在不同真空度下的卷心菜真空冷却实验对比研究

Vacuum Cooling of Cabbage in Different Low Pressures

在卷心菜真空冷却实验中,真空度是影响冷却时间和效果的主要因素。本文通过设定不同的自动补气阀工作压力范围来控制真空室的压力,进行卷心菜真空冷却实验,并分析了此过程中水分在低压下的气化过程。实验发现,自动补气阀工作压力范围分别为700 Pa-900 Pa、1000 Pa-1200 Pa和1300 Pa-1500 Pa时,当温度最低处(表叶)达到预定的0．7℃时,耗时分别为11 min、22 min和43 min,中心温度分别为3．86℃、6．68℃和9．11℃。结果表明：700 Pa～900 Pa的自动补气阀工作压力范围,对卷心菜进行真空冷却实验的效果较好；对于特定食品的真空冷却,应该可以找到各自恰当的自动补气阀工作压力范围,以提高冷却的效率。

The conventional chamber for vacuum cooling has been modified with installation in different automatic air compensating valves so as to control the range of steady operating pressure. Cabbage was vacuum cooled with the newly-developed system of different pressure ranges. Low vacuum evaporation of water was evaluated. The results show that there is an appropriate pressure range that best cools a specific food specimen. For example, the optimal cooling pressure of cabbage ranges from 700 Pa to 900 Pa.