Gelatinization of Rice Starch in Aqueous Urea Solutions

Addition of urea to starch slurry causes gelatinization of starch at room temperature. The time required for gelatinization, type of gel formed, rheological properties and apparent viscosity of starch suspension in urea solutions were determined. The latter did not decrease significantly after storing for up to 8 weeks whereas that of cooked starch decreased sharply after one week of storage. Suspensions of starch in urea solutions did not show any fermentation and retrogradation during 8 weeks storage. Its is suggested that urea interacts with starch to form adducts or urea starch complexes. The magnitude of the latter and its abundance is dependent on the concentrations of urea and starch. The urea starch complex acquires very high affinity to water thereby causing swelling and gelatinization of starch.     

酸解氧化淀粉的制备及其性质研究

以玉米淀粉为原料、盐酸为酸解催化剂、过硫酸铵作为氧化剂可以在较短时间里得到粘度较低并具有一定氧化程度的酸解氧化淀粉。在制备过程中 ,酸解和氧化同时进行 ,可以缩短反应时间 ,提高反应效率。和酸解淀粉相比 ,其冷糊粘度较低且抗凝沉性较好 ,在一定程度上克服了酸解淀粉的缺陷 ,在食品和化学工业上具有较好的应用价值。     

淀粉/聚胺复合物纸张增强机理初探

研究了淀粉/聚胺复合物、阳离子淀粉及原淀粉在纸浆上的吸附类型,测定了淀粉/聚胺混合糊液及单一组分的黏度,探讨了淀粉/聚胺复合物在不同浆种纸张中的作用效果。结果表明,淀粉与聚胺形成了复合物,该复合物对再生浆的作用效果与阳离子淀粉相当,具有明显的增强作用。淀粉/聚胺复合物用量为1.5%时,可使纸板的裂断长增加22.6%,纤维留着增加率提高了6.8%。淀粉/聚胺复合物在纸浆纤维上的吸附为化学吸附和物理吸附共同作用的结果,与阳离子淀粉的吸附相似。     

羟丙基淀粉在浆纱中的应用

将淀粉在碱性条件下与环氧丙烷醚化而成的羟丙基改性淀粉肜于棉纱上浆,并与硫酸酯改性淀粉进行上浆性能比较,证实羟丙基淀粉的上浆性能均优于硫酸酯改性淀粉。     

微波辐射对淀粉上浆性能的影响

以玉米淀粉为材料,采用高效、节能、无害的微波辐射加工技术,使淀粉受微波辐射处理后结构和性能发生变化。通过视频显微拍摄的照片明显可见微波辐射使淀粉颗粒形态结构发生了转变;淀粉特性黏度测试结果充分证实了微波辐射引起淀粉大分子高频振动,导致其甙键断裂大分子降解。对微波辐射后的淀粉、原淀粉以及氧化淀粉和酸解淀粉的浆液与浆膜性能进行测试,实验结果表明:受微波辐射后的淀粉浆液黏度降低,且降低程度与微波辐射时间有关;浆液对纤维的黏附性有改善;浆膜的断裂强度和断裂伸长率、耐磨性和耐屈曲性、吸湿性各项指标较氧化淀粉和酸解淀粉有所改善或接近。     

不同米淀粉精细结构对其回生特性的影响

选用4种不同的淀粉,通过考察回生特性,探究相对分子质量、链长分布、短程有序性、相对结晶度及半结晶层状结构等精细结构影响回生特性的机理。结果表明：与糯米淀粉和粳米淀粉相比,小米淀粉和黑米淀粉回生值、硬度和热焓值较大,糯米淀粉储藏前后硬度和回生后的热焓值均较小,具有较好的抗回生特性。研究发现,这是由于小米淀粉和黑米淀粉的直链质量分数较高(小米淀粉15.55%、黑米淀粉11.22%),支链淀粉峰M_w较大(小米淀粉M_w=2.12×10⁷ g/mol、黑米淀粉M_w=2.25×10⁷ g/mol)、半结晶层厚(小米淀粉d=6.978 4 nm、黑米淀粉d=6.698 6 nm),且中长链占比大(小米淀粉B1链占比40.91%),易形成稳定的双螺旋结构,具有更高的表面有序度(小米淀粉0.76、黑米淀粉0.70),回生后2种淀粉分子重排更有序稳定。     

芸豆淀粉理化特性研究

淀粉是芸豆中的主要碳水化合物,其性质直接影响芸豆资源的开发与利用.以花芸豆、小红芸豆、红芸豆、小黑芸豆和小白芸豆等菜豆属芸豆为试验材料,采用湿磨法提取淀粉,以马铃薯淀粉和玉米淀粉为对照,分析芸豆淀粉的颗粒特性与糊化特性.结果表明,5种芸豆淀粉颗粒形貌相似,大淀粉颗粒多为卵圆形或肾形,小颗粒多呈圆形,淀粉颗粒长轴粒径介于玉米淀粉和马铃薯淀粉之间.淀粉颗粒偏光十字多为较粗的“X”形或斜“十”形,较明显.芸豆淀粉溶解度和膨胀度均随温度升高而增大,属限制型膨胀淀粉.芸豆淀粉的透光度明显小于马铃薯淀粉,冻融稳定性不及玉米淀粉和马铃薯淀粉.芸豆淀粉起糊温度、峰值黏度、破损值、最终黏度和回生值分别为76.6 ～ 77.8℃、117.3 ～ 150.9 RVU、5.0 ～ 32.0 RVU、205.1 ～225.2 RVU和91.9～104.2 RVU.芸豆淀粉糊表现出好的热稳定性、抗剪切,易回生.     

Physicochemical Properties of Starch Isolated from Bracken (Pteridium aquilinim) Rhizome

Bracken (Pteridium aquilinum) is an important wild plant starch resource worldwide. In this work, starch was separated from bracken rhizome, and the physicochemical properties of this starch were systematically investigated and compared with 2 other common starches, that is, starches from waxy maize and potato. There were significant differences in shape, birefringence patterns, size distribution, and amylose content between bracken and the 2 other starches. X‐ray diffraction analysis revealed that bracken starch exhibited a typical C‐type crystalline structure. Bracken starch presented, respectively, lower and higher relative degree of crystallinity than waxy maize and potato starches. Ordered structures in particle surface differed among these 3 starches. The swelling power tendency of bracken starch in different temperature intervals was very similar to that of potato starch. The viscosity parameters during gelatinization were the lowest in waxy maize, followed by bracken and potato starches. The contents of 3 nutritional components, that is, rapidly digestible, slowly digestible, and resistant starches in native, gelatinized, and retrograded starch from bracken rhizome presented more similarities with potato starch than waxy maize starch. These finding indicated that physicochemical properties of bracken starch showed more similarities with potato starch than waxy maize starch.     

淀粉材料重结晶及其控制

该文综述淀粉结晶、重结晶结构及其影响因素研究成果,指出淀粉重结晶本质是淀粉分子间氢键和范德华力累积作用大于淀粉与水或增塑剂小分子间相互作用;由此总结出如何有效控制淀粉制品结晶度和重结晶方法。     

用变性淀粉等添加剂改进淀粉膜强度的研究

以马铃薯淀粉为主要原料,通过制膜机制成了具有一定机械强度的可食性淀粉膜。为增加淀粉膜的机械性能,考察了变性淀粉等添加剂对淀粉膜性能的影响,试验发现添加马铃薯淀粉醋酸酯、海藻酸钠和卡拉胶等食品添加剂可以改进淀粉膜的强度。     

赤小豆淀粉性质的研究

本文研究测定了赤小豆淀粉的各种结构特性,发现淀粉颗粒粒径范围为18～80μm,平均粒径为40.8μm;偏光十字明显,其X-光衍射图样属A型晶体结构,结晶度为40.5%。淀粉碘复合物可见光吸收光谱的最大吸收波长为618nm,链淀粉含量33.2%。赤小豆淀粉在水中的溶胀能力较玉米淀粉大,比木薯淀粉小。赤小豆淀粉糊属于假塑性流体,糊抗剪切能力和凝沉能力均比玉米淀粉、木薯淀粉强,其冷、热糊粘度稳定性较好,单甘酯对赤小豆淀粉糊的影响较为特别。     

An Objective Illustration of the Inadequacy of the Official EC “Ewers” Method for the Determination of Starch

The Ewers method for starch determination is currently the Official EEC method for measurement of starch purity. In this communication we demonstrate that the use of trifluroacetic acid for solubilisation of starch prior to polarimetric measurements is preferred over the use of mineral acids since the degree of hydrolytic degradation observed with this reagent was minimal compared to mineral acids, thereby giving improved starch purity values. Of particular concern we demonstrate that the Ewers method is non-specific in that the addition of an epichlorohydrin cross-linked dextran as an adulterant enhances the value of starch purity obtained. The Ewers method however was able to detect agarose and carboxymethyl cellulose added to starch as adulterants. It is concluded that the Ewers method is not an acceptably satisfactory method for starch purity measurement on which to base quality control or eligibility for rebate and refund schemes.     

菠萝蜜种子淀粉提取及其理化性质的研究

以菠萝蜜种子为原料提取并纯化种子淀粉,对种子的化学组成及种子淀粉的性质进行了测定。结果表明:菠萝蜜种子含淀粉62.63%,实验室条件下种子淀粉的提取率为42.3%,菠萝蜜种子淀粉在透明度、冻融稳定性、膨胀度、低温溶解性均低于马铃薯淀粉,易老化,浓度>60 g/L的淀粉糊在90℃以上粘度较大,<70℃粘度下降并趋于稳定。     

双亲性淀粉浆料的研究进展

为提高淀粉的上浆性能,分析了对淀粉进行双亲性变性处理的意义,总结了双亲性淀粉浆料,包括阴阳离子型双亲性淀粉浆料、亲疏水型双亲性淀粉浆料,在纺织经纱上浆中应用的研究现状,论述了双亲性变性对淀粉浆料黏附性和浆膜力学性能的作用效果,并对今后双亲性淀粉浆料的研究方向进行了预测。认为亲疏水型接枝改性淀粉浆料品种及适宜于具体经纱品种的双亲性淀粉浆料品种,以及可降低均聚物产生、可控接枝支链长度的淀粉接枝改性方法将是今后双亲性淀粉浆料的重要研究方向。     

纺织上浆用氧化淀粉的表观性能及微观机理

氧化淀粉是由原淀粉与氧化剂在一定温度和pH值条件下反应制得的变性淀粉，氧化淀粉的氧化深度可根据氧化淀粉的羧基和羰基数量来判断。文中通过羧基含量对氧化淀粉粘度的影响、氧化反应对淀粉颗粒表面的作用等试验，对原淀粉和氧化淀粉颗粒的微观表面进行了分析对比，指出：氧化反应使淀粉颗粒表面的粗糙度增加；在制备羧基含量高的氧化淀粉时，粘度不能降得太低；高羧基含量的氧化淀粉对提高纱线的粘附力是不能忽视的。     

双变性淀粉制备及其在食品工业中应用

不同淀粉具有不同性能,大部分情况下原淀粉溶液不太稳定,对各类淀粉进行变性反应可 得到所需特性,从而满足生产要求,有时甚至需要双变性才能满足特殊要求;该文介绍双变性淀粉 制备及其在食品工业中应用。     

乙酰化柠檬酸酯化交联机械活化淀粉的制备及性质分析

以机械活化木薯淀粉为原料,醋酸酐为酯化剂,柠檬酸为交联剂,采用溶剂法制备乙酰化柠檬酸酯化交联淀粉,考察了机械活化时间、混合酸添加量、反应温度、反应时间、柠檬酸与乙酸酐质量比等因素对乙酰化柠檬酸酯化交联淀粉沉降积的影响,并对制备得到的酯化交联淀粉进行结构表征及性质测定.结果表明,制备最佳工艺条件为:机械活化时间40 mi...     

Physicochemical Nature of Banana Pseudostem Starch

SUMMARY: Starch was isolated from banana pseudostem and its properties were compared with those of potato, corn and tapioca. The starch granules are irregular in shape and are bigger in size than those of the fruit starch. At 60°C, the granules start to swell, gradually increase in size, attain their maximum size at 75°C and do not rupture even after heating to 100°C. The intrinsic viscosity of the starch (2.05) is similar to that of potato starch (2.00). The amylose content of the starch compares well with that of banana fruit and potato (tuber) starch (21%). In general, banana pseudostem starch resembles potato starch.     

Untersuchungen über die Retrogradation der Stärke in konzentrierten Weizenstärkegelen. Teil 1. Herstellung konzentrierter Gele,Einfluß der Stärkekonzentration und Herstellungsbedingungen auf die Retrogradation der Stärke

Investigations on the Retrogradation in Concentrated Wheat Starch Gels. Part 1. Preparation of Concentrated Gels, Influence of the Starch Concentration and Conditions of Preparation on the Starch Retrogradation . A method for the preparation of homogenous, concentrated wheat starch gels is described. The influence of the starch concentration and conditions of gel preparation has been investigated by determination of gel strength (Avrami-analysis) and solubilized starch. An increase in starch concentration from 40 to 55% caused a corresponding increase in gel strength of the fresh gels, an enhanced increase in gel strength during storage and a reduction of soluble starch. The time of heating during gel preparation had little influence on retrogradation. The influence of the temperature of heating (130° and 100°C) was dependent on the starch concentration: with 40 and 50% gels a strong increase in water soluble starch is observed with the higher temperature, whereas the gel strength is increased with the 50% gels only. The amylose content in the gel extracts shows that both starch fractions take place in retrogradation. The water binding capacity of the insoluble starch is decreased during storage demonstrating that the retrogradation also occurs in the insoluble starch and significantly contributes to the increase in gel strength. Retrogradation in concentrated starch gels therefore proceeds inside and on the surface of the swollen starch granules as well as in the solubilized starch leached out during the heating process.     

交联氧化复合变性甘薯淀粉在粉丝生产中的应用

本文讨论了用氧化剂处理甘薯淀粉,使其增白。在轻度氧化处理的基础上进一步用交联剂处理,提高淀粉凝胶的强度,即抗剪切、抗水、热能力。交联氧化复合变性甘薯淀粉与蚕豆淀粉配合使用制成的粉丝,与全蚕豆粉丝相比,品质没有显著差异。生产过程简单,易于控制。