posted on 2020-03-17, 14:39authored byAndrew
J. Caffrey, Larry A. Lerno, Jerry Zweigenbaum, Susan E. Ebeler
Ultra-high-performance liquid chromatography (UHPLC) accurate mass
tandem mass spectrometry is a powerful tool for identifying and profiling
plant metabolites. Here, we describe an approach to characterize glycosidically
bound precursors of monoterpenoids, norisoprenoids, volatile phenols,
aliphatic alcohols, and sesquiterpenoids in grapes. Chromatographic
separation of glycosylated compounds was evaluated using phenyl–hexyl
(reverse phase), glycan/hydrophilic interaction, and porous graphitic
carbon (PGC) stationary phases. PGC provided the best UHPLC separation
for 102 tentatively identified aroma precursors in Vitis vinifera L. cv. Riesling and Muscat of Alexandria
berries. Monoterpene-triol, monoterpene-tetraol, and sesquiterpenol
glycosides were tentatively identified for the first time in grapes,
and a C6-alcohol trisaccharide was tentatively identified for the
first time in any plant. Comparison of glycosylated aroma molecules
in Riesling and Muscat of Alexandria grapes showed that the two varieties
were distinguishable based on relative abundances of shared glycosides
and the presence of glycosides unique to a single variety.