Fast microwave-assisted free sugars washing and hydrolysis pre-treatment for the flow injection determination of starch in food

The approach used consists of a flow injection (FI) manifold assisted by a focused microwave digestor for both fast washing of free sugars and acceleration of the hydrolysis step prior to the determination of starch in food. The action of microwaves reduces both the times for removal of free sugars to a 5 min single washing cycle with ethanol/water and that of the subsequent starch hydrolysis to a 10 min step. The sugars formed in the starch hydrolysis are in-line derivatised and photometrically monitored at λ=460 nm. In this way, automation of pre-treatment and determination is achieved with the minimum of both cost and time. The precision of the overall method, expressed as relative standard deviation, is 3.75% and the total analysis time is 38 min. Comparison of the results, obtained in applying the method to flour and bread, is in agreement with those provided by the manual method.     

Separation and fluorodensitometric determination of some purine derivative drugs by thin-layer chromatography on starch and cellulose

Summary Purine derivative drugs, aminophylline, theophylline, xantinolnicotinate, 6-mercaptopurine, 6-thyoguanine, azathioprine, 1-methylxantine, 3-methylxantine, 1-methyluric acid, 1,3-dimethyluric acid, 6-thioxantine, 2-amino-6-methylmercaptopurine, were separated by thin-layer chromatography on rice starch and cellulose by three different solvent systems. Conditions for quantitative fluorodensitometric determination of purine derivatives drugs were investigated.     

Heterogeneity of starch granules and the effect of granule channelization on starch modification*

This paper reviews the discovery of channels ID starch granules and progress of research on their effects on granule modification and digestibility, their nature, hypotheses on how they are formed and why they are present, and genetic control of their occurrence. Emphasized ID the relationship of channels to starch derivatization. Channelization ID presented as additional evidence of the heterogenous nature of starch granules from source to source and within a single source. A new method of determining the location of anionic entities within starch granules that utilizes reflectance confocal laser scanning microscopy ID described.     

Thermal transitions of gluten-free doughs as affected by water, egg white and hydroxypropylmethylcellulose

The thermal performance of a gluten-free bread dough consisting of a blend of non allergenic corn and cassava starches (75:25) with hydroxypropylmethylcellulose (HPMC) as gluten mimetic hydrocolloid in conjunction with egg white (EW) was determined by differential scanning calorimetry. In order to analyse the effects of different levels of the components (water: 80-110%, HPMC: 0-2% and EW: 0-10% over the starch blend) on the thermal transitions of the dough, a Doehlert design and a response surface methodology were used.The analysis of variance showed that EW did not affect the onset temperature of gelatinisation and HPMC did not affect the peak and conclusion temperatures. HPMC-water interactions mainly controlled the onset temperature of starch gelatinisation. On the other hand, the peak and conclusion temperatures were determined by the additive and opposite effects of water and EW.     

RADICAL GRAFTING REACTIONS ONTO STARCH AND OTHER WATER-SOLUBLE COPOLYMERS IN ISOLATED GEL DROPLETS

A novel radical grafting copolymerization process has been designed for water-soluble polymers which avoids the problems of conducting grafting reactions in highly viscous polymerization media. A variety of water-soluble graft copolymers having starch or dextran as the backbone chain with grafted side chains of polyacrylamide (—AM—), poly (acrylic acid ) (—AA—), poly (acrylamide-co-acrylic acid) (—AM—NH_4AA—) or poly ( acrylamide-co-2-acryiamido-2-methyl-l-propanesulphinic acid) (—AM—AMPS—) have been synthesized in gel droplets using aceric sulphate redox initiator, and their properties compared. The reaction conditions were optimized taking into account reaction kinetic data and the observed properties of the products produced under different reaction conditions. The effects of the ratios of [backbone]/[graft monomer], [ AM]/[ AA]/[AMPS] , [Ce~(4+)]/[ S_2O_8=] and pH value on the reaction rate , conversion, grafting degree, grafted chain length and the product molecular weight have been investigated.     

淀粉在挤出过程中的性质变化

淀粉作为一种重要的可再生资源,有着很好的发展前景,而挤出要在对淀粉进行的改性加工中发挥着重要作用,本文参考了近期的有关文献,介绍了挤出机机械特性及共挤出物作用两方面因素对淀粉挤出物性质的影响及其大致机理。     

羟乙基淀粉的羟乙基取代位置的研究

将羟乙基淀粉进行甲基化-水解-还原乙酰化反应，产生羟乙基葡萄糖的部分甲基化糖醇乙酸酯衍生物，应用气相色谱/化学电离质谱（GC/CIMS）和气相色谱/电子轰击质谱/质谱（GC/EIMS/MS）联用技术研究了羟乙基在淀粉糖环上的取代位置，发现G-2位取代的量是总取代量的82.0％。     

主成分-人工神经网络在近红外光谱定量分析中的应用

近红外光谱的主成分由非线性迭代偏最小二乘法（ＮＩＰＡＬＳ）求出。主成分作标准化处理后,作为Ｂ－Ｐ神经网络的输入结点进行非线性迭代。该法的优点是,充分利用了全光谱的数据,得到消除噪声后的最佳主成分,能建立非线性模型,Ｂ－Ｐ神经网络迭代时间显著缩短。用该法对大麦中的淀粉含量进行了定量分析研究。结果为：校准和预测的相关系数分别为０．９８１和０．９５３,校准和预测的相对标准偏差分别为１．７０％和２．４８％。     

两性淀粉螯合剂吸附性能的研究

采用玉米或红薯淀粉，经环氧氯丙烷交联、醚化剂阴、阳离子化，制得两性淀粉。研究了离子化的方式 、条件与产品螯合容量的关，制得了向种络合容量相当高的两性淀粉，并研究了它们的使用条件及反复利用的可能性能，试验表明两性淀粉螯合剂是一种高效的污水处理剂。     

氧化铅@碳纳米复合材料的制备与表征

以淀粉为碳源, 高温碳化含有硝酸铅的淀粉干凝胶, 制备了氧化铅@碳纳米复合材料,氧化铅颗粒无团聚, 粒径可调, 近于单分散, 且分布均匀, 可作为铅酸电池的电极材料, 有望提高其充放电性能和使用寿命.