Determination of flavonoids in Citrus grandis (Pomelo) peels and their inhibition activity on lipid peroxidation in fish tissue

The peels of pomelo contribute 30% of the fruit weight and yet it has been dump without recognizing the possible nutritional value of the peels. Study has been carried out to identify flavonoid content of the peels and analysed the activity of the flavonoid towards inhibition of lipid peroxidation. Optimization of flavonoid extraction was conducted using aqueous solvent (methanol and ethanol), extraction time (1-3 h) and extraction temperature (50°C-80°) via water bath extraction. The total content of flavonoids was quantitatively determined by using coloration methods with chromogenic system of NaNO2–Al (NO3)3–NaOH and and it was found that the extraction at 65°C for 2 h in aqueous ethanol was the optimized condition for maximum flavonoids i.e. 190.42mg/L. A spectrophometric analysis was performed to evaluate flavonoid activity towards lipid peroxidation in the fish tissue. There was reduction in Peroxide value (PV) indicated the inhibition of lipid peroxidation in fish treated with pomelo peel as evidence of concurrency of positive flavonoid activity.