Relationship between monolayer and multilayer water contents, and involvement in gelatinization of baked starch products

Water sorption was investigated using a gravimetric technique to determine the involvement of water in gelatinization for baked starch products. The water isotherm could be described well using both the GAB and the Smith equations. Baked products with higher GAB monolayer water content (M0C) could be made from dough with higher water content. In addition, M0C was found to be correlated with both the Smith parameters wb and w′, whereas the multilayer water content (MC) was reflected more in w′ than wb. Although the desorption process maintains more water than adsorption, the ratio of M0C to MC was constant irrespective of sorption process. Both M0C and MC showed good correlations with the gelatinization parameters, but the correlations were weaker in the case of adsorption. Therefore, gelatinization may reflect water desorption characteristics, suggesting that hydration is incomplete in the adsorption process and new binding sites of water would be involved to a greater extent in gelatinization.