小麦粉中的淀粉对其糊化特性的影响

从小麦粉中提取淀粉、直链和支链淀粉,再将其按不同的梯度添加到原小麦粉中去,用RVA来测定其粉糊化特性,以此来研究同源小麦淀粉、直链和支链淀粉对其糊化特性的影响规律。随着淀粉或支链淀粉添加量的增加,小麦粉糊化时的峰值黏度、低谷黏度、崩解值、最终黏度、衰减值和峰值时间都出现了上升的趋势,而糊化温度则表现为降低趋势。随着直链淀粉添加量的增加,小麦粉糊化时的峰值黏度、低谷黏度、崩解值、最终黏度、衰减值、峰值时间和糊化温度都出现了下降的趋势。     

淀粉结构对浆料性能的影响

研究直链淀粉和支链淀粉比例对浆料性能的影响。以高直链玉米淀粉和蜡质(支链)玉米淀粉为原料,运用光学显微镜、差示扫描量热仪研究了高直链玉米淀粉糊化所需要的条件;测试比较了不同比例的直链淀粉和支链淀粉混合浆液黏度、浆液黏附性能、浆膜性能等指标。结果表明:高直链玉米淀粉在130℃下糊化15min才能完全糊化;随着直链淀粉含量的增加,浆液的黏度下降,黏度热稳定性提高;浆膜的断裂强度、断裂伸长、耐屈曲性及磨耗增加,但对棉、涤棉粗纱的黏附力降低。认为浆料中直链淀粉和支链淀粉比例对其上浆性能有明显影响。     

支链淀粉结构对稻米淀粉糊化特性的影响

支链淀粉结构的不同是导致直链淀粉含量相近的水稻品种间品质差异的主要原因。本研究利用优化后的酶法测定了26个不同类型水稻品种的稻米支链淀粉的结构参数,分析了支链淀粉结构与淀粉RVA成糊特性及DSC热特性的相关性。结果表明,26个品种间平均链长、平均外链长与起始糊化温度、最高糊化温度、终结糊化温度呈正相关;A∶B值与起始糊化温度呈负相关。平均链长、平均外链长与消减值呈正相关,与峰值黏度、崩解值呈负相关;A∶B值与峰值黏度、崩解值呈正相关,与消减值呈负相关。将参试品种按AC分成11%~13%和13%~15%两组后,其支链淀粉结构与稻米淀粉RVA成糊特性及DSC热特性间的相关性与全部品种间基本一致。综上,支链淀粉结构对淀粉RVA成糊特性及糊化温度有较大影响,低平均链长、平均外链长及高A∶B值的稻米淀粉RVA成糊特性较好、糊化温度较低。     

小麦淀粉中不同性状淀粉对流变学性质的影响

普通小麦淀粉与糯质小麦淀粉因直链淀粉的含量不同而表现出不同的凝胶特性,流变学测试表明:支链淀粉含量与淀粉糊化液流体的假塑性负相关.     

板栗贮藏失水过程对淀粉及其加工特性的影响研究

摘 要：目的 探究板栗石灰化过程中主要生理品质和加工特性的变化。方法 以贵州‘仓更’板栗为原料,测定板栗失水石灰化过程中的总淀粉、直链、支链淀粉含量和相关酶活性的变化;采用扫描电镜、红外光谱和X射线衍射分析板栗原粉和淀粉结构差异;通过糊化性质和流变特性评估其加工特性。结果 石灰化后板栗总淀粉、直链、支链淀粉含量显著（P＜0.05）降低,淀粉酶活性先升高后降低;板栗原粉中生成了更多直链淀粉-脂质复合物,淀粉颗粒表面出现裂纹;淀粉分子有序结构减少,相对结晶度下降;淀粉糊化温度升高,热焓值下降,淀粉结构稳定性变差;且淀粉糊表现为假塑性流体,具有剪切稀化现象,淀粉糊黏弹性下降。结论 板栗淀粉酶活性的上升,淀粉水解以及淀粉结构的变化与板栗石灰化的发生密切相关并改变其生理品质和加工特性。     

莲藕淀粉的晶体特性研究

提取莲藕淀粉,对天然淀粉及糊化、存放过程中不同状态下的莲藕淀粉的结晶特性进行了测定,结果表明:天然莲藕淀粉的晶体结构为B型,直链淀粉为V型,支链淀粉无晶体结构;糊化过程中淀粉晶体崩解,随着糊化时间的延长,出现微小结晶;存放过程中淀粉糊和淀粉胶均比较稳定,结晶度仅有微小回升。     

超声波对玉米淀粉分子结构影响

研究淀粉颗粒经超声波处理后,淀粉分子量分布变化、直链淀粉与支链淀粉组分变化。结果表明,随着超声波时间延长,淀粉水解率逐渐增加,支链淀粉分子量显著降低,直链淀粉含量升高,形成新的直链淀粉脂质复合物。     

水分含量对大米淀粉糊化和回生的影响

用差示扫描量热仪和动态流变仪对不同水分含量的大米淀粉糊化、短期回生和长期回生特性进行了研究。试验结果表明：水分含量越低，大米淀粉越难糊化。水分含量低于50％时，常压下难以使大米淀粉完全糊化。对于大米淀粉的短期回生，水分含量越低，短期回生速度越慢，淀粉凝胶达到稳定的时间越长。对于大米淀粉的长期回生，水分含量60％时，大米支链淀粉最易重结晶，淀粉体系长期回生速度最快。直链—脂类复合物的解体温度随着水分含量的降低而升高。     

支链聚合度对菠萝蜜种子淀粉老化特性的影响

本研究以菠萝蜜种子淀粉(jackfruit seed starch,JFSS)为原材料,将其分离成直链淀粉和支链淀粉。将直链淀粉与五种不同支链聚合度的支链淀粉以1:1质量比进行混合,并进行糊化/老化处理,制备具有不同支链聚合度的老化JFSS(retrograded JFSS,RJFSS:M1’、M5’、M6’、M11’和BD’)。M1的支链聚合度最低,BD的支链聚合度最高。5种RJFSS样品显示出从致密到松散结构的显著变化。高脱水收缩形成致密结构,低脱水收缩相反。支链聚合度增加,5种RJFSS样品的Avrami指数和转变温度升高,重结晶速率、老化焓、老化度、相对结晶度、吸光度比降低。热力学特性、结晶结构和短程分子有序度的结果证实了不同支链聚合度RJFSS的老化特性。结果表明,支链聚合度是影响淀粉在贮藏过程中老化特性的重要结构因素。     

大米淀粉胶凝和回生机理的研究

利用差示扫描量热仪和动态流变仪对 3种不同大米淀粉的胶凝和回生过程进行了研究。实验结果表明 :在淀粉糊化后的冷却胶凝过程中 ,在 95～ 80℃会有大量淀粉分子通过氢键交联聚合 ,直链淀粉含量越高 ,交联聚合越多 ,这些氢键的形成使得凝胶的硬度和弹性增大 ;在后期储藏过程中 ,主要是支链淀粉的重结晶随时间延长而逐步增大 ,而直链淀粉和脂类的复合物以及直链间的聚合变化则不明显 ,但直链淀粉的存在加速了支链淀粉的重结晶 ,支链淀粉的重结晶是后期凝胶硬度增大的主要因素。     

Relationship between α-amylase degradation and physico-chemical properties of sweet potato starches

Six varieties of sweet potatoes, grown under identical conditions, produced starches that displayed different characteristics. Susceptibility to pancreatic α-amylase varied between starches produced by the different clones. Structural characteristics at various levels, such as ratio of major fractions, size of amylose, gelatinization temperature and granule morphology, were also different between clones. Correlating structural attributes with susceptibility led to the suggestion that granule structure, including amylopectin: amylose ratio and molecular associations, were important critical factors in the hydrolysis of sweet potato starch granules. High amylopectin content of sweet potato starch was associated with a high gelatinization temperature and correspondingly less susceptibility to α-amylase attack. The hydrolysis pattern was correlated with degree of hydrolysis. Extensive surface erosion was shown to indicate a high degree of hydrolysis, whereas less surface erosion indicated less degradation.     

淀粉直支比定量技术及其在食品领域中的应用

天然淀粉中含有直链和支链两种形式的α-D-葡聚糖,二者的相对含量不仅与淀粉的糊化、老化、凝胶等理化性质和食品功能有关,还决定着淀粉的经济价值。淀粉直支比定量技术在含淀粉的粮谷类作物育种、淀粉的高值化利用以及食品品质保障和创新等领域具有广泛的应用。本文综述了当前食品科学研究和加工制造领域对淀粉直支比定量技术的需求,介绍和对比了各种经典和新型淀粉直支比定量技术的原理、优缺点和适用性,对淀粉直支比定量技术在未来食品领域的潜在应用提出展望。     

糙米复配粉中淀粉直/支比对挤压速食粥品质与结构的影响

糙米是一种营养丰富的全谷物食品,但较差的适口性、蒸煮性和消化性制约着其成为主流餐桌食品。为改善其食用品质,本文通过分析不同淀粉直/支比(0.176、0.196、0.216、0.236、0.256、0.276)糙米复配粉的原料特性以及其对挤压速食粥糊化特性、复水品质、质构特性与结构的影响,探究制作糙米挤压速食粥原料复配粉最优的淀粉直/支比。结果表明:随着淀粉直/支比的增加,糙米复配粉的糊化温度和峰值温度增加,挤压速食粥米粒横截面的光滑度及紧密度增加。当淀粉直/支比为0.256时,挤压速食粥米粒横截面的结构最均一、最紧密,复水时间达到12.6 min,米汤固形物损失率和径向膨胀率最小(0.153 g和2.282%),此时的硬度、胶着度和耐咀性明显高于淀粉直/支比0.276,达到3323.85 g、1242.76 g·s和744.73 g。可见,糙米复配粉中淀粉直/支比0.256为制作挤压速食粥的较佳比例。     

The effect of the structure of native banana starch from two varieties on its acid hydrolysis

Two banana starches were studied to analyze the effect of the acid hydrolysis on their molecular structure, and the impact in their physicochemical features. The native banana starches exhibit differences in the amylose content, molar mass, gelatinization parameters, X-ray diffraction pattern, and pasting profile. These results suggested that different acid hydrolysis mechanisms may be operative in these two starches. The kinetic hydrolysis is different in both banana starches that are related to the crystalline packing of the starch molecules. This was confirmed by the amylose content, the X-ray diffraction pattern, and the thermal study in the acid hydrolyzed starches at different times. The acid-treated Roatan starch showed higher retrogradation than Macho starch, a phenomenon that increases in the sample hydrolyzed for the longer time. This pattern is related to the amylose/amylopectin ratio, the reduction in the molar mass and the gyration radius. The acid hydrolysis of banana starches, although they have some similarities, they are different.     

60Co-γ射线及微波辐照双重作用下淀粉的结构表征

通过60Co-γ射线及微波双重辐照制备辐射变性淀粉,测试辐射变性淀粉的糊化温度及溶解度.同玉米原淀粉和H2O2氧化淀粉相比,γ辐射、微波改性亦能提高淀粉的糊化温度和溶解度,降低淀粉黏度;采用丁醇沉降法分别测定其直链、支链淀粉含量,得出辐射变性淀粉的直链淀粉含量高达58.9%,相比玉米原淀粉,辐射变性淀粉的支链淀粉的降解...     

Structure-viscosity relationships for starches from different rice varieties during heating

The effects of starch particle size and leached amylose on the viscosity of rice starch dispersions and changes of short-range structure and amylose content in starch granules of different rice varieties during heating were investigated. It was found that starch granule swelling increased rice starch dispersion viscosity during heating. The viscosities of the starch dispersions during heating were principally dependent on granular volume fraction and independent of starch variety. A distinct correlation between the amount of leached amylose and swelling of starch granules was also found. High initial amylose concentrations in starch granules reduced swelling during heating, thereby reducing rice dispersion viscosities. Fourier-transform IR spectroscopy indicated that the loss of short-range order was significant when the temperature reached the pasting onset temperature. The short-range order of waxy and medium grain rice starches was higher than that of long grain rice starches before gelatinization. The loss of order of waxy and medium grain rice starches was greater than that of long grain rice starches during heating, which was due to the presence of amylose, restraining the swelling and disruption of starch granules during heating.     

Comparison of Morphology and Physicochemical Properties of Starch Among 3 Arrowhead Varieties

Arrowhead (Sagittaria trifolia var. sinensis) is a source of starch worldwide, but arrowhead starch has been rarely studied. In this work, starch was separated from arrowhead corm. The morphology and physicochemical properties of starch were then investigated and compared among 3 different arrowhead varieties (Purple‐corm, Hongta, and Japanese). Results showed that starches from the 3 varieties similarly featured an oval shape containing a visible polarization cross, a C_A‐type crystalline structure, and an ordered structure in the external granule region. However, starch content, granule size, crystal characteristics, and pasting properties differed among the 3 varieties. Japanese arrowhead exhibited the highest starch content and degree of ordered structure in the external granule region, as well as onset, peak, and final gelatinization temperature. Purple‐corm arrowhead starch demonstrated the highest amylose content and relative degree of crystallinity, smallest granule size, and lowest swelling power and solubility. Purple‐corm arrowhead starch also showed the highest gelatinization enthalpy, as well as peak, trough, final, and setback viscosities. This starch further presented the lowest breakdown viscosity and degree of hydrolysis by HCl and porcine pancreatic α‐amylase. These findings can provide useful references for arrowhead variety selection in food and nonfood industries.     

Characterization of Residues from Partially Hydrolyzed Potato and High Amylose Corn Starches by Pancreatic α‐Amylase

High amylose corn starch (HACS) and potato starch were hydrolyzed by pancreatic α‐amylase in vitro. Residues after hydrolysis were collected and characterized for their physicochemical properties and molecular structure. Compared with raw starches, residues had lower apparent amylose contents and higher resistant starch contents. The gelatinization enthalpy of residues from HACS increased while enthalpy of residues from potato starch decreased from 15.4 to 11.3 J/g. Peak viscosity and breakdown values of the residues from potato starch were markedly decreased but final viscosity values did not show much change. Chain length distribution of debranched amylopectin from the residues indicated that the relative portion of short chain in the residue decreased for both starches. More molecules with intermediate chain length (DP 16—31) were found in residue after 48‐h hydrolysis of potato starch.     

Rice Starch Molecular Size and its Relationship with Amylose Content

The composition and starch molecular structure of eight rice varieties were studied. Waxy and non‐waxy (long‐, medium‐, and short‐grain) rice varieties from California and Texas were used. The amylose contents were measured using the Concanavalin A method and were found to be related to the type of rice: waxy ≈ 1.0%, short and medium grain 8.7–15.4%, and long grain 17.1–19.9%. The weight‐average molar masses (M_w) of the starches varied from 0.52 to 1.96×10⁸ g/mol. As would be expected, a higher M_w of rice starch correlated to lower amylose content. The range of M_w of amylopectin was 0.82 to 2.50 ×10⁸ g/mol, and there was also a negative correlation of amylopectin M_w with amylose content. Amylose M_w ranged from 2.20 to 8.31×10⁵ g/mol. After debranching the amylopectin with isoamylase, the weight‐average degree of polymerization (DP_w) for the long‐chain fraction correlated positively with a higher amylose content. California and Texas varieties were significantly different in their amylose content, starch M_w (short‐ and medium‐grain only), and amylopectin M_w (p < 0.05).     

Wheat starch production,structure, functionality and applications—a review

Starch is the main component of wheat having a number of food and industrial applications. Thousands of cultivars/varieties of different wheat types and species differing in starch functionality (thermal, retrogradation, pasting and nutritional properties) are grown throughout the world. These properties are related to starch composition, morphology and structure, which vary with genetics, agronomic and environmental conditions. Starches from soft wheat contain high amounts of surface lipids and proteins and exhibit lower paste viscosity, whereas that from hard cultivars contain high proportion of small granules and amylose content but lower gelatinization temperature and enthalpy. Waxy starches exhibit higher‐percentage crystallinity, gelatinization temperatures, swelling power, paste viscosities and digestibility, but lower‐setback viscosity, rate of retrogradation and levels of starch lipids and proteins than normal and high‐amylose starches. Starches with high levels of lipids are less susceptible towards gelatinization, swelling and retrogradation and are good source of resistant starch, while that with high proportion of long amylopectin chains are more crystalline, gelatinize at high temperatures, increase paste viscosity, retrograde to a greater extent and decrease starch digestibility (high resistant and slowly digestible starch and low rapidly digestible starch).