Study On The Preparation Of Fat Substitute From Corn Bran

This research used agricultural waste-corn bran as raw material, mainly studied theprocess for preparing fat substitute from corn bran fiber with carboxymethylmodification. A Response Surface Methodology (RSM) was used for optimization ofpreparation of fat substitute. Then the utilization of corn bran fat substitute in spongecake was studied.The alkali protease and thermostable α-amylase was used to hydrolyzing residualprotein and starch, respectively. The yield of dietary fiber was94.6%(dry weight basis).The water binding capacity and expansibility of dietary fiber was2.88g/g and5.14ml/g,separately. The carboxymethyl was choosed for concenting with corn bran fiber toobtain the mouthfeel of fine and smooth. The functional groups of corn bran fatsubstitutes were identified using a Fourier transform–infrared (FT-IR) spectroscopytechnique. The apparent viscosities of each simples with different carboxymethyl degreeof substitution have a shear~thinning phenomenon, which also showed that the resultantsystem was pseudoplastic. But, the fat substitute with low DS only have high viscosityproperties and poor processability. With the increasing of DS, the fat substitute samplecontain viscoelastic properties which indicated that space network structure formed inthe sample. It was contribute to the improvement of the simulation of fat functionalproperties.The response surface methodology was employed to optimize the four mostsignificant factors: alkali concentration, the ratio of sodium hydroxide to chloroaceticacid, etherification temperature and etherification time. The DS was defined as theresponse function of the design. The model predicted a maximum DS of0.5190underthe optimal conditions of alkali concentration (19.92%), the ratio of sodium hydroxideto chloroacetic acid (1.11:1), etherification temperature (70.47℃) and etherificationtime (4.48h). Finally, a verification experiment was carried out under the correcttedoptimal technological conditions of alkali concentration (19.92%), sodium hydroxide tochloroacetic acid (1:1), etherification temperature (70℃) and etherification time (4.5h).Experimental value of response at the optimum conditions was measured as0.506,indicating a good agreement with the predicted value.The baking loss of sponge cake was decreased to15.9%and16.5%, respectively,with substitution level of10%and20%. The volume remain unchanged under substitution level of10%. Texture of the sponge cake was measured using the textureanalyzer. The texture parameters have little changes under substitution level of20%. Bythe sensory evaluation, the sensory score of sponge cake with substitution level of20%was similar to the full fat sample’s. The sensory evaluation results show that the low~fatsamples under substitution level of20%were acceptable. The experimental dataanalysis were performed using statistical software package, SPSS19.0for determiningthe regression coefficients of the polynomial model. There were remarkable correlationsbetween sensory and instrumental parameters (hardness, chewiness, resilience,cohesiveness and adhesiveness). The high regression coefficients of the polynomialmodel indicated that this mathematical model was highly significant. In this regressionmodel, the model was highly significant and indicated a high degree of correlationbetween the texture data and sensory evaluation.