Use of modified whey protein in yoghurt formulations

Substituting native or denatured whey protein ingredients for milk protein in yoghurt formulations resulted in excessive elasticity and grainy texture. These characteristics were incompatible with the smooth and short texture expected from yoghurt. Whey protein ingredients were modified to produce yoghurts with acceptable texture properties. Alteration of the ratio of α-lactalbumin to β-lactoglobulin, heat denaturation and hydrolysis treatments were applied to whey protein to improve their behaviour in yoghurt formulations. Ingredients with increased proportion of α-lactalbumin or made from partially hydrolyzed protein produced yoghurts that closely matched the characteristics of control yoghurt. The effect of whey protein ingredients on yoghurt rheological properties and dispersibility was related to the concentrations of reactive thiol groups that determined the extent of cross linking during acidification. During storage, yoghurt firmness and viscosity increased and syneresis decreased. Yoghurt microstructure was altered by whey protein ingredients, which significantly reduced void spaces and increased gel matrix compactness.