As for the moisture content data, there is no correlation was observed between the plasticizer and the studied drying conditions, because the data variation is small: between 12 and 13.9 for the films plasticized with glycerol (Table 1) and 9.2 and 10.7 for the films plasticized with sorbitol (Table 2). According to the statistical analysis of the WVP experimental

Caspase inhibitor values listed in Tables 1 and 2, the linear, quadratic, and interaction parameters of drying temperature (X1) and relative humidity (X2) are not statistically significant (p > 0.05). Therefore, the WVP of amaranth flour films plasticized with glycerol and sorbitol does not depend on the drying process. On the other hand, the WVP of flour films prepared with sorbitol is lower than that of glycerol-containing films (Tables 1 and 2). The better water vapor barrier selleck inhibitor properties of edible films containing sorbitol as plasticizer compared with those of the films containing glycerol might be due to the fact that sorbitol is less hygroscopic (Kowalczyk & Baraniak, 2011). The

difference between both plasticizers in terms of WVP values was also reported by several authors in the case of protein films (Gennadios, Weller, Hanna, & Froning, 1996; Kowalczyk & Baraniak, 2011; McHugh, Aujard, & Krochta, 1994; Wan, Kim, & Lee, 2005). According to the analysis of variance (ANOVA), the second-order models obtained for the drying time, represented as equations (14) and (15), are statistically significant (p < 0.05) and predictive (Fcalculated > Flisted). Therefore, the drying time data ( Tables 1 and 2) are adequately correlated with T (X1) and RH (X2). For glycerol: equation(14) t=7.59−2.23X1+0.31X12+2.63X2+0.90X22(R2=0.90)

For sorbitol: equation(15) t=6.88−1.92X1+0.37X12+2.60X2+0.81X22−0.50X1X2(R2=0.99) The drying time corresponds to the time required for the films plasticized with glycerol or sorbitol to reach a moisture content of 3.04 g H2O/g db (Tables 1 and 2). Oxalosuccinic acid As drying to those final moisture contents virtually takes place during the constant rate period, the drying rate is controlled by heat and mass transfer in the external gas phase. Hence, the drying time is almost a linear function of the T and is inversely related to the RH (figure not shown). The water sorption isotherms of flour films plasticized with glycerol or sorbitol as plasticizer are presented in Fig. 5. The experimental data obtained for these films at 30 and 40 °C fit by the GAB model well. The parameters for the GAB equation are summarized in Table 3. All the water sorption curves of the films are sigmoid in shape, revealing a slower increase in the equilibrium moisture content until aw 0.6; thereafter, there is a dramatic increase in the slope of the isotherm, indicating the presence of non-bound or free-state water associated with enhanced solubilization ( Hernández-Muñoz, Kanavouras, Ng, & Gavara, 2003; Su et al., 2010). For the films containing sorbitol, at lower aw (<0.