PRESERVATION OF OREOCHROMIS NILOTICUS FISH USING FROZEN GREEN TEA EXTRACT: IMPACT ON BIOCHEMICAL, MICROBIOLOGICAL AND SENSORY CHARACTERISTICS

The present study aims to increase the shelf life of Nile tilapia (Oreochromis niloticus) fish using frozen green tea extract (GTE) with different concentrations (2, 4 and 6\%, w/v). Biochemical characteristics (pH, total volatile basic nitrogen, trimethylamine-nitrogen and thiobarbituric acid), microbiological parameters (total viable bacterial count, psychrophilic bacteria and total mold and/or yeast count) and sensory quality outlines were determined during storage period at 4C. The results indicated that the samples stored on frozen GTE had better biochemical and microbiological characteristics, which resulted in increasing the shelf life of fish samples. The samples stored on frozen GTE with different concentrations (2, 4 and 6\%, w/v) were rejected after 10, 14 and 14 days of storage while control sample was rejected after only 6 days. It could be concluded that application of frozen GTE is a promising technique for the preservation of fish as it gives longer shelf life compared to normal ice. According to our results, the best concentration applied for preservation was 4\% GTE because it is lower in cost than 6\% GTE and had the same impact on the shelf life.