Effects of green tea natural extract on quality parameters and lipid oxidation during storage of tench (Tinca tinca) fillets

Green tea (Camellia sinensis) is a good candidate as an antioxidant additive to be used to produce foods with a longer shelf life. The aim was to investigate the effects of two levels of green tea extract (GTE) on quality parameters, lipid oxidation and food safety of tench fillets during cold (+2 °C) and frozen storage (-25 °C). Sixty-eight tench were killed by live chilling, filleted and divided into 4 groups and treated with a sprayed solution of: distilled water/ethanol mixture (control group, C); ascorbic acid (AA); and two levels of GTE (GTE5 and GTE10, respectively). Quality parameters, chemical composition, lipid oxidation products and microbiological load were assessed on no treated and treated fillets. Results showed that GTE had no negative effect on physical traits and resulted to be comparable to AA used as reference synthetic antioxidant. At 7 days of refrigeration, the GTE treated fillets showed a similar antioxidant capacity of synthetic AA in delaying lipid oxidation. In frozen samples, the best results were obtained by GTE5 treatment while higher levels of GTE seemed to exert a pro oxidant effect. No significant inhibitory effects of GTE were observed on the microbiological load of treated fillets.