【作者】 封欣；

【导师】 林宝凤；

【作者基本信息】 广西大学 ， 应用化学， 2007， 硕士

【摘要】 氧化淀粉是工业化应用最广的变性淀粉之一，它通常以浆液的形式处于不同的使用环境中，因此其凝沉特性是用好氧化淀粉的关键问题之一。已有的研究大多关注氧化淀粉的生产工艺和用途的开发，对氧化淀粉的凝沉性的研究较少，为此本文对氧化淀粉的凝沉特性进行了较为系统深入的研究。采用断裂性能测试法、浊度法、脱水收缩法、X-射线衍射法、酶解法以及DSC等方法多角度地研究了氧化程度、糖和无机盐、储存温度以及氧化淀粉浆液的水含量对氧化淀粉凝沉特性的影响，探讨了氧化淀粉凝沉的成因以及与所研究因素的关系。研究结果表明：1．氧化淀粉的凝沉性随着氧化程度的增加先降低后升高。当氧化程度较低时，凝沉程度的变化主要受直链淀粉含量和羧基、羰基含量的影响，随着直链淀粉含量的减少和羧基、羰基含量的增长，凝沉程度越来越低。当氧化程度较高时，凝沉程度的变化受分子量的影响较大，随着分子量的降低，凝沉程度又有所升高。2．无论是蔗糖还是葡萄糖都有加速氧化淀粉凝沉的作用，并且蔗糖或葡萄糖的加入量越大，氧化淀粉的凝沉速度越快，其中葡萄糖对氧化淀粉凝沉性的影响更大。无机盐(NaCl)有减缓氧化淀粉凝沉的作用，而且少量的盐对氧化淀粉的凝沉性就会有较大的影响，盐的加入量越多，氧化淀粉凝沉速度越缓慢。3．储存于4℃的氧化淀粉样品最易结晶，凝沉程度最大；储存于25℃的氧化淀粉样品不易结晶，凝沉程度最小；储存于-18℃的结晶程度和凝沉程度居于二者之间。根据Avrami方程计算的结果，储存于4℃时的凝沉速率是-18℃储存时的1.21倍，是25℃储存时的1.67倍。储存在0℃以下的氧化淀粉样品的均一的凝胶结构遭到破坏，变成多孔的海绵结构。4．在较长的储存期内(＞7d)，当氧化淀粉浆液的水含量为70％-85％时，水含量越高，越易于凝沉。在较短的储存期内(≤7d)，氧化淀粉浆液的水含量对氧化淀粉的凝沉性影响不大。本文的研究结果将为生产具有较高储存稳定性和良好品质的氧化淀粉制品提供理论依据，并对氧化淀粉用途的开发和性能的改善有重要的指导意义。更多还原

【Abstract】 Oxidized starch was one of the most widely used modified starches in industry. It was usually used at various environments as paste, so its retrogradation was a key problem in its application. Previous literatures mostly focused on its production process and application development, but its retrogradation was seldom reported, so the retrogradation of oxidized starch was systematically studied in this paper.The effects of oxidation levels, sugar and inorganic salt, storage temperatures and moisture contents on retrogradation of oxidized starches were studied from multi angles by break properties measurement, turbidimetric method, measurement of syneresis, X-ray diffraction, measuring the resistance to enzymatic hydrolysis, DSC and so on. The genesis of retrogradation and the relations between the factors and retrogradation were discussed. The results were:1. As the oxidation level was higher and higher, the retrogradation of oxidized starches decreased at the beginning and then increased. When the oxidation level was lower, the retrogradation was mostly influenced by amylase, carboxyl and carbonyl contents. While the amylase content decreased, and the carboxyl and carbonyl contents increased, the retrogradation decreased. When the oxidation level was higher, the molecular weight had a great effect on retrogradation. While the molecular weight decreased, the retrogradation increased in some extent.2. Both sucrose and glucose increased the retrogradation rate of oxidized starch. As the concentration of added sucrose and glucose was increased, the retrogradation rate also increased. The effect of glucose was more effectively than sucrose. Inorganic salt retarded the retrogradation, and only a bit of salt could decrease retrogradation effectively. As the concentration of added salt was increased, the retrogradation rate gradually decreased.3. The oxidized starch sample stored at 4℃had the highest crystallinity and retrogradation degree, the sample stored at 25℃had the lowest crystallinity and retrogradation degree, and the sample stored at -18℃had intermediate crystallinity and retrogradation degree. When the gelatinized starch was stored at 4℃, the retrogradation rate calculated by Avrami equation was 1.21 times of that stored at -18℃, and 1.67 times of that stored at 25℃. The gel structure of oxidized starch sample which was stored below 0℃would be reinforced and form a spongy porous structure.4. After storage for a long time (>7 d), the oxidized starch sample with more moisture content retrograded more easily, while moisture content ranged from 70% to 85%. Otherwise, at early stage (≤7 d) the moisture contents had little effect on retrogradation.The research results provided a theoretical foundation for producing oxidized starch products with good storage stability and high quality. These would also be of great guiding significance for developing the uses of oxidized starch and improving the properties of oxidized starch.更多还原