Emulsions stabilised by whey protein microgel particles: towards food-grade Pickering emulsions
Emulsions stabilised by whey protein microgel particles: towards food-grade Pickering emulsions
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DOI：
10.1039/c4sm00179f
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发表时间：
2014-01-01
期刊：
影响因子：
3.4
通讯作者：
Binks, Bernard P.
中科院分区：
文献类型：
--
作者：
Destribats, Mathieu;Rouvet, Martine;Binks, Bernard P.
我们已经研究了一类新的食品级颗粒，乳清蛋白微凝胶，作为稳定剂的磷脂-水乳液。亚微米颗粒在所有pH值下在有盐和无盐的情况下稳定水包油乳液。所有乳液均成乳状，但表现出优异的抗聚结性。在水分散体中的微凝胶的性质和所得的乳液特性之间存在明确的相关性。对于其中颗粒不带电的条件，具有相对大的液滴的流体乳液被稳定，而由带电颗粒稳定的乳液含有较小的絮凝液滴。结合光学显微镜的液滴和分光光度法的解决的水相，使我们能够估计使用有限聚结现象的颗粒的界面吸附密度。我们推导出两类粒子排列。当它们是中性的或当它们的电荷被盐屏蔽时，获得颗粒的完全吸附，从而在界面处产生至少一个颗粒单层。相比之下，只有约50%的颗粒吸附时，他们被充电与乳液滴被覆盖不到半个单层。这些发现得到了支持的直接可视化液滴界面使用冷冻扫描电子显微镜。不带电粒子高度聚集，并在界面处形成连续的二维网络。否则，颗粒组织为由无颗粒区域分离的单个聚集体。在这种情况下，我们认为，一些颗粒在界面处扩散，导致形成连续的蛋白质膜。带电粒子显示桥接相邻液滴的相对界面以形成致密粒子盘的能力，所述致密粒子盘保护液滴免于聚结;这是含有稀疏覆盖液滴的乳液的絮凝和稳定性的主要原因。
We have investigated a new class of food-grade particles, whey protein microgels, as stabilisers of triglyceride-water emulsions. The sub-micron particles stabilized oil-in-water emulsions at all pH with and without salt. All emulsions creamed but exhibited exceptional resistance to coalescence. Clear correlations exist between the properties of the microgels in aqueous dispersion and the resulting emulsion characteristics. For conditions in which the particles were uncharged, fluid emulsions with relatively large drops were stabilised, whereas emulsions stabilized by charged particles contained smaller flocculated drops. A combination of optical microscopy of the drops and spectrophotometry of the resolved aqueous phase allowed us to estimate the interfacial adsorption densities of the particles using the phenomenon of limited coalescence. We deduce two classes of particle arrangement. Complete adsorption of the particles was obtained when they were neutral or when their charges were screened by salt resulting in at least one particle monolayer at the interface. By contrast, only around 50% of the particles adsorbed when they were charged with emulsion drops being covered by less than half a monolayer. These findings were supported by direct visualization of drop interfaces using cryo-scanning electron microscopy. Uncharged particles were highly aggregated and formed a continuous 2-D network at the interface. Otherwise particles organized as individual aggregates separated by particle-free regions. In this case, we suggest that some particles spread at the interface leading to the formation of a continuous protein membrane. Charged particles displayed the ability to bridge opposing interfaces of neighbouring drops to form dense particle disks protecting drops against coalescence; this is the main reason for the flocculation and stability of emulsions containing sparsely covered drops.