Study On The Physical And Che Mical Properties Of Hydrolyzed Hydroxypropyl Corn Starch And Its Application In Hard Capsule

At present,animalic gelatin is mostly used in hard capsulesin our country.Unfortunately,due to some problems in the medicinal properties and safety of the gelatin,such as cross-linking reaction and the risk of carrying the virus.In addition,with the religious factors,the gelatin capsule was rejected by some people.Therefore,it is necessary to look for plantcapsule materialtotake the place of gelatin.The modified starch,which could be the main materialof capsule,is an effective way to take the place of gelatin capsules.In this paper,themodified corn starch,whichhas treated by acid hydrolysis and etherification,is used as material for the study of the capsule producing process.The main research contents and the conclusions are as follo ws:(1)The corn and high-amylose(G80)was modified throughthe means ofacid hydrolysis and etherification in different acid time(6h,12 h,18h,24h)and different content of propylene oxide(10%,20%,30%).And the structural and functional attributesof modified starchwere compared.The results show that when the amount of propylene oxide was 10%,the degree of substitution of starch for 6 h was significantly higher than that without acidification.The solubility and swelling ability ofmodifiedcorn starch increased with the increase of the degree of substitution.However,with the increase of acidification time,the solubility increases and the swelling ability decreases.Acidity,etherification and acid hydrolysis and etherification compound modification increased the transparency of corn starch,and the transparency of starch paste increased with the increase of acidification time and degree of substitution,G80-related starch show a consistent pattern.But under the same processing conditions,the solubility,swelling ability and paste transparency of G80 modified starch were all lower than that of cornmodified starch.The freeze-thaw stability of hydroxypropyl corn starch is higher than that of the original starch.Each treatment can improve the freeze-thaw stability of G80.The freeze-thaw stability of corn and G80 of related modified starch increases with the increase of substitution degree.The double modified starch reduces the gelatinization temperature.The gelatinization temperature and gelatinization enthalpy of the modified starch and the gelatinization enthalpy of corn and G80 are significantly smaller with the increase of the degree of substitution.The apparent viscosity of corn and G80 increases after hydroxypropylating,and increases with the degree of substitution.With the prolongation of the acidification time,the apparent viscosity of the double modified starch decreases.corn and G80-related starch showed elastic properties and shear thinning characteristics.The dynamic modulus of corn starch was less than that of the original starch.The shorter the acidification time,the greater the degree of substitution,the greater the dynamic modulus of the double modified starch.The dynamic modulus of G80 double modified starch decreases with the increase of substitution degree,and the apparent viscosity and dynamic modulus of G80-related starch are less than that of corn-related starch.The longer the acidolysis time,the higher the degree of substitution,the polarized cross deformation of the two kinds of starch,the more obvious the surface micropores and the depression.Denaturation did not change the crystalline structure of the starch.Acid hydrolysis of 24 h corn double modified starch,the crystallization area of the outer surface of a part of the corrosion.G80 relative crystallinity is less than corn,the longer the acid hydrolysis time,the greater the relative crystallinity.(2)The double modified starch is used to filmand the film properties is studied with different degrees of substitution of corn and different acidification time.The results showed that the tensile strength and tensile modulus of the double modified starch film decreased with the increase of the acidification time,and the transparency of the film increased with the different degree of substitution and different acidification time.The elongation of the film at break was the highest and the moisture permeability about acid solution of 18 h double modified starch was the smallest.With the increase of the degree of substitution,the tensile strength and tensile modulus of the modified starch film decrease,and the elongation at break,moisture permeability and light transmittance increase.Through the comparison of important indexes such as tensile strength and moisture permeability,acid hydrolysis of 12% propylene oxide with 20% acid hydrolysis of hydroxypropyl starch is better for capsule material.(3)Capsules were prepared by aciding 12 h of propylene oxide with 20% of the double modified cornstarch as raw material.The results show that the higher the concentration of starch,the higher the sol temperature,the smaller the condensation time of the capsule,the larger the wall thickness of the capsule.The time of condensation is the longestwhenthesolder time is 50 min.When the starch concentration is 15%,the appearance of the capsules is the best,and the tensile strength is the largest.When the starch concentration is 18%,the elongation at break is the largest.When the sol temperature increases,the tensile strength increases and the elongation at break decreases.The tensile strength reached the maximum at 180 r /min,and the elongation at break increases with increasing agitation speed.When the sol time is 30 min,the tensile strength and elongation at break are the highest.