VARIATIONS IN WATER CONTENT DUE TO FREEZING AT CRYOGENIC TEMPERATURES
Abstract
Variations in water content owing to freezing at cryogenic temperatures were evaluated in the kinetic drying process of garlic. The drying conditions were constant temperatures of 40°C, 50°C and 60°C with an airflow of 1.8m/s. Samples of garlic that were fresh, dry, and in the process of drying were frozen in liquid nitrogen before determining their water content. As a reference, samples that were not frozen were monitored at the same time. During the kinetic drying, the samples subjected to cryogenic freezing varied from 0 to 70% in water content compared to those not cryogenically treated. These resultants contrast with those found in wholly dried or wholly fresh samples, which showed a difference of 0.55 and 1.17% respectively. The results suggest that the diverse phenomena which occur during freezing at cryogenic temperatures depend principally on the water content of the material before it is subjected to this process. These variations are highly important if correcting this difference in the dry base water content of physical chemical tests in the process of preservation (e.g. drying), but have little effect when these changes are made in tests with fresh or wholly dried samples.
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