Study On The Preparation, Properties And Application Of Stearate Corn Starch By Extruder

It is studied about the preparation of Stearate Corn Starch (SCS) by the method of extrusion. Also, the properties, structure and the applications of the SCS are discussed in this paper.Firstly, Stearate Corn Starch is obtained from corn starch by esterification with stearic acid in twin-screw extruder. In single factor experiments, it is studied about the effects of the varieties of factors on the degree of substitute (DS) and reaction efficiency (RE), including reaction temperature and screwing speed, moisture content, recruitment of stearic acid and hydrochloric acid etc. Based on those data got from above test, the perpendicular experiments are designed to optimize the technology. The optimum technology conditions gotten are follows: moisture content 24%, temperature 120℃, screw speed 100r/min, stearic acid 3% (w/w), 2mol/LHCL 1.0mL/ 100g. The DS of the product gotten in optimum is about 0.01234, and its RE is 72.60%, and white degree is 89.7%.Secondly, the normal properties of SCS are discussed in this paper. The SCS paste shows shear-thinning properties, which should belong to Dilatability Liquid. The solubility and the stability of freezing-thaw rise. With the introduction of C18 chain into starch granule, SCS gets the ability of emulsification. It is show that the temperature to form paste of SCS after extrusion is increased by RVA.Thirdly, the structure of SCS is researched with modern instruments. The data from Infra-red spectrometer shows the weakening of the intensity of the peak, it reflects to hydroxyl bond stretching. Its reason is that there is a decrease in the concentration of hydrogen-bonded hydroxyls, as they are converted into ester groups in starch during the reaction. The result of SEM photos and X-ray diffraction reveal that the crystalline structure of corn starch was decayed, and the reaction mainly occurs at amorphous.Lastly, it is investigated about the application of SCS as emulsifier in the glutinous rice balls in order to resolve the problem of cracking for improving its dietary quality. The optimum formula is: the proportion of glutinous rice dough and filling 3.5﹕1(w/w), moisture content of glutinous rice dough 53.08%, recruitment of SCS 4%. After adding appropriate amount of SCS, the cracking ratio of frozen glutinous rice balls and the loss ratio of the ball during boiling are decreased. Compared to frozen glutinous rice balls without SCS, the cracking ratio of glutinous rice balls with SCS is reduced by 47.5% and the permeation of the solution gotten from cooking frozen glutinous rice balls with SCS is increased by 14.3%.