Comparison of Procedures for Resveratrol Analysis in Beer: Assessment of Stilbenoids Stability through Wort Fermentation and Beer Aging

Vesna Jerkovic, Fanny Nguyen, Aurore Timmermans and Sonia Collin¹
Unité de Brasserie et des Industries Alimentaires, Faculté d’Ingénierie biologique, agronomique et environnementale, Université catholique de Louvain, Croix du Sud, 2 bte 7, B-1348 Louvain-la- Neuve, Belgium
¹ Corresponding author. E-mail: sonia.collin@uclouvain.be

J. Inst. Brew. 114(2), 143–149, 2008 | VIEW ARTICLE

ABSTRACT
Three resveratrol extraction procedures were compared in beer. Two-step pre-cleaning with toluene and cyclohexane allows 76% trans-resveratrol recovery by solid-phase extraction (SPE) before RP-HPLC-MS/MS analysis. This procedure proved much more efficient than liquid/liquid extraction, which requires solvents that are too hydrophobic for stilbenoids. SPME-GC-MS, where the main limiting factor is non-reproducibility from fibre to fibre, is an interesting alternative for resveratrol quantification in complex mixtures where pre-cleaning is too difficult. With the optimized SPE procedure, 5 μg.L^-1trans-resveratrol was detected in four commercial beers. However, concentrations of stilbenoids in beer should be higher taking into account the presence of cis-stilbenoids. During fermentation, trans-resveratrol was partially regenerated from its glucoside, more stable through beer aging. Adding a stilbenoids-enriched ethanolic hop extract after fermentation significantly increases the beer stilbenoids potential.

Key words:
Aging, beer, fermentation, piceid, resveratrol, RPHPLC-MS/MS, SPME-GC-MS, stilbenoids, wort.