| Porous starch, a new type of modified starch, has various advantages as a kind of absorbent with high efficiency, innocuity and safety. It can be widely used in many industries, including food, dairy industry and agriculture, and is becoming a study hotspot. Waxy rice starch is used as material to prepare for OSA starch, which is used to prepare for porous OSA starch by glucoamylase production by monascus purpureus. The technological conditions of monascus purpureus fermentation, waxy rice starch suitably OSA starch and then partially enzymolysised to prepare porous OSA starch were be researched, also studied on the parts of physical and chemical properties of porous OSA starch. The results of this study were not only good for beneficial the expanding the applications of waxy rice starch, but also beneficial for the promotion of modifying research of porous starch, and provide theory for practice. The main contents and results described as follows:(1) The liquid fermentation conditions of monascus purpureus strains were be studied, and the optimal fermentation conditions were be determined by orthogonal experiments, the results as follows: the fermentation time was 6 days, fermentation temperature was 32 to 35℃with the initial pH of 4.5 to 5.0, and inoculum size was 12%. At the same time, the monascus glucoamylase was be preliminary purification and identification, and partly enzymatic properties were be studied which showed that the optimum temperature was 50℃, the optimum pH was 4.5 to 5.5, at the 40℃enzyme activity is stable when which rapid inactivation at 60℃.(2) The glucoamylase from monascus purpureus was used to enzymolysis OSA starch to prepare porous OSA starch. Use central composite design and response surface analysis method study on the major factors: reaction time (A), reaction temperature (B), pH(C), starch suspension (D) and enzyme dosage (E) which influenced on oil adsorption. The result showed that, the regression equation of oil adsorption is: Oil Adsorption = 107.03 -1.57×A+0.21×B-3.40×C-1.11×D-1.75×E+0.79×A×B+0.20×A×C-3.08×A×D-1.75×A×E+0.45×B×C+0.80×B×D+1.09×B×E-3.85×C×D-1.65×C×E-4.30×D×E+0.25×A~2-3.2×3×B~2-2.76×C~2-1.54×D~2+0.98×E~2. The order of major factors which influenced on the oil adsorption is: pH>enzyme dosage>reaction time>starch suspension>reaction temperature. The best technological conditions can be obtained: starch suspension 24.74%, reaction time 22.86h, pH 4.17, reaction temperature 47.11℃, enzyme dosage 103.56U/g.(3) The partial properties of porous OSA starch were studied. The experimental results showed that:①Compared with the raw starch, the peak viscosity (PV) ,hot paste viscosity (HPV), final viscosity (FPV) and anti-impairment (SB) of OSA starch were increased when the peak time and pasting temperature of starch were advanced, when OSA starch was hydrolysised, the peak viscosity (PV), hot paste viscosity (HPV) and final viscosity (FPV) of porous OSA starch were increased with extinction impairment (SB) reduced. Compared with the OSA starch, the collapse value (BD) and peak time change litter, gelatinization temperature decreased slightly.②After enzymolysised, the OSA group of porous OSA starch still exists, and compared with the OSA starch, porous OSA starch contain more of the OSA group per unit mass.③The SEM photos also showed that the higher hole rate of porous OSA starch which confirm the truth of formation of porous starch clearly. To compared with the original starch and OSA starch, the ratio of volume of porous OSA starch have been improved, and oil absorption and water absorption of porous OSA starch were increased, and the increase in the rate of water than oil.④The emulsifying stability of OSA starch and porous OSA starch significantly better than the original starch, and the emulsifying stability of porous OSA starch better than OSA starch.
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