Antioxidant efficiency of oregano in frying and storage of fried products

The effect of oregano on the oxidative stability of cottonseed oil during frying of potato chips and on the storage stability of the products was studied. The ground spice or an ethanol-derived extract was added to the oil before frying. The results showed that both additives decreased the rates of accumulation of conjugated dienes, polar compounds, polymerized triacylglycerols, dimeric triacylglycerols and the p-anisidine value of the frying oil, while the hydrolytic compounds were not affected. The major decrease was observed in the accumulation of polymerized and dimeric triacylglycerols. The storage stability of the produced chips was estimated by the rate of increase of the peroxide value and of the conjugated dienes in the oil absorbed by them. Both rates were depressed when oregano was added to the frying oil, with the protective action of oregano extract being considerably greater than that of ground oregano. The protective action of oregano extracts obtained by successive extractions with petroleum ether (PE), diethyl ether (EE) and ethanol (EtOH) and added to the chips after frying was also examined. The results showed that the EE and EtOH extracts were very effective against oxidative deterioration.