真空冷冻干燥过程中微生物数量变化规律的初步研究

Preliminary Study of Microorganism Variation In Vacuum Freeze Drying Process

真空冷冻干燥技术是将含水物料中的水冷冻成固态冰,在高真空条件下利用水的升华性能,使物料在较低温度脱水而达到干燥目的的一种干燥方法。本研究将对市售的胡萝卜、香菇进行真空冷冻干燥,通过控制冻干的最终温度以及达到终结温度后的冻干时间,比较冻干前后各批次果蔬中微生物的数量(包括细菌总数以及大肠菌群总数),得到果蔬冻干过程中冻干过程中微生物的变化规律。结果显示胡萝卜、香菇在冻干过程中微生物数量的变化与温度、干燥时间呈正相关,在终结温度为60℃,干燥时间为6 h的情况下,干品品相良好,并能成功抑制微生物的生长。

Vacuum freeze-drying technology is a drying method that freezes water in aqueous materials into solid ice and uses the sublimation performance of water under high vacuum conditions to dehydrate the material at a relatively low temperature to achieve drying.In this study,the carrots,shiitake mushrooms sold in the markets were vacuum freeze-dried by controlling the final temperature of lyophilization and drying time after reaching the final temperature.The number of microorganisms(including the total colonies number of bacteria and coliform bacteria)in each batch of fruits and vegetables before and after freeze-drying was compared.The relationship between the freeze-dried temperature and the number of microorganisms during freeze-drying process of fruits and vegetables was obtained.The results showed that carrots and shiitake mushrooms had a good product phase at the end of lyophilization at a temperature of 60℃and a drying time of 6 h,and had the best effect of inhibiting the growth of microorganisms,the total number of colonies and Coliform bacteria were positively related to the final temperature of lyophilization and drying time after reaching the final temperature.