Preservation of Fresh Whitefish with Gamma Radiation

Abstract

This paper is an outline of a recent study which shows that the storage life of fresh whitefish (Coregonus clupeaformis) is extended considerably by the low levels of gamma radiation. On the basis of bacteriological and sensory evaluations, a dose of 150,000 rads proved to be the most effective treatment; the samples exposed to this level of radiation were judged acceptable up to 29 days of storage in ice. Fish treated with 75,000 rads were acceptable up to 22 days whereas those treated with 300,000 rads, though bacteriologically acceptable, received lower sensory scores throughout the experiment.Bacteriological studies showed that unirradiated fresh samples were dominated by Gram-negative microorganisms belonging to the genera Pseudomonas, Achromobacter, and Flavobacterium. Samples treated with 150,000 rads showed survival of Gram-positive microorganisms belonging to the genera Corynebacterium and Micrococcus which were replaced by Gram-negative microorganisms after 29 days of storage.