Moisture Sorption Characteristics of Freeze Dried Blueberries |
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| Authors: | LOONG TAK LIM JlUMlNG TANG JIANSHAN HE |
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| Affiliation: | Author Lim's present affiliation: the Dept. of Food Science, Univ. of Guelph, Guelph, ON, Canada, NlG 2Wl. Author Tang, formerly with the School of Nutrition &Food Science, Acadia Univ., Wolfville, NS, Canada, is currently with the Dept. of Agricultural Engineering, South Dakota State Univ., Brookings, SD 57007. Author He is with Food Research Division, Sichuan Research Institute of Light Industry, Cheng Du, China, 610081. Address inquires to Dr. J. Tang. |
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| Abstract: | Moisture sorption isotherms of freeze dried lowbush blueberries at 4, 16, 25, 35, and 45°C were determined using indirect gravimetric method. Moisture sorption kinetics at these temperatures and 75% RH were also investigated. The isotherms followed a type III shape with a temperature inversion effect at 0.9 water activity. They were best described by the GAB equation. Net isosteric heat of moisture sorption in freeze dried blueberries, determined using the Clausius Clapeyron equation, varied from 5.5 to 0.25 kJ/mol as moisture content changed from 8 to 36% (dry basis). Moisture adsorption kinetics in freeze dried blueberries were well described by the first order kinetics equation. The rate constant followed the Arrhenius relationship with an activation energy of 38.6 kJ/mol. |
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| Keywords: | blueberries freeze dried moisture sorption isotherms |
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