Roasting Effect on Chemical Parameters, Antioxidant Capacity and Oxidative Stability of Citrullus Lanatus Kernels Oil

Abstract

Due to its high content in linoleic acid, which is a polyunsaturated fatty acid, Citrullus lanatus oil is prone to oxidation. However, roasting generates Maillard reaction products having an antioxidant effect capable to preserve lipids against oxidation. Therefore, this study investigated the impact of roasting on C. lanatus kernels oil properties. The treatments consisted of roasted kernels in an oven at 180°C for 20 min compared to unroasted kernels. Oil were extracted using a press coupled with a thermoregulator without heating (control), at 60°C and 100 °C for unroasted kernels and without heating for those roasted. The chemical parameters, antioxidant capacity and oxidative stability of these oils were evaluated. The result showed that roasting did not significantly influence the pH of oils and the pH were acidulous (5.23 ± 0.00 to 5.50 ± 0.01). In addition, roasting increased oil acidity and peroxide value; while iodine and saponification values decreased. Roasting also increased the total phenol content, antioxidant capacity and oxidative stability of C lanatus kernels oil. Roasted kernels oil was of good quality and classified as "semi-drying or di-unsaturated oils" with the best resistance to auto- and thermo-oxidation. Our results suggest that roasting at 180°C for 20 min would extend the shelf life of C. lanatus kernels oil without compromising its quality.