微波杀菌动力学及其影响因素的研究

本实验研究了不同温度条件下微波杀菌动力学D值;并且就食品体系中相应的pH和盐浓度对微波杀菌效果的影响作了探讨;同时对微波杀菌的机理进行了初步的研究。结果表明,相同温度下,微波功率越大,细菌的致死率越高;相同功率下,设定微波温度越高,其D值越小;当pH低于最适生长温度时,细菌对微波的敏感性增加,致死率提高;金黄色葡萄球菌(60℃)在20g/L的NaCl溶液中的致死率最大,而大肠杆菌(55℃)致死率随NaCl浓度增加而降低。微波处理后的金黄色葡萄球菌,经Flou-3/AM作用,其荧光值随温度的升高而增加,说明微波致金黄色葡萄球菌死亡的原因主要是改变了细胞膜的通透性。

Study on Microwave Irradiation Kinetics of Staphylococcus aureus and Escherchia coli Destruction and Affecting Factors

In this paper, the kinetics of destruction of bacteria cells suspended in a solution by microwave irradiation with a microwave oven were studied. The destruction rates at different powers were studied. The results showed that the rate of cell destruction is higher in 900 W than 100 W under the same temperature. The destruction kinetics of S.aureus and E.coli with microwave exposure in the same temperature were also compared. S.aureus has significantly higher D-values (5.05 min at 55 ℃, 2.60 min at 60 ℃ and 1.21 min at 65 ℃) than E.coli (41.7 min at 50 ℃, 4.06 min at 55 ℃, 1.57 min at 60 ℃) respectively microwave energy. When pH is of lower optimum pH, the susceptibility of cells to physical and chemical treatments increases. With the increasing concentration of salt in the solution (8.5 g/L,20 g/L and 40 g/L), the destruction rate of S.aureus is highest at the concentration of 20 g/L at 60 ℃, while the rate of E.coli decreases with the increasing concentration of salt. S.aureus were treated with microwave at different temperature, subsequently interacted with Flou-3/AM respectively. The results showed that the permeability of cell membrane is changed after microwave treatment.