• Food Science and Preservation
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• v.10 no.4
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• pp.459-465
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• 2003

This study was carried out to investigate the changes in internal pressure according to various freezing methods, as basic research to protect the destruction of tissues when fruits and vegetables are frozen. The rate of weight loss, caused by the freezing of fruits and vegetables, was found to be the least (0.44∼1.38％) when the immersion freezing method was applied. The difference in the rate of weight loss was the highest when freezing methods were applied to watermelon, and the freezing rate of watermelon whose moisture contents were greater have relatively greater influence on the weight loss. The difference in internal pressures was the least and caused by the volume increase and decrease, when pear, apple, and melon were frozen using the immersion freezing method, while the diffeyence the greatest when the air-blast freezing method was used. As the freezing rate was greater, the internal pressure was less. However, the internal pressure of strawberry and watermelon was the greatest when the immersion freezing method was applied. Frozen without using the thermal equalizing method, the change in internal pressure of fruits was about 2 psig. In contrast, the internal pressure of watermelon applied with the thermal equalizing method was changed in a way similar to that of watermelon not applied with the method, but the former generated a certain level of internal pressure and maintained a significantly low level of internal pressure (about 1.3 psig). When thawed, the internal pressure of samples to which the thermal equalizing method was applied was less than that of what the thermal equalizing method was not applied to. In comparison with the application of multi-step thermal equalizing method, 3∼4 times of application of the thermal equalizing method to the freezing resulted in the decrease of fluctuation range of internal pressure.