Results
Equations (1)–(4) as presented in Table 1, which model the dependence of EMC
of whole milk powder on aw in the temperature range of 5–35 °C, were investigated and reviewed. Analyses of residuals and correctness of fit tests were carried out after
determination of indicators. The comparison of Halsey, Henderson and Oswin models for water adsorption and desorption is given in Table 2. Chung-Pfost model did not achieve convergence. Oswin’s equation (4) gave the best results. The statistical values showed that this model, both for water adsorption and desorption, had the smallest RMSE and the highest R2. The standardized residuals of this model were uncorrelated (Durbin-Watson test), (Draper and Smith 1981). F-test and p (probability) were acceptable. These values determine the relevance of the regression function. F-test (Myers 1990) should be the highest as possible, and p value (Mandel 1964) should be the lowest as possible. Halsey’s and Henderson’s equations had high RMSE (Chowdhury and Das 2012) and undesirable values of F-test, d, p and R2 (Akanbi et al. 2006).