Wines with both a high pH and high titratable acidity (TA) are problematic due to their increased likelihood of fault development. Most interventions to reduce either pH or TA would be exacerbated by the other parameter. Cation exchange is an effective treatment to reduce wine pH while minimally increasing TA; however, this practice is used infrequently due to the perceived complexity and concern that it will diminish wine quality. Valvin Muscat, Norton, and Chambourcin wines were treated with a streamlined cation-exchange process in both 2013 and 2014 and Syrah in 2014 only. Wines were also treated with depleted cation-exchange resin and with tartaric acid addition. Treated wines were then evaluated by descriptive analysis and chemically characterized including measurement of TA, pH, total phenolics, tannins, anthocyannins, organic acids, elemental content, ethanol, and quantification of key aroma compounds. As previously demonstrated, cation exchange reduced wine pH by exchanging K⁺, Ca⁺², and Na⁺ cations with H⁺. While descriptive analysis revealed no consistent differences, results within varietal and vintage cation-exchange treatments showed reduced “yeasty” and “rotten egg” aromas in 2014 Norton and increased “cherry” aromas in 2014 Syrah. Quantification of aroma compounds by GC-MS indicated numerous, though inconsistent, changes following cation-exchange treatment. In 2013 Valvin Muscat, linalool was reduced from a mean of 1.7 to 0.9 mg/L, but no significant change was found in 2014. Vanillin in 2014 Chambourcin was reduced from a mean of 635 to 33 ug/L following cation exchange, but similar reductions where not observed in other wines. Both charged and depleted resin treatments caused reduced ethanol between 0.2 to 0.7% ABV, with most of the ethanol removal occurring at the start of treatment, suggesting the reduction was due to wine/resin interaction rather than cation exchange.

Funding Support: Missouri Department of Agriculture and the Missouri Wine Marketing and Research Council