The Effect of Enzyme, Cap Management, and Tannin on Phenolics in Merlot (2016)

This study examined the impact of 5 winemaking techniques on the phenolic composition of Merlot. The treatments were as follows: 1) Control, 2) Stomping grapes during a delestage (otherwise identical to control), 3) Lafase Grand Cru (Laffort) at crush, 4) VR Supra (Laffort) at crush, and 5) Both Lafase Grand Cru and VR Supra at crush. All other treatments were the same between wines. All wines had a delestage operation performed at 2 Brix, where stomping occurred for the stomping treatment. There were no major chemical differences between wines. Stomping had very little effect on phenolic chemistry. VR Supra and Grand Cru alone increased color, but when combined color was lowered (corresponding to lower anthocyanins). No other impacts on phenolic qualities could be observed, except tannin was increased and gallic acid decreased in the wine treated with VR Supra. The sensory impact of the VR supra treatment cannot be adequately assessed due to it being an outlier. Overall, the treatments tended to slightly increase Fruit Intensity and Body relative to the Control. The stomped wine tended to be the most preferred wines for all but the May 3 Tasting. Grand Cru + VR Supra also tended to be regarded fairly highly. The Control wine tended to be the least preferred. These results were not very strong, however, and more studies on the impacts of these treatments on the chemical and sensory qualities of wine should be performed. Additionally, more work should be done to examine the impact of these treatments on wine during aging.

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