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.

ABSTRACT

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 meqO2/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.