Sorption isotherms and thermodynamic properties of freeze-dried colostral whey powders with different additives

作者：Yu, Huaning; Li, Yunfei^*

来源：International Journal of Food Science and Technology, 2012, 47(3): 613-619.

DOI：10.1111/j.1365-2621.2011.02884.x

• Colostral whey powder
• freeze drying
• maltodextrin
• sorption isotherm
• sucrose
• thermodynamic properties

Moisture adsorption isotherms of colostral whey (CW) powders with different additives (maltodextrin and sucrose) were determined using gravimetric static method at 1535 degrees C in the water activity range of 0.0670.76. The moisture adsorption isotherms obtained were typical sigmoid curves, and the modified-Halsey and GuggenheimAndersonde Boer (GAB) equations gave the best fit to experimental data among five well-known equations. Addition with maltodextrin into CW powders could effectively decrease equilibrium moisture content (EMC), whereas addition with sucrose increased EMC in the water activity of 0.430.76 at 15 and 25 degrees C and in the water activity of 0.210.76 at 35 degrees C, respectively. Thermodynamic properties including net isosteric heat of sorption and differential entropy were determined from adsorption data using ClausiusClapeyron equation. The results showed that net isosteric heat of sorption of all the samples decreased exponentially with increasing EMC. Enthalpyentropy compensation theory was applicable for adsorption process of all the samples, and the adsorption processes were enthalpy-driven.

• 出版日期2012-3
• 单位上海交通大学