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KMID : 1024619980180020176
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Food Science of Animal Resources
1998 Volume.18 No. 2 p.176 ~ p.184
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Influence of Freezing Rate on the Aroma Retention in a Freeze Drying System
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Byun Myung-Hee
Choi Mi-Jung
Lee Seong
Min Sang-Gi
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Abstract
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The objective of this study was to investigate the effects of freezing rate on aroma retention and to examine the mechanism of aroma retention during freeze drying process. Our experiments were carried out with self-manufactured freeze-dryer. Gelatin gels (2% w / w, 8020mm) containing diacetyl(2mg/ml) were frozen unidirectionally (Neumann’s model) from the bottom at -45, -30, -20, and -15 and followed with freeze-drying. Under the upper conditions we measured freezing rate and the change of temperature and pressure during freeze drying. Freeze-dried gelatins were cut horizontally into 5 mm thickness from the bottom measured and diacetly contents. Besides, we observed the effect of the relative humidity of the diacetyl contents freeze-dried gelatin during storage. The retained diacetyl content was increased at high freezing temperature and in order of 0∼5, 5∼10, 10∼15, 15∼20 mm section from the bottom of the sample. It was observed that the retained diacetyl content was high in 15∼20 mm section. The retained diacetyl content and freeze-dried gelatin stored in the condition of high relative humidity was decreased significantly but in the low relative humidity case, was it decreased in small amount. The results of our experiment resents that the low temperature freezing and low humidity storing condition is effective for preserving aroma compound in food.
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KEYWORD
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freeze drying, freezing rate, aroma retention
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