Effect of Electron Beam Irradiation on Physiological Character of Listeria innocua

Listeria innocua was used to investigate the effects of different electron beam irradiation dosages (0.00, 0.75, 1.50, 2.25, 3.00, 3.75 and 5.00 kGy) on the inactivation and physiological status of Listeria innocua (including cell membrane permeability, leakage of intracellular ions, activity of Na⁺K⁺-ATPase and Ca²⁺Mg²⁺-ATPase, membrane potential, pH of bacterial suspension). The results show that the logarithm of total number of Listeria innocua decreases from 8.9 to 1.4 after 5.00 kGy electron beam irradiation with D₁₀=0.69 kGy, and the bactericidal effect is significant. With the increase of dosage, the cell membrane permeability and the leakage of intracellular ions (K⁺, Ca²⁺ and Mg²⁺) increase significantly. The activities of Na⁺K⁺-ATPase and Ca²⁺Mg²⁺-ATPase decrease significantly, and membrane potential and the pH of bacterial suspension also decrease significantly. According to the above results, electron beam irradiation causes the disorders of physiological metabolism of Listeria innocua, which accelerates the death of the bacteria.