Effects of ‘hoja de malvón’ disease on the composition, sensory properties and preference of Malbec wines from Mendoza, Argentina

F Casassa¹, S Sari¹, S Avagnina¹, V Longone², C Césari², G Escoriaza², C Catania¹, M Gatica²

¹Centro de Estudios de Enología; ²Laboratorio de Fitopatología, EEA Mendoza, Instituto Nacional de Tecnología Agropecuaria (INTA), San Martín 3853 (5507) Luján de Cuyo, Mendoza, Argentina

Abstract: ‘Hoja de malvón’ is a grapevine wood disease widespread in Argentina that decreases vineyard productivity and longevity. This study was conducted during two consecutive vintages to assess its influence on the general composition, sensory attributes and preference of Vitis vinifera L. cv Malbec wines. Batches of 120 kg of grapes harvested from vines with different degrees of (visual) symptoms of the disease were separately vinified. Grapes were grouped in three treatments: T1, grapes from vines with no symptoms; T2, grapes from vines with 10%–50% symptoms; and T3, grapes from vines with 50%–100% symptoms. Basic analyses of the grapes prior to crushing, and basic wine analysis were undertaken, together with spectrophotometric analyses of the wines after three months of bottle aging. The kinetics of alcoholic fermentation (AF) was followed daily and additionally the wines were assessed by a sensory panel. T3 grapes were characterized by comparatively lower initial sugar contents and higher titratable acidity. The AF kinetics were unaffected in the wines arising from the diseased grapes. There was no clear-cut effect of the disease on the wines’ pH, volatile acidity, and total acidity; however, the later spectrophotometric analyses showed that the total phenolic index was the highest in T2 wines for both vintages. In 2005, the color index (CI) was higher in T3 and showed the lowest value in 2006. The sensory properties of the wines were different in the two vintages. In 2005, T2 and T3 wines were perceived as having higher color intensity, violet hue and spicy notes, T2 being the most preferred wine. In 2006, T1 and T2 showed a much better sensory profile than T3, but no preference for any wine was detected. This study demonstrates that only in 2005 wines made from grapes with 10%–50% symptoms showed an improved and recognizable compositional and sensory profile. Our results suggest that the effects of the ‘hoja de malvón’ disease on wine quality are not always positive. Therefore, the reduction in productivity, consistency, uniformity, and vineyard longevity that this disease causes may be more important than the slight improvement, if any, in wine quality.

Keywords: ‘hoja de malvón’ disease, wine, chemical composition, sensory properties, wine preference