Abstract:

The killing effect of high energy electron beam (HEEB) irradiation on main microorganisms in rice as a
function of irradiation dose, irradiation time and material thickness was examined using single factor and orthogonal array
experiments, aiming to find the optimal conditions for microbial inactivation of rice. Results showed that the efficacy of
HEEB irradiation against the total number of colonies, total combined molds and yeasts count (TYMC) and E. coli. varied
with the treatment conditions, showing a positive correlation with irradiation dose. The optimum conditions for HEEB
irradiation were determined as follows: irradiation dose, 4 kGy; irradiation time, 6 s; and material thickness, 10.5 cm. Under
these conditions, the total number of colonies in rice was 82 CFU/g, the total number of mold and yeast colonies was 2 CFU/g,
and E. coli was not detected. Thus, the microbial inactivation efficiency of HEEB irradiation for rice was more than 99%.

Key words: high energy electron beam, rice, microorganisms