Study of the Effects of Essential Oils of Cumin, Savory and Cardamom as Natural Antioxidants on the Flavor and Oxidative Stability of Soybean Oil During the Storage.

Oxidation reactions in edible oils and fats are regarded as a cause of spoilage. Use of antioxidants can prevent oxidation. In this research, effects of adding three essential oils (cumin, savory and cardamom) at three different concentrations (0.2, 0.4 and 0.6 %, v/v) on acid value, peroxide value, induction period and flavor of soybean oil were evaluated at different storage times and temperatures according to Taguchi's experimental design. Based on the results of this study, type of essential oil, its concentration, storage temperature and storage time indicated significant effects (probability (P) <0.05) on acid value, peroxide value and induction period. However, savory and cardamom showed the highest impact on the evaluated parameters having the most effect on the induction period. Also, based on the results obtained for acid value, all the essential oils from this study indicated significant effects on the acid value. Cumin and savory showed significant effects on the peroxide value. Soybean oil containing the essential oils from this study had good flavor and high desirability with no clear preference among the three essential oils on the flavor and desirability by the sensory panel (P>0.05). In addition, two concentrations of 0.4 and 0.6 (%, v/v) can be regarded as suitable concentrations for reducing free fatty acids as well as peroxide value and enhancing the induction period of soybean oil. Concentration of essential oil within the studied range did not show any significant effect on the flavor of soybean oil. Two temperatures of 20 and 30oC were found to be optimal temperatures for enhancing induction period and reducing the peroxide value of soybean oil. Effects of storage time and temperature on the acid value were also significant (P < 0.05). Storage times of 2 and 4 months were found to be appropriate storage times for optimum induction period of soybean oil, but storage times of 2 and 6 months were optimal times for minimum peroxide value. Increase in the storage time and temperature caused a decrease in the flavor and desirability of the oil. The results of this study showed that the essential oils can be suggested as natural antioxidants in oil industry. [ABSTRACT FROM AUTHOR]