Impact of a thermal treatment at different pH on the adsorption behaviour of untreated and enzyme-modified egg yolk at the oil-water interface

Adsorption properties of egg yolk proteins were investigated with or without enzymatic modification with phospholipaseA2 (PLA2) and after a thermal treatment atpH4 and 6.5. Heat treatment was assessed from60to90◦Cresulting in awiderange of protein denaturation degrees,whichwerecorrelated with the interfacial protein load of emulsion droplets. Itwasshownthat denatured proteins, i.e. protein aggregates are able toadsorbattheoil--waterinterfaceandthat,mostnotably,granuleconstituentsplayanimportant role in stabilisation of the oil--water interface at pH 4. Moreover, it was shown that after a thermal treatment of untreated egg yolk (not enzyme treated) an even higher protein load is reached than when PLA2-treated egg yolk is used for emulsification. Heat-treated natural egg yolk is therefore supposed to be an appropriate alternative for PLA2-treated egg yolk for producing stable emulsions. The SDS-Page profiles show that the composition of the interfacial film is highly influenced by a modification with PLA2 at pH 4 while at pH 6.5 the interfacial composition of adsorbed proteins is less influenced.     «

Adsorption properties of egg yolk proteins were investigated with or without enzymatic modification with phospholipaseA2 (PLA2) and after a thermal treatment atpH4 and 6.5. Heat treatment was assessed from60to90◦Cresulting in awiderange of protein denaturation degrees,whichwerecorrelated with the interfacial protein load of emulsion droplets. Itwasshownthat denatured proteins, i.e. protein aggregates are able toadsorbattheoil--waterinterfaceandthat,mostnotably,granuleconstituentsplayanimportant...     »