Impact of mechanical and manual grape harvesting on physicochemical aspects of merlot musts and wines produced in the campanha gaucha region – Brazil

The Campanha Gaucha region shows a remarkable potential for the production of wines. There, the first grape mechanical harvester in Brazil were introduced. The objective of this study was to evaluate possible differences in the physicochemical characteristics of musts and wines elaborated with grapes obtained by manual and mechanical harvesting. The experiment was conducted in 2018, with two treatments (T1 - manual harvest, T2 - mechanical harvest), using ‘Merlot’ grapes. The parameters analyzed were density, reducing sugars, pH, total acidity, and tartaric and malic acids. Moreover, soluble solids, gluconic acid, ammonia, and potassium were analyzed just in musts, while ethanol, glycerol, lactic acid, Folin-Ciocalteu index, color intensity, and hue were analyzed just in wines. T2 musts presented higher values for most of the variables, and non-significant differences for density, total acidity, tartaric acid, and potassium. For wines, all the significantly different values were higher in T2, except density, and were respectively the following for T1 and T2: ethanol, 11.3 and 12.4%; pH, 3.68 and 3.73; density, 0.9934 and 0.9926; and Folin-Ciocalteu index, 46.08 and 50.27. In summary, the two different harvesting techniques influenced the physicochemical characteristics of musts and wines.