Preparation Of Soybean Oil Corn Starch Ester By Using Immobilized Lipase And Its Applieation In Ice Cream

The soybean oil starch ester was synthesized by using Novozym435as biocatalyst, corn starch and soybean oil as substrate in solvent-free system. In order to improve the reaction activity of starch, the corn starch was pretreated using NaOH/Urea/H2O solution. The physico-chemical properties of soybean oil starch ester were analysed and compared with pretreatment starch. Then applications of the soybean oil starch ester substituted for butter in low fat or fat free ice cream were investigated in this thesis.The optimum pretreatment reaction conditions of starch pretreatment were the ratio of NaOH to urea is2, the concentration of the NaOH/urea/H2O solution is9%, the amount of ethanol is50%, the pre-cooling temperature is-12℃, the concentration of starch is5%and the pretreatment time is12min. After pretreatment the cold water solubility of starch has been increased from0.7%to96.8%. And the degree of substitution soybean oil starch increased from0to0.0250.The optimum pretreatment reaction conditions of enzymatic esterification of soybean oil with pretreatment starch were water activity<0.01, reactive temperature was60℃, reaction time was30h, the ratio of soybean oil to pretreatment starch was6(w/w) and the amount of was7%. Under this congdition the degree of substitute of soybean oil with pretreatment starch was0.0302.The solubility, emulsifying and freeze-thawing stability of soybean oil starch ester increased with the increase of its degree of substitute, but the transparency of soybean oil starch ester decreased with its degree of substitute. The transparency of soybean oil starch ester was improved when the presence of sucrose, but decreased when the presence of sodium chloride and citric acid.The application of soybean oil starch ester as fat replacer was investigated. The results showed that the soybean oil starch ester could replace the butter partially or fully in the production of ice creams. When addition of soybean oil starch ester into the ice cream, the rate of melt was decreased and the degree of expansion was increased.