Effect of gamma irradiation under various atmospheres of packaging on the microbial and physicochemical properties of turmeric powder

Highlights: • Gamma irradiation effectively reduced microbial contamination of turmeric powders. • Gamma irradiation increased the extraction yield of bioactive compounds. • Gamma irradiation increased the antioxidant activities of the samples significantly. • Irradiation increased the curcuminoid content and total phenolics of samples. - Abstract: This study investigated the effect of gamma irradiation (0, 5, 10, and 15 kGy) under various atmospheres of packaging (air, N₂, and vacuum) on the microbial load and physicochemical properties of turmeric powder, including antioxidant activities, total phenolic content (TPC), color parameters, and curcuminoid content. The efficiency of irradiation in reducing microbial contamination in the samples was observed even at the lowest dose. By increasing the irradiation dose, the microbial load was not detectable. Irradiation in the presence of oxygen had synergistic effects on the extraction of curcuminoids and TPC, and increased the antioxidant activity of the methanolic extracts: highest activity was observed at 15 kGy. Generally, gamma irradiation up to the dose of 10 kGy under air atmosphere not only ensured microbial safety and desirability of turmeric powder, but also improved the extraction yield of bioactive compounds and, consequently, antioxidant activities of the samples.