HIGH-PRESSURE EFFECTS ON EMULSIFYING BEHAVIOR OF WHEY-PROTEIN CONCENTRATE

Oil-in-water emulsions (0.4 wt% protein, 20 vol% n-tetradecane, pH 7) prepared with solutions of pressure-treated (up to 800 MPa) whey prote in concentrate (WPC) as emulsifier give a broader droplet-size distrib ution than emulsions made with native untreated protein. There was a d ecrease in emulsifying efficiency with increasing applied pressure and treatment time. In contrast, pressure treatment of corresponding WPC emulsions made with the native protein had little effect on emulsion s tability. In the pressure-treated emulsion the protein is probably alr eady conformationally modified so that pressure has little additional effect. However, in solution the native structure of the whey protein is modified by pressure resulting in loss of emulsifying efficiency.