Biochemical degradation of 22 fish species due to microbial spoilage in major fish markets of bhopal

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Abstract

Microbial spoilage of fish and its biochemical changes has been reviewed. Naturally fishes were dominantly contaminated by gram positive and gram negative bacteria’s such as pseudomonas, aeromonas, salmonella, shigella, vibrio spp. Growth of these microorganisms in fish caused spoilage of the fish. Microorganisms predominate spoilage of cold storage fish were pseudomonas and aeromonas. Soon after fish death, enzymatic reaction precedes which uses glycogen as energy sources and stop as the glycogen depleted from the tissue. This process named as “rigor mortis”. Fish spoilage start at the end of rigor mortis. So, fish spoilage could be delayed by retaining flesh glycogen through reduction in energy consumption. It can be done by preventing vigorous moving of fish during hauling/catching. Delay in spoilage was also due to lactic acid production resulted from glycolyis, which reduced fish flesh pH, so that inhibit microbial growth. Immediately after rigor mortis the flesh pH increase to normal pH, caused contaminating microorganisms grow, degrade NPN protein such as trimethylamine oxide (TMAO) to trimethylamine TMA. Later stage of spoilage contaminating microorganisms degrade protein compound result in compound that exert putrid smell such as H2S, methyl mercaptan and dimetyhyl sulfide.