1993 Fiscal Year Final Research Report Summary
Study on the Transport Phenomena and Quality Determination of Agiricultural Products Based on Noueguilibrium Thermodynamics
| Project/Area Number |
04806035
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
農業機械
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| Research Institution | Mie University |
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Principal Investigator |
KAMEOKA Takaharu Mie Univ. Bio-resources Associate Professor, 生物資源学部, 助教授 (90177600)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Water Adsorption / Diffasivity / Storage / Africultural Products / Thermodynamics |
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| Research Abstract |
The attempt at a statistical treatment of water sorption by foods of low moisturre content was made, based on the approximate method for deriving the Dubinin-Astakhov (DA) equation from Weibull distribution function of adsorption energies. A modified DA equation suitable for foods was also derived by changing the meaning of the three parameters theoretically. A new expression of equilibrium moisture content equation for rice was shown by the use of modified DA equation.
Interactions between water and saccharide in food are very important. The Water activity cefficient in saccharide-water systems was measured by freesing point depression. Glucose-water systems were used, being ideal solutions. Freezing point depression in these systems was proportional to mole fraction and the accuracy of the experimental data was confirmed. Maltose-water systems behaved as ideal solutions. For tow systems, water activity coefficient decreased from 1.0 at mole fractions above 0.02 in sucrose-water systems.
Sorption data of crystalline saccharides and a corn starch were obtained using static method at 10 ﾟC.Each crystalline saccharide sorbed a negligible amount of water at water activity below each saturation point. Amorphous data of sucrose were on the smooth curve expolarated by the sucrose-water solution curve. DA equation showed good agreement with the amorphous data in the range of water activity from 0 to saturation point. As a result, it was shown that DA equation is also applied successfully to the non-porous foods.
Based on the above-mentioned water sorption of highly moistened food and nonequilibrium thermodynamics, an equation was derived for the water movement coefficient in vegetable. the quality of vegetable was discussed by the friction coefficient inside this equation. A modefied Arrhenius-type equation was also derived for the diffusivity of water in low moistened food. the activation energy was expressed as a function of temperature and moisture content.
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Research Products
(4 results)
