Ecology, Environment and Conservation Paper

QUALITY EVALUATION OF ROHU (LABEO ROHITA) DURING FROZEN STORAGE

K. Sravani, K. Dhanapal, A. Balasubramanian, M. Vanitha and G.V.S. Reddy

Abstract

Quality of frozen Labeo rohita (Rohu) stored at -400C was evaluated through proximate, biochemical, microbial and sensory analyses. After 90 days of storage, frozen fish were found with reduced moisture, lipid and protein content while the ash content fluctuated throughout the storage period. The organoleptic quality of the frozen stored fish was influenced by the Total Volatile Base Nitrogen (TVBN). Thiobarbutric acid (TBA), Free Fatty Acids (FFA) and microbial counts. Total Plate Count of mesophilic bacteria increased gradually from a log value of 2.85 cfu/gram of meat on 1st day of storage to 3.12 cfu/gram of meat on 30th day and decreased to 2.67 cfu/gram of meat on 90th day of frozen storage. Staphylococcus aureus count decreased from the first day storage count of 2.21 cfu/gram of meat to Est. < 1.0 cfu/gram of meat on 90th day. The psychrophilic count of rohu increased with storage period from an initial log value of 2.73 cfu/ gram of meat to 3.24 cfu/gram of meat up to 90th day of storage. Whereas the sulphur producing bacterial count increased up to 30th day of storage and then showed a decreasing trend. In the case of other mesophilic and psychrophilic bacteria such as E.coli, Faecal strepto cocci, Pseudomonas spp., Aeromonas spp., and other pathogenic microorganisms like Vibrio spp., Salmonella spp. and Listeria monocytogens were absent throughout the frozen storage period. The freshness based on over all sensory score decreased with increase in storage period. On correlating the overall sensory score with frozen storage period, the frozen stored fish was found acceptable for consumption upto 113 days.