Drying Kinetics of Hydrated and Gelatinized Corn Starches in the Presence of Sucrose and Sodium Chloride

Drying behavior of the hydrated corn starch, hydrated starch/sucrose, and hydrated starch/sodium chloride mixture and their gels were investigated. Drying data were obtained on slabs of samples in a laboratory tunnel dryer at 40 to 70 °C. The rate-of-drying curves for hydrated starches with or without sucrose showed that the moisture movement may be the result of capillary action rather than diffusion. In the hydrated starches containing sodium chloride, case-hardening was the controlling mechanism. In gelatinized samples, however, diffusion was the main mechanism. The effective diffusivity was estimated by the methods of slopes. Gelatinization of starch reduced the moisture diffusivity significantly. The presence of sucrose or sodium chloride decreased the coefficient significantly in hydrated starch, but their effect was small in gelatinized samples.