哈密瓜汁中大肠杆菌超高压杀灭效果研究

Effects of High Hydrostatic Pressure Processing on E.coli Inactivation in Hami Melon Juice

以鲜榨哈密瓜汁为原料，研究超高压（压力100~500 MPa，时间10~20 min，温度35~55℃）对哈密瓜汁中的大肠杆菌的杀菌效果。并采用透射电镜、平板计数等方法，考察大肠杆菌的结构特征变化和哈密瓜汁中的微生物总数，建立超高压处理哈密瓜汁中的大肠杆菌的杀菌动力学。结果表明，温度越高、压力越大，大肠杆菌死亡速率越大，降低一个对数级所需要的时间越短，500 MPa，45℃条件下保温保压20 min，大肠杆菌的死亡数量可达到5.95个对数级；说明超高压对哈密瓜汁大肠杆菌有良好的杀菌效果，同时发现超高压处理破坏了大肠杆菌的细胞结构，内含物结构紊乱、泄漏、出现大片透电子区，哈密瓜汁中微生物总数由1.30＆#215;105 CFU/mL降低至8 CFU/mL，符合GB 19297-2003果、蔬汁饮料卫生标准的标准要求，说明超高压杀菌对哈密瓜汁中的大肠杆菌有良好的杀菌效果。

The effect of high hydrostatic pressure on E.coli inactivation in fresh melon fruit juice is investigated after high hydrostatic pressure processing （100~500 MPa, 5~20 min, 35~55 ℃） . The changes of E.coli structural characteristics are obtained by transmission electron microscope （TEM）, and the plate count method. Kinetics of Escherichia coli in Hami melon juice is established after high hydrostatic pressure processing. It is shown the higher the temperature and the pressure, E.coli death rate increases. It needs a shorter time to reduce a logarithmic. Under the condition of 500 MPa, 45 ℃, 20 min, the deaths number of E.coli can reach up to 5.95 log. Meantime, it is discovered that high hydrostatic pressure processing can destroy the cellular structure of E.coli, and disorder inclusion structure, finally, leakage, large electron transmission areas are found. The total number of microorganisms in Hami melon juice decrease from 1.30＆#215;105 CFU/mL to 8 CFU/mL, which met the requirements of GB 19297-2003“fruit, vegetable juice beverage hygiene standards” standard. It determines that the high hydrostatic pressure processing has good sterilization effect to E.coli in Hami melon juice.