Impact of water stress on the phenolic composition of cv. Merlot grapes, in a typical terroir of the La Mancha region (Spain)

As environmental issues come more to the fore, vineyards residues are being looked at as solutions rather than problems. Aiming to develop a sustainable methodology for musts acidity correction in the process of winemaking, much needed in warm regions, the present study was performed according to Circular Economy values.

Wine polysaccharides (PS) play an important role in balancing mouthfeel and stability of wine and even influence aroma volatility. Despite this, there is limited research into the effect of winemaking additives on the polysaccharide profile and other macromolecules of New Zealand (NZ) Pinot noir wine. In this study the influence of a selection of commercial S. cerevisiae strains on the chemical profile, including polysaccharides, of New Zealand Pinot noir (PN) wine was investigated. Research scale PN fermentations using five strains of commercially available S. cerevisiae (Lalvin EC1118 and RC212, Levuline BRG YSEO, Viallate Ferm R71 and R82) were undertaken. PS were qualified and quantified using HPLC-RID.

From the beginning of the yeast autolysis process, several interesting intracellular and cell wall constituyents are released to the media providing different characteristics to the wine, being this process extensively studied in sparkling wines due to their important contribution to their properties (1-2). Yeast derived products (YDs) try to emulate the natural yeast autolysis compounds release enhancing the organoleptic characteristics of resulting wines (2-3). This study is a comprehensive evaluation of the impact of the addition of different YDs added to base wine on the chemical, physical and sensory characteristics of the resulting sparkling wines. METHODS: Chardonnay base wine was employed to carry out this study. Three experimental YDs were added at 5 and 10 g/hL to the tirage liqueur: a yeast autolysate (YA), a yeast protein extract (PE) and an inactivated dry yeast from Torulaspora delbrueckii, (TD), and two commercial specific inactivated dry yeast: OPTIMUM WHITE® (OW) and PURE-LONGEVITY®(PL). After second fermentation, measurements were carried out after 3, 6, 9 and 18 months of aging on lees. General enological parameters, proteins, polysaccharides (HPLC-DAD-RID), volatile compounds profile (GC-MS), foaming characteristics (Mosalux), and descriptive sensory analyses were carried out.

Gli autori presentano gli ultimi risultati delle ricerche dei DIAF sulla meccanizzazione delle operazioni colorali in zone di difficile accesso e transitabilità quali le aree marginali, i terreni terrazzati e altre realtà agricole caratterizzate da spazi estremamente ristretti (vivaismo, orticoltura, ecc.).

In the last decades the growers of the Portuguese Dão winegrowing region (center of Portugal) are experiencing changes in climate that are influencing either grape phenology berry health and ripening. Aiming to study the relationships between climate indices (CI), seasonal weather and grapevine phenology, in this work long-term climate and phenological data collected at the experimental vineyard of the Portuguese Dão research centre between 1958 and 2019 (61 years) for the red variety Touriga Nacional, was analyzed. The trends over time for the classical temperature-based indices (Growing Season Temperature – GST -, Growing Degree Days – GDD, Huglin Index – HI and Cool Night Index – CI) presented a significantly positive slope while the Dryness Index (DI) showed a negative trend over the last 61 years. Regarding grapevine phenology, an average advance of 4.5 days per decade in the harvest day was observed throughout the last 61 years. Consequently, the weather conditions during the ripening period have changed, showing an increasing trend over time in the average temperature (higher magnitude in the maximum than in the minimum temperature) and a decrease in the accumulated rainfall. A regression analysis showed that ~50% of harvest date variability over years was explained by the temperature-based indices variability. These observed effects of climate change on bioclimatic indices and corresponding anticipation of harvest date can still be considered advantageous for the Dão terroir as it allows to achieve an optimal berry ripening before the common equinox rains and, therefore, avoid the potential negative impacts of the rainfall on berry health and composition.