Danielle Fox, Mitchell Davey, and James Harbertson*
*Washington State University, 2710 Crimson Way, Richland, WA, 99354-1671 (jfharbertson@wsu.edu)

Cabernet Sauvignon wines that had frozen dead Cabernet Sauvignon (CS) or Riesling (WR) leaves added at two dosages (2 or 4 g/kg must; low and high) prior to fermentation in 2022 were analyzed chemically and subjected to descriptive analysis. Basic wine analysis showed no significant changes to wine chemistry attributable to the treatment. Targeted solid-phase microextraction gas chromatography-mass spectrometry (SPME GC-MS) of volatile compounds revealed significant changes in compounds related to grassy, tropical, and citrus aromas in the treated wines. Treatments with high dosages of frozen CS leaves had significantly more 3-hexen-ol (grassy aroma) in a dose-dependent fashion and several fruity esters, phenylacetaldehyde and citronellol. Wines made with frozen leaves from WR also differed from the control in most volatile aroma compounds, but typically at significantly lower concentrations than in the larger CS frozen leaf additions. Descriptive analysis using nine panelists (five males) rated 13 ortho- and three retro-nasal attributes. Three taste and three mouthfeel attributes were also rated. Only two ortho-nasal attributes differed significantly (artificial fruit/confectionary and herbal). The high CS leaf addition was the only treatment significantly different from the control for artificial fruit/confectionary. Most leaf treatments reduced perception of herbal attributes and had a pronounced artificial fruit/confectionary attribute. Increased perception of artificial fruit coincided with increased concentrations of fruity esters and grassy alcohols only for the large CS leaf addition, which had both significant chemical and sensory changes. The sensory results show that the primary difference between the wines was based on the freeze-killed leaf addition. Secondarily, the sensory data shows that at low leaf dosages, there isn’t enough difference between the different frozen leaf additions to worry that leaves from different varieties would have substantially different chemical and sensory outcomes.

Funding Support: Washington Wine Commission