Canopy Management and Enzyme Impacts on Merlot, Cabernet franc, and Cabernet Sauvignon. II. Wine Composition and Quality

Merlot, Cabernet franc, and Cabernet Sauvignon vines in Niagara-on-the-Lake, Ontario, were subjected to four treatments in a randomized complete block experiment: hedged control, cluster thinning at veraison (CT), basal leaf removal (BLR), and CT+BLR. Musts from each treatment replicate (CT+BLR excepted) were thereafter either left untreated or treated with one of ColorPro or Color X enzymes. In most cases, CT and CT+BLR treatments had the highest wine anthocyanin and phenol concentrations and the highest color intensities (A(420) + A(520)). Leaf removal resulted in small increases in wine color intensity and anthocyan in and phenol concentrations. Cluster thinned and BLR treatments both reduced titratable acidity (TA) and increased pH relative to controls, but BLR tended to be more effective than CT. The CT+BLR treatments usually resulted in the lowest TA and the highest pH. Enzyme treatments increased wine TA and reduced pH and typically increased color intensity, total anthocyanins, and phenols. Both viticultural and enological treatments had noteworthy impacts on individual wine phenolic compounds and anthocyanins, although the viticultural treatments were more efficacious. The viticultural treatments enhanced intensities of several aroma and retronasal descriptors (e.g., black fruit, black pepper, tobacco) and reduced those of others (e.g., bean/pea, mushroom). The CT+BLR treatment has the potential to substantially improve fruit and wine composition in cool-climate regions; negatively, excessive leaf removal could result in lowered ethanol and undesirable increases in pH. Enzyme treatment has the potential for increased color intensity, but with occasional increases in TA.