Ogawa Satoshi, Decker Eric A, McClements D Julian
Biopolymers and Colloids Research Laboratory, Department of Food Science, University of Massachusetts, Amherst, MA 01003, USA.
J Agric Food Chem. 2003 Apr 23;51(9):2806-12. doi: 10.1021/jf020590f.
Oil-in-water emulsions containing cationic droplets stabilized by lecithin-chitosan membranes were produced using a two-stage process. A primary emulsion was prepared by homogenizing 5 wt % corn oil with 95 wt % aqueous solution (1 wt % lecithin, 100 mM acetic acid, pH 3.0) using a high-pressure valve homogenizer. This emulsion was diluted with aqueous chitosan solutions to form secondary emulsions with varying compositions: 1 wt % corn oil, 0.2 wt % lecithin, 100 mM acetic acid, and 0-0.04 wt % chitosan (pH 3.0). The particle size distribution, particle charge, and creaming stability of the primary and secondary emulsions were measured. The electrical charge on the droplets increased from -49 to +54 mV as the chitosan concentration was increased from 0 to 0.04 wt %, which indicated that chitosan adsorbed to the droplet surfaces. The mean particle diameter of the emulsions increased dramatically and the emulsions became unstable to creaming when the chitosan concentration exceeded 0.008 wt %, which was attributed to charge neutralization and bridging flocculation effects. Sonication, blending, or homogenization could be used to disrupt flocs formed in secondary emulsions containing droplets with high positive charges, leading to the production of emulsions with relatively small particle diameters (approximately 1 microm). These emulsions had good stability to droplet aggregation at low pH (< or =5) and ionic strengths (<500 mM). The interfacial engineering technology utilized in this study could lead to the creation of food emulsions with improved stability to environmental stresses.
采用两步法制备了由卵磷脂 - 壳聚糖膜稳定的含阳离子液滴的水包油乳液。使用高压阀均质机将5 wt%的玉米油与95 wt%的水溶液（1 wt%卵磷脂、100 mM乙酸、pH 3.0）均质，制备出初级乳液。用壳聚糖水溶液稀释该乳液，以形成具有不同组成的次级乳液：1 wt%玉米油、0.2 wt%卵磷脂、100 mM乙酸和0 - 0.04 wt%壳聚糖（pH 3.0）。测量了初级和次级乳液的粒径分布、颗粒电荷和乳析稳定性。随着壳聚糖浓度从0增加到0.04 wt%，液滴上的电荷从 - 49 mV增加到 + 54 mV，这表明壳聚糖吸附到了液滴表面。当壳聚糖浓度超过0.008 wt%时，乳液的平均粒径显著增加，并且乳液对乳析变得不稳定，这归因于电荷中和和桥连絮凝效应。超声处理、搅拌或均质可用于破坏在含有高正电荷液滴的次级乳液中形成的絮凝物，从而制备出粒径相对较小（约为1微米）的乳液。这些乳液在低pH（≤5）和离子强度（<500 mM）下对液滴聚集具有良好的稳定性。本研究中使用的界面工程技术可导致创建对环境应力具有更高稳定性的食品乳液。
