淀粉链/支比对淀粉-壳聚糖交联薄膜结构及性质的影响

本文以4种玉米淀粉(waxy、normal、G50、G80)制备淀粉-壳聚糖交联薄膜,利用扫描电子显微镜(SEM)、红外光谱分析仪(FTIR)、X-射线衍射仪(XRD)、接触角仪(CA)及热重分析仪(TGA)探讨了不同淀粉-壳聚糖交联薄膜的结构和性质差异。结果表明,壳聚糖自交联薄膜的断面易产生孔洞,而淀粉-壳聚糖交联薄膜断面中无孔洞结构;随着直链淀粉含量升高,交联薄膜断面的粗糙形貌更加明显。在交联体系中,壳聚糖与淀粉分子形成新的氢键,G50、G80自交联薄膜在2θ=17.36°附近弱衍射峰消失,4种淀粉-壳聚糖交联薄膜整体均呈无定型态;壳聚糖自交联薄膜的水接触角CA=76.57°±1.35°,不同链/支比淀粉与壳聚糖交联后,淀粉-壳聚糖交联薄膜的接触角均增大,且支链淀粉含量越高,薄膜的亲水性越强;同时,淀粉-壳聚糖交联薄膜的热稳定性低于壳聚糖或淀粉自交联薄膜。以上结果可为淀粉-壳聚糖交联薄膜在食品包装中的合理应用提供参考。     

淀粉-脂肪酸复合物的研究进展

文章综述了淀粉-脂肪酸复合物的复合机理、制备方法及条件,重点讨论了影响淀粉-脂肪酸复合物形成的因素,发现淀粉结构、脂质结构、脂质浓度以及不同工艺参数对淀粉-脂肪酸复合物的影响很大,并以此为基础探究复合物对淀粉性质的影响,综述了淀粉-脂质复合物在淀粉基食品中的应用进展,以期为进一步推广和完善淀粉-脂质复合物在食品工业中的应用提供参考。     

锥栗直链淀粉-脂肪酸复合物的结构特性

以自制锥栗直链淀粉为原料,利用DMSO水溶法在3种不同结晶温度下(30、60、90℃)制备己酸、葵酸、硬脂酸的直链淀粉-脂肪酸复合物,并对其结构特性进行了研究。试验结果表明:与锥栗直链淀粉比较,锥栗直链淀粉-脂肪酸复合物的吸水率、碘亲合力、蓝值、微晶比例与结晶度都下降;就己酸、葵酸、硬脂酸而言,较长的链长或较高的温度均有利于复合物的形成与稳定;锥栗直链淀粉-脂肪酸复合物属于典型的V型晶体,且它们的微晶比例、结晶度与脂肪酸性质有关,同一温度下制备的不同脂肪酸复合物,其微晶比例与结晶度均随脂肪酸碳链增长而降低;同种脂肪酸与锥栗直链淀粉形成的复合物,其微晶比例与结晶度则随复合物形成温度升高而降低。     

脂肪酸的链长和不饱和度对脂肪酸-普通玉米淀粉复合物理化性质的影响

为探讨脂肪酸对玉米淀粉性质的影响,采用快速黏度分析仪、差示扫描量热仪及动态流变仪研究了6种不同链长和不饱和程度的脂肪酸对普通玉米淀粉糊化性质、热学性质及流变学性质的影响。研究结果表明,添加6种脂肪酸对普通玉米淀粉的糊化温度无明显影响,可使普通玉米淀粉的峰值黏度约下降8.22%~14.71%。除棕榈酸外,其余脂肪酸均能使普通玉米淀粉的糊化焓值降低,脂肪酸碳链越短,不饱和度越低,普通玉米淀粉的糊化焓值越低。共轭亚油酸-普通玉米淀粉复合物的抗老化效果最好,添加共轭亚油酸使原淀粉长期老化率约下降28.36%。随着脂肪酸不饱和度的增加,普通玉米淀粉的表观黏度逐渐增加。添加6种脂肪酸使普通玉米淀粉的tanδ降低,有利于其弹性凝胶的形成。     

脂肪酸碳链长度与不饱和度对脂肪酸-普通玉米淀粉包合物体外消化性质的影响

采用HCl/KOH法制备了脂肪酸-普通玉米淀粉包合物,并采用水解度曲线法测定了包合物的体外消化性质,利用X-射线衍射仪、红外变换光谱分析仪分析了包合物的结晶结构。研究表明,7种脂肪酸均在结晶温度为60℃时与玉米淀粉的复合能力最强。除亚麻酸外,玉米淀粉与其余6种脂肪酸的最佳复合比例均为10:1。不同脂肪酸与玉米淀粉形成包合物所需时间不同。脂肪酸与普通玉米淀粉的复合能力随脂肪酸链长及不饱和度的增加逐渐减弱。随着脂肪酸链长及不饱和度的增加,脂肪酸-玉米淀粉包合物的缓慢消化淀粉含量增加,水解率、相对消化率和血糖指数均降低。普通玉米淀粉与脂肪酸复合之后,晶型由A型转变为VI型,结晶度随脂肪酸链长及不饱和度增加而逐渐降低。红外光谱分析结果也表明普通玉米淀粉与脂肪酸形成了络合物。     

淀粉结晶结构对淀粉水解过程的影响

本文采用广角Ｘ射线衍射分析技术研究了玉米原淀粉以及超声波，电场，磁场作用后的玉米淀粉微晶的组成，性质及其变化规律，测试了玉米淀粉在不同物理场作用下基本晶体参数，研究了不同物理场对淀粉结晶结构的影响情况。     

脂肪酸链长对高直链玉米淀粉—脂质复合物结构及理化性质的影响

目的：探究淀粉—脂质复合物的形成机理。方法：采用12~18个碳链的脂肪酸与脱支/非脱支高直链玉米淀粉复合,利用差示扫描量热仪、X-射线衍射仪、傅里叶红外光谱仪等分析复合物的热特性、结晶结构及有序结构等,探究脂肪酸链长及脱支/非脱支高直链玉米淀粉对淀粉—脂肪酸复合物结构及性质的影响。结果：脱支处理的淀粉与脂肪酸的复合率随碳链的增长而降低,其中月桂酸复合率最高(15.00%);未脱支处理的淀粉与脂肪酸的复合率随碳链的增长先升高后下降,其中软脂酸复合率(13.73%)最高。复合物的热特性、结晶结构、分子有序度等与其复合程度有关,淀粉和脂肪酸复合后,糊化峰值温度升高,热稳定性升高,经复合后,淀粉由B型结晶结构转变为V型。结论：脂肪酸链长及淀粉脱支对淀粉—脂质复合物结构及理化性质具有较大影响。     

淀粉-配体复合物的制备及结晶结构研究

以B-型微晶淀粉为原料,经二甲亚砜溶解后,分散到热水中,随后加入一定比例的硬脂酸、单硬脂酸甘油脂、棕榈酸和异戊醇的乙醇溶液中,再经过混合、结晶、离心分离、洗涤,制得淀粉-配体复合物。采用X-射线衍射仪对得到的复合物进行分析和测试,结果发现在单硬脂酸甘油脂∶淀粉质量比为1∶4的和硬脂酸∶淀粉质量比为1∶5的条件下制备的V-型复合物的晶型结构最优。     

球磨对绿豆淀粉结晶结构和糊流变特性的影响

采用偏光显微镜、X-射线衍射等测试方法，研究了绿豆淀粉在机械球磨过程中结晶结构的变化；运用Brookfield旋转粘度计测得不同浓度的淀粉糊在不同温度和剪切速率下的表观粘度，建立了相应的流变模型。结果表明机械球磨使得淀粉结晶结构受到破坏，由多晶态转变成无定形态；经球磨处理的绿豆淀粉糊仍保持假塑性流体特征，但随着球磨程度的增大，糊稠度大大降低，流动性增加，且越来越趋向牛顿流体特征。     

不同链淀粉含量玉米微晶淀粉理化性质研究

分别以蜡质玉米淀粉、玉米淀粉及高直链玉米淀粉为原料,在酸醇介质中制备不同水解率微晶淀粉,测定不同微晶淀粉水解性能并研究其颗粒形貌、结晶结构、溶解度及消化性。结果表明:淀粉颗粒内部结构致密性依次减弱,支链淀粉含量高的淀粉较易被试剂进攻;经酸醇处理后,三种微晶淀粉均保留原来晶型,颗粒形态没明显变化,没破碎和膨胀出现,但颗粒表面变粗糙;随直链淀粉含量增加,相似条件(水解率和温度)淀粉溶解度逐渐降低;in-vitro消化体系中三种淀粉及其微晶淀粉消化速度依次降低。     

The Influence of Environment on Starch Content and Amylose to Amylopectin Ratio in Wheat

There is evidence that starch content plays an active role in determining dough rheological characteristics. The aim of this study was to determine the influence of environment on starch content and amylose: amylopectin ratio, and how this affects breadmaking quality. Ten hard red spring wheat cultivars were planted in three different environments in a randomized complete block design with three replications. Total starch content, amylose: amylopectin ratio, milling, rheological and baking characteristics were measured. Starch content was significantly influenced by the environment. It was significantly negatively correlated with loaf volume, wet gluten content and flour protein content across the three environments. Starch content and protein content were significantly negatively correlated, yet the value was relatively small (r = −0.4) and the relationship was therefore not directly inverse, and other factors influenced this relationship. Some cultivars interacted with specific environments, and they ranked high for starch content and loaf volume. Amylose: amylopectin ratio was very consistent for the three environments but was not significantly correlated with breadmaking quality characteristics across the environments, although there were significant correlations at individual environments. Cultivar choice and environment where cultivars are planted will therefore affect the starch content. High starch content will not necessarily lead to poor baking quality.     

脂肪酸不饱和度对高直链玉米淀粉-脂肪酸复合物结构和热性能的影响

本文研究了脂肪酸不饱和度对高直链玉米淀粉-脂肪酸复合物热性能、微观结构、粒径分布及Zeta电位的影响。结果表明,高直链玉米淀粉与脂肪酸形成复合物后热稳定性降低,且复合物的热稳定性随脂肪酸不饱和度的增加而降低;高直链玉米淀粉与脂肪酸形成复合物的结晶结构为V型,结晶度随着不饱和度的增加而减小;高直链玉米淀粉-脂肪酸复合物有两种存在形式,分别为颗粒表面凸起的球晶和嵌在颗粒表面的层状或絮状结构,后者存在形式随脂肪酸中双键个数的增加而减少;高直链玉米淀粉与脂肪酸形成复合物后淀粉颗粒变小,分散液稳定性增加。总之,脂肪酸不饱和度对高直链玉米淀粉-脂肪酸复合物的结构和热性能具有明显影响。     

Effect of amylose/amylopectin ratio and extent of processing on the physical properties of expanded maize starches

Low-density expanded starchy products are often desirable, particularly in the snack food industry. Levels of shear and amylose are often deemed crucial factors for expansion. In this study, maize starches containing low (waxy), normal and high levels of amylose were compared after processing. Low shear processing used a popping head (similar to a rice-cake machine), while high shear (~450 kJ kg⁻¹) samples (pellets and directly expanded) were created using twin-screw thermomechanical extrusion. Native starches and ground extruded materials (<106 µm) were popped using the same conditions (230 °C, 4 s, water content 12% wwb). All samples tested created fused aerated cakes, which had little or no remaining crystallinity, except for the directly popped waxy sample, which retained ~17% of its original crystallinity. Water absorbances and solubilities were influenced greatly by the starch source and marginally by the amount of processing. On processing, waxy samples showed increased solubility while those with normal amylose content had greater absorption. The densities of all the popped samples were similar despite marked differences in shear regime history and the major variations in the amylose and amylopectin ratios. These results challenge the expected relationships between shear and different starches’ potential to expand.     

甘薯块根膨大过程中质构特性和淀粉直/支比的研究

甘薯块根膨大过程中质构特性和淀粉组分的变化对甘薯的品质和用途有着重要影响。本研究选取3种甘薯类型和4个时期,通过质地多面分析法(TPA)和双波长碘比色法,分析其质构特性和淀粉直链淀粉和支链淀粉比值(淀粉直/支比)随块根膨大的变化规律。结果表明,甘薯淀粉直/支比在扦插后80天开始下降,至扦插后110天达到谷值,之后小幅回升;整体上,甘薯扦插后的天数与淀粉直/支比、内聚性和弹性呈显著负相关(r =-0.390, r= -0.367, P <0.05;r= -0.634, P <0.01);与硬度呈显著正相关(r= 0.590, P <0.01)。淀粉直/支比与块根的内聚性、弹性和咀嚼性呈显著正相关(r =0.368, P <0.05; r= 0.463, r= 0.642, P <0.01);综合分析发现,扦插后80~110天（块根膨大高峰期至膨大后期）收获的甘薯适合水果型(生食型)甘薯的开发。     

直链淀粉/支链淀粉比例对酯化淀粉薄膜增塑剂迁移的影响

通过选择不同直链淀粉/支链淀粉比例的酯化淀粉,制备了不同结构特征的淀粉基薄膜,并对这些结构对抑制增塑剂邻苯二甲酸二乙酯(DEP)在微波条件下迁移的影响进行了研究。结果表明,直链淀粉/支链淀粉比例为零的waxy酯化淀粉薄膜材料中分子间相互作用力强,有序微区尺寸较大,抑制DEP迁移的程度最大。直链淀粉/支链淀粉比例为50%的G50酯化淀粉薄膜材料中,分子间相互作用力虽弱,但较大的有序微区及内部致密的结构起到了较好地限制增塑剂迁移的作用。直链淀粉/支链淀粉比例为80%的G80酯化淀粉薄膜材料中虽微晶存在,但分子间相互作用力较弱、有序微区尺寸小、增塑剂迁移量最大。因此,可以通过改变直链淀粉与支链淀粉的比例来降低酯化淀粉薄膜中增塑剂的迁移,为更好地合理设计及安全使用淀粉基薄膜材料提供了基础数据及理论依据。     

Rheological properties and phase transition of cornstarches with different amylose/amylopectin ratios under shear stress

The rheological properties and phase transition of cornstarch with low moisture content under shear stress was investigated using a mixer with twin‐roller rotors by the variation of torque as functions of temperature and time. Cornstarches with different AM/AP ratios (wx: 4:96, maize: 29:71, Gelose 50: 62:38, and Gelose 80: 77:23) were used as model materials in the experimental work. The results showed that, as the AM content increased from 0 to 77%, the maximum torque increased from about 54 to 66 N/m and the final torque increased from about 27 to 47 N/m, respectively, and a longer mixing time was required to achieve a stable state (constant torque value). Microscopic and differential scanning calorimetry (DSC) studies showed that the phase transition reflected by changes of birefringence and endotherms could well be associated with the torque curve measured by the mixer. The higher gelatinization temperatures of the starches with higher AM content, and especially the existence of multi‐phase transitions at high temperatures, could explain the rheological behaviors detected by the mixer. The technique can be used to study the starch melting and destructuration under shear stress with low moisture content (<45%), which represents the most of extrusion conditions for starch‐based materials.     

Effect of Acid Hydrolysis on Starch Structure and Functionality: A Review

Acid hydrolysis is an important chemical modification that can significantly change the structural and functional properties of starch without disrupting its granular morphology.

A deep understanding of the effect of acid hydrolysis on starch structure and functionality is of great importance for starch scientific research and its industrial applications. During acid hydrolysis, amorphous regions are hydrolyzed preferentially, which enhances the crystallinity and double helical content of acid hydrolyzed starch. This review discusses current understanding of the effect of acid hydrolysis on starch structure and functionality. The effects of acid hydrolysis on amylose content, chain length distribution of amylopectin molecules, molecular and crystalline organization (including lamellar structure) and granular morphology are considered. Functional properties discussed include swelling power, gelatinization, retrogradation, pasting, gel texture, and in vitro enzyme digestibility. The paper also highlights some promising applications of acid hydrolyzed starch (starch nanocrystals) in the preparation of biodegradable nanocomposites, bio-hydrogen, and slowly digestible starch-based healthy foods.     

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。