The Controlling Of Enzymatic Hydrolysis Of Materials For Producing Starch Sugar

Now, the process of enzymatic hydrolysis of starch to produce starch sugar, is completedmainly by three steps, including starch gelatinization, liquefaction and saccharification.Liquefaction is a very important link in the process of starch sugar production, DE value ofwhich directly affects the speed of follow-up saccharifying process, the yield of reducingsugar and the quality of products.There are many researches in this aspect for so long, butthey are only limited to a kind of fixed substrate and a kind of fixed enzyme, once thesubstrate or the enzyme is changed in the production, the research will lose the originalsignificance so that the liquefied DE value can’t be controlled.Therefore, this paper mainlyexplored the controlling of the liquefied DE value when the enzyme or the substrate wasreplaced.This research will provide theoretical guidance for solving relevant issues inpractical production.First of all, a kind of starch (substrate1) and a kind of thermostable α-amylase (enzyme1) were chosen for this experiment. Then a mathematical model was established, throughBox-Behnken design and response surface analysis, which reflected the relationship betweenDE value （Y）and substrate concentration（X1）, dosage of amylase（X2）as well as liquefiedtime（X3）.The model was as followed: Y=17.48+1.22875X1+1.6875X2+1.41125X3+0.07X1X2+0.64X2X3-0.3725X1X3+0.01875X12-0.19875X22+0.01875X32， with coefficient ofdetermination as98.75%. Moreover, the study also validated that the model had a betterfitness with the actual situation by experiment.On the basis of mathematical model already established, the relationship of liquefied DEvalue between one kind of amylase (enzyme1) and another kind of amylase (enzyme2) addedwas explored.Then this paper got the following formula:DE (enzyme2)=DE (enzyme1)-theinteractive influence value of substrate concentration with optimal temperature difference×(substrate concentration-20)-the interactive influence value of dosage of amylase withoptimal temperature difference×(dosage of amylase-14)+the interactive influence value ofliquefied time with optimal temperature difference×(liquefied time-5)-the influence value of optimal temperature difference.Then the verification experiment was done under the conditionof another kind of amylase (enzyme3) was added to replace the original one. And the resultproved that this formula can be used to predict the liquefied DE value after the amylase wasreplaced.Then the relationship of liquefied DE value between one kind of substrate (substrate1)and another kind of substrate (substrate2) used was explored. And the following formula wasgot: DE (substrate2)=DE (substrate1)×effective substrate proportion.Also the verificationexperiment was done under the condition of another kind of substrate (substrate3) was usedto replace the original one. And the result proved that this formula can be used to predict theliquefied DE value after the substrate was replaced.Finally，protein content and density were determined for different kinds of starch.Theresult showed that the protein in the starch might have negative effect on the liquefaction ofstarch. And for the same source of starch, increasing the density of starch might hinder thehydrolysis of enzyme.