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Changes in glycosylation patterns of monoterpenes during grape berry maturation in six cultivars of Vitis vinifera

Godshaw, Joshua, Hjelmeland, Anna K., Zweigenbaum, Jerry, Ebeler, Susan E.
Food chemistry 2019 v.297 pp. 124921
Vitis vinifera, cultivars, developmental stages, genetic relationships, glucosides, glycosylation, hydrolysis, monoterpenoids, odor compounds, odors, sugars, tandem mass spectrometry, wine grapes, wines
Plants conjugate monoterpenoids to sugars, rendering them non-volatile. Hydrolysis of these glycosidic precursors frees the volatile aroma compounds. Here, we profile intact monoterpenyl glycosides in six Vitis vinifera grape berry cultivars. Relative concentrations of twenty-six monoterpenyl glycosides, including nine new putatively identified compounds, were analyzed by UHPLC–QTOF MS/MS at three times during grape maturation (pre-véraison, véraison, and post-véraison). Total glycoside content reached a maximum in Muscat cultivars post-véraison but remained relatively constant in all other cultivars. Three types of monoterpenyl glycosides predominated in all samples: malonylated monoterpenol glucosides, monoterpenol hexose-pentoses, and monoterpendiol hexose-pentoses. The two Muscat cultivars were not differentiated at the earlier developmental stages but could be differentiated post-véraison. In contrast, similarities between Chardonnay and Pinot noir glycoside profiles developed post-véraison. Overall monoterpene glycoconjugation patterns may align with underlying genetic relationships among cultivars. By understanding monoterpene glycoconjugation in wine grapes, scientists and winemakers can better understand grape and wine aromas.