Week: 8

Fishmeal and fishoil production plant

Fishmeal and fishoil

Airdried

On the market

Quality changes during preservation

Protein mink digestibility, in vivo tests Heated Protein mink digestibility, in vivo tests Fishmeal A matter of time and temperature Drying temperature, °C Mink digestibility, % 100 88 70 91 70 (5 seconds) 94

Heated Lipids more or less unaffected if proper manufactured Otherwise risc of rancidity

Cool / freeze Prolonged shelflife

Other preservation methods Proteins Lipids Salted No effects Might rancid Smoked Airdried Might deterioate Rancid Fermented Proteins → peptides ≈ bitter taste Might get rancid

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.