gamma irradiation of brown rice: effects of dose, variety, paddy age, and packaging on fungal control, shelf-life and post-harvest cost estimate

Background: brown rice offers superior nutritional value compared to polished white rice but is less favored in rice-consuming countries due to its limited shelf-life. this study evaluates the efficacy of gamma irradiation in reducing fungal contamination in brown rice and extending its shelf-life, considering factors such as paddy age, rice variety, and packaging type.methods: the efficacy of gamma irradiation (0-1 kgy) in reducing fungal contamination in brown rice was evaluated. rc-160 and sl-7 rice varieties (240 kg per variety) were harvested from central luzon (region iii) during the dry season (march–april 2023). one kg of two and eight-week-old paddy grains were packed in either super bag™, an international rice research institute developed hermetic packaging, or conventional polyethylene bags. mold and yeast counts were quantified using 3m petrifilm™ following association of official agricultural chemists official methods. fifty g of each sample were homogenized in butterfield’s phosphate buffer, serially diluted, plated, and incubated at 25±1 °c for 3-5 days. statistical analyses were performed using one-way anova and tukey’s hsd post-hoc test with statistical tool for agricultural research (star) software, version 2.0.1 (irri).results: gamma irradiation at one kgy significantly (p<0.05) reduced mold and yeast counts, with effects sustained for up to eight months. paddy age and packaging type had no significant influence on fungal load. a dose of 0.58 kgy achieved a 1-log (90%) reduction in aspergillus niger, while 3 kgy achieved complete inactivation, extending shelf-life up to six months. cost analysis showed irradiation, logistics, and added storage fees increased retail price per kg by 0.14, 0.04, and us$0.02, respectively.conclusions: gamma irradiation effectively controls fungal contamination and extends brown rice shelf-life, potentially enhancing consumer confidence and promoting wider adoption of brown rice.