Effect of gamma radiation on microbiological and oil properties of black cumin (Nigella sativa L.)

Black cumin samples obtained from the market have been irradiated under 2.5 kGy, 6 kGy, 8 kGy, and 10 kGy doses, respectively. Along with the increase in the dose of irradiation, both the free fatty acid and peroxide values of the samples increased, whereas oil contents, iodine numbers, refraction index and Rancimat values decreased. In the composition of fatty acids, while the percentages of unsaturated fatty acids decreased; trans fatty acid levels increased. Microbial count of the samples decreased as the dose of irradiation increased. It has been observed that total bacterial count as well as total count of yeast and mould reduced to the undetectable limit.