Hannah Charnock, Gary Pickering, and Belinda Kemp*
*Cool Climate Oenology & Viticulture Institute (CCOVI), Brock University, 1812 Sir Isaac Brock Way, L2S 3A1, Canada (bkemp@brocku.ca)

The Maillard reaction (MR) is a non-enzymatic reaction between sugars and amino acids that occurs gradually during production and aging of traditional method sparkling wines. The reaction generates a cascade of volatile compounds and several Maillard reaction-associated products (MRPs), including furans, thiazoles, and other heterocycles that exhibit caramel, roasted, and toasted aromas. Metal ions have previously been shown to accelerate formation of MRPs in model systems, so a modified sparkling base wine was evaluated to determine if the addition of metal ions increased the concentrations of MRPs during aging. Chardonnay base wine was modified by adding a single amino acid (lysine, glycine, or cysteine; 0.01 M) and fructose (0.02 M), along with Ca or Mg at zero, low (10 mg/L), or high (50 mg/L) levels. All components were selected for their known involvement in the MR and their presence in sparkling wine. Due to the low pH and temperature conditions of sparkling wine during production and aging (pH ~3.2; 12 to 14°C), the MR occurs slowly (months to years). Thus, an accelerated aging regime, whereby samples were held at 50°C and sampled at intervals of 0, two, and four weeks, enabled rapid evaluation of the potential role of metal ions on MRP formation. MRPs were quantified by HS-SPME-GC-MS, sugar concentration was measured by enzymatic assay, and amino acids and free metal ions were evaluated by capillary electrophoresis. Preliminary analysis showed that mean fructose levels decreased between the two and four week intervals. Free metal levels did not vary systematically by treatment during aging. Analysis of amino acids and MRPs is currently underway. Understanding the effect of MR-precursors in the presence of Ca and Mg ions in modified base wine conditions is a key step toward characterizing the MR in sparkling wine.

Funding Support: Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery