Ron Runnebaum,* Alex Yeh, Anna Hjelmeland, and Shelby Byer
*UC Davis, 3160 RMI North

Anthocyanins are important flavonoid compounds that contribute to the color and overall quality of red wines. This study seeks to understand how vineyard site impacts the quantity and behavior of anthocyanins in Pinot noir wines throughout wine aging. Pinot noir wines were made from grapes of the same clonal material on 15 different vineyard sites located throughout California and Oregon. Grapes were transported to the UC Davis Teaching and Research Winery and processed, fermented, and aged under repeatable, experimental parameters. Wines were fermented in quadruplicate, blended, and racked into kegs postfermentation, and bottled to age. Wines from the 2015 vintage were sampled at three points: three months postfermentation (from the stainless steel keg), eight months postfermentation (from the screwcap bottle), and 20 months postfermentation (from the screwcap bottle). These wines were characterized by quantifying anthocyanin and polymeric pigment concentrations with a high-performance liquid chromatography method with UV-vis detection. The data were analyzed using analysis of variance measuring for the effects of vineyard and age. Malvidin-3-glucoside (M-3-g) was consistently present in the highest concentration. The ratio of M-3-g to all other anthocyanins ranged from 2.5 to 6 initially, while after 20 months, the range was ~2.5 to nearly 8. Delphinidin-3-glucoside, with its tri-hydroxyl substitution, was anticipated to decrease more rapidly relative to M-3-g. The ratio of D-3-g to M-3-g was determined, however, to range from 0.033 to 0.094 at three months and from 0.030 to 0.097 at 20 months, with one exception. The anthocyanin concentration of some wines appeared to reach a pseudo steady-state between the second and third sampling point. These outcomes may be a result of our consistent winemaking and aging protocols, which minimize oxygen exposure. Future analysis will examine whether anthocyanin concentration continues at near steady-state under these bottle aging conditions.

Funding Support: Jackson Family Wines