Receptomics and its potential for wine analysis

Receptomics is a novel bio-analystical approach based on parallel screening of large numbers of biological recpetors to evaluate potential bioactives, such as aroma and taste compounds. It also holds promise to augment or replace human sensory evaluation of food and beverages. This paper describes a novel microfluidic technique developed in Wageningen for anlaysis of complex liquitd food samples against large arrays of human sensory and health-related receptors- expressed in a human cell line, inside a flow cell. A small pre-study on the analysis of red and white wine against a nearly complete set of bitter receptors is also reported. To ensure the cells would tolerate undiluted wine, it was necessary to first neutralisee the wine pH and remove the alcohol. To observe specific activation of receptors, the 16-times diluted sample was contrasted with the 2-, 4- and 8-times diluted samples. Surprisingly, it was found that both Shiraz and Gewurztraminer wines induced at higher concentrations a negative signal with some of the receptors that were expected to give positive signals (TAS2-R4, -R7, -R39 and -38PAV) in this two wines. This is somewhat unexpected in light of pure compound assays and observations in other bitter drinks such as beer and coffee. The lack of positive signals may be due to the fact that the pH was adjustd and/or that the assay lacked sensitivity as it was only possible to analyse diluted wine. To further evaluate the potential of receptomics for direct analysis of wine taste, it will be required to (i) identify and correct for the dip-inducing factor (ii) analyse non-bitter wines after the addition of bitter compounds as positive controls and compare them to bitter wines, and (iii) repeat the tests with pH-insensitive reporters of receptor activation.