【作者】 李岩；

【导师】 王占忠；

【作者基本信息】 天津大学 ， 食品科学， 2015， 硕士

【摘要】 葛根,作为一种营养丰富并且具有独特药理作用的药食两用作物,基于其分布广、产量高、具有保健价值等特点,越来越受到人们的关注。作为葛根主要成分的淀粉,是综合开发葛根资源、提高附加值的重要基础组分。前期的研究证实,三偏磷酸钠能够显著改善葛根淀粉糊的热稳定性和冻融稳定性等。三偏磷酸钠对葛根淀粉性质为什么会产生这样的影响,对淀粉颗粒作用的微观本质又是什么。本文选择葛根淀粉为原料,重点考察三偏磷酸钠对葛根淀粉颗粒微结构方面的作用特点和机制,以期对葛根淀粉的深度开发及利用提供理论指导。本文用正丁醇—异戊醇沉淀的方法将纯化后的葛根淀粉进行分级。通过扫描电子显微镜、X-射线衍射、红外光谱等方法考察分级后得到的直链淀粉和支链淀粉的颗粒形貌以及微结构方面的特性。两种分级淀粉的颗粒大小不一,呈无规律的聚集态。直链淀粉的结晶结构属于A型与B型的结合,支链淀粉则是无定形结构。另外,采用酶法水解两种分级淀粉,研究了分子的链长与数量。结果表明支链淀粉分子链的数量多于直链淀粉,但是链长却较短。同时还考察了原淀粉、直链淀粉和支链淀粉的溶解度、膨胀率以及热特性。以三偏磷酸钠作为交联剂,在不同交联剂添加量(5%,10%,12%)、不同反应温度(35℃,45℃,55℃)和不同反应时间(1h,2h,3h)的条件下合成葛根交联淀粉。以葛根原淀粉作为对照,对不同交联度的变性淀粉的微观形态、结晶性质、淀粉结构以及凝沉性、冻融稳定性和热特性等物化性质进行了系统研究。在此基础上,以低交联度和高交联度的交联淀粉为原料,再次分级进行结构和性质的研究,考察交联反应对淀粉结构的影响。研究结果证实,交联反应主要发生在结构牢固的结晶区,并且对直链淀粉的结晶结构也有破坏作用。随着交联键的引入,淀粉的透明度降低,溶解性和膨胀率减小,冻融稳定性明显提高,热稳定性增强。这些结构和性质的研究,将对葛根淀粉产品的加工过程和贮存方式有一定帮助,也有利于认识淀粉改性中的结构变化和反应机制,从而对改性实现有效控制。更多还原

【Abstract】 Kudzu, a nutrient-rich industrial crop product, is an important traditional Chinese herb. It is receiving increasing attention due to its widespread cultivation, high yield and healthy application. Starch, which has a series of special properties, is a main ingredient of kudzu. In this thesis, the structure and cross-linked reaction of kudzu starch were systematic studied so as to suggest some ideas for applications in food fields.The kudzu amylose(AM) and amylopectin(AP) were fractionated from kudzu starch by using n-butanol and isoamyl alcohol. The morphological features and micro-structure of two fractionated starches were investigated by scanning electronic measurement(SEM), X-ray diffraction(XRD) and Fourier transform infrared spectroscopy(FT-IR). Amylose and amylopectin showed variable in size and irregular aggregation. According to XRD patterns, amylopectin was amorphous and amylose was a superposition of the A and B type patterns. Using enzymolysis, chain structure of amylose and amylopectin molecule was analyzed. Amylose molecule had less average number of chains each molecule but longer average chain length compared with those of amylopectin molecule. At the same time, the solubility, swelling power and thermal property of kudzu native starch, AM, and AP were studied.Kudzu native starch was cross-linked in the presence of sodium trimetaphosphate(STMP)(5%, 10% and 12%) at the different temperature(35℃, 45℃, 55℃) in 1h, 2h and 3h. The morphology, crystalline structure, molecular structure, retrogradation, freeze-thaw stability and thermal properties of cross-linked starches with different degrees of substitution were investigated systematically with the comparison with kudzu native starch. Then low cross-linking starch and high one were fractionated to study the structures and properties. The results showed that cross-linking reaction was came up in the crystalline region and crystalline structure of amylose was destroyed. The transmittance, solubility and swelling power were reduced, while freeze-thaw stability was improved with the addition of cross-linked bond. The research of structures and properties will be helpful for the process of food processing and storage and the control of starch modification.更多还原