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Esbjerg Campus, April 4-5, 2003. FISH. Global catch / harvest. After Catch Decomposition. Composition of a fish Water 65 – 80 % Fat 1 – 20 % Protein 14 – 20 % Vitamins Minerals. Fatty acid composition of fish Min. Max. 14:0 6 8 16:0 10 19 16:1 6 11 18:0 1 4

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FISH

Global catch / harvest


After Catch

Decomposition


Composition of a fish

Water 65 – 80 %

Fat 1 – 20 %

Protein 14 – 20 %

Vitamins

Minerals


Fatty acid composition of fish

Min. Max.

14:0 6 8

16:0 10 19

16:1 6 11

18:0 1 4

18:1 9 28

18:2 1 2

18:3 1 2

18:4 2 5

20:1 2 13

20:2 0,2 0,6

20:4 1 2

20:5 5 18

22:1 1 21

22:5 1 3

22:6 7 13


Oil = mainly triglycerides

Triglycerides → free fatty acids

peroxides

Free fatty acids → ketones

aldehydes


Amino acid composition, fish, g/kg

Lysine 12,3

Methionine 4,7

Cystine 1,5

Treonine 6,6

Tryptofane 2,0

Isoleucine 7,0

Leucine 11,2

Histidine 3,6

Fenylalanine 6,0

Tyrosine 5,1

Valine 8,4

Asparagine 14,3

Serine 6,9

Glutamic acid 20,6

Proline 5,7

Glycine 8,2

Alanine 8,8

Ornithine 0,1

Arginine 8,7

Hydroxyproline 0,7


Proteines → poly-peptides

Poly-peptides → free amino acids

Free amino acids → biogenic amines

Biogenic amines → TMA, DMA, NH3


Amino acid decomposition

Lysine → cadaverine

Histidine → histamine


THEREFORE:

Preservation






Quality changes

during preservation


Heated

Protein mink digestibility, in vivo tests

Fishmeal

A matter of time and temperature


Heated

Lipids

more or less unaffected

if proper manufactured

Otherwise risc of rancidity


Cool / freeze

Prolonged shelflife



Vitamins in fish

A 50 - 5.000 I.U./g

D 0 - 1.000 I.U./g

Pantothenic 1 - 20 μg/g

During heat processing

the vitamins will be destroyed

Depending upon the temperature


SUMMARY

  • Fishes are cold blooded vertebrates.

Fish muscle is biochemically similar to mammals.

  • Fish proteins breakdown more rapidly than mammals.

Fish muscle have certain associated problems like

endogenous enzymes, free amino acids and small peptides etc.

Lipids from fish contain high levels of polyunsaturated fatty acids.

The stability of fish lipids is short due to their

polyunsaturated nature.


SUMMARY

Most spoilage of fish is due to bacterial breakdown.

One spoilage characteristic found in fish and not in muscle foods

is trimethylamine formation.This odoriferous amine is responsible for the fish smell associated

with spoiling fish.

fish meat has high level of polyunsaturated fatty acids,

which are unstable.

Chilling of fish immediately after harvest is very important

part of preservation.


The end

Hope you now have a better understanding of fish nature

Hope you understood my english

Hans Otto Sørensen

Laboratory manager

TripleNine Fish Protein

Denmark


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