Fish Microbiology and Quality Assurance

Unit 8 - Spoilage of fresh and processed fish and fishery products

8.2.2. Microbiology and spoilage of chilled fish
Holding the fish in low temperature close to freezing point of water affects the microflora of fish. The low temperature reduces microbial and enzymatic activity resulting in extension of shelf life of fish. Factors such as quality of fish, method and duration of chilling and efficiency of storage method influence the quality of chilled fish. Many microorganisms associated with fish survive low temperature and spoilage is mainly caused by psychrotrophs. Among the bacterial flora dominance of Gram negatives is observed over Gram positive bacteria. Chill storage brings about changes in composition of microflora, and mesophiles are gradually dominated by psychrophiles. The low temperature, however, helps to maintain fish in good condition only for a short time. The prolonged storage under chill condition leads to growth of psychrophilic microorganisms resulting in spoilage of fish.