The Preparation And Application Of Stearate Corn Starch By Microwave

It is studied in this thesis the preparation of Stearate Corn Starch(SCS), which is synthesized with corn starch and stearic acid by microwave radiation, and the properties, structures and applications in lemon emusified flavor are researched too.In the single factor experiments, the effects of some factors, which include the power of microwave, the time of radiation, the content of water, stearic acid and hydrochloric acid, on the degree of substitute(DS) and reaction efficiency(RE) are studied. According to these results, the perpendicular experiments are designed. The most optimal process condition is as follows: the power of microwave 800W, the content of water 36%, the time of radiation 5.5 min, the content of HCl 0.105%(w/w), the content of stearic acid 3%(w/w). The DS of the product is 0.008940,RE is 52.33%.The viscosity of SCS paste is lower compared to native corn starch. The SCS paste is shear-thinning, belonging to Pseudoplastic Liquid, and also has thixotropic. The transparency of SCS decreases with the increase of DS,but higher than native corn starch. The retrogradation of paste decreases and the stability of freeze-thaw increases.Otherwise, the SCS gets the ability of emulsification.The structure of SCS is studied with modern instruments. It can been seen from the Infra-red spectrometris that the weaking of the intensity of the peak which is between 3000～3700 cm-1,due to hysroxyl bond replaced, from the SEM photos and X-ray diffraction that the reaction mainly occur in amorphous region,from DSC that the glass transition temperature of SCS is higher than native starch and dextrin,from HPLC that the occurrence of indigestible components by microwave radiation and from HPGFC that the molecular weight decreases.Due to the introduction of C18 chain into starch granule, SCS gets the ability of emulsification. It can be used in emulsified flavor as food additive. When stearate corn starch is used in lemon emulsified flavor, the optimum condition is as follows:the content of stearate is 18%,the content of lemon flavor is 6%,the homogenizing temperature is 20℃,and the homogenizing time is 4.5min.By obserbation of emulsified flavor that diluted 1000 times,it can be found that the lemon emulsified flavor don't deposit within 48h.