【作者】 肖勇生；

【导师】 邬应龙；

【作者基本信息】 四川农业大学 ， 食品科学， 2009， 硕士

【摘要】 多孔淀粉是一种新型的变性淀粉,作为吸附剂,具有高效、无毒、安全等优点,可广泛地应用于食品、日用化工、农业等行业,正逐渐成为一个研究热点。本文以糯米淀粉为原料制备辛烯基琥珀酸糯米酯化淀粉,再利用紫红曲霉发酵生产的生淀粉糖化酶液制备辛烯基琥珀酸糯米酯化多孔淀粉;初步探索了紫红曲霉发酵产生淀粉糖化酶的培养条件,以及糯米淀粉经过适当酯化后再部分酶解制备酯化多孔淀粉的工艺条件,且对酯化多孔淀粉的部分物理化学性质进行了研究,旨在拓展糯米淀粉的深加工方法,也拓宽了变性淀粉的应用范围,为实际生产提供一定的理论依据。主要研究内容和结果如下:(1)对紫红曲霉菌株液态发酵产生淀粉糖化酶的培养条件进行研究,经正交优化实验初步确定其最适发酵工艺条件为:发酵周期6天,控制培养温度为32-35℃,保持培养基初始pH值为4.5-5.0,接种量控制在12%左右。同时对紫红曲霉菌所产生淀粉酶进行了初步纯化和鉴定,并对其部分酶学性质进行了试验研究,结果表明其最适作用温度为50℃,最适作用pH值为4.5-5.5,在40℃酶活力较稳定,在60℃以上迅速失活。(2)以紫红曲霉生淀粉糖化酶酶解辛烯基琥珀酸糯米酯化淀粉制备多孔淀粉,并采用中心组合试验设计与响应面分析方法对影响酯化多孔淀粉吸油率的主要因素:反应时间(A)、反应温度(B)、反应pH(C)、淀粉乳浓度(D)和酶液添加量(E)进行了研究。结果表明,吸油率的回归方程为:吸油率=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~2-3.23×B~2-2.76×C~2-1.54×D~2+0.98×E~2。同时由方差分析可知各因素对吸油率影响的大小顺序为:pH＞酶用量＞反应时间＞淀粉乳浓度＞反应温度。通过响应面的数值最优组合分析得到最佳工艺条件:淀粉乳浓度24.74%,反应时间22.86h,pH 4.17,反应温度47.11℃,酶用量103.56U/g。(3)对糯米酯化多孔淀粉的部分理化性质进行了研究。实验结果表明:①糯米淀粉经过OSA酯化后,淀粉的峰值粘度(PV)、热糊粘度(HPV)、最终粘度(FPV)和消减值(SB)都呈升高趋势,出峰时间和糊化温度也比原淀粉提前;酯化淀粉经过酶解后,形成的糯米酯化多孔淀粉峰值粘度(PV)、热糊粘度(HPV)和最终粘度(FPV)呈升高趋势;消减值(SB)减小;同酯化淀粉相比,崩解值(BD)、出峰时间变化不大,糊化温度稍微减小;②糯米酯化淀粉经过酶解后,OSA基团仍然存在,且与糯米酯化淀粉相比,单位质量的酯化多孔淀粉含有的OSA基团较多;③通过扫描电镜可以观察到,糯米酯化多孔淀粉经过紫红曲霉淀粉酶水解后,开孔率都比较高,明显形成多孔淀粉,且其比容积比原淀粉和酯化淀粉都有所提高,相比原淀粉和酯化淀粉,经过酶解得到的酯化多孔淀粉吸油率和吸水率都有所提高,且吸水率的提高率大于吸油率。④酯化淀粉和酯化多孔淀粉的乳化稳定性较原淀粉有明显提高,且酯化多孔淀粉的乳化稳定性略优于酯化淀粉。更多还原

【Abstract】 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.更多还原