Interfacial rheological properties of Tween 20:β-lactoglobulin mixed systems as affected by phenolic antioxidant compounds

Composition and rheological properties of interfacial layers are important parameters that influence both chemical and physical stability of multiphasic systems. From the chemical viewpoint, the addition of phenolic antioxidant molecules represents a valid tool for the oxidative prevention, provided that these compounds are allowed to localize at the interfacial layer where most of the oxidative reactions are considered to occur. This study was thus aimed to evaluate the effect of the addition of some phenolic antioxidant compounds on both the air/water and olive oil/water interfacial rheology of Tween 20:β-lactoglobulin mixed adsorbed layer. Gallic acid, catechin and quercetin, characterized by different polarity and surface properties, were used. All the polyphenols under investigation affected the surface viscosity but the most profound effect was produced by catechin which caused a significant reduction in surface viscosity. Also in the case of olive oil/water interfacial rheology the phenolic molecules influenced the behaviour of the emulsifiers adsorbed layer even if the highest effect was observed with quercetin addition.