【作者】 李丽莎；

【导师】 马晓军；

【作者基本信息】 江南大学 ， 粮食、油脂及植物蛋白工程， 2008， 硕士

【摘要】 近年来,米淀粉已成为研究的热点,尤其是糯米淀粉,它不仅冻融稳定性好、质构柔滑似奶油、易消化,而且具有口感细腻、热量低、无过敏性等优点。本文进一步对糯米淀粉进行抗老化改性处理并对其在蔴薯类冷冻冷藏食品中的应用进行了研究。本文以糯米淀粉为原料,分别进行羟丙基化、乙酰化及乙酰化羟丙基复合改性处理,通过单因素及正交试验确定不同食品级糯米改性淀粉的最佳工艺参数。同时,采用扫描电子显微镜、X-射线衍射仪、快速粘度测定仪、差示量热扫描仪等现代分析手段对改性前后糯米淀粉的物理化学性质进行对比研究,并将所制备的糯米改性淀粉添加到蔴薯中,考察抗老化效果。根据试验中影响糯米淀粉变性程度和变性剂反应效率的因素,同时兼顾到生产成本和实际的食品安全要求,分别确定了羟丙基化糯米淀粉的最佳工艺条件:环氧丙烷添加量16% (v/w),NaOH用量1.2% (w/w),反应温度45℃,淀粉乳浓度40%,反应时间16h;乙酰化糯米淀粉的最佳工艺参数:乙酸酐添加量8% (v/w)、体系pH值8.5、体系温度25℃、淀粉乳初始浓度40%、反应时间1h。然后根据两者的最佳工艺协同制备乙酰化-羟丙基糯米淀粉。通过分析糯米淀粉改性处理前后物理化学性质的变化得出:与原淀粉颗粒相比,变性淀粉的颗粒均受到一定程度的破坏。变性处理前后糯米淀粉颗粒晶型未发生变化,仍属于A型结构。随着羟丙基化或乙酰化变性程度的增加,淀粉的糊化温度降低,糊的峰值粘度增大,糊化焓值降低。添加NaCl、柠檬酸及蔗糖均可提高糯米淀粉及其变性淀粉的透明度。经羟丙基化或乙酰化处理后的糯米淀粉老化焓值、老化率与浊度的增大程度均远低于原淀粉,而且冻融稳定性高于原淀粉。采用如下配方:糯米粉100%、羟丙基化糯米淀粉100%(以糯米粉计)、乙酰化糯米淀粉0.5%(以总粉计)、水110%(以总粉计)、糖20%(以总粉计)、水溶性单甘酯1%(以总粉计)制成蔴薯产品,与市售产品相比,在冷冻及冷藏条件下分别储存30d后,前者的硬度明显低于后者,表现出较佳的抗老化性能。更多还原

【Abstract】 In recent years, waxy rice starch with good properties, such as high freeze-thaw stability, creamy fat-like mouthfeel, highly digestible, low-calorie and hypoallergenic, has become a focus in the starch research and application field.Firstly, it was studied in this dissertation how to prepare the hydroxypropylated, acetylated and acetylated hydroxypropyl waxy rice starch, and what the optimum conditions for production of them were. Secondly, the physicochemical properties, especially retrogradation property of the native waxy rice starch and the modified starch above, were investigated by Scanning Electron Microscope (SEM), X-Ray Diffractometer, Rapid Viscocity Analyzer (RVA) and Differential Scanning Calorimeter (DSC). Finally, the quality of waxy rice cake was improved by addition of hydroxypropylated waxy rice starch.Taking waxy rice starch as raw material, on account of the extent of substitution for food grade, the optimum conditions for hydroxypropylation were as follow: the ratio of starch to propylene oxide 25:4 (w/v), sodium hydroxide 1.2% (w/w), reaction temperature 45℃, starch slurry 40%, reaction time 16 h. The optimum conditions for acetylation were as follow: the ratio of starch to anhydride 12.5:1(w/v), pH 8.5, reaction temperature 25℃, starch slurry 40%, reaction time 1 h. The production of acetylated hydroxypropyl waxy rice starch was done by acetylation of hydroxypropylated starch on the condition above.The chemical treatment of waxy rice starch with propylene oxide or acetic anhydride resulted in changes of starch granule structure. The X-ray diffraction patterns showed the characteristics of A-type in both native and modified waxy rice starch. Modified starches had lower gelatinization parameters (To, Tp, Tc and△H) than those of native starch by using Differential Scanning Calorimeter (DSC). Rapid Visco Analyzer (RVA) showed that pasting temperature of modified starch decreased, whereas peak viscosity increased compared to the native starch. The addition of NaCl, citric acid and sucrose all improved the clarity of paste.The anti-retrogradation property of modified waxy rice starch improved compared to the native starch. The anti-retrogradation property was increased in the order: native starch< acetylated starch < hydroxypropylated starch < acetylated hydroxypropyl starch. With the increase of the extent of substitution (DS or MS), the△H_r and ratio of the retrogradation decreased. The absorbance of starch was increased as the storage time prolonged. The native starch had the highest value of△H_r, ratio of the retrogradation, and absorbance. The freeze-thaw stability was substantially improved by the modification of hydroxypropylation and acetylation.By selecting experiments, the optimum formula was as follow: waxy rice flour 100%, hydroxypropylated waxy rice starch 100%, acetylated waxy rice starch 0.5% in total, water 110% in total, sugar 20% in total, water-soluble monoglycerides 1% in total. The samples with addition of hydroxypropylated waxy rice starch had much better quality of anti-retrogradation than the product after stored at 4℃or -18℃for 30 days, respectively.更多还原