Effect of Interfacial Activity of Eugenol and Eugenol Esters with Different Alkyl Chain Lengths on Inhibiting Sunflower Oil Oxidation

Abstract Effects of eugenol esters with different alkyl chain lengths and combinations of eugenol + eugenol esters on sunflower oil oxidation at 338, 358, and 378 K are evaluated by determining different kinetic parameters. Also, water content and reverse micelles size of sunflower oil samples are monitored during oxidation. Eugenyl acetate shows higher antioxidant activity than eugenol in sunflower oil, while eugenyl butyrate, eugenyl hexanoate, and eugenyl decanoate shows lower antioxidant activity than eugenol. Antioxidant activity of eugenol esters decreases by increasing their alkyl chain length. Eugenol shows a synergistic effect with eugenyl acetate and eugenyl butyrate on increasing the induction period and antioxidant activity values, while it shows an antagonistic effect with eugenyl hexanoate and eugenyl decanoate. Also, combinations of eugenol + eugenyl acetate, as well as, eugenol + eugenyl butyrate stabilize the reverse micelles at longer period of time (3263 min for eugenol + eugenyl acetate and 2900 min for eugenol + eugenyl butyrate) than eugenol (2750 min). In addition, eugenol + eugenyl acetate and eugenol + eugenyl butyrate decrease the magnitude of temperature‐related effects on sunflower oil oxidation to the higher extent than eugenol did. Practical applications : Recent studies have suggested that the antioxidants with ability to locate at the active sites of lipid oxidation can efficiently reduce lipid oxidation in bulk oil. Despite a remarkable focus on antioxidant activity of eugenol, there is no information regarding improving its interfacial performance through esterification method. Also, there are few published data regarding the effects of esterified antioxidants on physicochemical changes during the oxidation of bulk oil. In this study, eugenol is esterified with anhydrides with different alkyl chain lengths to increase its accessibility to the active site of lipid oxidation, that is, water–oil interface of reverse micelles in sunflower oil. Effects of eugenol esters on stability of reverse micelles and critical reverse micelles concentration of lipid hydroperoxides have been investigated for the first time.