Temperature and Cap Management Effects on the Chemical, Phenolic, and Chromatic Composition of Pinot noir Wines from the Central Coast of California

Background and goals Applying different fermentation temperature regimes to Pinot noir is commonplace, however, their effects, when combined with cap management, are not understood. Three fermentation temperature regimes (cold, hot, and a combination of cold and hot) were combined with a regime consisting either of two punch-downs per day (PD), or no punch-downs (No PD).

Methods and key findings Wines were analyzed for microbial composition, phenolic compounds, and chromatic characteristics up to one year after bottling, as well as after accelerated aging (five weeks at 38°C). There was no effect of fermentation temperature or cap management on the basic chemistry of the wines, but a correlation between fermentation temperature, acetic acid, and populations of acetic acid bacteria was found. Hot fermented wines were 67% higher in tannins at pressing and had 41% more anthocyanins at peak extraction, relative to cold fermented wines. No PD wines showed higher levels of anthocyanins and small polymeric pigments than PD wines. Anthocyanin content at pressing was a key predicting factor of final polymeric pigment content.

Conclusions and significance Fermentation temperature was a key factor for phenolic retention in Pinot noir wines, with cap management being less relevant. Most of the polymeric pigment formation occurred during the early stages of bottle aging. Different phenolic and chromatic profiles can be achieved by applying contrasting fermentation temperature regimes to Pinot noir wines, which should inform wine style. These contrasting profiles could also be blended at judicious amounts to increase complexity and aging potential.