Chanamai R, Herrmann N, McClements DJ
Department of Food Science, University of Massachusetts, Amherst, Massachusetts, 01003
J Colloid Interface Sci. 1998 Aug 15;204(2):268-76. doi: 10.1006/jcis.1998.5569.
Ultrasonic attenuation spectroscopy was used to study flocculation and shear-induced disruption of flocs in oil-in-water emulsions. The ultrasonic attenuation spectra (1 to 150 MHz) of a series of 10 wt% corn oil-in-water emulsions (r32 = 0.2 µm) were measured. Depletion flocculation was induced in the emulsions by adding different concentrations (0 to 0.2 wt%) of a nonadsorbing biopolymer (xanthan) to the aqueous phase. At low frequencies, the attenuation coefficient of the emulsions decreased with increasing flocculation due to overlap of the thermal waves generated by the droplets. These observations were in good agreement with a theory recently developed to account for the influence of droplet flocculation on the ultrasonic properties of emulsions. The ultrasonic technique was also used to monitor the breakdown of flocs under shear flow. The dependence of the ultrasonic properties of emulsions on flocculation means that ultrasonic attenuation spectroscopy can be used to study droplet interactions in concentrated emulsions. Copyright 1998 Academic Press.
超声衰减光谱法被用于研究水包油乳液中絮凝以及剪切诱导的絮凝物破坏。测量了一系列10 wt%玉米油包水乳液（r32 = 0.2 µm）的超声衰减光谱（1至150 MHz）。通过向水相中添加不同浓度（0至0.2 wt%）的非吸附性生物聚合物（黄原胶），在乳液中引发耗尽絮凝。在低频下，由于液滴产生的热波重叠，乳液的衰减系数随着絮凝增加而降低。这些观察结果与最近为解释液滴絮凝对乳液超声特性的影响而发展的理论高度一致。超声技术还被用于监测剪切流作用下絮凝物的分解。乳液超声特性对絮凝的依赖性意味着超声衰减光谱法可用于研究浓乳液中的液滴相互作用。版权所有1998年学术出版社。
