COMPARISON STUDY OF THE EFFECTS OF DIFFERENT CRUDE GREEN TEA POLYPHENOLS ON THE QUALITY OF DRIED CATFISH DURING AMBIENT STORAGE

The comparative antioxidant effect of adding different crude green tea polyphenols (GTP) and vitamin C (VC) on the susceptibility of dried catfish (Clarias gariepinus) quality changes during ambient storage was investigated. Catfish fillet was treated with different concentrations of GTP: 1% NaCl plus 0.01% GTP, 1% NaCl plus 0.03% GTP and 1% NaCl plus 0.01% of VC before drying process. Control muscle sample (CK) was treated only with 1% of NaCl solution (without GTP extract) contained only 1% NaCl, but not GTP. Samples were oven-dried for 5 days at 45C. The quality change was evaluated over a course of 4 weeks for pH, volatile basis nitrogen, peroxide value, thiobarbituric acid reactive substances and free fatty acid. The results indicated that the most effective antioxidant was GTP and there was no significant differences (P < 0.01) between laboratory-extracted crude green tea polyphenol and commercial crude green tea polyphenol. This study pointed out that GTP is a good natural antioxidant in comparison with VC and CK, so, it could be easily used in food industry to improve quality and shelf life of food products.