Vesna Jerkovic

Fate of key odorants in Sauternes wines through aging.

Recent work has revealed the importance of polyfunctional thiols in young Sauternes wines, but very little is yet known about the fate of such compounds during aging in the bottle. In this study, two Sauternes wines were investigated by gas chromatography-olfactometry (GC-O) aroma extract dilution analysis (AEDA), gas chromatography-mass spectrometry (GC-MS), and gas chromatography-pulsed flame photometric detector (GC-PFPD) after XAD 2 and thiol-specific extractions. Most polyfunctional thiols (3-sulfanylpropyl acetate, 2-sulfanylethyl acetate, 3-methyl-3-sulfanylbutanal, etc.) proved to be completely degraded after 2 years of bottle aging in a cellar. Only 3-sulfanylhexan-1-ol was still found in aged samples at concentrations above its threshold value. Most other key odorants found in the young noble rot wine were still detected 5-6 years after harvest: varietal aroma (alpha-terpineol), sotolon, fermentation alcohols (3-methylbutan-1-ol and 2-phenylethanol) and esters (ethyl butyrate, isobutyrate, hexanoate, and isovalerate), and oak maturation-related compounds (guaiacol, vanillin, eugenol, beta-damascenone, trans-non-2-enal, beta-methyl-gamma-octalactone, gamma-nonalactone, and furaneol), as well as three newly identified aromas exhibiting interesting cake, honey-like, and dried apricot odors: homofuraneol, theaspirane, and gamma-decalactone. Interestingly, abhexon, never mentioned in sweet wines before, was found to be synthesized during bottle aging. An optimized extraction method allowed us to quantify this honey/spicy compound at levels close to its threshold value (up to 7 microg/L after 5-6 years), thus suggesting a key role of this strong odorant in old Sauternes wines.

Potentiality of red sorghum for producing stilbenoid-enriched beers with high antioxidant activity

trans-Piceid and trans-resveratrol were authenticated for the first time by high-resoution mass spectrometry in red sorghum grains. A 0.4-1 mg/kg amount of trans-piceid and up to 0.2 mg/kg trans-resveratrol were quantified by reversed phase high-performance liquid chromatography-atmospheric pressure chemical ionization(+)-tandem mass spectrometry. The white sorghum samples contained only traces of trans-piceid (up to 0.1 mg/kg), and trans-resveratrol was absent. In much lower amounts than procyanidins, stilbenoids are not able to contribute significantly to the exceptional antioxidant activity of red sorghum (ORAC, 83-147 μmol TE/g; AAPH, 0.61-1.79 min/mg kg(-1)). More than 10 mg/kg of total stilbenoids have been reported in some hop varieties. Yet, as hop is a minor wort ingredient as compared to cereals, red sorghum could be the main source of trans-piceid in beer. Hop remains, however, the single source of cis-piceid.

Stilbenic Profile of Cocoa Liquors from Different Origins Determined by RP-HPLC-APCI(+)-MS/MS. Detection of a New Resveratrol Hexoside

trans-Resveratrol and trans-piceid were recently discovered in chocolate. In the present work, both were quantified by RP-HPLC-APCI(+)-MS/MS in 22 cocoa liquors from 11 different countries. A very large range of concentrations was observed for trans-piceid. The most concentrated sample (Arriba 06) reached 0.4 and 2.6 mg/kg of trans-resveratrol and trans-piceid, respectively, but in other cultivars stilbene levels were five times lower. Neither cis-resveratrol nor cis-piceid was found in cocoa liquors. An unknown compound eluting 0.5 min before trans-piceid and present at concentrations up to 0.8 mg/kg of trans-piceid equivalents in cocoa liquors was tentatively identified by HRMS as a trans-piceid-like hexoside.