Effect of Some Essential Oils on Stability of Corn Oil at Frying Temperatures
Tuğba İNANÇ and Medeni MASKAN, University of Gaziantep, Engineering Faculty, Food Engineering Department - Gaziantep, TURKEY

In this study the effect of the essential oils of seven plants; cinnamon, rosemary, sage, turmeric, clove, thyme and oregano enriched with carvacrol on the oxidative stability of corn oil at different temperatures. Experiments were conducted by using Petrooxy device, a rapid small scale oxidation test, after design of the study was created from Design Expert program. Two-factor central composite design was employed to determine the effects of two independent variables, namely concentration of essential oil (X1: 1500 – 5000 ppm) and temperature (X2: 150–180 °C), on the induction time of corn oil. In order to compare the results with a synthetic antioxidant, BHT, another design was made with a concentration range (60 - 350 ppm) containing the legal upper limit of BHT, 200 ppm. The results revealed that increasing temperature decreased the induction time of the all samples and the high induction times were recorded at 150°C. However, the effects of the essential oils were found not to be statistically significant due to low content of their active components, except oregano oil because of its enriched content with carvacrol. The oregano oil also provided with the highest induction time of the corn oil when it was compared with BHT, thus it could be strong alternative to BHT. The antioxidative effect and capacity of the essential oils to retard the oxidation followed the order: oregano > thyme > clove > turmeric > sage > cinnamon > rosemary.