Effect Of High Hydrostatic Pressure And Acid Hydrolysis On Structure And Physicochemical Properties Of Starch

In this paper,the main hydrolyzed starch was hydrolyzed by starch with high hydrostatic pressure and hydrochloric acid,and B-type potato starch and C-type tapioca starch of different types and crystal forms were selected as the research object.Traditional hydrolysis was performed using hydrochloric acid,0.5,2.4,8,12 and 24 h,determine the optimal hydrolysis time;determine the optimal hydrolysis pressure by using 0.1,100,200,300,400,and 500 MPa pressure and holding pressure for 30 minutes to perform high hydrostatic pressure and synthesizing acid hydrolysis with starch.Comparing with the traditional acid hydrolysis,to explore the advantages of high static pressure acid hydrolysis;to study the effects of high static pressure on the acid hydrolysis before and after,and to find the best way for high static pressure and acid hydrolysis;on this basis,A 6-week high hydrostatic pressure synergistic hydrolysis was performed to prepare nanocrystals.The effect of adding no catalyst and adding this catalyst on the formation of nanocrystals was compared.By using polarized light microscopes,X-ray diffraction analyzers,Fourier infrared spectrometers,Raman spectrometers,and X-ray photoelectron spectroscopy equipment,the particle morphology,long-range structure,and short-range structure of starches were analyzed;instruments such as rotational viscometers were used.A systematic study was conducted on the solubility,acid resistance,anti-aging,and freeze-thaw stability of the modified starch to increase the added value of the starch.The specific results are as follows:（1）Effect of acidification time on starchThe hydrolysis rates of potato and tapioca starch reached the maximum of 10.47%and 11.76%respectively after hydrolysis for 12 h.With the increase of time,the particle size decreased,the crystallinity first increased and then decreased,and the crystallinity at12 h was the largest.Potato starch is hydrolyzed from the inside to the outside,and tapioca starch is hydrolyzed from the outside to the inside.Hydrolysis of starch by hydrochloric acid cuts the linear and branchedα-1,4 andα-1,6 glycosidic bonds,respectively,and the molecular weight decreases.Potato,cassava starch,acid resistance,solubility and retrogradation were the highest at 12 h hydrolysis,and the freeze-thaw stability was the best.（2）Effect of high pressure synergistic acid hydrolysis on starchThe hydrolysis rates of potato starch and tapioca starch reached a maximum of 13.16%and 16.32%at 400 and 100 MPa,respectively.The hydrolysis rate after 30 min of hydrolysis was greater than the hydrolysis rate after 12 h of hydrolysis.This proves that the pressure can promote starch hydrolysis.As the pressure increases,the particle size of the particles decreases,the potato is the smallest at 400 MPa,and the tapioca is the smallest at500 MPa.Potato and tapioca starch had the highest crystallinity and the smallest molecular weight at 400 and 100 MPa,respectively.The freeze-thaw stability of potato starch was the best at 400 MPa,and that of tapioca starch was the best at 500 MPa.Pressurization hydrolysis not only promoted the hydrolysis of starch but also increased the stability of starch.（3）Effect of High Hydrostatic Pressure Synergy on StarchThe hydrolysis rate of potato and tapioca starch was the highest before the synergy of high hydrostatic pressure.The particle size of the pellets decreased,and the crystallinity increased by 31.89%and 34.96%.Potato starch begins to hydrolyze from the short axis,and tapioca starch begins to hydrolyze from the spherocyst.The potato starch had the highest acid resistance,solubility and retreatability after hydrolyzing for 12 h before high hydrostatic pressure.The tapioca starch had the highest acid resistance,solubility and retreatability when hydrolyzed 12 h before high hydrostatic pressure.This shows that the first hydrolysis after pressure treatment of starch has good physical and chemical properties.（4）Preparation of starch nanocrystals and their effects on structure and propertiesFrom the above results,the optimal conditions for the preparation of nanocrystals:potato and tapioca starch selection pressure was 400 and 100 MPa,time was 12 h,plus FeCl₃ catalyst.Potato and tapioca starch hydrolyzed with FeCl₃ catalyst for 6 weeks hydrolysis rate of the maximum 27.57%and 32.40%,than the hydrolysis rate without FeCl₃ solution,nano-sized particles reached 35.06%and 50.34%,it is proved that adding FeCl₃ solution Can promote the hydrolysis of starch.The cassava starch acidified under the addition of FeCl₃ catalyst has good dispersibility,and the solubility reaches 100%at 90°C at 6 weeks of hydrolysis.