Preparation Of Acidolysis-esterification Composite Modified Rice Starch And Its Application In Starch Film

The edible starch membrane can be eaten,biodegraded package materials,which is widely used in food industry,especially in food packaging.Acid-thinned and esterified starch have the advantages both of the acid thinned starch and esterified starch.There are great capacity of membrane-producing,high transparency,resistency to extension and solutabilty in it.It's a excellent raw material to produce edible starch membrane.The essay adopts acidfied and esterified method to produce the modified starch by rice starch and applies it into the production of edible starch membrane in order to explode a new method to utilize the rice starch.The main contents and results of the reserch are following:(1) The certification of the optimum conditions of acidolysis:Use rice starch as material,viscosity and the rate of amylose as indicates.By single factor tests,the research on the impacts from concentration of hydrochloric acid,temperature,time and the rate of amylose in raw material are conducted.The optimum conditons of acidolysis of highest amylose rice starch are certified by orthogonal tests:concentration of hydrochloric is 0.15mol/L,temperature is 45℃,and time is 2h.The capacity of membrane producing increases along with the rate of amylose.In this condition,the rate of amylose in acid-thinned rice starch is 39.5%.(2) The certificaiton of the optium conditions of esterification:take acidolysis rice starch as material,degree of substitution by phosphate and efficiency of reaction as indicates.By single factor test,the research is conducts on the impacts on the degree of substituion by phosphate concertration of phosphate and urea,temperature and time.The optium conditons of esterification are obtained by single factor tests:pH5.4,temperture 140℃,time 1 hour,the concentration of phosphate 10%(in dry starch),concentration of carbamide 6%(in dry starch).The main indicates of the modified starch are:DS is 0.242, RE is 76.07%,viscosity 0.424Pa·s,rate of dehydration 24.93%,transparncy 6.9%(3)The property analyisis of the modified starch:The comparasion of modified and immodifed starchs in mobility, gelatinization characteristics and molecule structures shows that:The viscosity, disintegration, subduction are obviously lower than rice starch.The rate of amylose in modified starch are apparently higher.The loss and storage modulus are similar but the modified starch are lower.All this results indicates that acid-thinned and esterified starch have the advantages both of acidolysis starch and esterified starch--good stability,freeze and thaw stablity and so on.(4)The production of edible starch membrane:Take rice starch and modified starch,sodium alginate,glycerol,gelatin as material to produce starch membrane.Using folding strength,resistence of extension as indicates,the tests to study the impacts from fortifier,plasticiser,rate of starch,temperature of drying on the properties of membranes are operated.The orthogonal tests certify the best prescription and technology parameters:glycerol 1.0%,sodium alginate 0.5%,gelatin 0.7%.starch 10%,temperature of dessication 38℃.The properties of the starch membrane in the conditons are water permeable rate 5.736%,the solubility in hot water 92.30%,thickness 0.041mm,resistence of exstension 46.392Mpa,elongation at break 4.284%.The properties all better than rice starch membrane.