The effect of starch gelatinization and solute concentrations on T-g ' of starch model system

The effect of starch gelatinization on glass transitions in a starch/water model system and how the concentrations of added solutes (sucrose and sodiu m chloride) affect the glass transition temperatures of the gelatinized sta rch solution was investigated. The starch suspension samples were heat trea ted in a Differential Scanning Calorimeter (DSC) under different time and t emperature regimes to achieve different degrees of gelatinization. The gela tinization characteristics (onset, peak and end temperatures and enthalpy) and the glass transition values of a potato starch were determined using th e DSC. The results showed that the starch concentrations had no effect on g elatinization characteristics and the T-g' of the gelatinized potato starch but had clearly increased their Delta C-p in the T-g' region. Annealing at a temperature slightly below the T-g' of -5 degrees C, led to maximal free ze-concentration in the total/partial gelatinized starch and a higher T-g' value at about -3 degrees C was obtained. The T-g' values of the totally ge latinized starch samples were slightly lower than those of partially gelati nized samples. The T-g' of the gelatinized starch decreased with increasing concentrations of sucrose or sodium chloride. Sodium chloride had a strong er depressing effect on T-g' than sucrose. (C) 2000 society of Chemical Ind ustry.