EQUILIBRIUM MOISTURE CONTENT OF THREE MILK POWDER PRODUCTS UNDER STORING TEMPERATURES
Equilibrium moisture content of skimmed milk powder spray, whey powder spray, and yoghurt powder spray were determined using a gravimetric dynamic method with continuous recording of changes in sample weight. Equilibrium data for adsorption and desorption of water from three milk powder products were investigated at ambient temperatures in the range of 20 40oC and water activity ranging from 0.4 to 1.0. Sorption capacity decreased as temperature increased. Rehydration of dried material resulted in hysteresis. Five models available in the literature (Chung-Pfost, GAB, Halsey, Henderson, Oswin) were evaluated by determining the best fit to the experimental data. The Oswin equation was found to be a good model for moisture adsorption and desorption of milk powder spray, the Chung-Pfost equation was a good model for whey powder spray, and the Henderson equation for yoghurt powder spray.
Stencl, J. and Homola, P. (2001). EQUILIBRIUM MOISTURE CONTENT OF THREE MILK POWDER PRODUCTS UNDER STORING TEMPERATURES. Acta Hortic. 566, 527-532
adsorption, desorption, modelling, sorption isotherm, water activity