Effect of viscosity, sodium caseinate and oil on bitterness perception of olive oil phenolics

Olive oil phenolics contribute to the sensory and technological quality of extra virgin olive oil (EVOV). Recent research indicates that these phenolics have a beneficial effect on health. However, their bitter taste limits use of EVOV or extracted phenolics as functional ingredients in many food products and it is therefore of interest to use different approaches to reduce their bitter taste. The effect of viscosity, sodium caseinate and oil on perceived bitterness was studied. A Stevens plot was made for the relationship between aqueous concentrations and bitterness perception. Increasing viscosity using carboxymethyl cellulose was found to have a relatively small effect on bitterness. Modification of existing flavour release models to describe the release of non-volatile tastants indicated that the small effect of viscosity on bitterness perception could be related to a small amount of tastants adsorbed onto the tongue compared to the total amount of tastants present in the sample. Adding sodium caseinate to an oil-free or a 65% oil in water system, caused a reduction in bitterness. Bitterness scores were estimated on the basis of the free (unbound) phenolics concentration in the aqueous phase and the relationship found from the Stevens plot. Estimated scores corresponded well to experimental findings, assuming relatively weak phenol-protein binding and oil-water partition coefficients around one. (C) 2003 Elsevier Ltd. All rights reserved.