Agroclimatic characterization of Monreale DOC appellation for vine growing

The study of cultural practices to delay ripening and the characterization of their effect on wine composition is important in the mitigation of accelerated ripening caused by higher temperatures

There is currently a trend towards the production of wines with low alcohol content. To achieve this, grapes with low sugar content must be used. There are techniques at the vineyard level that can delay ripening and avoid excessive sugar accumulation without, a priori, affecting the final polyphenol content. Postveraison shoot trimming (PVST) is experimentally evaluated for these purposes, but its impact under Uruguayan climatic conditions with high interannual variability is not known. The aim of this work is to assess the PVST in Tannat and Merlot cultivars and their impact on yield components, plant balance and berry primary composition. In this study, two commercial vineyards of 10 years old Tannat and Merlot (grafted on SO4) at Canelones Department were selected. During the 2020-201 growing season, grapevines were submitted to PVST when grapes reached 15º Brix. In a randomized block, trimmed (T) and control (C) plants were evaluated with three repetitions each cultivar. Evaluation of the evolution of primary berry composition during ripening, measurement of yield components and plant balance were performed. For both cultivars, PVST did not affect yield components. Merlot reached 5.4 kg per plant and Tannat 7.1 kg, with not statistical significance between treatments. However, statistical differences were observed in terms of plant balance. In Merlot Ravaz Index reached a difference of 5.3 (12.0 in T and 6.7 in C) meanwhile Tannat reached 3.5 of statistical difference (13.7 in T and 10.2 in C). The tendency to imbalance for the treated plants had an impact on the final grape composition. Merlot grapes showed statistical difference in final total acidity (0.3 g of difference between treatments) while treatments impact final sugar content on Tannat grapes (10.0 g of difference between treatments). Further studies are needed to assess the impact of different canopy management techniques in our conditions.

The plasticity of grapevines in response to diverse growing conditions is influenced, among other factors, by the extent to which the roots explore the soil and the ability to accumulate and retrieve water and nutrients.
Newly planted grapevines, in particular, face challenges due to limited resources. The young plant’s ability for a fast and intensive penetration of the soil is vital in periods of water scarcity. The selection of an appropriate, site-specific rootstock significantly impacts both, the quality of the fruit produced and the economic success of the wine estate.

Despite their trace concentrations, volatile sulfur compounds (VSCs) are an important category of flavour-active compounds that significantly contribute to desirable or undesirable aromas of many foods and beverages. In wines, VSCs in the form of polyfunctional thiols, notably 3-sulfanylhexan-1-ol (3-SH), 3-sulfanylhexyl acetate (3-SHA), and 4-sulfanyl-4-methyl-pentan-2-one (4-MSP), possess extremely low olfactory thresholds (≈ ng/L) and pleasant “tropical aroma” notes. They have received much attention with respect to their sensory contributions, quantitative occurrences, biogenesis, and thiol management through viticulture and winemaking. However, the fate of these potent volatiles are still not fully understood.

One of the major determinants of wine quality is the aroma. Wine aroma is the human perception of the matrix of grape and yeast derived volatiles and their interaction that contribute to flavour wine. Most common are higher alcohols, ester and aldehydes. In previous studies the formation of characteristic volatile compounds have been linked to the metabolism of branched-chain and aromatic amino acids
(BCAAs) in synthetic grape must. Here we report on an investigation to assess the impact of the initial amino acid concentration on the production of aroma compounds by the industrial yeast VIN13 grown in both synthetic and real grape musts.