Effect of pretreatments on oil yield and active components of black cumin (Nigella sativa) seeds.

In the present study the effect of pretreatments on oil extraction yield and active components of Nigella sativa has been studied. Nigella sativa seeds are pretreated with microwave heating and steam conditioning at different times and then oil is extracted from the seeds by using 2 methods i.e., hydrodistillation and supercritical fluid extraction. The effect of pretreatments on the oil extraction yield, the samples with higher yield of oil from both methods hydrodistillation and supercritical fluid extraction are further analysed by Gas chromatography mass spectroscopic analysis to see the effect of pretreatments on active components of oil. In case of hydrodistillation method, the samples pretreated with microwaves at 3 min i.e., HM3 has shown highest yield (0.892%) when compared to H0 (0.436%) In supercritical fluid extraction, the samples pretreated with microwaves at 3 min, HS3 has shown highest yield (9.44%) when compared to SO (4.10%). Even though steam pretreatment has shown increase in the yield of oil, % increase in yield is less when compared to microwave pretreated sample. H0 oil sample has shown Thymoquinone content of about 19.40% and pretreated sample HM3 has shown 26.73%.The sample S0 has shown Thymoquinone content of about 8.35% and pretreated sample SM3 has shown 11.53%. Although there is increase in yield in supercritical fluid extraction Thymoquinone content is less compared to that of hydro distillated sample. This may be due to low operating pressure (70 atm) used in supercritical fluid extraction. Further by improving the process conditions like pressure it is possible to obtain more yield of oil and significant rise in thymoquinone content. Thus the pretreatments proved to be useful for increasing the yield of oil without any detrimental effects on antioxidant activity and quality of oil.