Federico Casassa,* Sean Kuster, Grace Putman, Gabriela Rivas, Dallas Parnigoni, Emily Stoffel, James Nelson, and Bob Coleman
*Wine and Viticulture Department, California Polytechnic State University San Luis Obispo (Cal Poly), 1 Grand Avenue, San Luis Obispo, CA, 93407 (lcasassa@calpoly.edu)

Pinot noir wines from the Sta. Rita Hills AVA of California were produced with five contrasting cap management protocols: pump-overs, performed at two full-volumes/day (PO); punch-downs, performed twice/day for 3 min each (PD); no cap management (NoCMgmt); air mixing, at two additions/day (AM); and nitrogen mixing, at two additions/day (NM). Redox potential spikes up to 340 mV were observed during maceration in AM wines. NM wines consistently showed negative mV values with subtle -40 mV spikes during N mixing. Temperature was controlled during fermentation (24 to 28°C), trending 2°C lower in PO wines. Alcoholic fermentation was completed in all wines within 10 days, with a slower rate of total soluble solids depletion in NoCMgmt wines. PO wines had lower alcohol levels (12.76%) than PD wines (13.76%), and acetic acid doubled in AM wines. AM wines showed the lowest levels of acetaldehyde and NoCMgmt the highest. Anthocyanins and tannins were 50% lower, and total phenolics were 44% lower in AM wines. Total polymeric pigment formation was favored in PD wines at 40% higher and 42% higher relative to PO and AM wines, respectively. The tannin, anthocyanin, total phenolic, and chromatic profiles of PD and NM wines were statistically indistinguishable, but lower in NoCMgmt wines, and the lowest in AM wines. An accelerated aging experiment was established by placing the wines in air-tight glass ampoules, then incubating them for five weeks at 38°C. After accelerated aging, alcohol, pH, titratable acidity, acetic acid, tannin, and total phenolics levels were essentially unchanged and consistent with those measured at bottling. Whereas anthocyanins dropped by 70% and polymeric pigments increased by 106% across all wines, the trend described at bottling for these phenolics persisted. Sensory analysis is currently underway. Present results emphasize the well-documented subpar effects of excessive oxygen dissolution, even during alcoholic fermentation, on Pinot noir wines.

Funding Support: Star Lane and Dierberg Vineyards, LLC (Santa Ynez, CA, USA), E. & J. Gallo Winery (Healdsburg, California, USA), and Treasury Wine Estates (St. Helena, California, USA).