Development and validation of an LC-FTMS method for quantifying natural sweeteners in wine

The quality of a wine largely depends on the balance between its sourness, bitterness and sweetness. Recently, epi-dihydrophaseic acid-3'-O-β-glucopyranoside (epi-DPA-G) and astilbin, two molecules obtained from grapes, have been shown to contribute notably to the sweet taste of dry wines. To study the parameters likely to affect their concentration, a new method was developed and optimized by LC-FTMS. Three gradients and five C18 columns were tested. Good results in terms of linearity (r² > 0.9980), repeatability (RSD ≤ 3%), recovery (≥89%) and LOQ (≤20 µg.L^-1) were obtained. The method was used to screen epi-DPA-G and astilbin in red wines of several vintages over one century. Both compounds were detected in all wines at concentrations varying from 1.2 to 14.7 mg/L for epi-DPA-G and from 0.5 to 42.6 mg/L for astilbin. Therefore, this new method can be used to quantify epi-DPA-G and astilbin reliably in wine.