Structure and selected functional properties of gamma‐irradiated potato starch

Potato starch was modified with γ‐rays applying doses of 5, 10, 20 and 30 kGy. The effect of irradiation on starch structure was assessed on the basis of blue value (BV), A680/A545 ratio, apparent amylose content and λmax. The results showed that modification of starch led to the reduction of all parameters connected with the starch‐iodine complex. The main effects of γ‐irradiation on starch granules revealed by scanning and transmission electron microscopies were cracks on the surface. Low‐temperature nitrogen adsorption data showed that modification with γ‐rays increased specific surface area and volume of mesopores and decreased their average diameter. DSC data indicated decreased crystallinity of starch and facilitated retrogradation taking place after irradiation in the 20% starch gels. Treatment with γ‐rays influenced also functional properties of potato starch increasing water absorption, least gelling concentration, solubility, paste clarity and susceptibility to α‐amylolysis, and decreasing fat absorption and viscosity.