Emulsion properties of casein and whey protein hydrolysates and the relation with other hydrolysate characteristics

Casein and whey protein were hydrolyzed using 11 different commercially ava ilable enzyme preparations. Emulsion-forming ability and emulsion stability of the digests were measured as well as biochemical properties with the ob jective to study the relations between hydrolysate characteristics and emul sion properties. All whey protein hydrolysates formed emulsions with bimoda l droplet size distributions, signifying poor emulsion-forming ability. Emu lsion-forming ability of some casein hydrolysates was comparable to that of intact casein. Emulsion instability was caused by creaming and coalescence . Creaming occurred mainly in whey hydrolysate emulsions and in casein hydr olysate emulsions containing large emulsion droplets. Coalescence was domin ant in casein emulsions with a broad particle size distribution. Emulsion i nstability due to coalescence was related to apparent molecular weight dist ribution of hydrolysates; a relative high amount of peptides larger than 2 kDa positively influences emulsion stability.