Validation of γ-radiation and their effect on phenolic compounds, antioxidant activity, and microbial load of fennel ( Foeniculum vulgare ) seeds and cinnamon ( Cinnamomum verum ) sticks.

The aim of this study was to validate the optimum doses of γ-radiation and its effect on the antioxidant capacity and microbial load of fennel seeds and cinnamon sticks. Gamma irradiation was applied in different doses 0.0, 2.5, 5.0, 7.5, 10, and 15 kGy. The findings stated that increasing gamma dose significantly ( p  < .05) increased the total phenolic content of the fennel seeds; however, it was decreased in cinnamon at doses higher than 5 kGy. The total flavonoid content was found higher after treatments at 5 kGy or more minor. After the gamma irradiation treatments, the antioxidant activities were enhanced. The microbial load of these spices was reduced after treatment. Doses more than 10.0 kGy are required to lower the bacterial load in samples, while only 5.0 kGy is sufficient to eliminate fungi growth. The partial least squares regression analysis stated the application of 7.5 kGy and reflects the most valid treatment doses for radiation treatments of fennel seeds and cinnamon sticks. Accordingly, it can be discovered that the γ-radiation at a dose of 7.5 kGy could be considered a suitable dose for the preservation and decontamination of these spices and also for enhancing its antioxidant capacity. Three spices were subjected to gamma irradiation at different doses. The application of gamma radiation significantly reduces the level of the microbial load in the spices. Gamma irradiation improved the antioxidant capacity of the spices. Gamma irradiation can be applied as an effective preservative method in the food industries.