不同直链/ 支链比的玉米淀粉分子质量及其构象

采用凝胶渗透色谱(GPC)和十八角度激光光散射(MALLS)技术,以二甲基亚砜为流动相测定蜡质玉米淀粉、普通玉米淀粉、直链/ 支链比1:1 的高直链玉米淀粉(G50)、直链/ 支链比4:1 的高直链玉米淀粉(G80)的分子质量及其分布以及在二甲基亚砜(DMSO)溶液中的均方根旋转半径和构象。结果表明：分子质量最大的是蜡质玉米淀粉,其重均分子质量达到了1.416 × 108g/mol,其次是普通玉米淀粉2.744 × 107g/mol 与G50 1.026 × 107g/mol,最小的是G80 的3.992 × 106g/mol;均方根旋转半径也是随着直链淀粉含量的增加依次减小;蜡质玉米淀粉在DMSO 溶液中的构象是较为紧密的无规则卷曲型,其他3 种玉米淀粉的构象均为球型。     

Enzyme Resistant Dextrins from High Amylose Corn Mutant Starches

This work was undertaken to investigate the effects of amylose content and chemical modification on enzyme resistant dextrin content of high amylose corn mutant dextrins. Dextrins made from high amylose corn mutant starches, including dull sugary 2 (du su2), amylomaize V, amylose extender dull (ae du), amylomaize VII, and chemically modified amylomaize V and VII, were characterized for moisture, solubility, reducing sugars, and enzyme resistant dextrin contents after dextrinization. Moisture content decreased, whereas soluble and reducing sugar contents rose rapidly in the first 60 min of conversion. Reducing sugar content began to decrease after 60 min of reaction, which corresponded to the onset of a rapid increase in enzyme resistant dextrin content. The enzyme resistant component in dextrin was not detected until fragments of low molecular‐weight saccharides were produced by hydrolysis. These fragments recombined into randomly branched molecules that were resistant to enzymatic digestion. One proposed mechanism contributing to the lower enzyme resistant dextrin content of chemically modified high amylose corn dextrins is that the introduction of modifying groups to starch presented a steric hindrance for transglucosidation and repolymerization reactions during dextrinization, consequently resulting in lower enzyme resistant dextrin content.     

慈姑直链淀粉的分离与分子结构

利用正丁醇法分离慈姑直链淀粉与支链淀粉,并对慈姑直链淀粉进行了深入研究。试验结果表明:慈姑直链淀粉与碘的络合物最大吸收波长为620.5nm,其蓝值为0.844,特性黏度[η]为127mL/g。测得慈姑直链淀粉的分子结构参数为:聚合度DP=640,黏均分子质量η=3.11×105。     

交联高链磁性淀粉的制备及其结构的研究

以链淀粉含量50%的交联玉米淀粉为原料,采取四种不同的磁化工艺引入磁性粒子,采用扫描电镜观测磁性淀粉颗粒形貌、表面结构及磁性粒子的大小和分布。结果表明,制备磁性淀粉的最佳工艺为氧化磁化法,其形成的磁粒大小和分布均匀,对淀粉形状和结构破坏较小,可形成纳米级(11.16nm~17.86nm)的超顺磁性淀粉。     

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 )。     

油炸过程中淀粉的颗粒形貌、结晶度与热力学特性变化

采用深层油炸模型,利用扫描电镜分析、差示扫描量热分析和x-射线衍射分析等现代仪器分析方法,研究了油炸过程中淀粉的颗粒形貌、结晶结构和热力学性质的变化规律。SEM分析表明,随着油炸温度的增加和时间的延长,淀粉颗粒形态发生了明显变化。在初炸时,淀粉颗粒逐渐膨胀;随着复炸的进行,淀粉颗粒崩解,相互靠近,融合形成大块的团聚体。同时,也导致了淀粉的碘蓝值逐渐减少。DSC测定结果表明,当初炸25 s和50 s时,淀粉分子发生了一定程度的糊化作用;当初炸75 s和100 s时,淀粉完全糊化;当复炸超过20 s时,淀粉在油炸过程中形成了淀粉-脂质复合物。X-射线衍射分析显示,当初炸超过75 s后,淀粉的结晶度均高于初炸25 s淀粉的结晶度;复炸40 s后淀粉的结晶度随油炸时间的延长而降低。     

生物发酵对玉米淀粉中直链淀粉含量影响的研究

以普通玉米淀粉为原料,通过微生物发酵,探讨发酵工艺参数对发酵后玉米淀粉中直链淀粉含量的影响。结果表明:不同接种量,种龄,淀粉乳浓度和发酵时间等因素对玉米淀粉中直链淀粉含量都有不同程度的影响,其中1号菌接种量2%,种龄12h,淀粉乳浓度20%,发酵时间1d,发酵温度36℃,摇床转数180r/min处理时,玉米淀粉中直链淀粉含量为50.37%最高,与发酵前直链淀粉含量相比增加了30.37%。     

热处理对不同直链淀粉含量的玉米淀粉理化性质的影响

采用快速黏度分析法、离心法、差示扫描量热分析法、动态流变仪分析法等,研究了干热与湿热处理对3种不同直链淀粉含量的玉米淀粉糊化性质、膨润性质、热力学性质、流变性质的影响,为淀粉的物理改性研究和加工应用提供理论依据。结果表明,干热处理使淀粉更易糊化,表现为3种玉米淀粉糊化温度降低,溶解度、膨胀度增加。湿热处理加大糊化难度,使3种玉米淀粉的糊化温度升高,膨胀度降低。热处理使玉米淀粉糊稠度、糊化焓值降低。蜡质玉米淀粉经热处理后,溶解度和老化率增加。流变性质测定结果表明,湿热处理不利于高直链玉米淀粉黏弹性凝胶的形成。     

High‐Amylose Starches to Bridge the “Fiber Gap”: Development,Structure, and Nutritional Functionality

Although high‐amylose starches are not a recent innovation, their popularity in recent years has been increasing due to their unique functional properties and enhanced nutritional values in food applications. While high‐amylose maize, barley, and potato are commercially available, high‐amylose variants of other main crops such as wheat and rice have once been developed more recently and will be available commercially in the near future. This review summarizes the development, structure, and nutritional functionality of high‐amylose starches developed and reported so far. The range of biotechnological strategies utilized are reviewed, as are the consequent effects on structural properties at different length scales, as well as sensory aspects of foods containing high‐amylose starch (HAS). This review identifies the molecular and microstructural features contributing to digestive enzyme resistance not only in native HAS but also in forms of relevance to food processing. During heat treatment, HAS tends to retain or form dense molecular structures that resist amylase degradation through the retention of the granular structure as well as helices (type‐2 resistant starch [RS]), reassociation of glucan chains (type‐3 RS), and formation of lipid–amylose complexes (type‐5 RS). The review also identifies opportunities for food manufacturers and consumers to incorporate HAS in food products and diets for better nutritional outcomes.     

玉米直链淀粉的制备及其特性

以普通玉米淀粉为原料,采用稀碱分散法制备玉米直链淀粉。以直链淀粉的得率和蓝值为评价指标,通过正交试验确定最佳分离工艺为NaOH溶液浓度0.35～0.45mol/L、NaCl溶液质量分数5%、离心力5439～7014×g。该法制备的玉米直链淀粉与丁醇法和乙醇分散法制备的直链淀粉以及直链淀粉标准品的特性进行对比,根据其蓝值、特性黏度及特性分子质量、质构特性、相对分子质量分布结果可知,稀碱分散法制备直链淀粉的纯度高于乙醇分散法和丁醇法,并且直链淀粉的凝胶特性和相对分子质量分布情况接近直链淀粉标准品。     

Single-Screw Extrusion of Defatted Soy Flour, Corn Starch and Raw Beef Blends

Effects of feed moisture, fat and corn starch levels and process temperature on physical properties of extrudates of defatted soy flour-amylose corn starch-raw beef blends were investigated using response surface methodology. Contour plots showed a convex curve of expansion ratio (ER) with moisture, concave curves of bulk density (BD) and shear-force (SF) with moisture, and concave cmves of SF with each of the four extrusion variables. Fat decreased ER and increased BD, whereas corn starch increased ER. Products with high ER and low BD and SF tended to have prominent air cells, continuous protein matrices, and smooth cell wall surfaces in scanning electron micrographs. The optimum extrusion conditions for minimal SF values, with 20% non-dehydrated beef muscle and varied amounts of defatted soy flour, were: 29.1% feed moisture; 2.96% feed fat; 22% feed corn starch; and 162°C process temperature.     

Morphology and Microstructure of Maize Starches with Different Amylose/Amylopectin Content

The morphology and microstructure of maize starches with different amylose/amylopectin ratios (waxy: 0/100; normal maize: 23/77; Gelose 50: 50/50; Gelose 80: 80/20) were studied by microscopy with ordinary and polarized light, scanning electron microscopy (SEM) and X‐ray diffraction (XRD). Generally, the granules of the amylopectin‐rich starches were more regular in shape than those of the amylose‐rich starches, but the surfaces of the amylose‐rich starches were smoother than those of the amylopectin‐rich starches. The birefringence and particle size of the granules were waxy > normal maize > G50 > G80, which also corresponds with the trend of molecular weight. Waxy and normal maize starches showed typical A‐type patterns, while G50 and G80 show B‐type patterns. Crystallinity increases with increasing the amylopectin content.     

高直链玉米淀粉添加对挤压荞麦面条结构、蒸煮品质及消化特性的影响

制备挤压荞麦面条,研究不同添加量（10%、20%、25%、30%）的高直链玉米淀粉（m/m,基于全粉）对挤压荞麦面条结构、蒸煮品质及消化特性的影响。结果表明,随着高直链玉米淀粉添加量的增加,挤压面条直径减小,糊化度降低。X射线衍射结果表明添加高直链玉米淀粉后,面条除了V型结晶峰外还存在未完全糊化的直链淀粉的典型B型峰。热力学性质结果也表明直链淀粉发生部分糊化。添加高直链玉米淀粉后,面条色泽变浅变亮,最佳蒸煮时间缩短,蒸煮损失率由9.90%增加到12.43%。当高直链玉米淀粉添加量为25%时,面条开始出现断条。面条硬度由2 105.709 g显著增加至3 680.401 g,弹性由0.961降低至0.866。扫描电镜结果表明,随着高直链玉米淀粉添加量的增加,致密的面条结构逐渐出现裂纹,且面条截面有较多未完全糊化的淀粉颗粒。淀粉体外消化实验表明,随着高直链玉米淀粉添加量的增加,淀粉水解率逐渐下降,预计血糖指数减小,抗性淀粉含量增加。当高直链玉米淀粉添加量为30%时,挤压荞麦面条的预计血糖指数从74.28降至66.31,抗性淀粉含量从34.43%增加至47.86%。     

优化毛细管电泳法测定山药淀粉中直链/支链淀粉

以市售新鲜怀山药为原料通过石灰水浸泡法制备山药粉,并通过正丁醇反复结晶法分离纯化直链淀粉与支链淀粉。利用碘做显色剂,使用毛细管电泳法测定山药淀粉中直链淀粉与支链淀粉的含量以及比率,本文分别对柠檬酸-磷酸盐缓冲液以及醋酸-醋酸盐缓冲液等不同缓冲液作为流动相进行了对比,实验发现醋酸-醋酸盐缓冲液对于分离测定直链淀粉与支链淀粉的效果较好。随后分析了不同p H条件下的醋酸-醋酸盐缓冲液进行的分离效果进行了比较,并测定其迁移率,当p H 4.8时分离效果最佳且其迁移率达到15.4。利用最佳条件使用纯的马铃薯直链淀粉与支链淀粉标准品,得出支链淀粉的保留时间约为1.8 min,而直链淀粉的保留时间约为2.9 min,对怀山药淀粉进行分析,从而得出怀山药中直链淀粉含量为19.49%。利用重复性试验以及回收率试验该方法的准确性与精确度能达到很好的效果。     

酸解时间对大米淀粉结构性质的影响

以4种不同直链淀粉含量的大米淀粉(0%的优糯3号、10.90%的稻花灿、21.03%的聚两优、28.46%的华优香占)为原料,酸解处理不同时间,以酸解大米淀粉的酸解率、颗粒形貌、结晶性质、溶解度的变化为指标衡量不同酸解时间对大米淀粉结构及性质的影响。结果表明,不同直链淀粉含量的大米淀粉具有不同的耐酸性,酸解时间对不同直链淀粉含量大米淀粉的结构和性质有着不同的影响。大米淀粉酸解率与直链淀粉含量成反比,优糯3号为50%而华优香占仅为30%;所有淀粉颗粒在酸解后均产生一定程度的破碎,偏光十字变形直至消失,酸解相同时间,直链淀粉含量高的大米淀粉破碎率低;酸解未改变淀粉的晶型,仍为A晶型;随着酸解时间的延长相对结晶度增加;淀粉的溶解度随着酸解时间的增加而增大。     

Changes in Starch and Protein on Extrusion of Corn Starch and Sunflower Protein Blends

We investigated the use of electron spin resonance spectroscopy (ESR) and the spin labelled fatty acid, 16 doxylstearic acid (16-DSA) in the study of starch and protein modification during extrusion processing of corn starch (CS), corn meal (CM), and their blends with sunflower protein isolate (SPI). Spectra due to binding of the spin probe to starch and protein were identified. Changes in spectra after extrusion of all materials indicated that: (1) ~90% of the starch was modified (gelatinized); (2) The globular protein structure was disrupted. These changes demonstrate that spin probes and ESR spectroscopy may be used to study starch and protein modification during extrusion and other food processes.     

直链/支链淀粉对鱼丸质构特性及感官品质的影响

为探究直链/支链淀粉对不同来源（海水鱼/淡水鱼）鱼丸的质构特性以及感官品质的影响,采用质构剖面分析法（texture profile analysis,TPA）测定鱼丸的质构特性,结合感官品质评定方法对鱼丸质构进行综合评定,并辅以持水性分析和微观结构观察,研究鱼丸凝胶性质。结果表明：相对于直链淀粉,支链淀粉在鱼丸加工工艺中能更有效地提高其硬度和咀嚼性。以鲅鱼肉作为鱼丸原料相较于巴沙鱼肉具有更高的蛋白质及更低的脂肪含量,更为优越的质构特性、感官品质以及持水性。     

直链淀粉和支链淀粉的表征

直链淀粉和支链淀粉是淀粉的两大主要组分,它们在分子结构以及分子聚集态等方面的差异导致其物化特性有所不同,具有不同直链和支链淀粉组成比例的淀粉在总体应用表现也不相同。本文通过讨论淀粉最新的研究进展,对直链淀粉和支链淀粉的纯度、分子结构、相对分子质量、晶体特性、热焓特性、黏度特性等进行综述。     

直链淀粉含量对大鼠肠道发酵产物的影响

目的:研究了不同直链淀粉含量的玉米淀粉对大鼠肠道发酵产物的影响.方法:将42只Wistar成年雌鼠随机分为7组,分别饲喂直链淀粉(AS)含量为0%、26.8%、53.8%、61.6%、75.7%、78.9%、85.8%的玉米淀粉饲料.喂养3周后解剖,测定各组体重、饲料效率及淀粉消化率、小肠内容物、盲肠内容物、盲肠组织重量以及盲肠中短链脂肪酸(SCFA)等指标.结果:61.6%AS、75.7%AS、78.9%AS和85.8%AS饲料组的淀粉表观消化率明显低于0%AS和26.8%AS饲料组.与0%AS和26.8%AS相比,高直链淀粉显著地增加了小肠内容物、盲肠内容物干重,75.7%AS组的盲肠内容物干重最高.高直链淀粉组盲肠中乙酸、丙酸和总SCFA的总量显著高于0%AS和26.8%AS组,53.8%AS组丙酸产量最高,61.6%AS组有最高丁酸和总SCFA产量,而75.7%AS有最高的乙酸、乳酸和琥珀酸产量,在高直链玉米淀粉中,78.9%AS组SCFA产量最低.结论:增加玉米淀粉中直链淀粉含量能明显降低淀粉的消化性,增加大鼠肠道中未消化残渣的量和盲肠中SCFA产量,但这种效果与直链淀粉的含量并没有明显的相关性.     

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。