Explore the vast range of titles available.

This research aimed to evaluate the impact of different options for winemaking on the color composition of Uruguayan Tannat red wines. The techniques evaluated were the substitution of ripe grape juice with immature grape juice and the heating of the crushed grapes before fermentation, called must replacement and hot pre-fermentative maceration, respectively. These procedures were proposed to reduce the alcohol content and increase the phenolic composition of the wine, according to the expected effects of climate change and current trends in consumer preferences. The investigation was made over three consecutive years (2016, 2017, and 2018). Both winemaking techniques allow the enhancement of the chromatic characteristics of wines via the modification of the phenolic composition. Additionally, such techniques allow the overcoming of the well-known limitations in the extractability of anthocyanins presented by the Tannat cultivar. Hot pre-fermentative maceration increases the proportion of the most oxidizable molecules delphinidin-3-O-glucoside, cyanidin-3-O-glucoside, and petunidin-3-O-glucoside, suggesting heat inactivation of polyphenoloxidases enzymes. Must replacement and hot pre-fermentative maceration are technological alternatives that could significantly improve the intensity and chromatic characteristics of red wines.

La adaptación del cultivo de la vid al cambio y la variabilidad climática implica conocer cómo los factores ambientales locales impactan en la fisiología de la vid, repercutiendo en el rendimiento, y la composición final de la uva. La composición de la uva en cosecha está determinada por las condiciones climáticas de la temporada ya que tienen un efecto sobre la fisiología y el desarrollo de la vid. El objetivo de este trabajo es estudiar el impacto de la técnica de viñedo de prepoda post envero sobre los componentes de rendimiento y composición de la uva en cosecha. Las evaluaciones se realizaron sobre un viñedo comercial en la zona sur de Uruguay de los cultivares Tannat y Merlot durante la vendimia 2021. La prepoda en envero no afectó el rendimiento, el número de racimos por planta y peso de racimo en los dos cultivares, pero si afectó el balance fisiológico de estos. Sobre la composición primaria de la uva en vendimia, Tannat alcanzó diferencias en sólidos solubles y Merlot en acidez total. Al alterar la canopia post envero se afecta el equilibrio fisiológico de las plantas. Esta tendencia al desequilibrio fisiológico debe continuar siendo estudiada a lo largo de varios ciclos productivos. Adaptation of grapevine cultivation to climate change and variability involves understanding how local environmental factors impact on grapevine physiology, impacting on yield, and final grape composition. Grape composition at harvest is determined by seasonal climatic conditions as they have an effect on grapevine physiology and development. The objective of this work is to study the impact of the post-veraison pre-pruning vineyard technique on the yield and composition components of the grapes at harvest. The evaluations were carried out on a commercial vineyard in southern Uruguay of Tannat and Merlot cultivars during the 2021 vintage. Pre-pruning at veraison did not affect the yield (kg of grapes per plant), the number of bunches per plant and bunch weight in the two varieties evaluated, but it did affect their physiological balance. On the primary composition of the grapes at harvest, Tannat reached differences in soluble solids and Merlot in total acidity. Altering the canopy after veraison would affect the physiological balance of the plants. This tendency towards physiological imbalance, should continue to be studied over several production cycles.

Este estudio resume los principales resultados de ensayos realizados en Uruguay con la variedad Tannat durante 25 años. Los vinos de este cultivar son emblemáticos del Uruguay. Tienen una gran tipicidad, con un color y composición polifenólica particulares. Se evaluaron distintas técnicas de vinificación, con el objetivo de mejorar la calidad de los vinos y mitigar los efectos del cambio climático. Las opciones evaluadas fueron: (I) empleo de enzimas de maceración, (II) maceración pre-fermentativa en frío, (III) extracción diferida de antocianos, (IV) maceración extendida, (V) extracción diferida de antocianos con maceración extendida, (VI) maceración pre-fermentativa en caliente, (VII) empleo de taninos enológicos. Los testigos de cada ensayo fueron vinos elaborados de manera tradicional (MT). La MPC fue la técnica que tuvo mayor impacto en el color y la composición fenólica de los vinos. Los contenidos de antocianos solamente fueron incrementados por la MPC y ENZ. Los contenidos de taninos poliméricos fueron incrementados muy significativamente por MPC, ME y la MPF. A su vez, los mismos tratamientos incidieron significativamente en los contenidos de taninos monoméricos. Los resultados obtenidos fueron diferentes según la técnica de elaboración, respondiendo a los objetivos procurados en cada caso, pero los efectos fueron distintos en cada año. Esto indica que el efecto de cada técnica está condicionado por el clima y su impacto en la composición de la uva. This study summarizes the main results of trials carried out in Uruguay with the Tannat variety for 25 years. The wines of this cultivar are emblematic of Uruguay. They have a great typicity, with a particular color and polyphenolic composition. Different vinification techniques were evaluated, with the aim to improving the quality of the wines and mitigating the effects of the climate change. The options evaluated were: (I) use of maceration enzymes, (II) cold pre-fermentative maceration, (III) delayed extraction of anthocyanins, (IV) extended maceration, (V) delayed extraction of anthocyanins with extended maceration, (VI) hot pre-fermentative maceration, (VII) use of oenological tannins. The controls of each test were wines made in the traditional way (MT). The MPC was the technique that had the greatest impact on the color and phenolic composition of the wines. Anthocyanin contents were only increased by MPC and ENZ. The polymeric tannin contents were very significantly increased by the MPC and the MPF. In turn, the same treatments had a significant impact on the monomeric tannin contents. The results obtained were different according to the winemaking technique, responding to the proposed aims, but the effects in each year were different. This indicates that the impact of each technique was strongly conditioned by the climate and its effect on the composition of the grapes.

This study summarizes the main results of trials carried out in Uruguay with the Tannat variety for 25 years. The wines of this cultivar are emblematic of Uruguay. They have a great typicity, with a particular color and polyphenolic composition. Different vinification techniques were evaluated, with the aim to improving the quality of the wines and mitigating the effects of the climate change. The options evaluated were: (I) use of maceration enzymes, (II) cold pre-fermentative maceration, (III) delayed extraction of anthocyanins, (IV) extended maceration, (V) delayed extraction of anthocyanins with extended maceration, (VI) hot pre-fermentative maceration, (VII) use of oenological tannins. The controls of each test were wines made in the traditional way (MT). The MPC was the technique that had the greatest impact on the color and phenolic composition of the wines. Anthocyanin contents were only increased by MPC and ENZ. The polymeric tannin contents were very significantly increased by the MPC and the MPF. In turn, the same treatments had a significant impact on the monomeric tannin contents. The results obtained were different according to the winemaking technique, responding to the proposed aims, but the effects in each year were different. This indicates that the impact of each technique was strongly conditioned by the climate and its effect on the composition of the grapes.

The aim of this research was to determine the effectiveness of the substitution of grape juice of grapes with different maturation degree and prefermentative hot maceration to obtain Pinot Noir and Tannat red wines with lower alcohol content and pH and higher color and phenolic compound concentrations. Immature grape juice was extracted of grapes harvested in veraison and kept at 4 °C until its use. In technological maturity, the grapes harvested were destemmed, crushed and distributed in 12 containers per cultivar. Six were controls while in the other six 3 L of the original grape juice were substituted by 3 L of unripe grape juice. Next, three containers from each experimental group were traditionally macerated, while the other three were submitted to a prefermentative hot maceration (one hour at 60–70 °C). All treatments performed a fermentative maceration of 7 days. Wines produced from substituted musts had lower alcohol content (14% off) and pH (9% off) and higher titratable acidity (48% more), but no other important changes in wine components were detected. Prefermentative hot maceration increased wine color intensity (50%), total phenolic compounds (66%), total anthocyanin (42%), proanthocyanidin (65%) and polysaccharide (95%) concentrations. The joint consideration of both techniques is an interesting tool to simultaneously mitigate the problems caused by climate change with respect to the maturity of the grape and improve the color of the wine and its concentration in polysaccharides and phenolic compounds.

The flavanol composition of red wine, stemming from grape skins and seeds, is a determinant factor of its quality. It has been proposed that the wine flavanol structure depends on the grape cultivar but with skin-derived flavanols prevailing in traditional red winemaking from mature grapes. However, this has not been confirmed for many cultivars. This study analysed the flavanol composition in grapes, wines, and pomace of Syrah, Marselan, and Tannat, Vitis vinifera cultivars known for their potential to yield tannic wines. Across two vintages, 20 wines were produced through traditional winemaking. Flavanols were analysed by HPLC–MS/MS before and after acid-catalysed depolymerisation of proanthocyanidins. Grapes of different ripeness were considered as vineyard with different agronomical characteristics. Nevertheless, each cultivar exhibited a characteristic flavanol composition in both grapes and wines. Notably, all Marselan wines had high proportions of seed-derived flavanols (high proportions of monomers, dimers and low of prodelphinidins), from grapes with high skin flavanol content. In contrast, Tannat and Syrah wines had high proportions of skin-derived flavanols, irrespective of the corresponding seed flavanol levels in grapes. Flavanol extractability from skins mainly regulated wine composition, being unusually low in Marselan, rising with ripeness in Syrah, and consistently high in Tannat, masking the high seed flavanol contents of its grapes. Therefore, wines with high proportions of seed-derived flavanols can be obtained from fermentative macerations of ripe grapes. Pomaces were found to be a rich source of flavanols, primarily from seeds where they largely remain unextractable.

Adaptation of grapevine cultivation to climate change and variability involves understanding how local environmental factors impact on grapevine physiology, impacting on yield, and final grape composition. Grape composition at harvest is determined by seasonal climatic conditions as they have an effect on grapevine physiology and development. The objective of this work is to study the impact of the post-veraison pre-pruning vineyard technique on the yield and composition components of the grapes at harvest. The evaluations were carried out on a commercial vineyard in southern Uruguay of Tannat and Merlot cultivars during the 2021 vintage. Pre-pruning at veraison did not affect the yield (kg of grapes per plant), the number of bunches per plant and bunch weight in the two varieties evaluated, but it did affect their physiological balance. On the primary composition of the grapes at harvest, Tannat reached differences in soluble solids and Merlot in total acidity. Altering the canopy after veraison would affect the physiological balance of the plants. This tendency towards physiological imbalance, should continue to be studied over several production cycles.