Analysis of water layers and the extent of gelatinization for commercial starch products

Water sorption characteristics were investigated using both the GAB and Smith models for commercial starch products to determine their involvement in the extent of gelatinization. The GAB monolayer water content, Wm, correlated well with the Smith parameter wb, whereas the R2 coefficient of Wm with the Smith parameter w′ exhibited a weaker correlation. The relationship between Wm and the multilayer water content, MC, could be expressed with R2 coefficients greater than 0.840 and the ratio of Wm to MC was constant at 1:2–1:3, irrespective of variations in ingredients and sorption processes. Thus, the coverage of particular water binding sites is considered to be simple, despite the various components of commercial starch products. In addition, both Wm and MC may be involved in the extent of gelatinization: swelling capacity and viscosity were intimately involved in the early stage of gelatinization.