导　　师： 扶雄

学科专业： 082202

授予学位： 硕士

作　　者： ;

机构地区： 华南理工大学

摘　　要： 本论文以木薯淀粉为原料,以三偏磷酸钠/(STMP/)为交联剂,醋酸酐为酯化剂,对淀粉进行复合变性,制备木薯交联酯化淀粉,再对木薯交联酯化淀粉进行预糊化处理得到适用于乌冬面的改性淀粉。对淀粉改性方法进行工艺优化,比对制备的不同改性淀粉进行物理化学性质、形态学、结晶学等性质进行系统研究,并且对其在乌冬面中的应用进行了研究。 以结合磷含量为指标,制备出具有稳定作用的木薯交联淀粉的条件为:淀粉乳浓度40/%,交联剂STMP用量为0.1/%/(占淀粉干基/),pH=10.5,温度50℃,反应时间2.5h,氯化钠用量为3/%。结合磷含量0.019/%。 以结合磷含量0.019/%的木薯交联淀粉为原料,以乙酰基含量为指标,制备交联酯化淀粉的优化工艺条件为:淀粉乳浓度40/%,醋酸酐用量为3/%/(占淀粉干基/),pH=9.0,温度30℃,反应时间2h。产品的乙酰基含量为1.06/%。乙酰化作用提高淀粉的淀粉透明度、膨胀度、溶解度和冻融稳定性。 对结合磷含量为0.019/%、乙酰基含量为1.06/%的木薯交联酯化淀粉进行预糊化处理,得到木薯交联酯化预糊化淀粉。交联酯化预糊化复合改性淀粉具有较高的糊稳定性、透明度、保水性,以及较低的起糊温度和凝沉性,明显改善了木薯原淀粉的性质。 偏光显微镜和扫描电镜的测试结果表明,交联淀粉和交联酯化复合改性淀粉颗粒偏光十字清晰可见,结构完整。红外光谱显示,淀粉经过交联酯化复合变性处理后,分子结构上引入新的化学基团,在1728cm-1处出现了明显的羰基特征吸收峰。X光衍射图谱显示,木薯原淀粉是“A”型结晶,改性后淀粉的结晶度发生轻微的变化,证明化学反应仅仅发生在淀粉颗粒的无定形区。交联酯化淀粉经预糊化处理后,颗粒结构破碎,结晶区被破坏,偏光十字消失,X光衍射图谱出现“馒头峰”。 添加交联酯化预糊化复合变性淀粉的乌冬面产品色泽白亮,生产过程中延展性好,不易断裂,复水后保水性好、烹饪过程耐煮性强,煮后不糊条、不并条、不夹生,口感好,细腻爽滑有嚼劲,并且储藏稳定性好。因此所制备的交联酯化预糊化复合变性淀粉可作为优良添加剂应用到乌冬面中。 In this paper tri-modified cassava starch, used especially for Udon noodles, was prepared firstly by cross-linking the native cassava starch with sodium trimetaphosphate /(STMP/) employed as the cross-linking agent, and then esterified in the presence of acetic anhydride, subsequently this dual-modified starch was further pregelatinized to obtain target modified starch. Processing conditions of starch modification were optimized, besides, physico-chemical, morphological, crystalline properties of various modified starch prepared in the experiment were studied systematically, as well as their application in Udon noodles. The proper operating conditions of preparing cross-linked cassava starch with stabilization ability, of which the effect was evaluated in terms of combined phosphorus content, were illustrated as follows: concentration of native starch slurry was 40/%, the amount of STMP 0.1/% /(w//w dry starch basis/), pH=10.5, 50℃, reaction time 2.5h, dosage of sodium chloride 3/%, and under such conditions the combined phosphorus content was 0.019/%. Dual modified cassava starch, attained by a combination of modification methods of cross-linking and esterification, was made on the base of cross-linked cassava starch, and acetyl group content was selected as an indicator for esterification process. Optimum operating conditions of this process were showed as follows: concentration of cross-linked cassava starch slurry 40/%, dosage of acetic anhydride 3/% /(w//w dry starch basis/), pH=9.0, 30℃, and the reaction continued 2.0h. Under the treatment of acetylation, paste clarity, swelling power, solubility, and freeze-thaw stability of native starch could be enhanced. Modified starch used especially for Udon noodles was prepared by further pregelatinization of the dual modified cassava starch with 0.019/% combined phosphorus content and 1.06/% acetyl group content. This dedicated modified starch had advantages of higher paste stability, clarity, water-holding capacity, and lower initial gelatinization temperature and retrogradation, and thus significantly improved properties of native cassava starch. Testing results derived from polarization microscope and Scanning Electron Microscopy /(SEM/) showed that the birefringence of barely cross-linked starch granules and dual-modified starch granules were clear and the structures of them were also well retained. Infrared spectra of this cross-linked and esterified starch indicated that after dual-modification treatment, new chemical group was introduced into the molecular structure, and there was a characteristic absorption peak of carbonyl group at 1728cm-1. While the X-ray diffraction analysis graph illustrated that crystallinity of dual-modified starch occurred only a slight change, which verified that chemical reaction merely happened in the amorphous zone of starch granules. When dual-modified starch went through further pregelatinization processing, its granule structure was broken, the crystalline area was destroyed, birefringence disappeared, and a“bread peak”occurred in the X-ray diffractogram. Udon noodles added with dedicatedly modified cassava starch acquired a series of excellent qualities described as follows: they were white and shining in color and luster, a better ductibility during processing, hard to break down, and good water-holding capacity after rehydration, strong ability in boiling resistance during cooking, and after cooking they wouldn’t stuck together, in addition to those, the noodles gained a wonderful taste with delicate texture and smoothness, and the products were stable in storage. Therefore, this tri-modified cassava starch could be used as desirable additive in the production of Udon noodles.

关 键 词： 木薯淀粉 交联 酯化 预糊化 糊性质

分 类 号： [TS231]

领　　域： [轻工技术与工程] [轻工技术与工程]