The effect of thermal and irradiation treatments on structural and physicochemical properties of octenyl succinate maize starches

•Thermal treatment of starch causes its strong depolymerization.•Thermal treatment influences starch structure stronger than UV irradiation.•Octenyl succinate groups stabilize starch structure.•Radical creation caused by thermal and UV energy in starch is inhibited by OS groups.•The addition of OS groups to starch makes it less digestible.