The occurrence of in-mouth coalescence of emulsion droplets in relation to perception of fat

We studied the relation between sensitivity of emulsions for in-mouth coalescence and perception of fat-related attributes, such as creaminess as well as the relation with in vivo perceived and ex vivo measured friction. Emulsions with varying expected sensitivity towards in-mouth coalescence were engineered, sensorially evaluated using a trained QDA panel and physico-chemically characterised using light scattering and microscopy. Physico-chemical characterisation of those in vivo and ex vivo processed emulsions confirmed the expected sensitivity of these systems towards in-mouth coalescence. Experiments showed that both shear-induced and surface-induced coalescences play a role in the occurrence of in-mouth coalescence. Furthermore, the emulsions were characterised by performing friction measurements under mouth-mimicking conditions to be able to identify a relation between perceived oral friction and perception of fat-related attributes. It is shown that the emulsions most sensitive towards in-mouth coalescence gave rise to the highest creamy mouth-feel and fatty sensations as well as oily taste sensation. This indicates that both aroma and mouth-feel are of importance in fat perception. Combining friction force measurements with sensory analyses indicated that occurrence of coalescence gives rise to an enhanced fat perception and also to a lowering of the orally perceived and experimentally measured friction. The results opened the way to manufacture reduced fat emulsions with a full-fat sensation. (C) 2007 Elsevier Ltd. All rights reserved.