Influence Of Ultrahigh Pressure On The Structures,Properties And Chemical Activity Of Starch

In order to reveal the activation mechanism of various modified starch equipment,this research adopted the mechanical force of ultrahigh pressure to modified starch.UHP is a kind of environmentally friendly,pollution free study to effect starch structure and the physical and chemical properties.The influence of ultrahigh pressure on the structures and properties of starch and chemical activity of starch are as follows:Using common corn starch and waxy maize starch as raw materials,using a laser confocal microscope（CLSM）and scanning electron microscopy（SEM）,X-ray diffraction（XRD）,polarizing microscope（PLM）,thermogravimetric analyzer（TGA）,differential scanning calorimetry（DSC）,Fourier transform infrared spectrometer（FT-IR）and rapid viscosity analyzer（RVA）,low field nuclear magnetic resonance（NMR）tester（LF-NMR）to study on ultrahigh pressure processing methods such as the pressure and the processing time of starch structure and the influence of the physical and chemical properties,and in the preparation of octenyl succinic anhydride modified starch（OSAS）treated by ultrahigh pressure,the effect of UHP on starch activity was determined.（1）Effects of UHP on the structure and properties of common corn starch.When UHP was200 MPa,the particel size of corn starch increased,the crystallinity decreased,the thermal stability and enthalpy of gelatinization decreased,and the infrared absorption intensity increased,which corresponds to the mechanochemical stress stage.However,when the UHP treatment was 350 MPa,the crystallinity of corn starch increased and the infrared vibration peak decreased.When UHP reached 600 MPa,a large number of particles were aggregated,the particle size increases exponentially,the T₂ value of the bound water inside the particles increased,and the crystallinity,infrared absorption strength,thermal stability and enthalpy of gelatinization decreased,which corresponds to the mechanochemical aggregation stage.The quality of OSAS was greatly improved when treated by UHP at 200 MPa and 500 MPa,while the quality of OSAS was poor at the stage of 350 MPa.The effect of different UHP time on corn starch was not obvious.（2）Effects of UHP on the structure and properties of waxy maize starch.Compared with common corn starch,waxy maize starch is more sensitive to ultrahigh pressure treatment.When UHP was 150 MPa,waxy maize starch particle size increases,crystallinity decreases,thermal stability and enthalpy of gelatinization decreased,and infrared absorption intensity increased,presenting the characteristics of mechanochemical stress stage.However,the crystallinity of waxy maize starch increased and the infrared vibration peak decreased when UHP was applied to 300 MPa.When UHP reached 500 MPa,it still belongs to the transition stage of aggregation in mechanochemistry.Waxy maize starch has been gelatinized under UHP treatment for 600MPa.The quality of OSAS was greatly improved when treated by UHP at 200 MPa and 500MPa,while the quality of OSAS was poor at the aggregation stage at 300 MPa.The effect of different UHP time on waxy maize starch was not obvious.（3）Effect of UHP on chemical activity of starch.UHP was conducive to the production of highly efficient reaction between OSA and starch molecules,and improved the chemical activity of starch and the quality of OSAS.Under mechanochemical stress stage and transition stage of aggregation in mechanochemistry,the DS,RE,S,SP and viscosity of OSAS were increased,the gelatinization temperature decreased,and the chemical activity of starch was higher than native starch.Therefore,using the two stages could prepare high-quality corn and waxy maize OSAS.At that moment,UHP increased the chemical activity of starch.This study could improve the performance of modified starch,enrich the variety of modified starch,and lay a theoretical foundation for the preparation of industrial equipment of modified starch.At the same time,a complete research system on the structure,physical and chemical properties and chemical activity of starch under UHP is formed to broaden the research on the modification of starch which is based on mechanochemistry.