Study On The Preparation And Properties Of The Castanea Henryi Resistant Starch

Castanea henryi, which belongs to Fagaceae Castanea, contains mainly starch, besidesprotein, fat, fiber and other nutrients in composition. The production of Castanea henryi inFujian province is very high, however, its way of the processing and utilization is traditional.Deep processing of Castanea henryi starch can improve the value-added of Castanea henryiproducts. Resistant starch is a general term of starch and degradation matters that are notdigested and absorbed by healthy human small intestine. The resistant starch is proved to havenot only excellent processing characteristics but also special physiological functions. Theresistant starch is added to food to improve taste, flavor, color and processing characteristics,besides, it increases healthy function of food. The extraction process of Castanea henryi starch,preparation process of Castanea henryi resistant starch and its proterties determination werestudied in this paper. The main results were as follows:1. By studying the effect of different concentrations of soak on the extraction rates ofCastanea henryi starch, the sulfurous acid was found to have a greater impact on extraction ratesof the starch, when its concentration changed from0.20%to0.30%. Through single factorexperiment and orthogonal trial, the optimal process condition of Castanea henryi starchextraction was determined that the concentration of sulfurous acid was0.30%, material-liquidratio was1:5, marinating time was24hours, stewing time was8hours. With this condition, theextraction rate of Castanea henryi starch reached45.85%.2. Through single factor experiment and four factors Quadratic rotary combination designexperiment, the effect of autoclaving condition, degradation condition and dying condition onCastanea henryi resistant starch yield were studied. A quadratic regression model wasestablished with resistant starch yield as dependent variable, starch concentration, autoclavingtime, storing time and dying temperature as independent variable:Y=6.47648-0.27751X₁+0.28660X₂-0.25914X₃+0.07968X₄-0.45220X₁²-0.51053X₂²-0.32492X₃²-0.10572X₄²-0.10937X₁X₄-0.10937X₂X₃A further demonstration experiment showed that the optimal concentration of starch was25%, autoclaving time was30min, storing time was24hours, and dying temperature was60℃.With this technology, the yield of Castanea henryi resistant starch reached6.46%. 3. The study on proterties of Castanea henryi resistant starch showed that Castanea henryistarch appeared to be globular or elliptical, and Castanea henryi resistant starch looked likesausage-shaped or irregular shape, that was completely different from Castanea henryi starch.X-ray diffraction showed that Castanea henryi starch was A type crystal and resistant starchrevealed B type crystal, which indicated Castanea henryi resistant starch formed new crystallinestructure after autoclaving treatment. Through Brabender viscosity curves, the viscosity ofCastanea henryi resistant starch was found to be significantly lower than that of native starch,which indicated Castanea henryi resistant starch was difficult to be gelatinization. The water-absorption value of Castanea henryi resistant starch was2.97%, but the water-absorption valueof native starch was6.86%, and the water-absorption value of resistant starch was obviously lessthan that of Castanea henryi starch. Compared to native starch, the solubility of Castanea henryiresistant starch was lower at the same temperature, and the solubility was gradually increasing,with the temperature going up. The retrogradation rate of Castanea henryi resistant starch wasfaster, but freeze-thaw stability of that is poorer. The Iodine absorption curves showed themaximum wavelength of iodine absorbed by Castanea henryi resistant starch was less than thatof iodine absorbed by native starch, which reflected polymerization degree of Castanea henryiresistant starch was lower. The molecular weight distribution of Castanea henryi resistant starchwas explained more concentrated by the fact that the absorption peaks of resistant starch wasnarrower than that of native starch. The enzymatic hydrolysis experiment found Castanea henryiresistant starch was strongly anti-enzymatic.