Stabilization of emulsions by OSA starches
Stabilization of emulsions by OSA starches
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DOI：
10.1016/s0260-8774(01)00206-0
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发表时间：
2002-09-01
影响因子：
5.5
通讯作者：
Schubert, H
中科院分区：
文献类型：
--
作者：
Tesch, S;Gerhards, C;Schubert, H
在连续机械乳化中，粗预混料的液滴首先发生变形和破碎。其次，新形成的界面必须稳定。乳剂在热力学上是不稳定的，因为液滴容易聚结。为了避免液滴聚并，必须考虑到不同的影响。本文的目的是研究使用OSA淀粉作为添加剂生产精细分散乳剂的可能性。实验是用两种市售的OSA淀粉进行的，它们的水溶液粘度主要不同。在实验中，考察了分散相含量、淀粉浓度、pH值以及不同离子强度的溶解盐的影响。通过水包油乳剂制备后的液滴大小分析，确定了水包油乳剂的乳化性能。界面张力的测量证明OSA淀粉是表面活性物质。乳化实验表明，OSA淀粉对液滴的稳定效果很好。研究发现，OSA淀粉的乳化效果与淀粉的种类和超过稳定所需淀粉的下限的淀粉浓度无关。乳化结果与pH值和离子价无关。因此，空间位阻是OSA淀粉的主要稳定机制。由于蛋白质主要通过静电斥力来稳定乳滴，因此乳化效果与pH有很大关系，这导致在等电点附近的pH值乳化效果较差。本文的研究结果表明，乳清蛋白可以被OSA淀粉代替，在蛋白质等电点附近的低pH值下具有特定的优势。(C) 2002年Elsevier Science Ltd.出版
In continuous mechanical emulsification, droplets of a coarse premix are first deformed and disrupted. Secondly, the newly formed interface has to be stabilized. Emulsions are thermodynamically unstable, as droplets tend to coalesce. To avoid coalescence of droplets, different effects have to be taken into account. The objective of this paper is to investigate the possibility of producing finely dispersed emulsions by using OSA starches as additive. Experiments were carried out using two commercially available OSA starches that differ mainly in viscosity of their aqueous solutions. In the experiments, the dispersed phase content, starch concentration as well as pH value and the influence of dissolved salts of different ion strength have been investigated. By droplet size analysis directly after production of oil-in-water emulsions the emulsifying properties of such starches were determined. Measurements of interfacial tension prove that OSA starches are surface active substances. It was shown by emulsification experiments that the stabilization of droplets by OSA starches is very efficient. The emulsification results achieved with OSA starches have been found to be independent from the type of starch and the starch concentration above the lower limit of starch needed for stabilization. The emulsification results are independent of pH value and ion valence. Therefore it can be concluded that steric hindrance is the main stabilizing tricchanism of OSA starches. As proteins stabilize emulsion droplets mainly by electrostatic repulsive forces, the emulsification result depends strongly on pH, which leads to poor emulsification at pH values near the iso-electric point. The results of the work presented here suggest that whey proteins can be substituted by OSA starches with a specific advantage at low pH values near the iso-electric point of the protein. (C) 2002 Published by Elsevier Science Ltd.