Whole Cluster and Dried Stem Additions’ Effects on Chemical and Sensory Properties of Pinot noir Wines over Two Vintages

The effect of additions of dried stems (DS) and whole clusters at 50% (50% WC) and 100% (100% WC) were investigated over two consecutive vintages of Pinot noir wines from the Edna Valley AVA of California (USA) at commercial scale. Addition of 100% WC led to significant increases in pH and volatile acidity. Anthocyanins, polymeric pigments, and color were more influenced by vintage than by the winemaking treatments, but they were unaffected or negatively affected in 100% WC wines. Conversely, the tannin content of the wines increased in accordance to the percentage of WC and stems added, with increases of 68% (50% WC), 100% (100% WC), and 90% (DS) in 2016 and 61% (50% WC), 123% (100% WC), and 137% (DS) in 2017 relative to control wines. Gas chromatography-mass spectrometry (GC-MS) data showed higher relative levels of ethyl cinnamate and benzaldehyde in 100% WC wines and relative abundance of esters in DS wines. Descriptive sensory analysis showed that 100% WC additions led to vegetal, cooked fruit flavors, and spicy (clove) notes, whereas DS additions produced wines that were more herbal, fruity, and astringent, with lifted fruity notes related to esters, and astringency sensations related to enhanced tannin extraction from the stems. Both WC and DS additions led to variable increases in perceived astringency, suggesting that they can be used to add mouthfeel and improve texture in Pinot noir wines.