The sensory and rheological characteristics of stirred yogurts varying in
fermentation temperature, heat treatment of milk, dry matter content and
composition of bacterial cultures were investigated. Two independent sensory
properties, non-oral viscosity and oral viscosity, were evaluated. To reflect these
properties precisely it was necessary to perform rheological measurements at both
small and large deformations. Non-oral and oral viscosities were successfully
modelled from a set of rheological variables by partial least squares regression,
resulting in a three component model explaining 83·8% of the variation in non-oral
viscosity and a two component model explaining 82·0% of the variation in oral
viscosity. Non-oral viscosity was highly correlated with the complex modulus (G*)
from the dynamic oscillatory measurements (r=0·823) and the viscosity obtained
from a Brookfield viscometer (with Helipath stand) operating at 5 rev./min
(r=0·862). Similarly, there were relationships between oral viscosity and the hysteresis
loop area from the viscometry test (r=0·867) and between oral viscosity and the
viscosity obtained from the Posthumus funnel (r=0·834).