Relative importance of cohesion and adhesion for sensory stickiness of semisolid foods

Sensory stickiness (sticky mouthfeel) was hypothesized to result from the viscoelastic and adhesive properties of a foodstuff. The objective of the present study was to investigate the relative importance of these two properties. Measurements consisted of compression - decompression cycles on a texture analyzer, with product, type of surface, the presence or absence of saliva and compression regime as variables. Products included commercial mayonnaises, custard desserts and warm sauces, varying in apparent viscosity (at shear rate of 10 s(-1)) between 0.3 and 18.3 Pa.s. Fairly good models were obtained, predicting sensory stickiness with R-2 = 0.85-0.92. The predictive value of the mathematical models did not increase when the surface characteristics approached those of the human tongue (use of porcine lingual mucosa). Different surfaces or the use of saliva resulted in differences in the absolute values of the parameters, but their relative values when comparing different products did not change. The parameters appearing in the predictive models represented product characteristics only. The type of surface was not an important factor in determining differences in sensory stickiness between these samples. For the products used in this study, adhesion was large enough to prevent detachment of the sample from the surfaces, i.e., adhesion was not limiting. Variations in perceived stickiness could be explained with R-2 = 0.86, based on only two product characteristics: consistency and 'long behavior' (the extent to which necking occurs during decompression). This was better than the correlation between sensory stickiness and apparent viscosity (R-2 = 0.77), confirming the relevance of 'long behavior' for sensory stickiness.