Effect of leaf-to-fruit ratios on phenolic and sensory profiles of Malbec wines from single high-wire-trellised vineyards.

BACKGROUND: The single high-wire system is a free canopy trellis system suitable for warm to hot climates. In a global warming scenario, it arouses as a technological solution since it prevents berry overheating and sunburn. Canopy management practices manipulate leaf-to-fruit ratios, affecting berry and wine composition. We aimed to evaluate the phenolic and sensory profiles of Malbec wines from single high-wire trellised vineyards in a hot region in Mendoza (Argentina) and to assess the effect of varying leaf-to-fruit ratios on these attributes. We manipulated leaf-to-fruit ratios by varying shoot trimming (experiment 1: 0.45 m, 0.80 m, and untrimmed) and winter pruning severity (experiment 2: 16, 24, 32, and >32 countable buds per meter). We characterized wine attributes by a descriptive analysis, color by the CIELAB space, and global phenolics compounds and anthocyanins by high-performance liquid chromatography with diode array detection.

RESULTS: We found that wines where shoots were trimmed to 0.80 m or left untrimmed had similar and greater intensity of color, violet hue, astringency, and alcohol and a richer aroma profile than wines where shoots were trimmed to 0.45 m. Meanwhile, wines from 16 and >32 buds/m treatments (the latter simulating a box pruning) were similar to each other and had higher color intensity, violet hue, acidity, alcohol, and astringency and a more complex aroma profile than the other pruning treatments.

CONCLUSIONS: The best quality wines were achieved by leaving 16 or >32 buds/m and by trimming shoots to 0.80 m or leaving them untrimmed. The modulation of cultural practices in sprawling canopies offers the potential to produce wines with different styles in hot regions. © 2020 Society of Chemical Industry.