【作者】 王凤平；

【导师】 阮晖；

【作者基本信息】 浙江大学 ， 食品科学， 2008， 硕士

【摘要】 本文主要研究脂肪酶耦合酯化反应,以玉米淀粉为原料制备辛烯基琥珀酸淀粉酯的工艺,并研究了所得淀粉酯的基本性质。首先研究了脂肪酶在磷酸缓冲液、有机溶剂体系、淀粉糊状态三种不同体系中的催化活性,同时研究了微波辐射对酯化反应的影响。试验证明在一定温度下淀粉吸水膨胀后,即在淀粉成糊状态下,进行酯化反应,此时脂肪酶活性较高,反应效率高。脂肪酶在玉米淀粉糊状态下,催化其与辛烯基琥珀酸酐反应,可制取具有两亲性质的辛烯基琥珀酸淀粉酯。试验研究了淀粉前处理时间,前处理温度,脂肪酶加入量,反应温度,辛烯基琥珀酸酐加入量,反应时间对产物取代度、反应效率的影响。通过正交试验得到酯化最优组合:淀粉前处理温度为65℃,前处理时间15分钟,反应温度40℃,脂肪酶和辛烯基琥珀酸酐（Octenyl Succinic Anhydride,OSA）的加入量分别是0.5%和6%,反应时间30分钟,可制得取代度为0.024的淀粉酯。运用现代分析技术对辛烯基琥珀酸淀粉酯的颗粒形态、晶体结构和热力学性质等进行了分析。红外光谱分析表明改性使淀粉分子在波长1713cm^-1处有新的吸收峰出现,证明辛烯基琥珀酸基团以酯键的形式与淀粉分子相连。淀粉经过酯化处理后,晶体类型没有发生变化,属于A型,但是淀粉颗粒的表面结构和形状发生很大变化。淀粉改性之后,熔晶的起始温度TO（Onset temperature）、最高温度TP（Peakmaximumtemperature）、回落温度TC（Conelusion temperature）升高,焓变⊿H（Enthalpyoftransition）降低。论文还研究了辛烯基琥珀酸酸淀粉酯糊的基本性质。玉米淀粉经酯化处理后,常温下凝沉性能升高,溶解度和透明度增加,冻融稳定性有所增强,表观粘度降低。表观粘度测定显示辛烯基琥珀酸淀粉酯具有剪切变稀现象,属于假塑性流体,表观黏度随着温度升高而下降。淀粉酯可用于稳定色拉油-水乳状液。更多还原

【Abstract】 In this paper the technique of lipase-coupling synthesis of octenly succinic anhydride （OSA） starch using corn starch as raw materials and its properties were studied.First we investigated the activity of lipase under different conditions: phosphate buffer, organic solvent system and starch paste system, at the same time research about effect of microwave radiation on the impact of esterification reactions was carried out. The results of experiments showed that when starch in paste state after swelling water, the lipase had higher activity and esterification showed higher efficiency.The pretreatment corn starch could react with alkenyl succinic anhydride under the catalyzing of lipase. The effects of parameters including pretreatment time, pretreatment temperature, reaction time, reaction temperature, quantity of OSA and lipase on DS and react efficiency were studied. The suitable parameters for the preparation were selected as follows: pretreatment time 15 minutes, pretreatment temperature 65℃, reaction temperature 40℃, reaction time 30 minutes, quantity of OSA and lipase 6% and 0.5% respectively. Under the conditions the OSA starch with DS 0.024 was obtained.The granules morphology, crystal structure and thermodynamic properties of OSA starch were analyzed by the modern analytical techniques. From FT-IR （Fourier transform infrared）results, a new absorption peak appeared at the wavelength of 1713 cm^-1, which suggested that starch molecules were linked with OSA in the form of ester bond. The X-ray diffraction proved that crystal structure of the modified starch was not changed, belonging to A-pattern as the native corn starch. SEM （Scanning electron microscope） showed the surface of starch granules was seriously destroyed after the reaction. While the DSC （Differential scanning calorimeter） indicated TO （Onset temperature）, TP （Peakmaximumtemperature）, TC （Conelusion temperature） of modified starch increased, whileΔH （Enthalpyoftransition） decreased.Moreover, the paste properties of OSA modified starch were investigated. The result showed that under the normal temperature, flocculability, transparency and freeze-thaw stability had been enhanced, while apparent viscosity decreased. The phenomenon of increasing shear force, and decreasing apparent viscosity, showed that it was a kind of Pseudo plastic Fluid. As the temperature increased, the apparent viscosity decreased. The modified starch could be used as emulsifier in the salad oil-water system.更多还原