芋头淀粉的研究

本文研究了芋头淀粉的性质,实验采用电子显微镜拍摄了芋头淀粉颗粒的形态;运用X射线衍射仪测定了X-光衍射图样及结晶结构;通过重结晶法制得纯度较高的芋头直链淀粉和支链淀粉,利用高效液相色谱仪测定了芋头淀粉及其直、支链淀粉淀粉的重均聚合度、数均聚合度、分子量分布及分散度等,并与大米淀粉进行了比较.研究了芋头淀粉糊在不同质量分数、pH值以及不同蔗糖添加量的条件下,Micro Visco-Amylo-Graph黏度曲线的变化情况.本研究为进一步了解芋头淀粉的特性及应用开发提供了一定的理论依据.     

乳酸菌发酵改善米粉食用品质的机理

以早籼稻为原料 ,研究了以乳酸菌发酵改善大米淀粉凝胶食用品质的机理 ,揭示了大米淀粉的功能性与结构之间的关系。GPC结果表明 ,淀粉颗粒经过凝胶柱被分成 2部分(FrⅠ ,FrⅡ ) ,FrⅠ区为支链淀粉 ,FrⅡ区为直链淀粉。乳酸菌发酵使大米中的支链淀粉的平均聚合度由 12 6 76 3GLU降低到 115 0 0 4GLU ,而直链淀粉的平均聚合度由 2 975 3GLU增加到 35 6 3 2GLU ;支链淀粉的平均链长由 6 1 2GLU下降到 4 5 0GLU ,直链淀粉的平均链长由 2 3 7GLU增加到 2 8 4GLU ;直链淀粉的含量由 12 33%增加到 17 37% ;蛋白质含量由6 89%下降到 4 2 0 %。拉伸试验证明 ,乳酸菌发酵使米粉的最大破短应力显著增强 ( p <0 0 1) ,伸展率 /断面收缩率及最大破短应变显著增加 ( p <0 0 1) ,杨氏模量显著下降 (p <0 0 1) ,经感官评定 ,米粉筋道柔韧。     

微细化大米淀粉的分子特性研究

以籼米为原料制备微细化淀粉 ,进行粒度分级后用凝胶色谱等方法研究微细化大米淀粉的分子特性。结果表明 ,不同粒度微细化大米淀粉的支链淀粉的最大波长在 5 6 0nm ,直链淀粉在 6 0 0～ 6 2 0nm出现最高峰 ,微细化后大米淀粉的粒度对淀粉级分的可见光吸收值影响不大 ,但对其分子量大小、分子量分布规律等有影响。微细化使淀粉分子有所降解 ,分子量分布变宽 ,分子的整齐度下降。随淀粉粒度的减小 ,直链淀粉含量和分子量降低 ,中间级分含量增高 ,支链淀粉含量和分子量几乎不变     

稻米淀粉的理化特性研究Ⅱ稻米直链淀粉和支链淀粉的理化特性

本文研究了稻米淀粉不同级分的理化特性及稻米类型对各级分理化特性的影响。结果表明 :稻米淀粉级分的理化特性有较大差异 ,稻米类型对各级分理化特性有影响。直链淀粉的碘结合力为 19.99～2 0 .31mgI2 /g淀粉 ,支链淀粉为 0 .0 6～ 0 .0 95mgI2 /g淀粉 。直链淀粉的碘兰值为 0 .2 0～ 0 .2 5OD/0 .1g淀粉 ,以籼稻直链淀粉的碘兰值较大 ;支链淀粉碘兰值为 0 .0 3～ 0 .10OD/0 .1g淀粉 。直链淀粉的特性粘度为 5 0～ 15 0mL/g ,以粳稻较大 ;支链淀粉的特性粘度为 5 0 0～ 95 0mL/g ,以糯稻最大 ,籼稻最小。直链淀粉与碘复合物的可见光最大吸收波长为 6 0 0～ 6 2 0nm ,支链淀粉为 5 2 0～ 5 40nm ,品种差异较小。分离纯化后直链淀粉的结晶度为 2 3%～ 2 5 % ,支链淀粉则无晶体结构 ,结晶度的品种差异较小。稻米支链淀粉的分子量为 4 7× 10 6 (籼稻 )～ 2 35× 10 6 (糯稻 ) ,直链淀粉的分子量为 0 .4 4× 10 6 (籼稻 )～ 1.6 2× 10 6 (粳稻 )。     

银杏淀粉的分离和纯化

用重结晶法可以得到纯度较高的银杏直链淀粉和支链淀粉。凝胶过滤色谱表明：银杏直链淀粉的分子量比玉米直链淀粉的小,而支链淀粉的分子量则具有较宽的分布。银杏直、支链淀粉的碘亲和力分别为19．19％和0．13％,蓝值分别是0．85和0．12,γmax为626nm和564nm;银杏淀粉中直链淀粉含量为33％。     

双波长法测定山药中直链和支链淀粉含量

使用双波长分光光度法测定不同品种山药中直链淀粉和支链淀粉的含量,根据双波长法的测定原理,确定山药直链及支链淀粉的测定波长和参比波长,直链淀粉分别为624 nm和410 nm,支链淀粉分别为538 nm和758 nm。试验结果表明,该测定方法标准曲线良好。直链淀粉在0~50μg/mL质量浓度范围内其碘复合物与吸光度呈线性关系(R~2=0.999 7),支链淀粉在0~250μg/mL质量浓度范围内其碘复合物与吸光度呈线性关系(R~2=0.998 4)。山药中直链淀粉含量为0.026 mg/mL,回收率在96.72%~98.73%之间;支链淀粉的含量为0.072 mg/mL,回收率在95.74%~97.87%之间,RSD均小于1.5%。     

双波长法测定木薯淀粉中直链和支链淀粉的含量

目的：分离纯化木薯淀粉中的直链和支链淀粉,建立同时测定木薯淀粉中直链与支链淀粉含量的双波长法。方法：采用正丁醇结晶法分离纯化直链和支链淀粉,蓝值比较法表征直链与支链淀粉的纯度;根据双波长法原理,分别在测定波长624、538nm,参比波长440、750nm处测定木薯淀粉中直链与支链淀粉含量。结果：分离纯化得到的直链与支链淀粉蓝值分别为0.979和0.144,分别落在0.8～1.2与0.08～0.22范围内,表明纯化后木薯直链与支链淀粉的纯度较高;直链淀粉在0～80mg/L质量浓度范围内其碘复合物与吸光度呈线性关系(r＝0.9992),支链淀粉在0～220mg/L质量浓度范围内其碘复合物与吸光度呈线性关系(r＝0.9995)。结论：正丁醇结晶法能有效地分离木薯直链与支链淀粉;双波长法操作快速、准确,无需分离即可同时测定木薯淀粉样品中直链和支链淀粉含量。     

双波长法测定小麦及小麦芽中直链、支链淀粉含量

采用双波长法对15种小麦品种的直、支链淀粉的含量进行了测定,并选择淀粉含量及支链/直链比有代表性的6个品种进行制麦试验,研究了小麦制麦芽期间淀粉含量的变化,以期探讨一种简便快捷的测定小麦及麦芽中淀粉含量的方法,并为筛选适合制麦芽小麦品种提供依据.根据碘-直链淀粉和碘-支链淀粉复合物的吸收光谱,选择直链淀粉的测定波长为631 nm和480 nm,支链淀粉的测定波长为554 nm和754 nm,依据回归方程可求出直链和支链淀粉的含量.直链淀粉的浓度在0～30μ/mL,支链淀粉在0～110μg/mL范围内符合比耳定律.制麦前后总淀粉降解程度与原小麦中支链/直链淀粉存在正相关性(P<0.1),相关系数r=0.802.     

提取工艺对大米淀粉的理化性质影响

通过试验测得碱提法和酶解法获取的2种淀粉的理化性质,得出如下结论:碱法大米淀粉中的直链淀粉高于酶法大米淀粉中的直链淀粉含量;碱法大米淀粉中支链淀粉含量低于酶法大米淀粉中支链淀粉含量;碱法大米淀粉和酶法大米淀粉的溶解度随着温度的升高而增大,碱法大米淀粉的溶解度对温度更为敏感;2种大米淀粉的淀粉-碘可见光吸收光谱的形状十分相似,都有最大吸收峰;酶法提取的大米淀粉的冻融稳定性比碱法提取的大米淀粉好。     

直支链淀粉对白酒生产的影响

本文比较了不同直支链淀粉含量的大米、高粱的糊化情况和蒸煮香气,并进行了实验室和窖池发酵试验。结果发现酿酒微生物代谢出的酶既能水解支链淀粉也能水解直链淀粉;同一品种的粮食直链淀粉越高,淀粉结构越紧密,糊化时间越长,粮香越浓;不同品种的粮食淀粉颗粒大小、结构不同,糊化时间也不同。不管是直链淀粉还是支链淀粉,只要糊化得好,出酒率差别不大。     

Starch Structure and Digestibility of Rice High in Resistant Starch

Starch digestibility and starch structure of a high‐resistant starch (RS) rice (RS111) was compared to that of a wild rice type (R7954). RS111 exhibited high RS content and incomplete starch hydrolysis in both cooked rice and retrograded rice flour. High RS rice RS111 had a higher λ_max of absorbance and blue value of iodine‐binding starch complex and contained a higher percentage of intermediate chains of amylopectin than R/954. X‐ray diffraction pattern of RS isolated from cooked high RS rice displayed a mixture of B‐ and V‐type that was more resistant to starch hydrolysis by alpha‐amylase. Resistant starch in RS111 is composed mainly of linear amylose and some low‐molecular‐weight amylopectin.     

The Influences of Chain Length of Amylopectin on Resistant Starch in Rice (Oryza sativa L.)

Amylopectin is the principle component of starch. To elucidate the relationships between amylopectin and resistant starch content, six rice mutants with altered fine structure of amylopectin were selected for comparative studies with the primary wild type and two types of amylose‐extender (ae) mutants. Significant differences in resistant starch content were observed among mutants with similarity or differences in amylose levels. Mutants high in resistant starch had significantly increased proportions of short amylopectin chains with DP≤12, decreased levels of intermediate chains with size of 13≤DP≤36, and decreased fractions of long chains with DP≥37. Additionally, there was a mutant different to ae, which was characterized by an increased level of short chains with 8≤DP≤12 and 13≤DP≤24, and a decreased proportion of long chains with DP≥37. The increased contents of short chains with 8≤DP≤12 and decreased of intermediate and long chains with 24≤DP were clearly associated with the increase of resistant starch in rice.     

Effect of amylose content and rice type on dynamic viscoelasticity of a composite rice starch gel

Amylose content is an important indicator to determine the utility of raw milled rice. Indica type rice with high amylose content is usually used for manufacturing rice noodles, while Japonica rice may be mixed partially to adjust the noodle texture. The effect of amylose and rice type on dynamic viscoelasticity of rice starch gel was investigated using a model starch composite in this study. The information will be helpful to control and obtain the required noodle texture by combination of different rice types. The results show that nonwaxy Indica and waxy Japonica rice starches in a composite mixture were incompatible and demonstrated their individual gelatinization behavior during heating. High amylose starch showed higher moduli and lower loss tangent values, as well as higher retrogradation rate. The starch gel made from Japonica rice starch showed a slow retrogradation rate even containing a similar amount of amylose to Indica starch. The storage modulus of the gel made from higher amylose rice was shown to be more independent of frequency. Not only amylose content but also chain length distribution in amylopectin affected the dynamic viscoelasticity of rice gel. Japonica rice starch, with fewer super-long chains in amylopectin, retrograded slower after gelatinization than Indica rice, thus the paste is too sticky for production of rice noodles.     

Comparative Study on the Starch Noodle Structure of Sweet Potato and Mung Bean

ABSTRACT:  Fine structure of sweet potato starch (SPS) and mung bean starch (MBS) by gel-permeation chromatography (GPC) showed that the amylose in SPS and MBS had 9.0 and 1.8 chains, respectively. The long chains of amylopectin in MBS (A_p-MB) were longer than those of amylopectin in SPS (A_p-SP), but the short chains of A_p-SP were shorter than those of A_p-MB. The structures of starch noodles of sweet potato (SPSN) and mung bean (MBSN) were analyzed by GPC, scanning electron micrograph (SEM), differential scanning calorimetry (DSC), and X-ray diffraction after hydrolysis by acid and enzymes. The results showed that the residues obtained with acid and enzymes in MBSN contained large amounts of high molecular weight fractions, and a relatively small amount of low molecular weight fractions, whereas those in SPSN contained some high molecular weight fractions and large amounts of low molecular weight fractions. SPSN exhibited higher digestibility by HCl, α-amylase, β-amylase, and pullulanase than MBSN. The surface of MBSN was more smooth than that of SPSN and the inside of MBSN contained long, thick, and orderly filaments, while there were many pore spaces inside SPSN from SEM. The DSC thermogram of the resistant residues from both starch noodles after acid/enzyme hydrolysis showed a broad endotherm peak near 100 °C (96 to 115 °C) due to the presence of the complexes of amylose-lipid and lipid-(long chains in amylopectin). Because of a lower content of branched amylose and a higher content of amylopectin in SPS, the structure of SPSN had a less distinct crystalline pattern and higher adhesiveness, whereas there was a higher content of amylose with a little branch and moderate amylopectin in MBS. Thus, the structure of MBSN had a stronger distinct crystalline pattern and good cohesiveness.     

Structural characterization of rice starch in rice cake modified by Thermus scotoductus 4-alpha-glucanotransferase (TS alpha GTase)

ABSTRACT:  Rice cake was produced with a thermostable 4-α-glucanotransferase from Thermus scotoductus (TSαGTase). Starch molecular fine structure, texture, and retrogradation for the enzymatically prepared rice cake were investigated and compared to those for control rice cake. The amylose content in TSαGTase-treated rice cakes decreased, whereas branched and linear malto-oligosaccharides ranging from maltose to maltoheptaose increased slightly. The average molecular weight of the enzyme-treated rice starch in rice cake decreased as amylopectin macromolecules were cleaved and reorganized into small amylopectin clusters. The number of shorter side chains (degree of polymerization [DP] < 9) increased, whereas the number of longer side chains (DP > 10) decreased through the disproportionation reaction of TSαGTase. After 24 h of storage at 4 °C, the enzyme-treated samples demonstrated significantly lower melting enthalpy of retrograded starch (0.4 mJ/mg) compared to that of the control (1.4 mJ/mg). The results indicated that TSαGTase treatment effectively inhibited starch retrogradation in rice cakes. It is suggested that the reduction of amylose content, the rearrangement of amylopectin, and the production of malto-oligosaccharides caused by TSαGTase treatment are responsible for the ineffective molecular reassociation of rice starch in rice cake.     

Structures and Physicochemical Properties of Acid‐Thinned Corn,Potato and Rice Starches

The structures and physicochemical properties of acid‐thinned corn, potato, and rice starches were investigated. Corn, potato, and rice starches were hydrolyzed with 0.14 N hydrochloric acid at 50 °C until reaching a target pasting peak of 200—300 Brabender Units (BU) at 10% solids in the Brabender Visco Amylograph. After acid modification the amylose content decreased slightly and all starches retained their native crystallinity pattern. Acid primarily attacked the amorphous regions within the starch granule and both amylose and amylopectin were hydrolyzed simultaneously by acid. Acid modification decreased the longer chain fraction and increased the shorter chain fraction of corn and rice starches but increased the longer chain fraction and decreased the shorter chain fraction of potato starch, as measured by high‐performance size‐exclusion chromatography. Acid‐thinned potato starches produced much firmer gels than did acid‐thinned corn and rice starches, possibly due to potato starch's relatively higher percentage of long branch chains (degree of polymerization 13—24) in amylopectin. The short‐term development of gel structure by acid‐thinned starches was dependent on amylose content, whereas the long‐term gel strength appeared dependend on the long branch chains in amylopectin.     

稻米淀粉及其级分的凝胶色谱分析

对糯稻、粳稻和籼稻的天然淀粉及其支链淀粉、直链淀粉进行凝胶色谱分析，以确定不同来源淀粉的组成、淀粉级分的特性。结果表明，籼稻淀粉和粳稻淀粉主要由支链淀粉、中间级分和直链淀粉组成，糯稻淀粉主要由支链淀粉和中间级分组成。采用正丁醇反复结晶法分离得到的直链淀粉和支链淀粉有较高的纯度。支链淀粉的分子量分布比直链淀粉的宽，粳米直链淀粉的分子量分布比籼米的宽，三种稻米支链淀粉的分子量分布差异不大。