Changes in the quality of oil extracted by hot pressing from black cumin ( Nigella sativa ) seeds and by solvent from the obtained cake during refining.

In this study, oil was extracted from black cumin ( Nigella sativa ) seed (BCS) by press, and oil was extracted from the obtained cake with a solvent. The changes in the quality of both crude oils obtained by pressing and by solvent were investigated during refining. Findings revealed that the p -anisidin value ( p -AV) and fatty acid profile did not change significantly, but there were significant differences ( p  < .05) in the peroxide value (PV), reflective index, pigment contents, free fatty acid content (FFA%), and antioxidant activity (total phenol content (TPC), thymoquinone, and DPPH inhibition) of BCS oils obtained by the two different methods. PV and FFA decreased to less than 15 meqO 2 /kg and 0.3%, respectively, in the refined oil. The TPC (65%), thymoquinone (45-97%), carotenoids (86-89%), and chlorophyll (75-85%) were removed from BCS oil, but the DPPH value was raised by about 33%. The current study gives a clear picture of the changes during refining in BCS oil, which can be a useful guide in food applications.