Effects of Gamma Irradiation on Microbial Composition of Some Selected Ethiopian Cereals (Maize and Sorghum)

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa University


Irradiation is a potentially useful technology for ensuring the safety and extending the shelf-life of food products. In this study the effects of γ-irradiation (1kGy, 5kGy and 10kGy) treatment on microbial safety of some selected Ethiopian cereals maize (BH; 166) and sorghum (Teshale) were investigated. In addition, its effect on their proximate composition was also studied. Each sample of the cereal grains were irradiated in polyethylene bags in duplicate and half of them were stored for 60 days. Microbial and proximate composition of the two cereals before and after irradiation was assayed. The results of this study revealed that total microbial load decreased significantly (P<0.05) in a dose dependent manner. The total plate count (TPC) after a gamma radiation dose of 5kGY reduced by more than 3log cycles and coliforms (TCC) and Total fecal coliforms (TFC) were below detection limit (<1log) at 5kGy in a sorghum (Teshale) and were eliminated at 1kGy in maize cultivar (BH; 166). The total aerobic molds were reduced significantly (P<0.05) as radiation dose increased and were undetectable (<1log) at 10kGy. Regarding the proximate composition there was no significant difference in (%) content of crude protein, carbohydrate and crude fat between the irradiated and unirradiated sorghum cultivar (Teshale) and maize. Only crude fiber increased with radiation dose for both cultivars. The result of this study showed 10kGy is an ideal dose for totally avoiding the aerobic plate count bacteria and molds from sorghum and 5kGy for maize (BH; 166). During storage for 60 days no significant change was observed in number of microbes compared to day zero which shows the possible shelflife extension and effectiveness of gamma radiation on the selected Ethiopian cereals. Key words; Ionizing radiation; food preservation; Post harvest losses; proximate composition.



Ionizing radiation; food preservation; Post harvest losses; proximate composition.