Stability of Emulsions Containing Both Sodium Caseinate and Tween 20.

The creaming and rheology of oil-in-water emulsions (30 vol% n-tetradecane, pH 6.8) stabilized by a mixture of commercial sodium caseinate and the non-ionic emulsifier polyoxyethylene sorbitan monolaurate (Tween 20) has been investigated at 21 degrees C. The presence of sufficient Tween 20 to displace most of the protein from the emulsion droplet surface leads to greatly enhanced emulsion creaming (and strongly non-Newtonian rheology) which is indicative of depletion flocculation by nonadsorbed surface-active material (protein and emulsifier). In emulsions containing a constant amount of surface-active material, the replacement of a very small fraction of Tween 20 by caseinate in a stable pure Tween 20 emulsion leads to enhanced creaming for a small fraction of the droplets, and this fraction increases with increasing replacement of emulsifier by protein. This behavior is probably due to depletion flocculation, although an alternative bridging mechanism is also a possibility. The overall stability of these sets of emulsions can be represented in terms of a global stability diagram containing regions of bridging flocculation and coalescence (low content of surface-active material), stability (intermediate content), and depletion flocculation (high content). Copyright 1999 Academic Press.

[1]  Dickinson,et al.  Viscoelastic Properties of Protein-Stabilized Emulsions: Effect of Protein-Surfactant Interactions. , 1998, Journal of agricultural and food chemistry.

[2]  E. Dickinson,et al.  Influence of an anionic surfactant on the rheology of heat-set β-lactoglobulin-stabilized emulsion gels , 1997 .

[3]  Dickinson,et al.  Rheology of Sodium Caseinate Stabilized Oil-in-Water Emulsions , 1997, Journal of colloid and interface science.

[4]  Povey,et al.  Creaming and Flocculation of Oil-in-Water Emulsions Containing Sodium Caseinate , 1997, Journal of colloid and interface science.

[5]  E. Dickinson,et al.  Depletion flocculation of emulsions containing unadsorbed sodium caseinate , 1997 .

[6]  D. Horne,et al.  Displacement of native and thiolated β-casein from oil—water interfaces—effect of heating, ageing and oil phase , 1997 .

[7]  J. Patino,et al.  Interfacial and foaming characteristics of protein-lipid systems , 1997 .

[8]  D. Dalgleish,et al.  Oil-in-Water Emulsions Stabilized by Sodium Caseinate or Whey Protein Isolate as influenced by Glycerol Monostearate , 1996 .

[9]  D. Dalgleish,et al.  Surface Properties of Oil-in-Water Emulsion Droplets Containing Casein and Tween 60 , 1995 .

[10]  E. Dickinson,et al.  Food Macromolecules and Colloids , 1995 .

[11]  M. Povey,et al.  The application of modified forms of the Urick equation to the interpretation of ultrasound velocity in scattering systems , 1995 .

[12]  D. Dalgleish,et al.  Casein adsorption on the surfaces of oil-in-water emulsions modified by lecithin , 1993 .

[13]  D. Clark.  Food colloids and polymers: Stability and mechanical properties , 1993 .

[14]  E. Dickinson.  An introduction to food colloids , 1992 .

[15]  E. Dickinson,et al.  Protein displacement from the emulsion droplet surface by oil-soluble and water-soluble surfactants , 1992 .

[16]  E. Dickinson,et al.  Competitive adsorption of lecithin and beta-casein in oil in water emulsions , 1991 .

[17]  Peter J. Wilde,et al.  The influence of surface composition and molecular diffusion on the stability of foams formed from protein/surfactant mixtures , 1990 .

[18]  W. K. Jordan,et al.  Action of Emulsifers in Promoting Fat Destabilization During the Manufacture of Ice Cream , 1989 .

[19]  P. Sherman,et al.  The interaction of sodium caseinate with monoglyceride and diglyceride at the oil-water interface and its effect on interfacial rheological properties , 1986 .