STARCH GELATINIZATION PHENOMENA STUDIED BY DIFFERENTIAL SCANNING CALORIMETRY

Abstract

ABSTRACT Differential Scanning Calorimetry (DSC) was used to study gelatinization phenomena of corn, potato, acid‐modified corn and smooth pea, and various legume starches. Two endothermic transitions were observed for starches heated in the presence of limited amounts of water (starch/water = 46–48% w/w). The effect of starch concentration on the shape of these two endotherms was studied for three legume starches. Considering the starch granule as a spherulite, the experimental data were treated thermodynamically by applying equations describing phase transitions of semi‐crystalline polymers. Experimental evidence suggested that a solvation‐assisted melting of starch crystallites took place during gelatinization and that the process was facilitated by the presence of the amorphous parts of the granule. The enthalpy change, ΔH, associated with the gelatinization varied among these starches within a range of 2.6–4.4 Cal/g. A comparison between DSC transition temperatures and characteristic gelatinization temperatures obtained by other methods was also made.