Antioxidant effects of green tea extracts on lipid oxidation of half-dried eels

Abstract

In order to explore the change of lipid oxidation of half-dried eels treated with green tea extracts and stored frozen, acid values, peroxide values, carbonyl values, and TBA values were measured. The eels were placed into the plastic bag and soaked for 1 hr in the solution mixed with distilled water and green tea extracts, and also vacuumed and stored frozen at -18 - -20°C for 9 months after being dried with a hot-air blower for 15 hrs at 35°C (Aw 90-91). The control consisted of eels prepared in the same way without any pre-treatment. At the end of the 1st month, 3rd month, 6th month, and 9th month, eel oil obtained from the samples were tested for its lipid oxidation. The activity of green tea extracts 1 mL was very similar to Vitamin C 500 µM 0.8 mL. The acid values, peroxide values, carbonyl values, and TBA values of eels treated with green tea extracts were lower than those of the control during 9 months of frozen storage (p<0.05). While the acid values and peroxide values of the control and eels treated with green tea extracts highly increased after the first month of frozen storage, the TBA values increased greatly on the third month of frozen storage. Compared to the control, the pre-application of green tea extracts to half-dried eels meaningfully prevented the generation of TBA compound during the frozen storage (p<0.01). In conclusion, pre-application of green tea extracts was effective in delaying early-stage peracid inducement and preventing the generation of secondary oxidation compounds, such as carbonyl compound and TBA compound, in the course of the drying and frozen storage.