The equilibrium moisture content of the powders for each temperature was plotted against the corresponding water activity to produce the sorption isotherms. Thewater activity is equal to the relative humidity divided by 100. Eleven different mathematical models, among many in the literature, were used to fit to the experimental data using regression analysis. The curve fitting and regression analysis were performed using MATLAB R2013b. Inc, MathWorks Natick, Massachusetts, U.S.A. The best fit was chosen according to the minimum sum of squares due to error for the fit, abbreviated to SSE, minimum standard error of the fit RMSE, minimum mean absolute percentage error (P), and the maximum degrees of freedom adjusted R-square, R2 Adj (R2 Adj > 0.98 is considered here to be a reasonable fit).