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KMID : 0380619870190030231
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Korean Journal of Food Science and Technology
1987 Volume.19 No. 3 p.231 ~ p.238
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Kinetic Study for Hygroscopic Behavior of Freeze Dried Soy Paste Powder
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이철원/Lee, Chul Won
유주현/이신영/황응수/Yu, Ju Hyun/Lee, Shin Young/Hwang, Eung Soo
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Abstract
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Two kinds of soy pastes with different colors (reddish brown and yellowish white) were dehydrated by freeze drying in powder form. Hygroscopic behaviors of powdered soy pastes were investigated under the conditions of various water acitivities (0.11-0.88) and three different temperatures (25,40 and 50℃), and presented a kinetic and thermodynamic interpretatons in the view point of qualities and storage stability. Moisture absorption isotherms of powdered soy pastes were of type II according with BET classification and can be described by the Henderson´s empirical equation. The safe storage moisture levels calculated by the Laurie´s equation were ranging from 5.5 to 3.98% dry basis with oaring temperatures. The moisture absorption process for powdered soy paste followed the Ist order kinetic in the difference of equilibrium moisture content and arbitrary moisture content and the initial step was characterized by very fast absorption of moisture. The change of, dispersion capacity and color difference for powdered soy paste were extremely dependent upon water activity under the storage and the maximum stability was found at safe storage moisture levels. Also, the variation of thermodynamic parameters with moisture content was significant at safe storage moisture content levels and suggested the considerable correspondence to storage stability of powdered soy paste.
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