Effects of Stripping Essential Oil from Nigella sativa L. Oil on Its Quality Characteristics

Black cumin (Nigella sativa L.) oil is one of the most important vegetable oils with food, therapeutic and medicinal uses; however, it has high acid and peroxide values even in fresh oil extracted by cold pressing. One of the main factors that can cause high peroxide value (PV) and acid value (AV) in the extracted black cumin oil (BO) is the presence of essential oils (EO), which are highly sensitive to oxidation. In this study, separation by steam was used to strip EO from BO, and the obtained oil quality was evaluated during storage in room conditions for 90 days. The AV and PV in BO without EO were lower and showed a lower increase compared to BO with EO during storage. Chlorophyll, carotenoid, thymoquinone, phytosterols and tocopherols were lower in samples without EO than those with EO. Fatty acid composition was similar in both types of oils, but linoleic acid (18:2) was decreased at a higher rate in the oil with EO during storage. Therefore, the obtained results show that steam stripping of EO from BO can be suggested to obtain oil with lower PV and AV and with a relatively longer shelf life.