糯小麦粉特性研究进展

由于糯小麦粉几乎不含直链淀粉,所以在食品工业和非食品工业上将有重要的应用价值.综述了近几年国内外糯小麦育种、糯小麦淀粉特性和糯小麦配粉研究进展.并阐述了其在食品工业中的开发和应用.     

糯小麦及其淀粉的研究和利用概况

糯小麦是一类直链淀粉含量极低的天然淀粉资源,糯小麦及其淀粉的研究和利用对我国粮食工业、食品工业、淀粉工业及相关产业具有积极的推动作用。综述了糯小麦的产生途径和品质特性,阐述了糯小麦淀粉的品质特性,并对糯小麦的发展及研究提出几点建议,为糯小麦的遗传育种、品质评价和精深加工提供理论参考。     

糯小麦品质特性与应用

简述了糯小麦淀粉特性与糯小麦粉品质特性,总结糯小麦在食品工业中的应用,并分析糯小麦的品质特性对食品的影响.     

糯性普通小麦的籽粒成分和淀粉品质研究

对5个组合的13个糯麦F6（或F5）株系及其亲本的籽粒成分，直链淀粉含量和膨胀势进行测定，以及分析了它们的淀粉糊化过程和糊化参数，比较它们之间的差异。结果表明：糯性小麦籽粒的蛋白质含量，湿面筋含量均高于相应的亲本，而淀粉含量则低于相应的亲本，糯性小麦株系的直链淀粉含量远远低于其亲本；糯麦淀粉的膨胀能力和吸水力大于其亲本；糯麦株系的RVA高峰粘度，低谷粘度，最后粘度，反弹值和峰值时间显著低于其亲本。糯麦株系面粉间的RVA粘度参数值大同小异，讨论了糯性小麦的应用前景。     

糯小麦淀粉品质特性研究

以糯小麦5017为材料,小偃6号作对照,对糯小麦A、B淀粉的直链淀粉含量及其他淀粉品质特性进行了研究.结果表明,糯小麦淀粉颗粒呈现明显的偏光十字,且A淀粉粒大于B淀粉粒;糯小麦A、B淀粉直链淀粉含量极低,分别为2.81%、0.30%,其直链淀粉含量的大幅度降低导致膨胀特性发生了改变;糯小麦淀粉糊对热不稳定,且不易形成凝胶,老化速度慢,糊透明度不高,但冻融稳定性较好.     

不同品种小麦粉黏度特性及破损淀粉含量的差异

以不同专用小麦以及直链淀粉含量极低的糯小麦为试验材料,研究不同品种之间小麦粉黏度特性和破损淀粉含量的差异及其相关性。结果表明,不同专用小麦之间,RVA图谱存在明显差异,糯小麦RVA图谱形状显著不同于非糯小麦。各专用品种小麦粉RVA谱线特征值中,小麦粉峰值黏度、稀懈值大小表现为弱筋小麦>中筋小麦>强筋小麦>糯小麦。破损淀粉含量在不同专用小麦品种之间大小顺序表现为:强筋小麦>中筋小麦>弱筋小麦>糯小麦。相关分析表明,峰值黏度、低谷黏度、最终黏度、反弹值以及峰值时间均与直链淀粉含量、直/支比例以及破损淀粉含量呈极显著正相关。     

乳化剂对糯小麦淀粉老化特性的影响

老化对淀粉的生理效价和生物降解具有决定性作用,糊化淀粉在存放过程中,淀粉分子发生自组,其直链淀粉及支链淀粉的直线部分趋向于平行排列,从无定形态回复到晶体态,出现老化现象,会导致淀粉基生物材料产品的品质和性能大幅降低。本课题对直链淀粉含量、水分含量及乳化剂种类对糯质小麦淀粉老化特性的影响进行研究,比较乳化剂对糯质小麦淀粉及普通小麦淀粉老化特性影响的异同。结果表明:直链淀粉的含量、水分含量都与糊化淀粉的老化程度呈正相关。直链淀粉的含量是决定淀粉老化程度的最主要因素,乳化剂与淀粉分子相互作用形成稳定的复合物,减缓了淀粉的老化。同时乳化剂的复配能一定程度地加强抗老化的效果。总体上讲,糯质小麦淀粉的各种良好的理化特性,使其在淀粉基生物材料抗老化上有更好的应用前景。     

糯小麦淀粉形态及内部结构的研究

利用偏光显微镜、扫描电镜和X射线衍射仪和激光共聚焦显微镜对糯小麦淀粉和普通小麦淀粉的颗粒形貌、结晶性质和内部结构进行了对比研究和分析。结果表明:糯小麦淀粉和普通小麦在颗粒形貌、颗粒大小分布、结晶结构和内部结构方面具有相似的性质。与普通小麦淀粉相比,糯小麦淀粉颗粒表面不平滑,存在较多凹坑,且能够观察到明显的微孔;两种小麦淀粉A型颗粒直径基本相同,但糯小麦淀粉B型颗粒直径小于普通小麦淀粉;糯小麦淀粉和普通小麦淀粉均呈现典型的A型结晶特征,但糯小麦淀粉的相对结晶度高于普通小麦淀粉;两种淀粉均呈现生长环结构,直链淀粉主要集中在颗粒中心部位。     

糯小麦淀粉分子-碘包合物的研究

本文通过测定糯小麦淀粉、糯玉米淀粉和谷物淀粉与碘结合后的吸收光谱，发现直链淀粉分子和支链淀粉分子在与碘分子形成包合物时存在结合速率（结合顺序）的差异。即直链淀粉首先与碘结合，只有当碘液的添加量足够大，与直链淀粉充分结合后仍剩余有一定量时，支链淀粉才与碘结合。同时，本文测定了几种糯小麦淀粉的直链淀粉分子含量，发现不同文献测量值之间的差异是计算基准不同造成的。     

表观直链淀粉含量对小麦淀粉凝胶流变特性影响的研究

探讨表观直链淀粉在小麦淀粉凝胶的流变学特性中的作用,寻找表观直链淀粉含量与流变特性参数间的相关性。运用动态流变仪对9种不同品种小麦淀粉的糊化和短期回生进行分析,找出流变特性参数,并运用SPSS分析其相关性。在表观直链淀粉含量相差较大的情况下,结合糯小麦淀粉来考察,直链淀粉对于升温、降温、时间扫描和频率扫描等过程的流变特性有着重要的影响;当直链含量相差较小时,在8个普通小麦品种间,直链淀粉对与降温过程和凝胶形成强度有着决定性的影响。在整个短期回生过程中,表观直链淀粉含量直接决定凝胶的流变特性,但是在表征流变特性上有一定的局限性。     

宁糯1~#小麦粉在LL面专用粉中应用研究

由于糯小麦几乎不含直链淀粉,所以在食品工业和非食品工业具有重要应用价值。小麦粉面团粘弹性与小麦粉中直链淀粉含量呈有较大关系,小麦粉直链淀粉含量适中或偏低时,制成面条具有较好韧性和食用品质;直链淀粉增加,面条硬度增加、持水力和粘弹性下降,调整直、支链淀粉比例,能改善面条质地、增加粘弹性。该文报道糯小麦粉在LL–面专用粉中配粉应用,及采用宁糯1#小麦粉替代部分淀粉后LL–面品质变化等研究,以期为面条专用粉配粉研究提供新的思路。     

Physicochemical and Functional Properties of Tetraploid and Hexaploid Waxy Wheat Starch

Waxy wheats possess unique starch functional properties that may be useful in specific end‐uses. To assess the physicochemical, thermal, and pasting properties, starches from seven waxy genotypes originating from two wheat classes, tetraploid durum and hexaploid hard red spring (HRS), were evaluated and compared with their counterpart non‐waxy wild types. The amylose content ranged from 2.3% to 2.6% in waxy durum lines, compared to 29.2% in normal durum control, and 2.1% to 2.4% in waxy HRS, compared with 26.0% in normal HRS control. Significant differences in the degree of crystallinity were observed between the waxy and control starches, despite similar A‐type X‐ray patterns, although differences between the two wheat classes were non‐significant. Both, control and waxy starches displayed an X‐ray peak corresponding to the amylose‐lipid complex, but the intensity of the peak was markedly lower in the waxy starches. The waxy durum starches exhibited the highest transition temperatures as measured by Differential Scanning Calorimetry (DSC), whereas, the enthalpy of gelatinization of most waxy genotypes was statistically higher than that of the controls. All waxy starches displayed high peak viscosity, high breakdown, and low setback profile as measured by the Rapid Visco Analyser (RVA). Texture analysis of RVA gels revealed significant differences between waxy and non‐waxy wheats, as well as between waxy tetraploid and hexaploid wheats, confirming that the nature and class of wheat starch would play a significant role when using waxy wheat blends in different wheat‐based products.     

Low‐ and Medium‐DE Maltodextrins From Waxy Wheat Starch: Preparation and Properties

The goal of the research was to prepare maltodextrins (MD) from waxy wheat starch and waxy corn starch (control). Waxy wheat starches with 0.2% protein, 0.2% lipid and ∼1% amylose were isolated from two flours by mixing a dough, dispersing the dough in excess water, and separating the starch and gluten from the resultant dispersion. The mean recoveries were 72% for the starches and 76% for the gluten fraction with 80% protein. Maltodextrins having low‐dextrose equivalence (DE) 1—2 and mid‐DE 9—10 were prepared by treatment of 15% slurries of waxy wheat starch and waxy corn starch at 95 °C for 5—10 min and 20—50 min, respectively, with a heat‐stable α‐amylase. Denaturing the enzyme and spray‐drying produced MD's with bulk densities of 0.3 g/cm ³. The powdery MD's were subjected to an accelerated‐rancidity development test at 60 °C, and an off‐odor was detected after 2 days storage for the low‐DE MD's from the two waxy wheat starches (WxWS₁‐MD 1.2 and WxWS₂‐MD 1.5), but not for the low‐DE waxy corn maltodextrin (WxCS‐MD 2.2) or a commercial waxy corn MD with DE 1. None of the mid‐DE 9—10 MD's developed off‐odor after 30 days storage at 60 °C. The experimental products WxWS₁‐MD 9.2, WxWS₂‐MD 9.9 and WxCS‐MD 9.1 showed high water‐solubility and gave 1—10% aqueous solutions of high clarity with no clouding upon cooling.     

复合酶法改性糯麦A-、B-型淀粉及对其结构和消化特性的影响

以从糯麦淀粉中分离所得的A-、B-型淀粉为研究对象,并以此作为受体,高直链玉米淀粉为供体,利用普鲁兰酶和分支酶协同处理对糯麦淀粉进行改性,测定其颗粒形态、结晶结构以及表观直链淀粉含量、溶解度、膨胀力等理化性质,并对其消化特性进行考察。结果表明：采用普鲁兰酶和分支酶两种复合酶法改性的糯麦A-、B-型淀粉,其预测血糖指数显著降低,表观直链淀粉含量显著增加、溶解度随着温度的增加而变大,膨胀力随着温度的增加基本保持不变。采用扫描电子显微镜观察到酶法改性后的淀粉颗粒形态出现孔洞结构,利用X射线衍射和傅里叶红外光谱分析相对结晶度和1 047 cm－1/1 022 cm－1处的比值可得,复合酶改性淀粉的长程有序结构和短程有序结构显著改善。通过普鲁兰酶预处理后再用分支酶改性,对糯麦A-型和B-型淀粉进行结构修饰,能够显著改善其消化特性。     

3种玉米淀粉的性质比较

研究了高直链玉米淀粉、糯玉米淀粉、普通玉米淀粉的粒度分布、糊流变、质构、冻融稳定性等物理化学性质,结果表明:3种玉米淀粉的颗粒形状差异不大。高直链玉米淀粉的粒度分布一致性较高,同样条件下糯玉米淀粉糊粘度大于其他2种淀粉,糯玉米淀粉的冻融稳定性大于普通玉米淀粉和高直链玉米淀粉,为玉米淀粉在食品中的应用奠定了基础。     

Multi‐scale structural and digestion properties of wheat starches with different amylose contents

The physicochemical and digestion properties of three wheat starches with different amylose contents were studied. Scanning electron microscopy (SEM) showed they displayed a spherical disc‐like form, a lenticular shape and an irregular morphology, respectively. Compared with waxy and normal wheat starches, high‐amylose wheat starch (HAWS) was characterised by the presence of lower molecular weight amylose fraction, and its granules demonstrated the highest resistance to the cooking. The changes in the IR ratio 1022/999–1047/1022 cm^?1 following the gel storage suggested the molecules of HAWS are more readily to re‐associate and re‐organise into a more organised status than other two starches. The determination of glucose release showed that HAWS had the lowest digestion kinetics (P < 0.001), and this difference in the digestion properties between HAWS and the other two starches might imply that starch molecular structure, in particular amylose structure is another key factor for manipulating starch digestion property rather than amylose content alone.