INFLUENCE OF PRESSURE AND TEMPERATURE STRESS DURING VACUUM PRE-COOLING ON THE QUALITY OF FRESH LEAFY VEGETABLE

研究了菠菜真空预冷过程中由于压力和温度急剧下降而产生的应力状况。分离出压力和温度的具体影响，以确定它们对质量下降的贡献。温度的快速下降，而不是压力被认为是负责L-抗坏血酸（阿萨）的下降。通过改变0.61 kPa的压力曲线，逐渐降压速率保持阿萨的水平。影响菠菜品质的临界终压范围为0.61- 0.8kPa。真空预冷菠菜比未预冷菠菜和冷水预冷菠菜呼吸量大，真空预冷曲线相似。在相同的压力条件下，但在不同的初始温度下，菠菜样品在5℃下储存4天，得到了类似的结果。

The stress conditions due to rapid decrease in pressure and temperature during vacuum pre-cooling of spinach were investigated. The specific influence of pressure and temperature were isolated to determine their contributions to quality degradation. The rapid decline in temperature rather than pressure was found to be responsible for the decline in L-ascorbic acid (AsA). By modifying pressure profile at 0.61 kPa, gradual pressure reduction rate retained the level of AsA. The critical final pressure affecting quality of spinach ranged from 0.61-0.8 kPa. Vacuum pre-cooled spinach respired more than the not pre-cooled and chilled water pre-cooled spinach using similar vacuum pre-cooling curve. Similar findings were obtained for spinach samples subjected to the same pressure condition but at different initial temperatures in a 4-day storage at 5℃.