MECHANISM OF STARCH GELATINIZATION IN NEUTRAL SALT-SOLUTIONS

DSC thermograms showed that salt affected the onset temperature (T0) and enthalpy change (DELTAH) of starch gelatinization and that the effect differed by type of salt and concentration. Anion effects seemed to parallel the structure-making and structure-breaking effects of water. At all concentrations, sulfate ions increased T0 and DELTAH, but thiocyanate suppressed them. T0 and DELTAH were affected by cations in a complex mode. In CaCl2 (3 molal) or LiCl (7-10 m) solution, starch gelatinized at room temperature but did not gelatinize in NaCl or KCl solutions at any concentration. Light micrographs taken at room temperature showed that in KSCN and KI solutions (>2m) starch gelatinization began at the hilum but in CaCl2 (3m) and LiCl solutions (7-10 m) starch gelatinization started at the periphery. It was concluded that the mechanism of starch gelatinization in salt solutions can be attributed to: (1) structure-making and structure-breaking effects on water and (2) electrostatic interactions between salts and hydroxyl groups of starch.