Carotenoid Levels in Maturing Grapes as Affected by Climatic Regions, Sunlight and Shade

Abstract

Carotenoids are thought to be precursors of C13-norisoprenoids including 1 which is responsible for kerosene odor in aged wines. Therefore, the carotene content of Riesling (R) and Chenin Blanc (CB) grapes as affected by maturity, climate and exposure was determined. Both beta-carotene and lutein concentrations were higher in grapes grown in warmer climates but decreased as grapes matured or if the grapes were exposed to sunlight. Generally the 2 carotenoids were found in higher concentration in CB although the differences were often minimal. 1 unidentified carotenoid was found in higher concentrations during the early stages of ripening in R but decreased at a faster rate than in CB. Since there were no major differences in carotenoid content between R and CB, some other factor(s) must account for the production of kerosene odor in R but not in CB. (Ch.W. Nagel, Pullman) [Z 146