Differential Thermal Analysis of Potato Starch Gelatinization

Abstract

The gelatinization of potato starch in water was studied by quantitative differential thermal analysis at various heating rates ranging from 0.02 to 20K min^-1. It was found that at a heating rate slower than 0.5K min^-1 the gelatinization state is at all times in equilibrium uring the temperature scan, while it is kinetically limited at a heating rate faster than 0.5 K min^-1. The heat of gelatinization was calorimetrically obtained as ΔH_cal =2.77 ±0. 15 kJ (glucose residue)^-1 (661 ± 36 cal (glucose residue)^-1) Using the transition curve drawn from the enthalpy level, the van't Hoff enthalpy for gelatinization was determined to be ΔH_vH=816±8kJ mol^-1 (195±2 kcal mol^-1). From the ratio of the van't Hoff enthalpy to the calorimetric enthalpy, the size of the cooperative unit during the gelatinization of potato starch was estimated to be 295 ± 10 (glucose residues) mor^-1).