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Esbjerg Campus, April 4-5, 2003

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Global catch / harvest

FISH

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Fish

Abt. 20.000 known species

Bony fish

Cod, plaice

Gristle fishRay

Shellfish

Shrimp, lobster

Bivalves

mussel

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After Catch

Decomposition

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Composition of a fish

Water 6580 %

Fat 120 %Protein 1420 %

VitaminsMinerals

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Decompositon of fish

1) enzymatic spoilage2) oxidative deterioration3) bacterial spoilage

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enzymatic spoilage (rigor)

Lactic acid produced

PH decrease

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enzymatic spoilage (rigor)

Lactic acid produced

PH decrease

Muscle becomes rigid

Muscle becomes pliable

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Species Temper

ature

F

Time from landing on deck to

entering rigor

hours

Time from landing on deck to

end of rigor

hoursin ice 2-8 20-65

37 4-8 54-64

42-44 5 45

62 2-5 16-20

trawled cod

87 1-2

rested cod fromaquarium

37 14-15 72-96

trawled redfish in ice 22 120

trawled whiting in ice 1 20

trawled plaice in ice 7-11 54-55

trawled coalfish in ice 18 110

trawled haddock in ice53

2-42

3724

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oxidative deterioration

rancid odors

colour changes

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Fatty acid composition of fish

Min. Max.

14:0 6 8

16:0 10 1916:1 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 1 220:5 5 18

22:1 1 21

22:5 1 3

22:6 7 13

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peroxidesFree fatty acids ketones

aldehydes

Oil = mainly triglycerides

Triglycerides free fatty acids

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bacterial spoilage

TMAO TMA + Formaldehyde

Decomposition of proteines

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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 3,6Fenylalanine 6,0

Tyrosine 5,1

Valine 8,4

Asparagine 14,3

Serine 6,9

Glutamic acid 20,6Proline 5,7

Glycine 8,2

Alanine 8,8

Ornithine 0,1

Arginine 8,7

Hydroxyproline 0,7

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Biogenic amines TMA, DMA, NH3

Proteines poly-peptides

Poly-peptides free amino acids

Free amino acids biogenic amines

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Amino acid decomposition

Lysine cadaverine

Histidine histamine

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Deterioration processes in fish

Lipids Proteins

Chemical, bacterial and endogeneous enzyme reactions

Oxidation of fatty acids

Hydrolysation of lipids to free fatty acids

Hydrolysation of proteins to peptides and

amino acidsDeamination of amino acidsDecarboxylation of amino acids

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THEREFORE:

Preservation

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Preservation

Salting

Smoking

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Cured Cod

Water % Fat % Protein %Raw 78 83 0,1-0,9 15-19

Salted 33 0,5 42

Smoked Haddock

Water % Fat % Protein %Raw 79 84 0,1-0,6 14-20

Smoked 72 0,9 22

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Preservation

Salted

Smoke

Heat

Cool

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Preservation

Salted

Smoked

Heated

Cooled

Fermented

Dry

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Fishmeal and fishoil production plant

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Fishmeal and fishoil

Ai i

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Airdried

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On the market

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Quality changes

during preservation

Heated

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Protein mink digestibility, in vivo tests

Fishmeal

Dryingtemperature, C

Mink digestibility,%

100 88

70 91

70 (5 seconds) 94

Heated

A matter of time and temperature

Heated

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Heated

Lipids

more or less unaffectedif proper manufactured

Otherwise risc of rancidity

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Cool / freeze

Prolonged shelflife

Other preservation methods

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Other preservation methods

Method Proteins LipidsSalted No effects Might rancid

Smoked No effects Might rancid

Airdried Might

deterioate

Rancid

Fermented Proteins

peptides

bitter taste

Might get

rancid

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A 50 - 5.000 I.U./g

D 0 - 1.000 I.U./gPantothenic 1 - 20 g/g

Vitamins in fish

During heat processing

the vitamins will be destroyed

Depending upon the temperature

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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 theirpolyunsaturated nature.

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Most spoilage of fish is due to bacterial breakdown.

One spoilage characteristic found in fish and not in muscle foodsis 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 importantpart of preservation.

SUMMARY

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The end

Hope you now have a better understanding of fish nature

Hope you understood my english

Hans Otto SrensenLaboratory managerTripleNine Fish Protein

Denmark