魚肉鮮度簡易測定法第5報魚肉水浸出液中の蛋白質の安定性に就て

Abstract

In the present report the stability of water soluble protein of fish meat against alcohol was examined concerning with freshness of the fish meat by the following method; 1.0cc of water extract of the meat (10 gms of meat: 100cc of distilled water) was taken into 50cc beaker and added absolute alcohol dropwise from burette with velocity of 2.0cc per minute; and the amount of alcohol required to form both turbidity and precipitation was determined. The concentration of alcohol necessary to coagulate protein in extract of fresh meat lies between 70 to 80%, while in the case of decaying meat 30 to 40% alcohol is enough to aggregate the protein. Probably this phenomenon involves the strength of hydration of the soluble protein. It was found that coagulation of protein occurs in lesser concentration of alcohol in the presence of HgC12 than in the absence of the salt. Also it was proved that alcohol coagulable nitrogen increased in parallel with the amount of HgC12 contained in the solution. Materials employed in the above experiments were mackerel, tuny fish and skipjack. In the light of the results obtained, one of the reason for non-precipitability of mercuric chloride in the extract of fresh fish meat may be due to the strength of hydration of the protein enough to prevent precipitation between protein and mercuric chloride.