscs " and common or species name   
b) mode of presentation;  
c) date and location of harvest  for live bivalve mo lluscs ; 
d) durability or shelf life  for live bivalve mo lluscs ;  
e) packing medium  for raw bivalve molluscs;  
f) name and ph ysical address of the processor;  
g) batch or lot number;  
h) content d eclaration  by weight, count, count per unit weight, volume  or per package;  
i) instruction for use ; 
j) storage i nstructions ; and  
k) The language on the label shall be Swahili and/or English Another language may be used 
depending on the designated market.  
 
10.3 The containers  may also be marked with the TBS Standards Mark of Quality.  
NOTE: The TBS Standards Mark of Quality may be used by the manufacturers only under license from 
TBS. Particulars of conditions under which the licenses are granted, may be obtained from TBS.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                                                                                                                                    TBS/AFDC 23(364 ) CD3 
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 Annex A  
(normative)  
Determination of  dead or damaged bivalve mollusc s 
 
Dead or damaged bivalve mollusc s shall be determined by counti ng the number of bivalve mollusc s in the 
container or a representative, then the percentage of  dead or da maged bivalve mollusc s is determined by 
dividing the amount of dead or damaged with the  total amount of bivalve mollusc s in the container or 
representative sample  
Calculation:  
 
Where:  
W1 = Amount of  dead or damaged bivalve mollusc s  
W0 = Total amount of  bivalve mollusc s in container or representative sample  
 
Annex B  
(normative)  
Determination of Deep Dehydration  
 
Deep Dehydration is the condition that results from excessive loss of body water/moisture greater than 
10% of the weight of the bivalve molluscs  in the sample unit or greater than 10% of the surface area of 
the block. Excessive loss of moisture clearly shown as white or abnormal colour on the surface which 
masks the colour of the flesh and penetrates below the surface, and cannot be easily removed  by 
scraping with a knife or other sharp instrument without unduly affecting the appearance of the bivalve 
molluscs.  
When declared on the label, percentage of deep dehydrated  bivalve molluscs shall be determined by 
counting the number of bivalve molluscs i n the container or a representative sample that shows excessive 
loss of water/moisture then dividing by the  total amount of bivalve mollusc s in the container or 
representative sample  
Calculation:  
 
Where:  
W1 = Amount of dehydrated mollusc s 
W0 = Total amou nt of bivalve mollusc s in container or representative sample