Effect of γ Ray and Electron Beam Irradiation on Microorganism Inactivation and Physicochemical Property of Flavor Dried Bean Curd

To investigate the diffferences between gamma ray and electron beam irradiation on microorganism and physicochemical property of flavor dried bean curd, samples were treated with gamma ray irradiation (0, 3.1, 5.9, 8.6, 11.4 kGy) and electron beam irradiation (0, 2.7, 5.5, 8.2, 10.8 kGy) to investigate the microbe quantity, nutrient content, physicochemical property and texture quality. The results showed that both gamma irradiation and electron beam irradiation could effectively reduce total bacterial count, molds and coliform bacteria of flavor dried bean curd. Gamma ray irradiation D₁₀ of bacteria and mould were 1.82 kGy and 1.72 kGy, and electron beam irradiation were 2.44 kGy and 1.79 kGy respectively. The inactivation effect of gamma ray irradiation on flavor dried bean curd was stronger than electron beam. The two irradiation way had no significant effect on moisture, protein and ash content of flavor dried bean curd, but fat content was significantly reduced after irradiation. The amino acids content of flavor dried bean curd processed with gamma irradiation did not change significantly, but when 5.5 kGy, electron beam irradiation could significantly affect the content of Val, Phe, Pro, Gly, Ala and Tyr. Gamma irradiation had a significant effect on peroxide value of flavor dried bean curd, however it had no significant correlation with the acid value. There was no significant correlation between electron beam irradiation and peroxide value of flavor dried bean curd, but acid value would increase significantly. Gama ray irradiation had no significant effect on hardness, cohesiveness, cohesivenes, chewiness and springiness of flavor dried bean curd, and electron beam irradiation also had no significant effect on hardness, cohesiveness, gumminess, but the dose above 5.5 kGy would affect chewiness and pringiness significantly. In conclusion, the irradiation effect of gamma ray and electron beam irradiation on flavor dried bean curd was different in some respects, nevertheless both of them had the potential to be used in dried bean curd. This research provided theoretical basis for the application of gamma rays and electron beam irradiation technology in the processing of dried bean curd.