Indice bioclimatique de qualité Fregoni

Different yeasts were isolated from spontaneous fermentation of Assyrtiko grape must in Santorini Island, Greece. Molecular typing revealed the presence of three Saccharomyces cerevisiae strains (S9, S13, S24) and one strain of the yeast species Nakazawaea ishiwadae (N.i). The four isolated strains were further tested in laboratory scale fermentations of Assyrtiko must in pure inoculation cultures and in sequential inoculation (72 hours) of each S. cerevisiae strain with the strain of N. ishiwadae. All fermentation trials were realised in duplicate.

To our knowledge all the studies about laccase kinetics and its inhibition have been performed with substrates and conditions very different from those of real grape juice. Moreover, none of these researches really measure enzymatic browning, since they have not taken into account what happens after the oxidation of o-diphenols in o-diquinones and their subsequent polymerization to form melanins1. For that reason, the aim of this research was to develop a new model to measure the kinetics of browning caused by Botrytis cinerea laccase under conditions much closer to those of grape juice and using the substrates naturally present in it.

The increase in air temperature that is occurring in many important wine-growing areas around the world is resulting in the decoupling between the phenolic and the technological maturity of grapevine berries. This new ripening pattern leads to the production of light-bodied high alcoholic wines, but this is in countertendency with the increasing consumers’ demand for wines with low-to-mid alcohol concentrations. The oenological techniques proposed to reduce wine alcohol content are often very expensive and lead to detrimental effects on wine quality. Many viticultural practices have been proposed to slow down sugar accumulation the berry. One possible strategy that was previously found to be suitable for Aglianico grapevine is post-veraison shoot trimming. The aim of this work was to assess the carry over effects on the following year of shoot trimming and vine water status on yield and total soluble solids because the expected reduction in vine fertility could lead to a reduction in the effectiveness of shoot trimming.

In interaction with climate and genetic or human factors, the soil is a major component of the viticulture terroir. The mineral composition of the soil influences vine performance and wine sensory attributes. Among the elements that vines take from the soil, nitrogen is the one that has the strongest impact on vine physiology, vigor and grape composition. In addition to its major effect on primary metabolites in berries, nitrogen plays also a decisive role in the secondary metabolism, especially in the production of key compounds for berries quality, like volatile thiols, methoxypyrazines and glutathione (GSH).

Le vigneron est confronté à une variabilité naturelle omniprésente, liée au millésime et aux facteurs pédoclimatiques. Depuis 10 ans, en Champagne, la relation qu’entretient le vigneron avec l’espace a évolué. Les exemples d’entreprises collectives à vocation territoriale se sont multipliés : gestion de l’hydraulique viticole, maillages de groupements de conseil viticole (Magister), sites en confusion sexuelle, réseau maturation, analyses de sols par secteur, …