Relation between sensory texture analysis and rheological properties of stirred yogurt

The sensory and rheological characteristics of stirred yogurts varying in f ermentation temperature, heat treatment of milk, dry matter content and com position of bacterial cultures were investigated. Two independent sensory p roperties, non-oral viscosity and oral viscosity, were evaluated. To reflec t these properties precisely it was necessary to perform rheological measur ements at both small and large deformations. Non-oral and oral viscosities were successfully modelled from a set of rheological variables by partial l east squares regression, resulting in a three component model explaining 83 .8% of the variation in non-oral viscosity and a two component model explai ning 82.0% of the variation in oral viscosity. Non-oral viscosity was highl y correlated with the complex modulus (G*) from the dynamic oscillatory mea surements (r = 0.823) and the viscosity obtained from a Brookfield viscomet er (with Helipath stand) operating at 5 rev./min (r = 0.862). Similarly, th ere were relationships between oral viscosity and the hysteresis loop area from the viscometry test (r = 0.867) and between oral viscosity and the vis cosity obtained from the Posthumus funnel (r = 0.834).