Phytochemical contents and oxidative stability of oils from non-traditional sources

Non-traditional plant oils, such as cold pressed black cumin (Nigella sativa) seeds oil and oils extracted by n-hexane in the lab conditions from food industry by-products, namely, apricot kernels (Prunus armeniaca), wheat germ (Triticum vulgare), grape seeds (Vitis vinifera), and tomato seeds (Lycopersicon esculentum) were investigated. Bioactive compounds such as phytosterols, tocopherols, and tocotrienols, and also fatty acid composition were determined by GLC and HPLC. The oxidative stability index of oils was evaluated by rancimat method. The fatty acid composition of lipids from apricot kernels was different from the other oils. The contribution of oleic acid in apricot oil amount 66.77%, while in the other oils ranged from 12.39% to 21.86%. The highest level of a-linolenic acid was determined in wheat germ oil (7.58%). Concerning phytosterols, b-sitosterol was major component in all oils extracted from non-traditional sources, with wheat germ oil being the richest in total phytosterol content. Wheat germ oil was very rich in campesterol and sitostanol. It was found that wheat germ, black cumin seed, tomato seed, and apricot kernel oils contained significant amount of citrostadienol. Concerning the vitamin E, it was found that black cumin seed oil contained highest amount of tocotrienols and gamma tocopherols, while, tomato seed oil contain highest amount of gamma-tocotrienols. Wheat germ oil was unique in having a high content of alpha-tocopherol. Apricot kernel and wheat germ oils showed the highest oxidative stability as shown from its induction period compared to the other investigated oils. It is recommended that these oils can be utilized as sources of value added products, natural antioxidants, edible, and healthy oils.