Effect of roasting on physico-chemical properties, antioxidant capacity, and oxidative stability of wheat germ oil

Wheat germ oil (WGO) is rich in highly concentrated nutrients, especially vitamin E and polyunsaturated fatty acids. In this study, changes in oxidative stability, bioactive components, volatile compounds, and antioxidant capacity of WGO extracted from wheat germ roasted at 180 °C for 0-20 min were investigated. In general, antioxidant capacity and oxidative stability of WGO increased with roasting. Compared to oil from unroasted wheat germ, oil from wheat germ roasted for 20 min demonstrated the highest total phenolics, but a slight reduction in total tocopherols and β-carotenoids content. Fatty acid profiles were not affected, whereas hydroxymethylfrufural (HMF) content increased significantly, suggested the extent of Maillard reaction increased significantly with roasting. Among volatiles, esters such as n-butyl acrylate and acids such as hexanoic acid prevailed in WGO from unroasted wheat germ. However, after roasting, the levels of these compounds decreased or disappeared and furfurans, pyranes, pyrazines, and pyrroles with high odor activity became the most abundant.