Discrepancy Between the Ability of Wine Experts and Consumers in Identifying Grape Smoke Exposure in Different Wine Matrices in California

Volatile phenols (VPs) are present in fresh smoke from wildfires due to thermal degradation of wood lignin and can absorb into grape berry skins where they are rapidly glycosylated. VPs and their glycosides can impact the sensory profile of wines that are characterized by smoky, medicinal aromas and a retro-nasal ashy "aftertaste." Anecdotal evidence indicates 15-20% of consumers cannot distinguish the retro-nasal ashy characteristic of smoke taint. It is difficult to mimic smoke-tainted wine through spiking with related smoke marker compounds due to their complex synergistic interactions with the wine matrix. This study compared smoke-impacted and non-smoke-impacted wines of Cabernet Sauvignon, Malbec, and Syrah varieties made from the same location (Napa and Sonoma). Smoke-impacted grapes were intentionally smoked on drying tables or naturally exposed to smoke during wildfires. The wines were blended through serial dilutions, achieving different levels of smoke impact. The free, total, and bound VPs of all wines were determined by GC-MS and LC-QTOF-MS, respectively. Wines were sensorially evaluated by 62 wine experts and 58 regular wine consumers separately; using a series of hedonic, Just-About-Right, and Check-All-That-Apply questions. Correspondence analysis determined that different levels of smoke impact were detected differently by wine experts and consumers. Experts could distinguish smoke impact at lower levels, as determined by VP analysis, and compared to consumers who were generally only able to distinguish smoke-impacted wines at higher levels. Further difference testing with an additional group of wine consumers, saw an increase in the sensitivity towards smoke when consumers were trained to identify/recognize the ashy attribute. PRACTICAL APPLICATIONS: This research provides winemakers with valuable insights into how wildfire smoke impacts wine flavor and the levels at which both expert and non-expert consumers can detect smoke taint. By understanding these sensory thresholds, wineries can make informed decisions on whether and how to treat smoke-affected wines-particularly through blending strategies. This enables them to manage quality in smoke-exposed vintages and transform wines that might otherwise be unsellable into acceptable, marketable products.