Effects of gamma-irradiation on the morphological, structural, thermal and rheological properties of potato starches

Changes in granule morphology, structural, thermal, gel textural and rheological properties of starches separated from two potato cultivars (Kufri Jyoti and Kufri Chipsona-2) caused by gamma-irradiation (Co60, 0.01, 0.05, 0.1 and 0.5 kGy) were studied. A complete disorganization of the crystalline structure and carboxyl content of 0.09–0.11% was observed in starches irradiated at 0.5 kGy. Irradiation of starch increased gelatinization temperatures (onset-, peak- and conclusion-temperature) measured using DSC. Peak viscosity, trough viscosity, breakdown viscosity, final viscosity and gel hardness decreased while gel cohesiveness increased with the irradiation. Irradiation effect on gumminess, chewiness, adhesiveness and retrogradation of gels varied with the cultivar. Kufri Jyoti native and irradiated starches showed greater retrogradation as compared to Kufri Chipsona-2 native and irradiated starches. Difference in recrystallization of molecules as revealed from percent retrogradation and enthalpy of retrogradation amongst starch from two cultivars was also observed.