Comparative analysis of mechanical properties of size film. II. Effect of blend composition and lubricants

The advent of very high speed shuttleless looms has increased the importance of sizing. Starch has been the most popular and economic size material. Synthetic binders are also being blended with starch to improve weaving loom efficiency. Blending may lead to give different properties, which can be suited for particular application. In the present study effect of blend composition in modified starch and synthetic size blends have been evaluated and mechanical properties like cohesion power, adhesion power, abrasion resistance, bending rigidity etc were studied. In general, it is being observed that paste characteristics and film properties of polyester resin blends are better but because of economic reasons PVA and acrylic polymers are preferred. In this study the effect of lubricant is also observed. It is analyzed that lubricant improves the various mechanical properties and hence the weaving performance of the material.     

Characterization of pre-gelatinized maize starch-zein blend films produced at alkaline pH

Biodegradable materials are considered as alternative to synthetic materials to alleviate the environmental burdens caused by petroleum based synthetic materials. Biopolymer blends have been extensively researched to improve the material properties of biopolymer-based materials for potential replacement of non-biodegradable materials. Compatible blends of pre-gelatinized maize starch (uncomplexed or complexed with stearic acid) and commercial zein in 0.1 M NaOH were used to produce the films. The effect of the ratio of uncomplexed starch, zein and starch complexed with stearic acid on the tensile, water vapour and oxygen barrier and thermal properties of the composite films were investigated. Blending zein with starch increased the tensile strength and reduced the tensile strain compared to starch films. Addition of starch complexed with stearic acid to the blend further increased the tensile strength and decreased the elongation at break. Both blending zein with starch and addition of starch complexed with stearic acid to the blend decreased the water vapour permeability, however, the oxygen permeability was increased compared to starch films. The starch-zein blend films had an endothermic temperature and thermal transition in between the uncomplexed maize starch and zein films suggesting possible compatibility at molecular level. The microstructure of the blend films also showed good miscibility of pre-gelatinized starch and commercial zein. In conclusion alkaline solvent (0.1 M NaOH) could produce compatible starch-zein blends that can produce films with improved tensile strength and water vapour permeability compared to starch films.     

Influence of environmental temperature during grain filling period on granule size distribution of rice starch and its relation to gelatinization properties

High temperature (HT) is the major environmental factor affecting grain starch properties of cooking rice cultivars. However, little information has been available on the effect of environmental temperature on the starch granule size distribution of rice grains. In this paper, five indica rice genotypes, including the wild type (9311) and its four mutants differing in amylose content (AC), were used to investigate the effect of environmental temperature on the starch granule size distribution, as well as its relation to AC and gelatinization properties of rice starch. Two temperature treatments (HT and NT) at filling stage were imposed to rice plants under the controlled temperature chambers. The result showed that HT increased the average diameter of starch granules and enhanced the proportion of large starch granules (LSG, D > 2.6 μm) by number, volume and surface area, respectively. However, influence of HT on GT and starch granule size distribution was relatively independent of their alteration in AC level for different rice genotypes. Therefore, HT-induced increase in the average diameter of starch granules and LSG percentage was strongly responsible for the higher starch gelatinization temperature and inferior cooked palatability of HT-ripening rice grains, which be not inherently associated with their varying AC level.     

热塑性可降解木薯淀粉的研究(Ⅱ)--改性木薯淀粉的性能

采用接枝技术使醋酸乙烯酯单体及丙烯酸甲酯单体在木薯淀粉分子链上进行了接枝共聚反应,碱化后制得改性木薯淀粉材料。结果表明,改性木薯淀粉材料的加工性能得到良好改善,并具有较好的力学性能及降解性能     

Effect of heating temperature on the particle size distribution in waxy wheat flour

The particle size of waxy (amylose-reduced) wheat (Triticum aestivum L.) starch was determined at isothermal temperatures by laser diffraction analysis. Flour samples were suspended in deionized water at temperatures ranging from 30 to 90 °C for 20–60 min. At 30 °C, all of the flour particles exhibited trimodal size distributions, i.e., the particles in the first, second, and third modes were <10 μm, 10–50 μm, and 51–300 μm, respectively. Control experiments with isolated starch indicated that the first and second modes were associated mainly with starch granules, whereas the third mode may have been related to gluten and gluten adhesion. The particle size distributions of waxy segregant wheat flours were temperature dependent. At 60 °C, there were significant changes in the particle size and distribution of waxy flours, which indicated the swelling of starch granules in response to elevated temperature. As the temperature increased, the peak particle size of waxy segregant wheat flours increased in different ways. The results suggest that variations in the swelling properties of selected waxy genotype flours may be due to the strength of starch–protein interaction and the capacity for starch granule gelatinization.     

小麦籽粒淀粉粒粒级分布特征及其与淀粉理化特性关系研究进展

小麦籽粒淀粉粒粒级分布范围大,而且呈现梯度分布,这是小麦淀粉粒区别于其他植物淀粉粒的一个显著特征。不同粒径的淀粉粒在理化特性上有极大的差异,因此除直/支链淀粉比例之外,淀粉粒粒级分布也是影响淀粉品质的重要指标。本文综述了国内外在小麦籽粒淀粉粒粒级分布及其与淀粉品质特性关系方面的研究进展,提出应注意小麦籽粒不同粒级淀粉粒分布特征及其形成机理与调控途径等领域的研究,以促进优质小麦品种选育和调优栽培技术的建立。     

小麦淀粉的粒度分布、组分及糊化特性对氮硫肥的响应

为明确氮硫肥对小麦淀粉粒度分布及主要理化特性的影响,以强筋小麦品种西农9718和中筋品种陕农138为材料,采用不同氮硫肥水平进行处理,系统分析了小麦A、B淀粉的粒度分布、淀粉组成、膨胀势及糊化特性对氮硫肥的响应。结果表明,强筋和中筋小麦品种的淀粉粒度分布基本一致。A淀粉粒体积分布占总淀粉的74.95%～75.43%,但淀粉粒数量远少于B淀粉粒。A淀粉的直链淀粉、峰值黏度、低谷黏度、崩解值、最终黏度以及回生值高于B淀粉,而B淀粉有更高的支链淀粉、膨胀势和糊化温度。不同氮硫肥处理改变了小麦淀粉的粒度分布,进而影响淀粉的组成和糊化特性。在施氮(230kg.hm-2)条件下,强筋品种西农9718和中筋品种陕农138的A、B淀粉分别在硫肥施用量为46和56kg.hm-2时有较低的直链淀粉含量、较高的膨胀势及较好的糊化特性。陕农138淀粉的粒度分布、组成及糊化特性对氮硫肥的响应比西农9718更敏感。适当的氮、硫肥配施有利于改善小麦的淀粉品质。     

马铃薯原淀粉及变性淀粉的特点及应用

马铃薯原淀粉是一种极为重要的天然高分子材料,具有其他植物淀粉不可替代的特性,可广泛用于食品工业、造纸工业、纺织工业和医药工业。通过物理、化学或其他方式将马铃薯原淀粉改造为变性淀粉后进一步拓宽了其用途。中国马铃薯分布广、种植面积大,为马铃薯原淀粉和变性淀粉的加工提供了巨大的原料来源。尽管受原料困扰和效益影响,马铃薯原淀粉和变性淀粉加工业在中国仍属于朝阳产业,产品的数量、种类和用途都将会有进一步的扩展。     

Biodegradable films based on rice starch and rice flour

Rice flour is a starchy material with low-cost, because it can be produced from rice that is broken during processing. The aim of this study was to develop biodegradable films based on rice starch and rice flour, and to characterize their physicochemical, microscopic and mechanical properties. Films from rice starch and rice flour were prepared by casting, with glycerol or sorbitol as plasticizer. SEM analysis of starch and flour films revealed compact structures. Rice flour films prepared in the present work have similar mechanical properties to those of starch based films. However, their water vapor permeabilities are two times higher than those of starch based films. Films with sorbitol were less permeable to water and more rigid, while films with glycerol are more plasticized and have poorer water vapor barrier properties. Therefore, preparing edible films from rice flour is a new alternative for using this raw material, which is sometimes much cheaper than commercial starches.     

不同类型小麦品种大、小淀粉粒的分离和特性

为给小麦品质育种提供依据,以3个不同类型的小麦品种(济南17号、扬麦12号和扬麦9号)为材料,分离了大、小淀粉粒,并对它们的特性(形状、大小、膨胀势、晶体特性、糊化特性等)进行了测定和分析.结果表明,大、小淀粉粒形状为椭球形或球形,品种间无差别,但其大小和含量在品种间存在很大差异;大淀粉粒的膨胀势大于小淀粉粒.大、小淀粉粒都为A型淀粉晶体,大淀粉粒的相对结晶度差别不大,但小淀粉粒的相对结晶度差别较大,表现为济南17号＜扬麦12号＜扬麦9号.品种内大淀粉粒的起始温度To、峰值温度Tp值和吸收热焓△H高于小淀粉粒,终止温度Tc值却比小淀粉粒低.     

Hydrothermal modification of wheat starch part 1. Effect of particle size on the viscosity of formed pastes

Aqueous starch suspensions (8 g/100 g) were prepared in a measuring flask of a Brabender viscograph and heated to temperatures of 74.0, 76.5, 79.0, 81.5, 84.0, 86.5, 89.0, 91.5 or 94.0 °C under continuous stirring. The resultant solution was cooled and frozen, and then defrosted and subjected to re-pasting in the Brabender viscograph.The heating and freezing of wheat starch suspension evoked changes in its properties, with the tendency and extent of these changes dependent on the pre-heating temperature. During re-pasting of the produced starch preparations in a Brabender viscograph, an increase occurred in particle size of the granules—and 8-fold increase in paste viscosity—compared with pastes produced from native starch. The viscosity of pastes was positively correlated with the size of formed gel sacks determined using a laser particle size analyzer. This was also found to depend on pre-heating temperature and changed according to a determined quadratic function. The strength of produced gels, measured with the oscillating–rotating viscometer, was higher than that of the gel produced from native starch and depended on the pre-heating temperature; however, these changes followed a determined quadratic function.     

The effects of puroindoline b on the ultrastructure of endosperm cells and physicochemical properties of transgenic rice plant

Endosperm texture is an important factor governing the end-product quality of cereals. The texture of wheat (Triticum aestivum L.) endosperm is controlled by puroindoline a and b genes which are both absent in rice (Oryza sativa L.). It has been reported that the endosperm texture of rice can be modified by puroindoline genes. The mechanism, however, by which puroindolines affect the ultrastructure of rice endosperm cells remains to be investigated. In this study, we observed the ultrastructure of endosperm cells and the morphology of isolated starch granules of the transgenic rice expressing the puroindoline b gene. SEM and TEM observations indicated that compound starch granules were embedded within the matrix material in non-transgenic rice, Nipponbare, whereas they were surrounded by spaces in the transgenic rice. The morphology and size of each starch granule were not different between non-transgenic and the transgenic rice. However, the transgenic rice flour showed smaller particle size, higher starch damage, and lower viscosity during gelatinization than that of non-transgenic rice. These results confirm that puroindoline b reduces the grain hardness in rice. Moreover, the results also suggest that puroindoline b functions at the surface of compound starch granules, and not on polygonal starch granules in rice endosperm.     

Effects of plasticizer on the mechanical properties of kenaf/starch bio-composites

Research and development of biodegradable bio-composite can replacement the synthetic polymer materials, which is used for automobile interior materials, finishing materials of air conditioner and refrigerator. To develop both components as biodegradable bio-composite, this research used natural polymer starch as matrix and kenaf fiber as a filler. Various plasticizer(polyvinyl alcohol, polyethylene glycol, glycerol) were added and examined the mechanical properties of the kenaf/starch bio-composites according to these plasticizer. The kenaf bast which cultivated in Korea was retted with 2 % NaOH solution. The plasticizer weighting 10 % of that of matrix was added. kenaf/starch composites were molded with hot press for 30 minutes at 130 °C and 3,500 PSI molding condition. The mechanical properties such as tensile strength, elongation, and young modulus of the kenaf/starch composites were measured. Also, we measured the SEM cross-section images in order to investigate interfacial adhesion properties of fractured surfaces. The order of strength size of composites were G (12.42 MPa) > PVA (9.72 MPa) > PEG (4.73 MPa) samples respectively. The tensile strength of PEG sample is lower than the control sample (5.40 MPa).     

皮裸燕麦胚乳淀粉形态结构及理化性质的比较

燕麦作为血糖生成指数较低的食品,被广泛应用于食品、医药工业。为比较皮、裸燕麦胚乳淀粉理化性质的差异,探究皮、裸燕麦在食品等加工利用方面的不同,以2个裸燕麦品种(白燕2号,坝燕18)以及2个皮燕麦品种(蒙燕1号,塔娜)为材料,通过扫描电镜观察燕麦胚乳淀粉颗粒的形态,采用X-射线衍射分析(XRD)、傅里叶变换远红外光谱、以及¹³C固体核磁共振等方法研究淀粉的理化性质,同时测定其支链淀粉链长和淀粉的消化速率。研究结果表明,燕麦胚乳中淀粉同时以复粒淀粉和单颗粒淀粉形式存在,复粒淀粉在淀粉提取中易破裂,形成不规则的多面体颗粒,粒径多在5～8μm。4个燕麦品种胚乳的淀粉均为A型晶体,但膨胀势和溶解度存在差异,裸燕麦坝燕18膨胀势最高,溶解度最低。皮、裸燕麦在淀粉晶体结构方面存在差异,皮燕麦淀粉较裸燕麦有更高的结晶度和表层有序度,裸燕麦淀粉无定形比例和表观直链淀粉含量更高,导致皮、裸燕麦在食品加工方面的差异。皮、裸燕麦支链淀粉链长分布不同,裸燕麦的长支链分布少,慢速消化淀粉(SDS)含量高,尤其坝燕18的SDS含量明显高于其他三个品种,更适合作为减肥食品。     

Functional properties of native,physically and chemically modified breadfruit (Artocarpus artilis) starch

Starch was isolated from breadfruit (Artocarpus artilis). It was further modified by oxidation, acetylation, heat–moisture-treatment and annealing. The functional properties of native and modified starches were then studied. Proximate analysis revealed that following modifications, the annealed (BANS), oxidised (BOS) and acetylated (BACS) starches retained higher moisture content compared to native starch (BNS), while heat–moisture treated starch (BHMTS) had lower moisture content. Crude fibre was reduced by following modifications, except that BNS and BANS had the same value (0.42%). Protein and fat contents were also reduced after modifications. Acetylation, oxidation and heat–moisture-treatment improved the swelling power of the native starch. The result indicates that all forms of modification reduced the solubility of native breadfruit starch. For all the starches, replacing the wheat flour by the starch resulted in increased alkaline water retention of the blends. Gelation studies revealed that native breadfruit starch is a better gelating food material than the modified derivatives. All forms of modification reduced pasting temperature, peak viscosity, hot paste viscosity and cold paste viscosity of the native starch, except that heat–moisture-treatment increased the pasting temperature. Setback value reduced after modifications, indicating that modifications would minimize starch retrogradation.     

糯小麦的开发和应用研究进展

旨在总结糯小麦的应用现状,分析制约糯小麦推广应用的关键问题,为糯小麦规模化推广应用提供参考。在糯小麦理化特性方面,重点简述糯小麦的淀粉构成及糊化特性;在糯小麦应用方面,主要对其在食品加工及其他工业生产领域的应用研究进行概述。其中,在食品改良方面,添加少量糯小麦可提升食品的口感和货架期,尤其在冷冻食品中具有独特优势;在酒精工业中,添加糯小麦可明显提升酒精转化率和白酒口感;此外,糯小麦可作为一种新材料,在新型食品开发、造纸、医药等众多工业生产领域有良好的应用潜力。糯小麦淀粉特性优异,在众多领域拥有广阔的应用前景,但目前有关糯小麦在食品加工中的应用价值研究尚未达成一致结果,且尚未见其大面积推广和成功用于商业应用的报道,这些均有待进一步研究。     

Anatomy and compositional variations within potatoes III. Gross compositional gradients

The degree of compositional variations within potato tubers has been related to the development anatomy of the tuber and to exact tissues. The principal component, starch, shows differences in granule size distributions and in composition that appear when the young tuber averages about 1/300 of mature volumetric size. These differences pertain at maturity. When starch differences have been established, growth by cell divisions diminishes and growth by cell enlargement becomes dominant. In the mature tuber the general gradients for specific gravity, percent total solids, and percent total nitrogen decrease from stem end to bud end for cortical, perimedullary and pith tissues. Relationship between specific gravity and total solids is less parallel because differences in cell size and size of minute intercellular spaces also influence tissue density. Relationship between total solids and total nitrogen gradients from cortical tissue to pith were inverse with toal nirogen being higher in those tissues of lower total solids. These variations suggest need for new approaches in basic research on tuber quality improvement.     

微波法制备莲子抗性淀粉工艺参数的优化

以速冻鲜莲为原料,用微波法制备 RS3型莲子抗性淀粉;在单因素试验的基础上,运用正交试验设计法优化莲子抗性淀粉工艺参数。试验结果表明,影响莲子抗性淀粉得率的主次因素顺序为：淀粉乳浓度＞微波时间＞微波功率。经优化后的最佳制备工艺条件为莲子淀粉乳液浓度 15%,微波时间 120 s,微波功率 640 W,在此工艺条件下莲子抗性淀粉得率为 39.53%,其得率虽低于压热法和超声波辅助压热法,但所需时间较短,操作简单,适合用于抗性淀粉的工业化生产或大批量制备。     

小麦淀粉辛烯基琥珀酸酐改性的研究

为了改善小麦淀粉的性能,采用湿法工艺制备小麦辛烯基琥珀酸淀粉酯,并从表面结构、糊的黏度、透明度和凝沉性四个方面分析了小麦淀粉辛烯基琥珀酸酐改性前后理化性质的差异。小麦辛烯基琥珀酸淀粉酯的湿法制备工艺为：反应时间3 h,pH值8.0,反应温度35℃,淀粉乳液浓度35%,酸酐加入量为淀粉干基重的3.0％~7.0%。该工艺所制备的小麦辛烯基琥珀酸淀粉酯的取代度为0.012 4~0.019 4。扫描电镜分析表明,经过辛烯基琥珀酸酐改性之后,小麦淀粉颗粒表面产生凹陷现象;小麦淀粉糊的黏度和透明度明显提高,并且随着取代度的增加呈增大趋势;小麦淀粉糊的凝沉性降低。     

Hydrolysis of granular corn starch with controlled pore size

Native corn (Zea mays L.) starch granules were hydrolyzed using glucoamylase at 50 °C for 1–8 h. The degree of hydrolysis over time was analyzed by the concentration of glucose released into solution. The pore sizes of hydrolyzed starch granules increased gradually with the degree of hydrolysis, as evidenced by scanning electron micrographs. It was deduced that every pore on the surface of granules was formed by hydrolysis of one enzyme molecule, so the size of pores distributed on the surface of starch granules was almost homogeneous for the same hydrolysis time. The specific surface area (S_BET), porosity, adsorptive capacity and mean pore radius of porous starch granules were determined to analyze the effect of digestion time on granule properties.