Sulphite dioxide reduction in wine ::management and control of oxygen added during bottling

Sulphur dioxide (SO2) antiseptic and antioxidant role allows it to preserve the wine from oxygen’s negative effects. However, its use is increasingly challenged by the concerns of consumers and producers who want to limit the chemical inputs in wines. During winemaking, many stages can lead to a transfer of oxygen to the wine. Bottling is crucial. In order to limit oxygen addition to the wine, various inerting devices have been developed by manufacturers. The first part of this work aims to understand the influence of bottle inerting sequence, rate work and pressure of inert gas, on the amount of oxygen in the bottle before filling. The results indicate that the level of oxygen brought to the wine depends on the settings implying to adapt them specifically to each bottling setup. Once inerted, the bottles are filled and corked. The influence of the filling nozzle and of the inerting devices on the oxygen addition was studied. The amount of oxygen brought to the wine during bottling was significantly reduced by the use of inerting devices. The influence of the filling nozzle and the setting conditions used was also highlighted. Thus, good management of oxygen addition requires the mastery of the bottling chain

Intensity and timing of defoliation on white cultivar Chasselas under the temperate climate of Switzerland

Aim: The objective of this work is to investigate the effects of early defoliation on cv. Chasselas under the temperate conditions of Switzerland, with particular attention to berry anatomical traits and wine sensory parameters. Methods and results: Defoliation (removal of 6 basal leaves + 6 lateral shoots per shoot) was completed during three developmental stages of grapevine, i.e., pre-flowering, late flowering and bunch closure, and at two intensity levels. The experimentation was performed repeatedly over four years. In addition to vintage effect, pre-flowering defoliation had a consistent impact on vine agronomic behaviour. The yield was highly affected by the technique (more than 30% loss). Earlier and more intense defoliation had more impact on yield, while post-berry-set defoliation had no effect on yield. Intensive defoliation also modified berry skin thickness and had a positive impact inhibiting Botrytis development. Wine composition and sensory analysis were not affected by the practice. However, pre-floral defoliation affected bud fruitfulness and vigour, i.e., trimming and pruning weights. This result noted a carryover effect that could affect vine sustainability under restrictive conditions. Conclusion: In the context of this study, pre-flowering defoliation seems to be an interesting practice to reduce vigour and control the high production potential of the cv. Chasselas. The intensity of early defoliation allows for the modulation of the impact on the yield in order to prevent excessive yield loss. Significance and impact of the study: Pre-flowering defoliation of the white cultivar represents a prophylactic solution to reduce both chemical entrants and bunch-thinning costs

Effects of operating parameters and fluid properties on the efficiency of a new vacuum evaporation method

A new process for vacuum evaporation was developed where evaporation takes place near the inner surface of a vortex as produced by a rotor submerged in the liquid. Contrary to the state of the art the new process does not need a vacuum vessel but the rotating liquid creates a geometrically stable low pressure void surrounded by a vortex stabilized by the equilibrium between centrifugal forces and the pressure difference. First tests with water and sugar solutions at concentrations similar to wine must showed evaporation rates in the upper range of thin-film evaporators. A test series was conducted to study the effect of the variation of process parameters. The heating power and thus the fluid temperature has the most important influence on the vaporisation rate. A second test series using sucrose solution of different concentration comes to the conclusion that this method is suitable for aqueous solutions but the vapour production rate drops significantly with increased sugar content using the current rotor design. The simplicity of the construction and the process handling make this new method a promising development for the wine production

Effects of operating parameters and fluid properties on the efficiency of a new vacuum evaporation method

A new process for vacuum evaporation was developed where evaporation takes place near the inner surface of a vortex as produced by a rotor submerged in the liquid. Contrary to the state of the art the new process does not need a vacuum vessel but the rotating liquid creates a geometrically stable low pressure void surrounded by a vortex stabilized by the equilibrium between centrifugal forces and the pressure difference. First tests with water and sugar solutions at concentrations similar to wine must showed evaporation rates in the upper range of thin-film evaporators. A test series was conducted to study the effect of the variation of process parameters. The heating power and thus the fluid temperature has the most important influence on the vaporisation rate. A second test series using sucrose solution of different concentration comes to the conclusion that this method is suitable for aqueous solutions but the vapour production rate drops significantly with increased sugar content using the current rotor design. The simplicity of the construction and the process handling make this new method a promising development for the wine production

Le kaolin contre drosophila suzukii ::efficacité et qualité des vins

Drosophila suzukii est un insecte polyphage se développant aussi sur vigne. En Suisse, il est contrôlé par des mesures prophylactiques et par le kaolin, poudre de roche à base d’aluminosilicate. Cette dernière adhère aux raisins, formant une barrière physique qui réduit les pontes du ravageur. Nous présentons ici nos connaissances récentes sur l’efficacité du kaolin contre D. suzukii et sur les propriétés chimiques et sensorielles des vins à base de raisins traités au kaolin. Dans 23 essais sur divers cépages, le kaolin (Surround WP®) a atteint une efficacité moyenne de 56% et aucune différence significative n’a pu être observée entre des applications de kaolin à 1% et 2% et entre des traitements préventifs et curatifs. Un essai supplémentaire sur le cépage rouge Mara a révélé que trois applications de kaolin à 1% ou 2% n’affectent ni la fermentation ni les propriétés chimiques des vins traités par rapport au témoin non traité. Même si la concentration d’aluminium dans les vins a légèrement augmenté avec la dose de kaolin appliquée, les niveaux d’aluminium mesurés restent largement inférieurs au seuil toléré. De plus, les dégustateurs n’ont pas pu distinguer l’arôme et le goût des vins issus de raisins traités au kaolin de ceux du témoin non traité. Nous concluons donc que le kaolin est efficace contre D. suzukii dans le vignoble sans entraîner de risques majeurs pour l’environnement, la qualité du vin et la santé humaine

Effect of drying on tartric acid and malic acid in Shiraz and Merlot berries

Background and Aims: Grape berries are dried to concentrate sugar and aroma compounds to produce specific wine style. This work aimed to characterise biochemical changes during drying of two different cultivars, considering in particular tartaric acid and malic acid evolution. Methods and Results: Shiraz and Merlot grapes were dried at nine, 15, 21 and 27°C and berries were sampled every 2 to 3 days and sorted by density using NaCl solutions to account for berry heterogeneity. Mass loss of up to 45%, increase in sugar concentration of 71% and decrease in malic acid concentration of 64% were observed. The TA declined by up to 49%. Conclusion: The decline in tartaric acid could be explained by enhanced potassium hydrogen tartrate precipitation inside the berry or during sampling. Significance of the Study: The tartaric acid precipitation causes important analytical biases in physiological experiments. This study illustrates that common analytical methods are often inappropriate and are the reason for inconsistent tartaric acid values in many studies

Laboratory device for the evaluation of selective vegetal fibres

Protection of the vineyard against diseases and pests may lead to pesticide residues in the wine. Traces of these active substances, even at concentrations below the legal limits, alarm the consumers and can compromise the potential to sale wines to some markets. A new oenological practice based on the use of selective vegetal fibres for the reduction of pesticide residues in wine is under evaluation by the International Organization of Vine and Wine. This technology, implemented on wine during filtration, is very effective for certain substances and impacts only little the wine quality. A laboratory pilot filtration device has been developed in order to confirm the efficiency of this treatment and its impact on the wine quality before its large-scale use in industrial conditions. This simple device is made of a peristaltic pump and a laboratory filter holder. Several wines with different fibre doses and filtration speeds can be rapidly tested, at bottle scale (75 cl). This pilot filtration device would be a quick and easy tool for the winemakers to evaluate the impact of a filtration on their wines using selective vegetal fibres in terms of efficiency to reduce the pesticide residues, chemical composition and of sensory quality

Laboratory device for the evaluation of selective vegetal fibres

Protection of the vineyard against diseases and pests may lead to pesticide residues in the wine. Traces of these active substances, even at concentrations below the legal limits, alarm the consumers and can compromise the potential to sale wines to some markets. A new oenological practice based on the use of selective vegetal fibres for the reduction of pesticide residues in wine is under evaluation by the International Organization of Vine and Wine. This technology, implemented on wine during filtration, is very effective for certain substances and impacts only little the wine quality. A laboratory pilot filtration device has been developed in order to confirm the efficiency of this treatment and its impact on the wine quality before its large-scale use in industrial conditions. This simple device is made of a peristaltic pump and a laboratory filter holder. Several wines with different fibre doses and filtration speeds can be rapidly tested, at bottle scale (75 cl). This pilot filtration device would be a quick and easy tool for the winemakers to evaluate the impact of a filtration on their wines using selective vegetal fibres in terms of efficiency to reduce the pesticide residues, chemical composition and of sensory quality

Maîtrise et contrôle de l'apport en oxygène lors du conditionnement

La gestion de l’oxygène au cours de la vinification représente un enjeu majeur pour garantir un vin de qualité tant au niveau de la couleur qu’en matière aromatique, et ce d’autant plus lorsque le vigneron souhaite limiter les teneurs en SO2. Les étapes classiques de la vinification (pompage, stabilisation, mise en bouteille, etc.) sont autant de phases au cours desquelles de l’oxygène peut être apporté au vin; elles doivent donc être réalisées avec attention. L’étape de mise en bouteille est particulièrement sujette à ces problèmes d’ajout d’oxygène non maîtrisés. C’est pourquoi différents systèmes d’inertage ont été développés. L’objectif de cette étude est de mettre en évidence la nécessité d’adapter les réglages de ces différents dispositifs d’inertage au niveau de la chaîne de conditionnement afin de pouvoir garantir une gestion optimale de l’oxygène à la mise en bouteille

UDP-Glucose 4-Epimerase Isoforms UGE2 and UGE4 Cooperate in Providing UDP-Galactose for Cell Wall Biosynthesis and Growth of Arabidopsis thaliana[W][OA]

Five Arabidopsis thaliana genes that encode UDP-glucose 4-epimerase (UGE) and represent two ancient plant UGE clades might be involved in the regulation of cell wall carbohydrate biosynthesis. We tested this hypothesis in a genome-wide reverse genetic study. Despite significant contributions of each gene to total UGE activity, none was essential for normal growth on soil. uge2 uge4 displayed dramatic general growth defects, while other mutant combinations were partially aberrant. UGE2 together with UGE3 influenced pollen development. UGE2 and UGE4 synergistically influenced cell wall galactose content, which was correlated with shoot growth. UGE2 strongly and UGE1 and UGE5 lightly supported UGE4 in influencing root growth and cell wall galactose content by affecting galactan content. By contrast, only UGE4 influenced xyloglucan galactosylation in roots. Secondary hypocotyl thickening and arabinogalactan protein carbohydrate structure in xylem parenchyma depended on the combination of UGE2 and UGE4. As opposed to cell wall galactose content, tolerance to external galactose strictly paralleled total UGE activity. We suggest a gradual recruitment of individual UGE isoforms into specific roles. UGE2 and UGE4 influence growth and cell wall carbohydrate biosynthesis throughout the plant, UGE3 is specialized for pollen development, and UGE1 and UGE5 might act in stress situations