Kalapuolisäilykkeiden säilyvyys

Authors

• Martti Kiesvaara Valtion teknillinen tutkimuskeskus, elintarvikelaboratorio, 02150 Espoo 15

DOI: https://doi.org/10.23986/afsci.71862

Abstract

A literature review is presented over the factors that limit the quality of fish semi-preserves. The most important are the changes in fat, microbiological spoilage, and excessive proteolysis. It is possible to reduce the oxidative changes in fats by anti-oxidants and exclusion of oxygen from barrels and retail packs. The carbonyl compounds are mainly formed after the packs are opened. The high salt content and the anaerobic conditions in barrel-salted fish inhibit the growth of most microbes. After processing the pH of semi-preserves decreases and the microbial flora consists mainly of representatives of the family Lactobacillaceae. The shelf life of the products is prolonged by preservatives. The amino acids and soluble peptides which are liberated by enzymatically catalyzed proteolysis diminish the effect of preservatives, possibly by a reaction of the amino groups. A promising preservative is tylosin lactate which has been found very suitable for fish semi-preserves. Excessive proteolysis which softens the muscle tissue too much may prove to be the most harmful effect. From the quality point of view the muscle tissue has to contain an adequate amount of free amino acids. However, the amino acids may accelerate the enzymatic proteolysis by raising the pH. A high content of salt and acid retards the proteolysis but also weakens the quality. To prolong the shelf life of fish semi-preserves new methods will have to be developed.