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

Abstract

RESUMENEfecto de la radiación gamma sobre la microbiología y las propiedaddes del aceite del comino negro (Nigella sativa L.)Muestras de comino negro adquiridas en el mercado fueron irradiadas a dosis de 2.5 kGy, 6 kGy, 8 kGy y 10 kGy, respectivamente. Coincidiendo con el aumento en la dosis de irradiación, se incrementaron tanto la acidez libre, como el índice de peróxidos de las muestras, mientras que se redujeron en el aceite el índice de yodo, el índice de refracción y la resistencia a la oxidación medida por Rancimat. En la composición de ácidos grasos aumentaron los niveles de ácidos grasos trans, mientras que se redujeron los porcentajes de ácidos grasos insaturados. El recuento de microbios presentes en las muestras descendió, conforme aumentaba la dosis de irradiación aplicada. Se observó como los recuentos totales de bacterias, hongos y levaduras se redujeron hasta un límite indetectable. PALABRAS-CLAVE: Comino negro -Composición en ácidos grasos -Irradiación -Nigella sativa -Propiedades físico-químicas y microbiológicas. SUMMARY 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. KEY-WORDS: Black cumin -Fatty acid composition -Irradiation -Nigella sativa L -Physicochemical and microbiological properties.

Evaluation the effect of gamma irradiation on microbial, chemical and sensorial properties of peanut (Arachis hypogaea l.) seeds

“…After 6 months of storage, only 9 kGy signifi cantly (p < 0.01) decreased the total acidity, while after 12 months of storage, both irradiation doses 6 and 9 kGy significantly (p < 0.01) increased the total acidity in peanut seeds. This fi nding is consistent with work carried out by other researchers who studied the eff ect of irradiation with doses up to 10 kGy on other oil seeds (black cumin seeds; Arici et al, 2007). However, on other hand, Wen et al (2006) found no signifi cant changes in pH and acidity following 4 and 8 kGy gamma irradiation in lucium fruit.…”

Fatty Acid Contents of Gamma Irradiated Sesame (Sesamumindicum L.) Peanut (Arachishypogaea L.) and Sunflower (Helianthus annuus L.) Seeds

“…The decrease in the unsaturated fatty acid content and the concomitant increase in the saturated fatty acid content are explained by De Camargo et al [10], who stated that the ratio of the oxidation rates of stearic, oleic, linoleic and linolenic acids was 1: 10: 100: 200. Another study suggested that, the decrease in unsaturated fatty acids during oil storage is mainly due to a molecular structure change in fatty acids [38]. …”

Effects of gamma and electron beam irradiations on the triacylglycerol profile of fresh and stored Castanea sativa Miller samples

“…Quality requirements demand enhanced conservation techniques for chestnuts and related products. In this context, decontamination methods based on high-energy electrons or γ-rays irradiation are being studied as alternatives; Arici et al (2007) irradiated black cumin with 2.5 to 10 kGy for the purpose of microorganism's elimination, while studying the effects on physico-chemical properties and on fatty acids profile. Irradiation beneficial effects include reduction of storage losses, shelf life extension, and improvement of microbiological and parasitological safety of foods, while being safe to the environment.…”