Application of probe tensile method for quantitative characterisation of the stickiness of fluid foods

This work applied a probe tensile separation method for quantitative characterisation of the stickiness of fluid foods and investigated its correlation to consumers’ sensory perception. Altogether 12 commercial fluid food products were tested. The maximum tensile force (Fm) and the work till the maximum force (Wm) were found to be useful parameters for stickiness prediction. Both of the parameters showed positive correlations with the results from sensory perception tests. It was found that, for some fluids, the total work done over the whole tensile separation (W) showed great discrepancy with the sensory perception, due to the existence of long force tail. The separation tests were performed over a wide range of probe speed (from 0.1 mm/s to 40 mm/s), but the inertial effect was found to be negligible. It was also demonstrated that, although the absolute value of force and work were highly dependent on the separation speed, the relative stickiness of foods was not affected as far as the tests were conducted under the same experimental setup. Possible mechanisms governing food stickiness were discussed. It was believed that pressure drop and cavitation of a suddenly stretched fluid could be critical in influencing consumers’ sensual perception of food stickiness.