Effect of microparticulated whey protein with varying content of denatured protein on the rheological and sensory characteristics of low-fat yoghurt

Ten types of microparticulated whey proteins with different particle sizes and denaturation degree were added to low-fat stirred yoghurts to obtain two protein levels (4.25 and 5.0%, w/w). Samples were compared to reference yoghurts manufactured with skimmed milk powder: a full fat (3.5%, w/w, fat; 3.5%, w/w, protein) and two low-fat (0.5%, w/w, fat; 4.25 or 5.0%, w/w, protein) yoghurts. A high native-to-denatured whey protein ratio (0.94-1.33) in microparticulated whey protein powders provided yoghurts with high creaminess and viscosity (high yield stress values and elastic modulus), a slow meltdown in the mouth, as well as creamy flavour and low syneresis. These sensory characteristics were related to those from the reference full fat yoghurt. Correlations between rheological and sensory variables showed that viscometry and oscillatory frequency sweep analyses are useful in prediction of texture attributes such as creaminess. (C) 2011 Elsevier Ltd. All rights reserved.