Bulk and interfacial viscoelasticity in concentrated emulsions: The role of the surfactant

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• 作者：Miguel Wulff-Pé ; rez^a ; Amelia Torcello-G&#xf3 ; mez^a ; Antonio Martí ; n-Rodrí ; guez^a ; Marí ; a J. Gá ; lvez-Ruiz^a ; Juan de Vicente ; ^a ; ^{jvicente@ugr.es}
• 关键词：Bulk rheology ; Interfacial pressure ; Adsorption ; Interfacial dilatational rheology ; Pluronic F68 ; Phospholipids ; Epikuron 145V
• 刊名：Food Hydrocolloids
• 出版年：2011
• 出版时间：June 2011
• 年：2011
• 卷：25
• 期：4
• 页码：677-686
• 全文大小：546 K

文摘

The aim of this study was to investigate and compare bulk and interfacial viscoelasticity of emulsions stabilized with two surfactants of a markedly different nature: the ionic phospholipids mixture Epikuron 145V and the steric emulsifier Pluronic F68. Emulsions of olive oil in water were prepared by high-pressure homogenization using only one of these surfactants. The impact of the surfactant used on the final linear viscoelastic properties was investigated by means of small-amplitude dynamic oscillatory shear tests, obtaining the values of the storage and loss moduli as a function of frequency, as well as by retardation and relaxation essays. Our results show that for concentrated emulsions, the viscoelastic properties are considerably different depending on which surfactant is used, i.e., the employed surfactant influences to a major extent the bulk rheological properties. In order to explain these differences, an interfacial study of the adsorbed surfactant layers has been carried out, measuring interfacial tension and dilatational viscoelasticity by means of the pendant drop technique. A correlation between the results obtained in bulk and interface has been found.