The Effect Of Annealing And Ultra-high Pressure Treatment On Structural And Functional Of Three Starches With Different Polymorphs

Physical modification of starch has attracted much attention recently for its invironmental friendness and safety.The effect of annealing?ANN?,ultra-high pressure treatment?UHP?,and dual modification of ANN and UHP on properties of three starches with different polymorphs was investigated.The main results obtained were as follows:No significant changes were observed on long-and short-range order of starch granules after annealing treatment.However,the functional properties were changed markedly by annealing treatment.The annealed starch showed the increased gelatinization temperatures,especially for T_o.The peak viscosity of wheat starch increased after annealing treatment,while annealed yam starch presented a decreased peak viscosity.A significant decrease was found in breakdown of annealed potato starch.Wheat and yam starches all displayed the decreased long-and short-range orders after UHP treatment,and the degree of decrease was polymorph-dependent.The molecular order of A-type wheat starch decreased with increasing treatment pressure.Yam starch presented a decreased ratio of 1047/1022 cm^-1 as the treatment pressure reached 600MPa,while little change was observed in other structural parameters.No significant changes was obseverd for UHP treated potato starch.These results indicated that yam and potato starches were more resistant to UHP treatment than wheat starch.UHP treated starch showed the increased gelatinization temperatures and decreased gelatinization enthalpy.An increased peak viscosity was observed for UHP treated wheat starch at 200 MPa,whereas the higher pressure treatment resulted in a decreased peak viscosity.Unlike wheat starch,the peak viscosity of yam and potato starches increased after UHP treatment.The in vitro enzymic hydrolysis of wheat and yam starch increased after UHP treatment,and the higher the pressure,the higher digestion percentage was.In contrast,little effect was observed for in vitro enzymic hydrolysis of potato starch.The coalescence of starch granules was observed for wheat starche after dual modification.Dually modified yam and potato starches underwent no significant changes in long-and short-range order.The ANN-UHP?dual modification of ANN followed by UHP at a pressure lower than 500 MPa?treated and UHP-ANN?dual modification of UHP at a pressure lower than 400 MPa followed by ANN?treated wheat starch showed no changes in crystallinity and FWHH?full width at half height?at 480 cm^-1.An increased gelatinization temperature was observed for dual modified yam,potato,ANN-UHP?at pressure below 500 MPa?and UHP-ANN?at pressure below 400 MPa?treated wheat starches,and the increase was more obvious for UHP-ANN treated starch.Completely gelatinization occurred for duallymodifiedwheat starch when the treatment pressure was 500 MPa or higher.An obvious increase was observed in peak viscosity for dually modified wheat starch,which showed a decreased peak viscosity.Unlike wheat starch,dually modified yam starch presented a decreased peak viscosity.Thedually modified potato starch showed a similar pasting profile with the annealed potato starch.The dual modification had a great effect on in vitro digestion profiles of wheat and yam starches,but had a little effect on potato starch.