海藻酸钠胶凝与大米淀粉糊化共存体系的构建

为探究浓缩诱导型海藻酸钠凝胶对大米淀粉糊化与回生特性的影响,主要用流变学方法确定浓缩诱导型海藻酸钠-钙离子凝胶的制备条件和淀粉的添加量,从而构建出海藻酸钠胶凝与淀粉糊化共存体系。结果表明：海藻酸钠溶液质量浓度为1?g/100?mL,钙离子溶液浓度为3?mmol/L时,热处理引起的水分蒸发作用使海藻酸钠-钙离子体系由初始的溶液状态（储存模量（G’）＜损耗模量（G”））转变成最终的凝胶状态（G’＞G”）,胶凝临界点的钙离子浓度为5.1?mmol/L。当淀粉质量浓度在4～6?g/100?mL之间时,淀粉与海藻酸钠-钙离子混合体系不仅由水分蒸发前的溶液状态（δ＞45°）转变为水分蒸发30?min后的似固态（δ＜45°）,并且具有良好的制备操作性。在以上配比条件下制备的淀粉与海藻酸钠-钙离子样品体系经过水分蒸发作用后在扫描电子显微镜下呈现紧密连结成片的网状结构,并且G’值上升、n值下降,证明按照上述浓度配制的体系能在水分蒸发过程中形成海藻酸钠胶凝与淀粉糊化共存体系。     

Retrogradation of Starch Mixtures Containing Rice Starch

ABSTRACT: Different starches often coexist in food systems. Starch retrogradation is the primary reason for quality deterioration of a food system during storage. This article addresses the retrogradation behaviors of several starch mixtures containing normal rice starch (NRS). Potato starch, tapioca starch, waxy corn starch, hydroxypropylated potato starch, hydroxypropylated tapioca starch, and acetylated tapioca starch were mixed with NRS. Starch suspensions were gelatinized and the relative solid content, (S′) measured by pulsed nuclear magnetic resonance, was used to characterize the retrogradation behavior of starch systems. The retrogradation behaviors of starch mixtures can be divided into two categories according to the additive or non‐additive nature of S′, for which the concept “regional moisture content” was introduced.     

贵州主产区不同品种荞麦淀粉性能的比较

选取贵州省主产区威宁县种植的11 种荞麦提取淀粉,测定了不同品种荞麦淀粉的理化性能、流变性能及体外模拟消化.结果表明,不同品种荞麦淀粉在理化、流变及消化性上均呈现出一定的差异性.其中,黔苦8 号、黔苦5号、贵甜荞1 号、贵黑米16 号荞麦淀粉具有较高的透明度;定苦1 号、黔黑荞1 号、黔苦3 号荞麦淀粉呈现较好的冻融稳...     

Studies on Varagu Starch

Starch has been isolated from the millet varagu in 63% yield. Study of the physical properties revealed: moderate swelling and low solubility power in water; extensive solubility in dimethyl sulfoxide, probably indicative of easy solvent penetration due to labile and heterogeneous bonding forces within the granule. Brabender amylogram indicated little retrogradation on cooling, owing to strong bonding between the linear and branched molecules of starch. The amylose content of the starch was 24% as determined by paper chromatographic fractionation and “Blue value” method.     

A novel size-exclusion high performance liquid chromatography (SE-HPLC) method for measuring degree of amylose retrogradation in rice starch

The objective of this study was to develop a new method to measure the degree of amylose retrogradation in rice starch using size-exclusion high performance liquid chromatography (SE-HPLC). This developed method is based on the change in molecule size related to the retention time of amylose. Results showed that SE-HPLC was able to provide accurate data to evaluate the amylose retrogradation by comparing with other well-established methods. The principle of the measurement was further studied in molecular level by molecular dynamic (MD) simulation. It indicated that amylose molecules were transformed from disordering configuration to ordering one due to the increase in Van der Waals (Vdw) and hydrogen forces, and decrease in bonded interaction during the short-term storage.     

The “Food Polymer Science” approach to the practice of industrial R&D,leading to patent estates based on fundamental starch science and technology

This article reviews the application of the “Food Polymer Science” approach to the practice of industrial R&D, leading to patent estates based on fundamental starch science and technology. The areas of patents and patented technologies reviewed here include: (a) soft-from-the-freezer ice creams and freezer-storage-stable frozen bread dough products, based on “cryostabilization technology” of frozen foods, utilizing commercial starch hydrolysis products (SHPs); (b) glassy-matrix encapsulation technology for flavors and other volatiles, based on structure-function relationships for commercial SHPs; (c) production of stabilized whole-grain wheat flours for biscuit products, based on the application of “solvent retention capacity” technology to develop flours with reduced damaged starch; (d) production of improved-quality, low-moisture cookies and crackers, based on pentosanase enzyme technology; (e) production of “baked-not-fried,” chip-like, starch-based snack products, based on the use of commercial modified-starch ingredients with selected functionality; (f) accelerated staling of a starch-based food product from baked bread crumb, based on the kinetics of starch retrogradation, treated as a crystallization process for a partially crystalline glassy polymer system; and (g) a process for producing an enzyme-resistant starch, for use as a reduced-calorie flour replacer in a wide range of grain-based food products, including cookies, extruded expanded snacks, and breakfast cereals.     

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).     

Starch Functionality in Cookie Systems

To study the function of starch in cookie baking, starch was isolated from a cookie flour and from cookies baked with the flour. Viscograms of starches indicated no detectable changes caused by cookie processing. Swelling power, solubility, gelatinization temperature range and enzyme susceptibility were unchanged by cookie preparation. X-ray diffraction patterns of starch isolated from cookies showed a strong “A” pattern. The starch was not affected by the baking process. Differential scanning calorimetry showed no apparent differences in phase transition peaks. Starch-gluten breads produced were of similar volume and quality characteristics. It was concluded that a) starch granules remain in their native condition during cookie baking, b) starch does not form a continuous structure in cookies and c) retrogradation cannot occur during cookie storage.     

Studies on Chemical Modifications in Heat-processed Starch and Wheat Flour

1,6-Anhydro-β-D -glucopyranose (levoglucosan) and oligosaccharides with these end units were present in 80% aqueous ethanol extracts from heat-processed starch and wheat flour. Evidence was adduced that the 1,6-anhydro-D -glucose units react further with starch and starch fragmentation products by external trans-glycosidation reactions to give branched structures, resistant to amylolytic enzymes. High performance liquid chromatography (HPLC), 13-carbon nuclear magnetic resonance (¹³C-NMR) and gas-liquid chromatography (GLC) were invaluable tools for fractionation, identification and quantification of 1,6-anhydrosaccharides, respectively. The analytical dietary fibre value comprising non-starch polysaccharides and Klason lignin, increased with the extent of oven-heating and extrusion cooking of wheat flour. This increase seemed to originate from mainly three types of reactions, namely: (1) chemical modification of starch to enzyme-resistant glucan structures by external transglycosidation, (2) polymers formed by the Maillard reaction and analysed as Klason lignin, and (3) strong retrogradation of part of the starch (“resistant starch”). Another effect was that the water soluble part of the arabinoxylan in wheat flour increased.     

油酸和麦芽糖醇混合物对玉米淀粉老化特性的影响

为探究油酸和麦芽糖醇混合物抑制玉米淀粉老化的效果,通过快速黏度分析、差示扫描量热分析、质构分析、动态流变分析、低场核磁共振分析、红外光谱分析和X射线衍射分析等方法比较不同复配比例的油酸和麦芽糖醇混合物对玉米淀粉糊化特性、老化特性、流变学特性、质构及结晶结构等的影响。结果显示：添加油酸和麦芽糖醇混合物后,玉米淀粉的糊化温度升高,回生值和老化速率降低,且当油酸和麦芽糖醇质量比为0.5∶1.5时,糊化温度最高（77.80 ℃）,回生值最低（1 218 cP）,老化速率比原淀粉降低了60%;油酸和麦芽糖醇混合物的添加能增大玉米淀粉的损耗角正切值和横向弛豫时间（T2）,形成较弱的凝胶结构,降低玉米淀粉凝胶的硬度、短程有序度和相对结晶度;当油酸和麦芽糖醇为0.5∶1.5质量比复配时,混合物对延缓玉米淀粉老化存在协同作用。这可能与麦芽糖醇能抑制淀粉体系中水分子运动、油酸能与淀粉形成淀粉-脂质复合物从而有效抑制淀粉重结晶有关。研究结果可为改善玉米淀粉加工特性、提高淀粉基食品品质提供一定的理论依据。     

二氢杨梅素对大米淀粉回生的抑制作

淀粉是大米中的主要成分,其回生程度直接影响大米制品的品质与货架期。该研究将属于多酚类化合物的二氢杨梅素（Dihydromyricetin,DMY）添加到大米淀粉中,研究不同添加量的DMY与大米淀粉的相互作用以及DMY对大米淀粉的溶解度、膨胀度、回生焓值、微观结构的影响,以期改善大米淀粉的回生特性。结果表明,随着二氢杨梅素的添加,大米淀粉的溶解度从4.49%增加至12.83%,膨胀度11.41%降至10.12%;淀粉表面由原来的紧密结构变化为疏松多孔结构;红外光谱1 047 cm-1/1 022 cm-1的比值从0.87降至0.78。较未添加的DMY的大米淀粉相比,低浓度的DMY已经显著影响大米淀粉回生特性。当DMY的添加量为5%时,大米淀粉的回生焓值、回生率以及相对结晶度分别下降了68.75%、71.86%、59.07%。总体而言,二氢杨梅素可以抑制大米淀粉的回生。因此,在淀粉制品加工时,可考虑添加DMY来调控淀粉基食品的回生现象。     

Probing the sol–gel transition of egg white proteins by pulsed-NMR method

The utility of pulsed NMR spectroscopy as a convenient means to monitor a sol–gel transition during heat-induced gelation of egg white proteins was investigated. This is based on the notion that, regardless of the mechanism of gel formation, the transition from sol to a gel state in such system is accompanied by the appearance of solid-like domain and a concomitant increase in the NMR signal attributed to protons in the solid-like fraction. The transition from sol to a gel state was clearly evident when the egg white was held isothermally at 80 °C in a water bath. The effects of some sugars and chemical cross-linking agents were also investigated in order to establish whether the method is capable of differentiating the relative effect of the chemicals on the kinetics of the gelation process. The results showed that pulsed NMR has a potential value as a complementary method to study sol–gel transition of food biopolymer.     

淀粉回生研究进展(I)回生机理、回生测定方法及淀粉种类对回生的影响

淀粉回生研究对改善食品品质有重要意义。本文从现代高分子科学理论出发,试图从分子结构到宏观体系的各个不同层面,解释与探讨淀粉回生机理与相关的回生测定方法,在此基础上,介绍了不同种类与来源淀粉的回生特性。     

Viscoelasticity of oxidized starch/low methoxy pectin mixtures in the presence of glucose syrup

The structural properties of mixtures of pectin, oxidized starch and glucose syrup were investigated using small deformation dynamic oscillation. In the absence of added calcium, preparations of low methoxy pectin with glucose syrup formed viscous solutions, which remained crystal-free at subzero temperatures. Samples of oxidized starch and glucose syrup, on the other hand, exhibited solid-like behaviour because of the crystalline nature of the amylose-like helices. Mixtures of the two polysaccharides with the co-solute clearly showed phase inversion from liquid to solid-like behaviour with increasing amounts of starch in the formulation. The transformation was reflected in the textural properties of samples, which varied from thick solutions to firm gels. The viscoelasticity of the system was modified further by the introduction of high methoxy pectin. Preparations of high methoxy pectin and glucose syrup formed rubbery gels whose amorphous nature underwent a glass transition during cooling.     

低温和超低温冷冻对糯米淀粉凝胶老化特性的影响

本文研究了糯米淀粉凝胶经过低温（-20、-40℃）和超低温（-195℃）冷冻后在4℃下冷藏过程中对糯米淀粉凝胶老化特性的影响。结果表明,低温和超低温冷冻的糯米淀粉凝胶在冷藏过程中都形成了海绵结构,且超低温冷冻的糯米淀粉凝胶的孔洞小且均匀,形成致密结构;随着冷藏时间的延长,糯米淀粉凝胶的结晶度增大,经过-20、-40、-195℃冷冻后冷藏21 d的淀粉凝胶结晶度分别为6.05%、5.37%和3.83%;糯米淀粉凝胶的老化焓值和硬度值均随着冷藏时间的延长而增大,但随着冷冻温度的降低,糯米淀粉凝胶的老化焓值和硬度值显著降低。由此显示糯米淀粉凝胶经过低温和超低温冷冻处理后,在4℃下冷藏过程中能够有效地抑制淀粉凝胶的老化,并且超低温冷冻处理能显著（p<0.05）的抑制糯米淀粉凝胶的老化。      

酶解耦合湿热处理对板栗淀粉消化性能与回生性能的影响

板栗淀粉的消化和回生性能制约着板栗食品产业发展,合理选择食品加工方法调控板栗淀粉的消化和回生性能对开发高品质营养健康的板栗食品具有重要意义。本文探究了普鲁兰酶酶解及耦合湿热处理对板栗淀粉的消化率、长期回生和多尺度结构的影响。结果显示,酶解处理增加了板栗淀粉的直链淀粉含量,改变了淀粉链长分布,提高了淀粉短程有序结构和结晶结构,从而降低了淀粉消化率;进一步的湿热处理促进淀粉链相互作用,提高了淀粉短程有序结构、结晶结构和纳米聚集体结构,导致了更低的淀粉消化率。在储存过程中,由于酶解导致更短的A链增加及易于重排的B1链降低,使得淀粉形成的结晶结构和纳米聚集体结构较少,从而降低了淀粉的回生程度;湿热处理促进了A链分子与其他分子的相互作用,加剧抑制淀粉分子重排程度,导致回生程度继续降低。因此,酶解耦合湿热处理可作为一种有效的调控淀粉消化和回生性能的方法,促进慢消化和低回生度板栗淀粉食品的开发。     

Starch retrogradation

Abstract

Starch granules heated in excess water undergo an order‐disorder phase transition called gelatinization (1) over a temperature range characteristic of the starch source. This phase transition is a non‐equilibrium process associated with the diffusion of water into the granule, hydration and swelling of the starch granules, uptake of heat, loss of crystallinity, and amylose leaching (1–3). On cooling, the starch chains (amylose and amylopectin) in the gelatinized paste associate, leading to the formation of a more ordered structure. These molecular interactions are termed collectively “retrogradation” and have important textural and dietary implications (not covered in this review). This review summarizes the present knowledge on amylose gelation and amylopectin crystallization, and on the factors that influence starch retrogradation.     

瓜尔胶和黄原胶对马铃薯淀粉糊化特性影响的比较研究

将马铃薯淀粉分别与瓜尔胶和黄原胶以一定的比例复配,探讨两种胶体对马铃薯淀粉黏度、热稳定性、凝沉性、冻融稳定性和质构特性等糊化特性的影响。结果表明:瓜尔胶提高了淀粉糊的黏度和冻融稳定性,降低了淀粉糊的热稳定性、凝沉性、硬度、黏附性、胶黏性和咀嚼性;而黄原胶增加了淀粉糊的热稳定性和冻融稳定性,但降低了糊的黏度、凝沉性、硬度、黏附性、胶黏性和咀嚼性;且随着两种胶体含量的不同淀粉糊化特性也不同。      

水分含量对莲子淀粉回生影响及分子动力学模拟分析

采用差示扫描量热仪和X射线衍射仪对不同水分含量的糊化莲子淀粉的回生特性进行研究。结果表明,水分含量是影响淀粉回生的重要因素,其过高或过低对莲子淀粉的老化都有一定的抑制作用;当水分含量70%时,莲子淀粉最易重结晶,体系老化程度最高;分子动力学模拟系统探讨了不同水分含量淀粉老化模型的分子构象、水分子扩散系数、非共价键相互作用等参数的变化,发现在水分含量70%体系中,直链淀粉分子结构更趋于有序化、非共价键相互作用更强,这可在微观层面解释莲子淀粉回生的机理。     

淀粉回生研究进展——水分子再分布对淀粉回生的影响

淀粉回生对食品品质至关重要,透彻地了解淀粉的回生机理是有效抑制淀粉回生的基本前提。回顾了前人淀粉回生机理研究的成果,从现代高分子科学理论到宏观体系的不同层面解释和探讨淀粉回生机理,在此基础上对水分子再分布对淀粉回生的影响进行了介绍。