True Thermal Conductivity Determination of Moist Porous Food Materials at Elevated Temperatures |
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| Authors: | D L Goedeken K K Shah C H Tong |
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| Affiliation: | Author Goedeken, formerly with Rutgers University, is now with The Pillsbury Co., 330 University Ave., S.E., Minneapolis, MN 55414;Author Shah, formerly with Rutgers University, is now with Harris Milford and Co., 933 Hylton Rd., Pennsauken, NJ 08110;Author Tong, formerly with Rutgers University, is now with Baparoma, 593 Rose Dr., Benicia, CA 94510. |
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| Abstract: | Thermal conductivity (k) of bread samples, moisture content 5% to 44%, (w/w, wet basis) and porosity 0.18 to 0.90, was measured in a sealed stainless steel vessel using the probe method from 25 to 85°C. Significant differences were observed in measured thermal conductivity before and after air pressure was applied to the sample indicating the influence of vapor phase moisture migration on thermal conductivity. The difference increased as temperature and moisture content were increased. True thermal conductivity of bread was found to agree with predictions using a volume fraction model when moisture migration was completely suppressed at an applied air pressure of 18 atm. |
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| Keywords: | thermal conductivity air pressure porous materials bread moisture migration |
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