COMPARATIVE STUDIES ON SOME UNDESIRABLE QUALITY CHANGES DURING FREEZING PRESERVATION OF TILAPIA (OREOCHROMIS NILOTICUS, HAMILTON-BUCHANAN, 1822) AND BELE FISH (GLOSSOGOBIUS GIURIS, LINNAEUS, 1766) AT LABORATORY CONDITION.

The comparative studies of Tilapia and Bele fish were investigated during freezing preservation at -18˚C for a period of 240 days. The overall acceptability score and proximate composition of Tilapia and Bele fish were studied during this period. Overall acceptability score of Tilapia and Bele fish increased from 9 to 5.5 and 9 to 4.8. The protein content (%) of frozen stored Tilapia and Bele fish dropped from 19.59 ± 0.05 to 18.31 ± 0.06 and 17.58 ± 0.03 to 16.14 ± 0.03. The fat content (%) of frozen stored Tilapia and Bele fish dropped from 4.57 ± 0.09 to 3.41 ± 0.04 and 3.75 ±0.03 to 2.90 ± 0.04 respectively. Moisture content of Bele fish is higher than Tilapia fish. With the increasing days of storage, moisture content of these fish is decreased. Water holding capacity, Drip loss and TVN value were used as parameter for the determination of the extent of spoilage changes of these preserved fish. Water holding capacity of Tilapia fish was 350g H2O/100g of fish but it gradually decreased to 315g H2O/100g. Simultaneously, in Bele fish initial value of WHC was 350g H2O/100g and final value was 287g H2O/100g. Percent drip loss of Tilapia and Bele fish were found to increase from 0 to 14 ml/100g fish and 0 to 16ml/100g fish , respectively. Total volatile Nitrogen (TVN) of Tilapia and Bele fish increased from 4.1 to 22.18 mg N/100g of fish and 6.5 to 27.72 mg N/100g of fish. From the preservation of frozen stored Tilapia and Bele fish observed that the Tilapia fish have a better shelf life than Bele fish.