Prediction of storage conditions of dehydrated foods from a water vapor adsorption isotherm

Abstract

The graphical relationship between the water activity (aW) and moisture (M), aW=M vs M, the interception of Rockland isotherm and the clustering function were proposed as three stability criteria to estimate the moisture content corresponding to the minimum of the integral entropy of the water adsorption of dehydrated foods. For this, three materials were analyzed: a sucrose-calcium powder (SA), vibro-fluidized drying pineapple powder (VFD) and capsules of paprika oleoresin in an alginate-zeolite matrix (NE) were analyzed. The three stability criteria showed that the maximum stability was similar to 4.9, 19.9 and 7.3 g water/100 dry solids for SA, VFD and NE, respectively. The results showed that the maximum in the graphical relationship of aW=M vs M, as well as the intercept of the local Rockland isotherms and the cluster function, indicated the equilibrium between the entropic and enthalpic mechanisms of water adsorption, which agrees with the minimum integral entropy and can be used as a criterion to select the best storage conditions.