Quality Changes of Cooking in Hypobaric-packaged Winter squash

Abstract

Quality changes of cooking in hypobaric-packaged winter squash fruits were studied in relation to the differences of cooking temperature (70, 80 or 100°C) and degree of vacuum (30 or 100 Torr) in packaging. The cooking of winter squash fruits packaged under reduced and normal pressures with the usual cooking methods was investigated.
Winter squash fruits cooked at 100°C or 80°C showed no changes in surface colour.In Winter squash fruits which were packaged under reduced pressure at 100 Torr or normal pressure, browning occured with cooking at 70°C, but the browning did not occur in winter squash fruits packaged under reduced pressure at 30 Torr and in ordinary cooked winter squash fruits.
There were no appreciable differences between hardness of winter squash fruits and degree of vacuum during cooking at 70 or 80°C. In the cooking at 100°C, winter squash fruits remained harder with the lowering of the degree of vacuum while those packaged under normal pressure remained hardest.
The content of total ascorbic acid in winter squash fruits was kept higher during cooking at 100°C. On the other hand, at temperatures below 100°C, the content in hypobaric-packaged winter squash fruits showed higher than that in winter squash fruits packaged under normal pressure or in ordinary cooked winter squash fruits. The higher degree of vacuum, the lower became dehydroascorbic acid content at all the temperatures. Winter squash fruits cooked under normal pressure at 100°C showed highest value of dehydroascorbic acid among all the treatments.
There were no considerable differences between sugar content and degree of vacuum in packaged winter squash fruits. However, sugar content in ordinary cooking was lower when compared with that of the cooking of packaged winter squash fruits except when cooked at 100°C.
It is suggested that cooking at 80°C or higher temperatures and under reduced pressures is good for keeping quality of winter squash fruits.