Josh Reynolds and Federico Casassa*
*Wine and Viticulture Department – Cal Poly San Luis Obispo, 1 Grand Avenue, San Luis Obispo, CA 93410 (lcasassa@calpoly.edu)

Three different Pinot noir clones (115, 777, and 828) grown in California (Santa Maria Valley AVA) were subjected to different maceration temperature regimes (cold: 10°C, hot: 25°C, and variable: 10°C first week/25°C second week) to determine the effect of maceration temperature on phenolic extraction across all three clones over two consecutive vintages (2019 and 2020). Triplicate fermentations were conducted for 14 days and anthocyanins, tannins, polymeric pigments, and total phenolics were fol- lowed during winemaking. Temperature across treatments stayed consistently higher in hot trials than in cold trials by at least 12°C throughout maceration, and fermentation reached completion up to four days earlier in hot trials across both vintages. Using aggregate data from all three clones across both vintages, measured at time of pressing, extraction of total phenolic compounds was 723 mg/L for cold treatments, 894 mg/L for variable treatments, and 1031 mg/L for hot treatments. The same data also shows differences among cold, variable, and hot treatments in anthocyanins (208, 265, and 284 mg/L, respectively), tannins (68, 81, and 123 mg/L, respectively), and polymeric pigments (0.40, 0.46, and 0.51 mg/L, respectively). Trends across the three clones were also visible using both vintages, with the lowest phenolic concentrations across the board in 115 and the greatest in 777. Vintage effect was present, with higher concentrations of total phenolics, tannins, and polymeric pigments in 2019 and higher values for anthocyanins in 2020. Color analysis of the averages of all three clones indicates negative correlation with temperature for Cielab lightness values across cold, variable, and hot (88.81, 87.35, and 85.36, respectively), with positive correlation for red values (9.41, 11.14, and 12.10, respectively), similar yellow values (6.42, 6.05, and 6.62, respectively), and positive correlation for color values, 420 + 520 + 620 nm (0.38, 0.44, and 0.52, respectively), measured at 1-month postbottling.

Funding Support: World of Pinot noir