Tuinier R
NIZO Food Research, 6710 BA Ede, The Netherlands
J Colloid Interface Sci. 1999 Oct 1;218(1):201-210. doi: 10.1006/jcis.1999.6327.
We have investigated the effect of an exocellular polysaccharide (EPS) on the phase behavior and the rheology of oil-in-water emulsions. Already at low EPS concentrations the phase separation occurs. The phase line can be described by depletion interaction theory. At high EPS concentrations and dispersed phase volume fractions above 10% there is a stable "gel"-like region in the phase diagram. A kinetic study showed that the rate of creaming decreases with increasing oil content due to hydrodynamic effects. This rate depends strongly on the concentration of EPS, which is related to the strength of the depletion interaction and the viscosity of the continuous phase. At low EPS concentration the creaming rate strongly increases with EPS concentration because of the stronger attraction. At higher EPS concentrations creaming is slowed down by the viscosity increase of the continuous phase and of the particle network which is formed. At high EPS concentrations this network becomes so strong that the gel prevents creaming. The rheological behavior of the "gel" was studied by measuring flow curves, which could be interpreted by a theoretical model for weakly aggregating particles. Copyright 1999 Academic Press.
我们研究了一种胞外多糖（EPS）对水包油乳液的相行为和流变学的影响。在低EPS浓度下就会发生相分离。相界线可用耗尽相互作用理论来描述。在高EPS浓度和分散相体积分数高于10%时，相图中存在一个稳定的“凝胶”状区域。动力学研究表明，由于流体动力学效应，乳析速率随油含量的增加而降低。该速率强烈依赖于EPS的浓度，而EPS浓度与耗尽相互作用的强度和连续相的粘度有关。在低EPS浓度下，由于更强的吸引力，乳析速率随EPS浓度强烈增加。在较高EPS浓度下，连续相和形成的颗粒网络的粘度增加使乳析减缓。在高EPS浓度下，这种网络变得非常强大，以至于凝胶阻止了乳析。通过测量流动曲线研究了“凝胶”的流变行为，流动曲线可用弱聚集颗粒的理论模型来解释。版权所有1999年学术出版社。
