Effects of electron-beam irradiation on the quality and shelf life of steamed crayfish

Crayfish were steamed for 10 min and vacuum-packed in a polyethylene bag. The steamed crayfish were irradiated by a high-energy electron-beam at doses of 0, 2.31, 4.26, 6.41, and 9.13 kGy, and then stored at 25℃. The color, total number of colonies, total volatile basic nitrogen, smell, and sulfur volatile substances were analyzed. The results showed that no significant change was observed in the values of L^* and b^*, but the value of a^* decreased significantly after irradiation compared with that in the control group. The steamed crayfish could be stored for 5, 11, 13, and 16 d after irradiation at doses of 2.31, 4.26, 6.41, and 9.13 kGy, respectively, when the number of colonies was less than 50000 CFU/g, and total volatile basic nitrogen was under 20 mg/100 g. Compared with crayfish in the control group, the smell similarity of crayfish irradiated in 2.31, 4.26, 6.41, and 9.13 kGy groups were 90.62%, 88.70%, 87.52%, and 68.60%, respectively. The crayfish in the 9.13 kGy group produced more dimethyl disulfide compounds than that in the other irradiated groups. Electron-beam irradiation could effectively prolong the shelf life of crayfish. The shelf life of crayfish irradiated at a dose of 4 kGy was more than 10 d at 25°C. The smell and the sulfur volatile substances of the crayfish increased significantly with a dose of more than 8 kGy. Therefore, the optimal absorbed dose for steamed crayfish is 6 kGy. (authors)