The sensory characteristics of low-fat yoghurts manufactured
with microparticulated whey protein could be 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.