Quantitative determination of beta-ionone in red wines and grapes of Bordeaux using a stable isotope dilution assay

Quantitative analysis of beta-ionone has been developed, using a stable iso tope dilution assay. This was applied to red wines from different cultivars and regions. The Burgundy Pinot noir wines exhibited the highest levels of beta-ionone. The variation in the levels of beta-ionone in grape samples a nd in their corresponding wines, of Merlot, Cabernet Sauvignon and Cabernet franc from Bordeaux regions was monitored at four different stages towards the end of maturation : the levels of beta-ionone were almost similar, exh ibiting only a slight decrease during maturation, beta-Ionone occurred in a ll the grapes and wines samples analysed at levels higher than, or close to its odour threshold which was determined in a model wine solution and was found to be of 90 ng l(-1). In a previously supplemented model wine solutio n with beta-ionone (250 ng l(-1)), the odour threshold was found to be of 9 80 ng l(-1) (total levels). (C) 1999 Elsevier Science B.V. All rights reser ved.