Rheological basis of oral characteristics of fluid and semi-solid foods: a review.

Oral viscosity plays an important role in the textural appreciation of fluid and semi-solid foods. Oral assessments of viscosity, thickness, stickiness and sliminess correlate with both small-deformation and large-deformation rheological measurements. Small-deformation measurements of viscosity at an oscillatory frequency of 50 rad.s-1 have the highest correlation with assessed thickness of texture but there is still much speculation as to what forces actually operate in the mouth.