Merlot grapes were harvested with three maturity levels (21.1, 23.1, and 25.1 Brix), and processed with or without the application of microwave-assisted extraction (MW). The detailed phenolic composition and color were followed during winemaking. The MW treatment did not affect the basic chemical composition of the wines. Upon crushing, MW caused a 211% improvement in anthocyanins in the wines of the first harvest and an 89% improvement in the wines of the third harvest. At bottling, MW favored the formation of pyranoanthocyanins and tannin-anthocyanin dimers. Tannin extraction was not affected by MW just after application of this process, but improvements of 30, 20, and 10% on MW-treated wines of the first, second, and third harvest, respectively, were recorded at pressing. The formation of polymeric pigments during aging generally increased along with harvest date and was only favored in MW-treated wines of the first and third harvest, with preferential formation of small polymeric pigments, in accordance with enhanced anthocyanin extraction in these wines. Initial improvements of wine color upon application of MW in the wines of the first, second, and third harvest were of 275, 300, and 175%, respectively. Although these differences subsided or disappeared for the wines of the second and third harvest during aging, the wines of the first harvest treated with MW retained 52% more color than Control wines at day 150 post-crushing. Results suggest the MW treatment was more efficient in extracting and retaining phenolics and color when applied to unripe fruit.

Pinot noir wines were produced over two consecutive vintages using four and six different winemaking techniques in 2014 and 2015, respectively. In addition to control wines, the separate and combined effect of cold soak (CS) and additions of 20% of whole clusters (WC) and 3% stems (S) were investigated for their impact on phenolics, color, volatile and sensory composition of the resulting wines. The basic chemistry of the wines was marginally, if at all affected by CS, WC or S treatments. For the cooler 2014 vintage, CS increased tannin extraction by 37% whereas for the warmer 2015 vintage, CS had no effect on tannin extraction relative to control wines. Addition of stems increased tannin extraction by 60%. Overall for both vintages, CS decreased anthocyanin extraction and color intensity. β-damascenone absolute concentration and Odor Activity Value were higher in control and control + WC wines than in CS wines, suggesting that the former wines were fruitier than CS wines. Sensory descriptive analysis of the wines indicated that control wines of the 2014 vintage were the least saturated in color, whereas CS + WC wines were the most saturated. However, the opposite was found in 2015 whereby CS decreased color saturation. Control wines were fruitier whereas WC wines were less fruity but higher in floral and bitter almond aromas. This aroma shift was most likely due to the influence of the added stems. Whole clusters and stem additions had a moderate effect of on the diversity of aromas and a larger, enhancing effect on bitter taste and astrigency within the sensory profile of these Pinot noir wines.