Physical modification of corn and potato starches using soaking, freezing, and drying

Effects of continuous soaking, freezing, and drying on physicochemical properties of corn and potato starches were investigated to prove potentials of sequential physical modification method. High temperature soaking showed the higher swelling power than low temperature soaking in both starches right after soaking. Freezing did not significantly rearrange the molecular structure of both starches. Drying greatly change the physicochemical properties of both starches in the order of freeze, air and spray dryings. Consequently, sequential treatment of soaking, freezing, and drying lowered RVA pasting characteristics (peak viscosity, breakdown, setback) as well as amylopectin melting transition temperature compared to native starch. Particularly, potato starch showed more significant change than corn starch, possibly due to the differences in water absorption, amylose content, crystallinity, granule size, etc. Overall, high temperature soaking and freeze drying significantly change the RVA, DSC and XRD characteristics in the sequential treatment of soaking, freezing and drying of starches.