Impact of Soaking Time at Room Temperature on the Physicochemical Properties of Maize and Potato Starch Granules

Starch-rich foods such as cereals and tubers are the main source of energy in human diet, but are rarely consumed in their native form, requiring cooking to deem them more digestible. The soaking of starch-rich matrices can reduce significantly energy consumption. In this work, native maize and potato starches are soaked in water (10g/100g water) at room temperature (20 degrees C) for up to 8h, and the physicochemical changes (morphology, particle size, apparent viscosity, and crystallinity changes) are monitored for soaking times of 1, 2, 4, 6, and 8h. Starch granules lose gradually birefringence, while the mean particle size increases by 7.0-9.0% by swelling effect. The apparent viscosity of the starch dispersion also increases about 5-7 times after 8h of soaking. Differential scanning calorimetry shows that the enthalpy required for achieving complete gelatinization decreased by about 80-90% after the 8h soaking treatment. Overall, the results indicated that soaking at room temperature offers an inexpensive mean for saving energy cost involved in starch gelatinization process.