Niclas Dermutz, L. Federico Casassa,* Margaret Thompsom, Paul Mawdsley, Michael Callahan, Fintan du Fresne, and Jean C. Dodson Peterson
*Wine and Viticulture Department, Cal Poly San Luis Obispo, 1 Grand Avenue, San Luis Obispo, CA 93407 (lcasassa@calpoly.edu)

We analyzed the effect of whole cluster fermentation (WC) at rates of 50% (50% WC) and 100% (100% WC) and of dried stem additions (DS) on Pinot noir (clone 777) from the Edna Valley AVA of California Central Coast. Wines were produced at industrial scale with treatments replicated three times in two consecutive vintages. In 2016, treatments affected most phenolic and chromatic parameters, with the exception of anthocyanins. After maceration, catechin and tannin levels were significantly higher in 100% WC and DS wines, while after nine months of bottle aging, wine color (AU 420 + 520 + 620 nm), tannins, and polymeric pigments were significantly higher, again, in 100% WC and DS wines. Additions of WC and DS generally increased pH (by 0.1 units in 2016 and by 0.18 units in 2017), and addition of 100% WC increased acetic acid in the final wines; this occurred consistently over the two vintages. In 2017, WC addition generally lowered anthocyanins but, together with DS, increased tannins and large polymeric pigments; however, there were no differences in wine color after malolactic fermentation. Sensory descriptive analysis of the 2016 wines after three months of bottle aging by a trained panel (n = 8) uncovered clear sensory effects of WC and DS additions relative to control wines. Although wines were aged in neutral barrels, only control wines displayed significantly higher oak aroma. Little sensory differences were found between 100% WC and 50% WC wines, with wines from these two treatments being perceived as more vegetal, higher in cooked aromas and more astringent. Conversely, DS wines showed higher brown hue and enhanced berry and herbal aromas, suggesting that they were aromatically more diverse than their control and WC wine counterparts.

Funding Support: Agricultural Research Institute (ARI). Chamisal Vineyards and Winery Staff are acknowledged for support on this project. Panelists from the Trained Wine Sensory Panel at Cal Poly are also thanked for their professionalism and commitment with this study.