Abstract: In this paper,plate count was adopted to detect the biological inhibiting effects of several preservatives such as gluconolactone,fumaric acid,glycine and so rbic acid,against the microorganism on fresh water fish.The results showed that the optimum half inhibit concentrations(IC50)are:the gluconolactone IC500.205%,the fumaric acid IC500 0.431%,the glycine IC50 0.172%,and the sorbic acid IC500.145%.The complex consisting of gluconolactone,fumaric acid,glycine and sorbic acid can reduce IC50to 35%.It is not only much more effective in preservation,but also in enhancing texture,anti-oxidation of fish oil and improsing flavor of the fish products.

Key words: fresh water fish, complex preservative, half inhibit concentration(IC50)