摘要
The equilibrium interfacial tension and dilational elasticity at the soy oil-water interface were studied in the presence of a lipophilic emulsifier, polyglycerol polyricinoleate (PGPR), in the continuous oil phase, and dairy proteins, 尾-lactoglobulin (尾-lg) or sodium caseinate, in the aqueous phase using drop shape tensiometry. The interfacial tension decreased with increasing PGPR concentration, and was <2聽mN聽m鈭? at PGPR concentrations beyond 1%. The presence of proteins in the water phase, 尾-lg and sodium caseinate, further reduced the interfacial tension. Even at the low concentrations (0.008%) tested, PGPR dominated the interfacial elasticity, which was only slightly affected by the addition of elevated levels of protein. While in the presence of 尾-lg (0.1%) in isolation, the system showed a high interfacial elasticity, the addition of PGPR lowered the elasticity, suggesting that PGPR interfered with protein-protein interactions at the interface, or caused displacement of 尾-lg. Interfacial elasticity at the oil-water interface showed little dependence on dilation or frequency of the sinusoidal oscillation, when the interface was dominated by PGPR.