Bio-protection by one strain of M. Pulcherrima: microbiological and chemical impacts in red wines

L’AOC Priorat, située derrière les montagnes du pré littoral de Tarragone, se caractérise par un climat méditerranéen avec une tendance à la continentalité et très peu de précipitation pendant le cycle végétatif. Les sols sont secs, pauvres et caillouteux, formés par des schistes. Au cours des années 2000 et 2001, une étude de l’influence du terroir sur la typicité des vins du Priorat a été réalisée en prenant comme référence trois cépages cultivés dans différentes parceIles pour mesurer l’effet du terroir et du mésoclimat sur la qualité des vins:

Fermentative aromas (especially esters and higher alcohols) highly impact the organoleptic profile of young and white wines. The production of these volatile compounds depends mainly on temperature and Yeast Available Nitrogen (YAN) content in the must. Available dynamic models predict the main reaction
(bioconversion of sugar into ethanol and CO2 production) but none of them considers the production kinetics of fermentative aroma compounds during the process of fermentation. We determined the production kinetics of the main esters and higher alcohols for different values of initial YAN content and temperature, using an innovative online monitoring Gas Chromatography device.

Primary and secondary metabolites are major components of grape quality and wine typicity. Their accumulation is interconnected through a complex metabolic network, which is still not well understood. This study aims to investigate how the enzymes of central carbon metabolism interact with anthocyanin biosynthesis during grape berry development: does the accumulation of anthocyanins, which represents a non-negligible diversion of carbon metabolic fluxes, require reprogramming of central enzymes or is it controlled downstream of central metabolism? To this end, 23 enzymes involved in central carbon metabolism pathways have been analyzed in the berries of 3 grape cultivars, which have close genetic background but distinct temporal dynamics of anthocyanin accumulation.

The variety Aragonez (sin. Tempranillo), recently introduced in the San Francisco Valley (9º02′ S; 40º11′ W) has revealed an excellent adaptation, with high potential of quality and yield, even without clonal material.

Over the past few decades, viticultural research has made numerous contributions which have made it possible to better understand the behavior of the vine as well as its response to the conditions imposed on it by the environment and agronomic practices. However, these results have only rarely been used in the practical management of vineyards because the research has been carried out using partial experimental models where reality is only represented by a few factors which are sometimes even made more complex by the introduction of elements foreign to the existing situation and difficult to apply to production (varieties, methods of cultivation, management techniques, etc.). To these reasons, one could add a low popularization of the results obtained, as well as the difficulty of implementing the scientific contributions, which does not allow the different production systems to fully express their potential. This limit of viticultural research can only be exceeded by the design of integrated projects designed directly on and for the territory. Indeed, only the integrated evaluation of a viticultural agro-system, which can be achieved through zoning, makes it possible to measure, or even attribute to each element of the system, the weight it exerts on the quality of the wine.