Impacts of spray drying conditions on stability of isoflavones in microencapsulated soybean extract

Abstract

Soybean extract rich in isoflavones has attracted widespread attention for dietary supplement and pharmaceutical purposes. However, it has poor solubility and low stability. Encapsulation using spray drying is a good alternative for overcoming these problems in soybean extract. Isoflavones profiles in soybean extract are altered during encapsulation and storage. The objective of this work was to investigate the effect of spray drying conditions on the isoflavones profiles and the various properties of microencapsulated soybean extract. The studied parameters comprised the type of wall material (maltodextrin [MD], gum arabic [GA], and β-cyclodextrin [βCD]), inlet air temperature (130–170?°C) and storage time (0–6?months), while the investigated properties included moisture content, particle size, hygroscopicity, morphology, isoflavones content, encapsulation properties, and Fourier transform infrared analysis. Type of wall material had a more significant impact on the properties of microencapsulated soybean extract than inlet air temperature. The degradation of total isoflavones during storage mainly depended on the inter-conversion level of isoflavones during encapsulation, hygroscopicity and heating history of microencapsulated soybean extract. The use of βCD as wall material could preserve total isoflavones after encapsulation and storage at 0.1–1.3 and 2.4–3.1 times that in the case of MD and 1.1–1.3 and 1.5–1.8 times that in the case of GA, respectively. Abbreviations AI aglycone isoflavones (daidzein and genistein)

AGI acetyl β-glucoside isoflavones (6″-O-acetyldaidzin and 6″-O-acetylgenistin)

βCD β-cyclodextrin

GA gum arabic

GI β-glucoside isoflavones (daidzin and genistin)

MD maltodextrin

MGI malonyl β-glucoside isoflavones (6″-O-malonyldaidzin and 6″-O-malonylgenistin)

SE soybean extract

SE-βCD microencapsulated soybean extract using β-cyclodextrin as wall material

SE-GA microencapsulated soybean extract using gum arabic as wall material

SE-MD microencapsulated soybean extract using maltodextrin as wall material

TI total isoflavones (sum of MGI, AGI, GI and AI)

     

酸催化水解阿拉伯胶制备L-阿拉伯糖工艺

阿拉伯胶是提取制备L-阿拉伯糖的理想原料,对阿拉伯胶进行酸催化水解可获得含L-阿拉伯糖、D-半乳糖、L-鼠李糖的反应液,优化酸水解条件使水解液中L-阿拉伯糖的含量和收率均达到最佳水平,是保证后续分离纯化工艺稳定性及产品品质的关键。利用单因素实验考察了反应时间、酸浓度、反应温度、固液比等因素对水解工艺的影响,获得了影响酸水解反应的关键因素及适宜的水解条件。结果表明:温度对L-阿拉伯糖的生成速率有明显影响。经优化,当固液比为1:10 (g/ml)、100℃、0.1 mol·L^-1 H₂SO₄水解90 min或90℃、0.1 mol·L^-1 H₂SO₄水解200 min,水解液中L-阿拉伯糖的相对纯度分别达85%和87%,水解收率高达85%。     

阿拉伯胶乳液对共轭亚油酸的氧化保护和在模拟胃肠液中的释放研究

共轭亚油酸(CLA)是一类具有多种生理活性的不饱和脂肪酸,极易被氧化,在食品工业中的应用受到很大限制。本文采用阿拉伯胶(GA)制备CLA乳液,从CLA氧化产物角度来评价GA对CLA乳液的氧化保护作用,同时对CLA在模拟胃肠中的释放动力学特征进行研究。结果表明,5.0%浓度时GA在乳液界面荷载量达到最大,此浓度下乳液中CLA的挥发性氧化降解产物浓度最低,氧化稳定性最好;在模拟胃液中释放率缓慢增加,粒径分布均匀;在模拟肠液中释放率加快,乳液出现大颗粒聚集。随着GA浓度增加,CLA挥发性氧化降解产物含量增加,氧化稳定性降低;CLA在胃部释放率有所增加,大颗粒聚集增多。但总体来说,GA乳液中CLA在模拟胃肠液中的释放显示出了良好的营养缓释性能,延长了CLA的释放时间,提高了CLA的生物利用度。     

New procedure for preparation of highly stable and well separated carbon nanotubes in an aqueous modified polyacrylonitrile

Carbon nanotubes (CNTs) due to their nonreactive surface can not effectively disperse in polymeric matrix. Efficient exploitation of CNTs properties to improve material performance is generally related to the degree of dispersion, saturation by the matrix and interfacial adhesion. In order to obtain a suitable dispersion, the CNTs usually need treatment before they can be utilized. In this work, an easy procedure for preparation a stable dispersion of well separated and individual CNTs in an aqueous polymeric solution by using of Gum Arabic (GA) and modified polymer has been described. The applied polymer was a modified water soluble acrylonitrile polymer. The modification was carried out through functionalizing polyacrylonitrile by 2‐aminoethanol. Individual dispersion of the CNTs in the aqueous GA solution after two month can be observed. By incorporating the modified polyacrylonitrile to the solution, the stability of the individual CNTs dispersion several times was increased in such a way that after six month, the CNTs were still kept at their individual positions. According to the suggested mechanism of dispersion, hydrogen bonds between GA/CNTs and the modified polyacrylonitrile chains can be formed that increasing the dispersion ability. The effects of salts and temperature on dispersion ability of GA were also studied.     

Real-time arabic handwritten character recognition

This paper considers the development of a real-time Arabic handwritten character recognition system. The shape of an Arabic character depends on its position in a given word. The system assumes that characters result from a reliable segmentation stage, thus, the position of the character is known a priori. Thus, four different sets of character shapes have been independently considered. Each set is further divided into four subsets depending on the number of strokes in the character. The system has been heavily tested and the average recognition rate has been found to be 99.6% where most of the misrecognized characters were actually written with little care. Thus, the system can be reliably used for the recognition of on-line handwritten characters entered via a graphic tablet.     

A new representation of shape and its use for high performance in online Arabic character recognition by an associative memory

The purpose of this study is to investigate a new representation of shape and its use in handwritten online character recognition by a Kohonen associative memory. This representation is based on the empirical distribution of features such as tangents and tangent differences at regularly spaced points along the character signal. Recognition is carried out by a Kohonen neural network trained using the representation. In addition to the Euclidean distance traditionally used in the Kohonen training algorithm to measure the similarities among feature vectors, we also investigate the Kullback–Leibler divergence and the Hellinger distance, functions that measure distance between distributions. Furthermore, we perform operations (pruning and filtering) on the trained memory to improve its classification potency. We report on extensive experiments using a database of online Arabic characters produced without constraints by a large number of writers. Comparative results show the pertinence of the representation and the superior performance of the scheme.     

哈萨克文转化系统的研究与实现

语言作为交流最基本的方式,在民族的发展过程中起着举足轻重的作用.哈萨克语作为语言的一种,对哈萨克民族的发展起着其应有的作用.但是由于历史的原因,哈萨克语在世界范围内形成了基于同一语言的两种文字形式这种特殊情况.这两种文字形式分别是以阿拉伯文字母为基础的哈萨克阿拉伯文字和以斯拉夫文字母为基础的哈萨克斯拉夫文字.这种特例,为哈萨克族科学技术的发展和文化的交流带来了不便,因此开发和完善哈萨克语这两种文字形式之间的计算机转换系统具有重要意义.本文将介绍用C#编写的哈萨克语的两种文字形式间的计算机自动转换程序,采用机器翻译的方法并在Windows环境下实现哈萨克语的两种文字形式间的智能转换.