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The biochemistry of fish processing - PowerPoint PPT Presentation


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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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Presentation Transcript
slide2

FISH

Global catch / harvest

slide7

After Catch

Decomposition

slide8

Composition of a fish

Water 65 – 80 %

Fat 1 – 20 %

Protein 14 – 20 %

Vitamins

Minerals

slide17

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

slide18

Oil = mainly triglycerides

Triglycerides → free fatty acids

peroxides

Free fatty acids → ketones

aldehydes

slide20

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

slide21

Proteines → poly-peptides

Poly-peptides → free amino acids

Free amino acids → biogenic amines

Biogenic amines → TMA, DMA, NH3

slide22

Amino acid decomposition

Lysine → cadaverine

Histidine → histamine

slide26

THEREFORE:

Preservation

slide38

Quality changes

during preservation

slide39

Heated

Protein mink digestibility, in vivo tests

Fishmeal

A matter of time and temperature

slide40

Heated

Lipids

more or less unaffected

if proper manufactured

Otherwise risc of rancidity

slide41

Cool / freeze

Prolonged shelflife

slide43

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

slide44

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.

slide45

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.

slide46

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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