Institute of Food, Nutrition and Human Health, Massey University, Auckland, New Zealand.
J Agric Food Chem. 2011 Jan 12;59(1):415-27. doi: 10.1021/jf103511v. Epub 2010 Dec 2.
The properties of whey protein isolate (WPI) stabilized oil-in-water (O/W) nanoemulsions (d(43) ≈ 66 nm; 0.5% oil, 0.9% WPI) and emulsions (d(43) ≈ 325 nm; 0.5% oil, 0.045% WPI) were compared. Emulsions were prepared by high-pressure homogenization, while nanoemulsions were prepared by high-pressure homogenization and solvent (ethyl acetate) evaporation. The effects of pH, ionic strength (0-500 mM NaCl), thermal treatment (30-90 °C), and freezing/thawing on the stability and properties of the nanoemulsions and emulsions were compared. In general, nanoemulsions had better stability to droplet aggregation and creaming than emulsions. The nanoemulsions were unstable to droplet flocculation near the isoelectric point of WPI but remained stable at higher or lower pH values. In addition, the nanoemulsions were stable to salt addition, thermal treatment, and freezing/thawing (pH 7). Lipid oxidation was faster in nanoemulsions than emulsions, which was attributed to the increased surface area. Lipase digestibility of lipids was slower in nanoemulsions than emulsions, which was attributed to changes in interfacial structure and protein content. These results have important consequences for the design and utilization of food-grade nanoemulsions.
乳清蛋白分离物 (WPI) 稳定的水包油 (O/W) 纳米乳液 (d(43) ≈ 66nm；0.5%油，0.9% WPI) 和乳液 (d(43) ≈ 325nm；0.5%油，0.045% WPI) 的性质进行了比较。乳液通过高压均质化制备，而纳米乳液通过高压均质化和溶剂 (乙酸乙酯) 蒸发制备。比较了 pH 值、离子强度 (0-500mM NaCl)、热处理 (30-90°C) 和冷冻/解冻对纳米乳液和乳液稳定性和性质的影响。一般来说，纳米乳液比乳液对液滴聚集和乳状液分层更稳定。纳米乳液在 WPI 的等电点附近对液滴絮凝不稳定，但在较高或较低 pH 值下仍保持稳定。此外，纳米乳液在加盐、热处理和冷冻/解冻 (pH7) 下稳定。纳米乳液中的脂质氧化速度比乳液快，这归因于比表面积的增加。纳米乳液中脂质的脂肪酶消化速度比乳液慢，这归因于界面结构和蛋白质含量的变化。这些结果对食品级纳米乳液的设计和利用具有重要意义。
