Explaining perceived oral texture of starch-based custard desserts from standard and novel instrumental tests

A number of in vitro and in vivo instrumental tests have been developed to reflect various aspects of the perceived oral texture of starch-based vanilla custard desserts. These tests include measurements of the food's infra-red reflectance (IRR), of the turbidity of spat-out rinse water, and of the friction between the food and the oral tissue. Also, images of spat-out foods have been digitally processed and image-processing parameters extracted. These tests, together with conventional rheological tests, were carried out on a set of vanilla custard desserts that varied systematically with respect to fat content (0-15%), starch content (3.3-5.1%), and type of modified starch (potato, tapioca, and waxy maize starch with various degrees of cross-liking) judged by nine highly trained QDA panelists. Three sensory dimensions could be identified from principal component analysis to summarize the sensory texture space of the custards. The results from instrumental measurements, together with the effects of ingredients, indicated that the fist dimension, running from roughness to creaminess, was related to lubrication. The second dimension, running from melting to thickness, was related to stimulus viscosity. Finally, the third dimension, running from airy to heterogeneous, was related to starch type. The results indicate that each sensory dimension has attributes that are either related to surface properties or to bulk properties of the food bolus and that saliva and starch break-down by salivary amylase-should be incorporated into instrumental measurements. Key sensory attributes from all three dimensions were predicted well from instrumental measurements.