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TCVN        :202x 
Version  1 
FROZEN TUNA  – SPECIFICATIONS  
Frozen tuna  – Specifications  
 
 
 
 
     
 
 
HA NOI  – 202x          TCVN               NATIONAL STANDARD  
DRAF T TCVN      :202x 
 
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   TCVN        :202x 
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Foreword  
TCVN      :202x prepared by National Agro – Forestry – 
Fisheries Quality Assurance Department; suggested by 
Ministry of Agriculture and Rural Development, verified by 
Directorate for Standards, Metrology and Quality, announced 
by Ministry of Science and Technology  
  TCVN      :202x 
 
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  TCVN        :202x 
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 NATIONAL STANDARD                                                TCVN        :202x            
 
 
 
Frozen tuna – Specifications  
Frozen tuna – Specifications  
 
 
 
 
1   Scope of application  
This Standard applies  to frozen tuna products for direct consumption or for pre -processing of yellowfin 
tuna ( Thunus albacares , Bonnaterre, 1788) and bigeye tuna ( Thunnus obesus , Lowe, 1839).  
2   Normative references  
The following references documents are very essential for the application of this standard. For the 
references has the publication year in it, the indicated version shall be applicable. For the references 
doesn’t have the publication year in it, then the latest version is applicable, including any amendments 
and modifications (if any).  
TCVN 4830 -1:2005 (ISO 6888 -1:1999, With Amd. 1:2003), Microbiology of food and animal feeding stuffs 
– Horizontal method for the enumeration of coagulase -positive staphylococci (Staphylococcus aureus 
and other species) - Part 1: Technique using Baird -Parke r agar medium  
TCVN 4884 -1:2015 (ISO 4833 -1:2013), Microbiology of the food chain - Horizontal method for the 
enumeration of microorganisms - Part 1: Colony count at 30 degrees C by the pour plate technique  
TCVN 7924 -1:2008 (ISO 16649 -1:2001) Microbiology o f food and animal feeding stuffs – Horizontal 
method for the enumeration of β -glucuronidase -positive Escherichia coli – Part 1: Colony -count technique 
at 44 °C using membranes and 5 -bromo -4-chloro -3-indolyl β -D-glucuronida  
TCVN 10780 -1:2017 (ISO 6579 -1:201 7), Micro bilogy of food chain - Horizonatal method for the detection, 
enumeration and serotyping of  Salmonella - Part 1: Dectection of  Salmonella  
ISO 11290 -1:2017 , Microbiology of the food chain — Horizontal method for the detection and 
enumeration of Listeria monocytogenes and of Listeria spp. — Part 1: Detection method  
TCVN 7905 -1:2008 (ISO/TS 21872 -1:2007), Microbiology of food and animal feeding stuffs – Horizontal 
method for the detection of potentially enteropathogenic Vibrio spp. – Part 1: Detection of Vibrio 
parahaemolyticus and Vibrio cholerae  
TCVN 5276:1990 , Aquatic products – Sampling and preparation of sample   TCVN      :202x 
 
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 TCVN 7602:2007 , Foodstuffs – Determination of lead content by atomic absorption spectrophotometric 
method  
TCVN 7603:2007 , Foods – Determination of cadmium content by atomic absorption spectrophotometric 
method  
TCVN 7604:2007 , Foods – Determination of mercury content by flameless atomic absorption 
spectrophotometric method  
AOAC 983.20 ,  Mercury (methyl) in fish and shellfish: Gas chromatographic method  
AOAC 988.11 ,  Mercury (methyl) in fish and shellfish: Rapid gas chromatographic method  
AOAC 990.04 , Mercury (methyl) in seafood: Liquid chromatographic - atomic absorption 
spectrophotometric method  
TCVN 6507 -3:2005 (IS O 6887 -3:2003), Microbiology of food and animal feeding stuffs – Preparation of 
test samples, initial suspension and decimal dilutions for microbiological examination - Part 3: Specific 
rules for the preparation of fish and fishery products  
TCVN 8352:2010 , Fish and fishery products - Determination of histamine content - Method using high -
performance liquid chromatography  
TCVN 11047:2015 , Fish and fishery products - Determination of histamine content - Fluorometric method  
TCVN 12153:2018 , Tuna’s raw material  
TCVN 12750:2019 (ISO 11035:1994) , Sensory analysis – Identification and selection of descriptors for 
establishing a sensory profile by a multidimensional approach  
QCVN  8-2:2011/BYT, National technical regulation on the limits of heavy metals conta mination in food  
3   Terms and Definitions  
This standard uses the following terms and definitions : 
3.1 
Tuna loin  
The flesh of fish without skin, fins, with or without bones, taken from the body of a tuna by cutting parallel to 
the backbone  
3.2  
Preliminarily prepare  
Process that includes cleaning steps; cut off the head and tail; fish fillet; skin type, dark meat, offal and 
with or without bone removal  
3.3  
Frozen tuna   
Tuna loin , other products cut from tuna loin  without additives, processing aids or additives, processing 
aids are frozen, ensuring the heart of the meat is in the best part. thickest reaches -18⁰C or below , stored 
and transported at -18⁰C or below.  TCVN        :202x 
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 4   Technical requirements  
4.1 General requirements  
Frozen tuna production facilities must meet current regulations on hygiene and food safety assurance . 
4.2 Requirements for raw tuna  
Raw tuna has a complete profile to meet current regulations.  
For raw tuna in fresh chilled or cold-preserved at a temperature of  - 10C to 40C meeting the organoleptic 
criteria according to grades 1, 2 or 3 according to TCVN 12153:2018 ; 
For raw tuna in frozen, always maintain the storage temperature at  - 180C  or lower before being put into 
the fact ory. 
4.3  Preliminarily prepare  
Preliminary processing is carried out in a period of not more than 25 minutes/fish and the temperature of 
the semi -finished products is always maintained at a temperature less than or equal to 4⁰C. 
4.4 Additives or processing aids  
The use of additives or processing aids that meet current regulations on dosage and use is allowed . 
The temperature of the incubation room is always maintained from  -1⁰C to 4⁰C and the incubation time 
does not exceed 36 hours . 
4.5  Freezing tuna loin  
Tuna loin  freezing is considered complete when the temperature at the center of the thickest part reaches 
-18⁰C or lower.  
4.6  Shaping  and packaging  
During shaping and packaging, the temperature at the center of the thickest part of the product is always 
maintained at -18⁰C or lower.  
Packaging and containers are made of materials that meet current regulations on ensuring food safety.  
4.7  Sensory criteria  
Table of sensory criteria is specified in Table 1  TCVN      :202x 
 
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 Table 1 - Sensory quality ranking of frozen tuna  
Name of index  Request  
Grade  AAA  Grade  AA Grade  A Grade  B 
External 
inspection  The surface of the 
fish is shiny, the 
fish mass is clear.  
Outer layers are 
clearly visible  
Fish with additives 
or processing aids: 
pink to bright red  
Fish without 
additives or 
processing aids: 
Rose red to dark 
purple  The surface of the 
fish is less glossy, 
clear, less fresh  
Only fat veins can 
be seen on the 
outer layer  
Fish with additives 
or processing aids: 
pink to bright red  
Fish without 
additives or 
processing ai ds: 
Rose red to dark 
purple  Fish is not shiny, 
less bright.  
Can't see the 
grease  
Fish with additives 
or processing aids: 
Dull and opaque 
fish color  
Fish without 
additives or 
processing aids: 
Slightly brown color  Fish is not shiny, 
not bright  
Can't see the 
grease  
Fish with additives 
or processing aids: 
Dull and opaque 
fish color  
Fish without 
additives or 
processing aids: 
Brown  
Muscle structure  The flesh is firm, 
elastic quickly 
when lightly 
pressed with the 
fingertips. No soft 
spots on the 
surface of the fish The flesh is firm, 
elastic slowly when 
pressed lightly with 
the fingertips. 
There are one or 
two very small soft 
spots on the 
surface of t he fish The fish is less firm, 
not fully elastic 
when pressed 
lightly with the tip of 
a finger. Some 
small soft spots on 
the surface of the 
fish The fish is tender, 
not elastic when 
lightly pressed with 
the fingertips. 
Large soft areas on 
the surface of th e 
fish 
Odor  Characteristic fresh smell of fish, no unpleasant smell  There is no 
characteristic fresh 
smell of fish  
NOTE :  Quality level grades  
AAA: Highest quality level for ready -to-eat or further product processing ; 
AA: Next level of quality for ready -to-eat or further product processing ; 
A: Quality level for further processing of products ; 
B: The next level of quality used for further processing of products . 
 
4.8   Food safety requirements  
4.8.1 Heavy metals content of chilled poultry fish 
The maximum heavy metal pollution limits for frozen tuna are specified in Table 2 .  
Table  2 - Heavy metals content  
No. Name of index  Maximum level 
(mg/kg)  
1 Cadimi (Cd)  0,1 
2 Lead  (Pb) 0,3 
3 Mercury (Hg) 1,0 
4 Mercury (methyl) ( MeHg)  1,0 
 
4.8.2  Histamin  TCVN        :202x 
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 Permissible limits for histamine content in frozen tuna products are specified in Table 3 .  
Table  3 - Permissible limit for histamine content  
Name of index  Sampling plan  Limits  
(mg/kg)  
n c m M 
Histamin  9 2 100 200 
IN WHICH:  
n is the number of sample taken.  
c is the maximum allowed sample in n sample can have results between m and M.  
m is low limit.  
M is high limit.  
If there is a sample has results higher than M mean does not meet standard.  
4.8.3   Microbiology index  
Permissible limits for microorganisms in frozen tuna products are specified in Table 4 . 
Table  4 – Permissible limits for microorganisms  
Criteria  Sampling plan  Litmit (CFU/g)  
n c m M 
1. Ready to eat products  
Total anaerobic plate count  5 2 104 105 
E.coli  5 0 Not detect  
Listeria monocytogenes  5 0 Not detect  
Vibrio choleral/25g  5 0 Not detect  
Salmonella /25 g  5 0 Not detect  
Coagulase -positive 
Staphylococcus aureus  5 0 Not detect 
2. Product s heat treatment before eating  
Total anaerobic plate count  5 2 5 x 105 5 x 106 
E.coli  5 2 5 x 102 5 x 103 
Salmonella /25 g  5 0 Not detect  
IN WHICH:  
n is the number of sample taken.  
c is the maximum allowed sample in n sample can have results between m and M.  
m is low limit.  
M is high limit.  
If there is a sample has results higher than M mean does not meet standard.  
5   Test methods  
5.1   Sensory evaluation methods  TCVN      :202x 
 
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 5.1.1 Sample preparation  
Sensory evaluation samples with a thickness of 2.5 - 3 cm, thawed by soaking in clean water with a 
temperature of 18 - 20 ⁰C until the piece of fish feels soft (about 15 - 20 minutes), placed on a white plate, 
clean.  
5.1.2 Evaluation methods  
Perform sensory evaluation according to TCVN 12750:2019  
A list of terms for sensory descriptions can be found in Appendix A .  
5.2 Cadimi determination  as TCVN 7603:2007 or TCVN 8126:2009.  
5.3 Lead determination as TCVN 7602:2007 or TCVN 8126:2009.  
5.4 Mercury determination  as TCVN 7604: 2007 (AOAC 971.21)  
5.5 Mercur methyl determination  as  AOAC 983.20 as  AOAC 988.11 as  AOAC 990.04  
5.6 Histamin determination as TCVN 11047:2015  or TCVN 8352:2010  
5.7 Listeria monocytogenes  detection as ISO 11290 -1:2017  
5.8 Vibrio choleral  detection as TCVN 7905 -1:2008 (ISO/TS 21872 -1:2007)  
5.9 Coagulase -positive Staphylococcus aureus  detection as TCVN 4830 -1:2005 (ISO 6888 -1:1999, 
with Amd 1:2003)  
5.10 S almonella  detection  as TCVN 10780 -1:2017 (ISO 6579 -1:2017)  
5.11 Total anaerobic bacteria determination  as TCVN 4884 -1:2015 (ISO 4833 -1:2013)  
5.12 E.Coli  detemination as TCVN 7924 -1 : 2008, TCVN 7924 -2:2008 (ISO 16649 -2:2001),  TCVN 
7924 -3:2008 (ISO 16649 -3:2005)  
6   Labeling  
According to current requirements on labeling.  
7   Transportation, storage, shelf -life and traceability  TCVN        :202x 
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 7.1   Storage  and transportation  
Frozen tuna must be stored, transported by specialized means, ensure food hygiene and safety and have 
an ambient temperature maintained at -18⁰C or lower.  
7.2 Traceability  
Comply with current legal requirement . 
  TCVN      :202x 
 
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 Appendix A  
List of terms for sensory description of frozen tuna products  
(Reference)  
No. Term  Scale  (0-5) Definition and assessment  
1. Appearance  
1.1 Surface gloss  No Gloss → Very Glossy  Use a sharp knife to cut the fish into 
slices, observe the cut surface and 
evaluate the light contrast from the 
surface  
1.2 Surface  
brightness  Very dark/dark →  Very 
light/fresh  Brightness as seen by the eye  
1.3 Translucent  No t ranslucent  → Very 
translucent  Hold the fish in front of the light source, 
if a part of the light is able to penetrate 
the meat, then the transparency is 
strong.  
1.4 Rainbow light  None → Very clear  Observe the rainbow on the surface. 
No rainbow is Grade A, if there is a 
rainbow, it is Grade B, from Grade B 
down it doesn't matter the rainbow  
1.5 Metallic luster  None → A Lot  Appearance of iridescence around 
points of decay, discolouration or 
discoloration, is a sign of poor qua lity 
1.6 Fatness  No fatness  → Very f atness  Observe the amount of fat more or less 
on the surface of the slice by assessing 
the amount of exudate on the surface 
after cutting  
1.7 Crushing degree  Not crushed → Very 
broken  Observe muscle mass  
1.8 Red (meat 
without additives 
or processing 
aids)  Rose red → Dark purple 
red Observe the white flesh of the fish 
body, pinkish red (like the color of a 
young watermelon), dark purple red 
(like the color of a ripe plum)  
1.9 Brown (meat 
without additives 
or processing 
aids)  Light brown → Dark brown  Observe the white flesh of the fish loin, 
light brown (low milk coffee) dark 
brown (dark chocolate color), for meat 
without additives or processing aids  TCVN        :202x 
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 No. Term  Scale  (0-5) Definition and assessment  
1.10 Red (meat with 
additives or 
processing aids)  Rose red →  Magenta  Observe the white muscle of the 
carcass meat, which is brighter red 
than the meat sample without additives 
or processing aids, and when 
defrosted it does not brown. When 
boiled meat is whiter than meat, no 
additives or processing aids are added.  
1.11 White (sunshine 
or TS gas color)  Bright white → Opaque 
white  Observe the white muscle of the fish 
body, the color is from bright white to 
milky white, there is dehydration, 
contraction and fragmentation of the 
muscle, the higher the intensity, the 
lower the quality.  
1.12 Amount of fat 
veins  None → Many  Only in the breast, see how much fat is 
on the surface of the slice  
1.13 Scratch degree  None → A lot  For assessment of whole fish, observe 
the skin surface, may be scratched but 
not deeply embedded in the flesh  
2. Structure  by hand  
2.1 Firmness  Very flimsy → Very sure  Hang the piece of fish up with 2 fingers, 
use the other hand to stretch the meat 
fibers with a moderate force. The more 
easily the fibers fall apart, the less firm 
they are, and vice versa.  
2.2 Elasticity  Not elastic → Very elastic  Apply a force to the surface of the fish. 
The easier it is for the product to return 
to its original shape, the higher the 
elasticity  
2.3 Soft spot  None → Many soft spots  Observe the meat surface, detect 
abnormal soft spots due to biochemical 
damage, the more soft spots, the 
higher the intensity.  
2.4 Flexibility  Not flexible → Very 
flexible  Using two fingers, roll a small piece of 
fish, round it on your hand, if the piece 
of fish is shaped according to the TCVN      :202x 
 
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 No. Term  Scale  (0-5) Definition and assessment  
hand's grip, it will be more flexible and 
vice versa.  
2.5 Stickiness  Non-stick → Very sticky  Use your fingers to see if the pieces of 
fish stick to your hand more or less, 
reflecting the fatty character of the 
product. Fresh is good, less fresh is 
sticky  
2.6 Shameful bottle  None → Many  By hand to judge on the piece of meat 
there are parts that are not soft and 
callous  
3. Structure by mouth  
3.1 Toughness  Not tough → Very tough  Use a knife to cut a piece of fish of 
sufficient size, chew and stir in the 
mouth with the front teeth and molars 
to assess the toughness of the fish 
meat.  
3.2 Flexibility  Not flexible → Very 
flexible  Use a knife to cut a piece of fish of 
sufficient size, chew and stir in the 
mouth with the incisors and molars to 
assess the plasticity of the fish meat.  
3.3 Roughness  Not grainy → Very grainy  Use a knife to cut a piece of fish to the 
right size, bite or chew the piece of fish 
a few times to evaluate the texture of 
the fish meat.  
3.4 Friction  Not frivolous → Very 
frivolous  Use a knife to cut a piece of fish of 
sufficient size, chew and stir in the 
mouth with the incisors and molars to 
assess the friabilit y of the fish.  
3.5 Succulent degree  Very dry → Very 
succulent   Use a knife to cut a piece of fish of 
sufficient size, chew and stir in the 
mouth with the front teeth and molars 
to evaluate the succulence of the fish.  
4. Smell  Cut a small piece, if necessary, then 
crush it, put the piece of fish up to your 
nose and smell it. Then eat a small 
piece, then exhale through the nose to TCVN        :202x 
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 No. Term  Scale  (0-5) Definition and assessment  
smell backwards and evaluate the 
flavor of the product  
4.1 Natural fishy 
smell  None → Very strong    
4.2 The smell of 
seaweed  None → Very strong    
4.3 The smell of cold 
air None → Very strong    
4.4 The smell of 
cucumber  None → Very strong    
4.5 Sweet corn smell  None → Very strong    
4.6 The smell of rice  None → Very strong    
4.7 The smell of 
watermelon  None → Very strong    
4.8 Metallic smell  None → Very strong    
4.9 Characteristic 
fish flavor  None → Very strong  It is a unique flavor to distinguish it from 
other meats, sensed by reverse smell  
4.10 Rancy oil  None  → Have    
4.11 The smell of 
lactic 
fermentation  None → Have    
4.12 The smell of 
rotten fish  None → Have    
4.13 Fishy smell  None → Have    
4.14 The smell of 
damp cardboard  None → Have    
4.15 Cold burning 
smell (cold 
storage)  None → Have    
4.16 The smell of 
rotten radish  None → Have    
4.17 Mùi khoai 
hà/sùng  None → Have    
4.18 The smell of 
sweet 
potato/sweetness  None → Have    TCVN      :202x 
 
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 No. Term  Scale  (0-5) Definition and assessment  
4.19 The smell of 
antibiotics  None → Have    
5. Taste  Cut a small piece, put it in your mouth 
to chew, focus to evaluate the taste felt 
on the surface of the tongue  
5.1 The sweetness 
of fish meat  None → Very strong    
5.2 Sour  None → Very strong    
5.3 Salty  None → Very strong