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KMID : 0380619900220010001
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Korean Journal of Food Science and Technology
1990 Volume.22 No. 1 p.1 ~ p.6
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Studies on the Measurement of Thermal Diffusivity and Thermophysical Characteristics of Defatted and Nondefatted Starches
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공재열/Kong, Jai Yul
김정한/김민용/정진웅/Kim, Jeong Han/Kim, Min Yong/Cheong, Jin Woong
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Abstract
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The thermal diffusivity of defatted and nondefatted starches were measured on the basis of one dimensional semi-infinitive theory. Differential scanning calorymetry was used to study the effects of cooling rate, fat and water contents on the enthalpy and entropy changes with the cooling rate of -2.5 -10℃/min. Thermal diffusivity of defatted and nondefatted straches were determined to be 4.14 x 10^(-4) - 4.96 x 10^(-4)(㎡ /h), 4.09 x 10^(-4) -4.81 x 10^(-4) (㎡ /h) in unfrozen state, and 2.78 x 10^(-3)3.91 x 10^(-3) (㎡ /h), 2.26 x 10^(-3) - 3.57 x 10^(-3) (㎡ /h) in frozen state respectively. On decreasing temperatures in frozen state, thermal diffusivities of starches were increased and entropy and enthalpy were decreased, and more rapid cooling rates resulted in a decrease in entropy. A linear relation was observed between enthropy, enthaly and water content. Thermal diffusivity was decreased, and entropy was increased with increasing fat content. With water content ranging from 35 to 90%, enthalpy and entropy of straches were found to be 107-216 (kcal/ mol), 0.45-0.94 (kcal/mol.K), respectively.
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KEYWORD
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