Effect of additives on physicochemical properties in amorphous starch matrices

The effect of the addition of non-reducing sugars or methylcellulose on the matrix physical properties and rate of non-enzymatic browning (NBR) between exogenous glucose + lysine in a starch-based glassy matrix were studied, using the methods of luminescence and FTIR. Amorphous starch-based matrices were formulated by rapidly dehydrating potato starch gel mixed with additives at weight ratios of 7:93 (additive:starch). Data on the phosphorescence emission energy and lifetime from erythrosin B dispersed in the matrices indicated that sugars decreased starch matrix mobility in a Tg-dependent manner, except for trehalose that interacted with starch in a unique mode, while methylcellulose, the additive with the highest Tg, increased the molecular mobility. Using FTIR, we found that methylcellulose decreased the strength of hydrogen bond network and sugars enhanced the hydrogen bond strength in the order: trehalose > maltitol > sucrose. Comparing those changes with the rate of NBR between exogenous glucose + lysine, we suggest that NBR rates are primarily influenced by matrix mobility, which is modulated by the hydrogen bond network, and interactions among components.