Mechanical properties and microstructure of heat-set whey protein emulsiongels: Effect of emulsifiers

A comparison of the viscoelastic properties of heat-set whey protein-stabil ized oil-in-water emulsion gels in the presence and absence of added emulsi fier has been complemented by structural information from confocal laser sc anning microscopy (CLSM). Emulsions (300 mL/L triolein oil, pH 7.0) were pr epared with pure beta-lactoglobulin (8 g/kg) or water-soluble surfactant (2 0 g/kg Tween 20) as emulsifier and commercial,whey protein isolate ( > 95% beta-lactoglobulin) added to the emulsion aqueous phase (80 g/kg )before he at treatment (85 degrees C). The differing effects of glycerol monopalmitat e and Tween 20 (polyoxyethylene sorbitan monolaurate) on the emulsion gel r heology has been interpreted in terms of the reaction of the filler particl es as determined by, the composition of the adsorbed layer around the emuls ion droplets. There is evidence from the CLSM of enhanced coalescence of em ulsion droplets during thermal treatment in the presence of the emulsifiers , and of an extensively phase-separated microstructure in rite ease of the emulsion gel containing Tween 20. (C) 2000 Academic Press.