The sensory characteristics of low-fat yoghurts manufactured with microparticulated whey protein could be clearly distinguished depending on the characteristics of the microparticles added. A high native-to-denatured whey protein ratio provided more viscous and creamy low-fat yoghurts, which were related to the reference full fat yoghurt. These results emphasize that the degree of denaturation of the whey proteins included in the MWP powder used as fat replacer is important for the sensory and rheological properties of the final yoghurts. In consequence, during the manufacture of the microparticulated whey proteins it is necessary to have full control of the parameters influencing the degree of denaturation of the whey proteins. The surface reactivity of the microparticles also appears to play a more important role in the final perception of graininess in the yoghurts, than the initial particle size of the MWP aggregates. Thus, a large particle size of the initial aggregates may in fact yield yoghurts with low graininess perception, if the microparticles are able to become an integrated part of the yoghurt matrix during the fermentation of the milk.
It was seen that some of the sensory attributes of yoghurts can be effectively predicted by rheological tests, such as an oscillatory frequency sweep, Posthumus funnel or viscometry analysis. This can ease the task in adapting the functionality of microparticulated whey proteins or other ingredients to the sensory perception of yoghurt.