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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