Effect of frozen period on the chemical, microbiological and sensory quality of frozen Tilapia fish (Sarotherodun galiaenus).

The study was designed to investigate the effect of duration of frozen storage on the chemical, microbiological and sensory profile of Tilapia fish (Sarotherodun galiaenus) collected from a research pond of the Agricultural Development Project, Akure, Nigeria, subjected to sixty days of frozen storage and analyzed at intervals of ten days. Protein content (%) ranges from 43.70 +/- 1.17-60.65 +/- 2.40. Protein decreases with increasing duration of frozen storage with the fresh samples (not frozen) having the highest protein content (60.65 +/- 2.40) while the least (43.70 +/- 1.17) was recorded for fish samples that were frozen for sixty days. Similar results were obtained for the fat content (%) where the highest fat content (9.72 +/- 0.25) was recorded for the fresh samples and the least value was recorded for those stored for sixty days. Ash content (%) and moisture content (%) do not show any significant change during storage. Mineral composition (Fe, Ca, Mg, P and Zn in mg/100g) and iodine content (microg/100g) of the samples showed a slight change with respect to duration of storage. pH values ranges between 5.20-6.90 while the total coliform count range was between 3.0 x 10(3)-7.5 x 10(6) with increasing values, as the duration of storage increases. Sensory evaluation of the fish samples on storage revealed that quality of the fish samples with respect to taste decreases with increasing duration of storage with the best quality (texture, odor and color) when freshly prepared; and that better quality during storage is obtainable during the first ten days of storage. These, by implication simply mean that fish should be stored for a short period of time to retain the taste, and provide both the protein and fat at optimal level.