Using vane geometry for measuring the texture of stirred yogurt

The relationship between vane geometry measurements and sensory perceptions of stirred yogurt texture was investigated. Descriptive profiling showed that the main perceptible textural difference between six commercial stirred yogurts was thickness (both visual and in-mouth). The yogurts were analyzed using the vane with a low constant rotation rate (generation of overshoot curves). Correlations with parameters extracted from the overshoot curves were significant for both visual and in-mouth thickness, but were higher for visual thickness. Visual thickness correlated highest with the maximum apparent stress. The maximum stress in an overshoot curve is often quoted to be equal to the material's yield stress. This was not found to be the case as the overshoot maximum decreased when the rotation rate was lowered. The physical nature of the visual thickness test was investigated to further aid interpretation of the results.