Displacement of native and thiolated β-casein from oil—water interfaces—effect of heating, ageing and oil phase

Covalent Modification of Emulsified β-Casein Resulting from Lipid Peroxidation

“…The hydrophobicity of these modified residues will depend on the structure of the reacting species. A more hydrophobic protein would be displaced less readily by a water-soluble surfactant from an oil-water interface as reported previously (6). In addition, if the interaction of the aldehydes with the emulsified ␤-casein is via Michael-type reaction, the carbonyl group of the aldehyde may subsequently participate in the formation of intra-and possibly intermolecular crosslinks with amino residues via the formation of Schiff bases, thereby further stabilizing the adsorbed protein to displacement by Tween 20.…”

“…Recently we reported that the displacement of ␤-casein from soya oil emulsions by the nonionic surfactant Tween 20 is dependent on the age of the emulsion with the protein being displaced more easily from freshly made samples (6). In this paper we show that some of the differences in the behavior of protein molecules in microfluidized emulsions arise from covalent modification of the adsorbed protein, the occurrence of which is dependent on the oil phase and the extent of which increases with storage time.…”

Working together: interactions between vaccine antigens and adjuvants

“…Within the context of protein-stabilized emulsions, hydrophobicity has been demonstrated to be the primary interaction mechanism [Junghans et al 2010], in which emulsifying proteins can be easily denatured [Jutila et al 2000] or displaced by nonionic surfactants such as polysorbates [Courthaudon et al 1991;Dickinson and Gelin, 1992;Rampon et al 2003aRampon et al , 2003bStevenson et al 1997] and sorbitan esters [Cornec et al 1996], among others [Courthaudon et al 1991]. This desorption tends to proceed as a gradual replacement of protein with surfactant [Rampon et al 2003a] at the oil-water interface resulting from a change in protein binding exchange kinetics [Dickinson and Gelin, 1992] in a manner that appears to be a function of protein structure [Cornec et al 1996;Stevenson et al 1997] and the timing of surfactant introduction [Courthaudon et al 1991].…”

“…These structural rearrangements appear to be more resilient to thermal denaturation than nonadsorbed proteins [Zhai et al 2011[Zhai et al , 2012, potentially due to α-helical conformation support imparted by the oil microenvironment. Moreover, the oil phase may have a considerable impact on adsorbed protein structure in comparison to native protein conformation, as oil polarity and chain disorder can vary folding of adsorbed proteins [Herrero et al 2011;Stevenson et al 1997;Venien et al 2000;Zhai et al 2011Zhai et al , 2012.…”

Stability of Emulsions Containing Both Sodium Caseinate and Tween 20

“…The complicated behavior of these mixed systems depends on the nature of the interactions between proteins and emulsifiers at the oil-water interface. As a general rule, simple non-ionic emulsifiers displace milk proteins from the interface because at high surfactant concentrations they produce a lower interface tension (3)(4)(5). However, various cases of coexistence of proteins and surfactants at the interface have also been reported, i.e., for the case of (oilsoluble) monoglycerides (6 -8), or (mainly water-soluble) phospholipids (9) as emulsifiers.…”