Impact of strain and inoculation time on yeasts interactions: mass spectrometry-based study.

Wine production is a complex multi-step process and the end-product is not easily defined in terms of composition and quality due to the diversity of the raw materials (grapes) and the biological agents (yeast and bacteria) used/present during the fermentation. Furthermore, linking what happens in the vineyard to the wine fermentation and ultimately to characteristics in the wine during ageing

A new process for vacuum evaporation was developed where evaporation takes place near the inner surface of a vortex produced by a rotor submerged in the liquid. Contrary to the state of the art the Vortex rotor 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 grape must were conducted to verify the theoretical predictions, test the performance under different conditions and study the effect of various process parameters (Rösti et al 2015).

The historian starts from a scientific, rigorous and recent definition of the wine-growing region. “A viticultural terroir is made up of several homogeneous units: geological and pedological elements (texture,
grain size, thickness, mineralogical nature, chemical components), geomorphological (altitude, slope, exposure), climatological (rainfall, temperature, insolation)”. Absent from this definition, the man is fortunately reintroduced a little further. By associating viticulture and winemaking, it forms a “couple” with the terroir and this couple.

Yeast species S. cerevisiae, S. uvarum, S. kudriavzevii and their hybrids present clear metabolic differences, even when we compared S. cerevisiae wine versus wild strain. These species and hybrids produced significantly higher amounts of glycerol, organic acids, 2,3-butanediol, and 2-phenyl ethanol and a reduction of the ethanol yield, properties very interesting in the sector to deal with climate change effects. To understand the existing differences, we have used several omics techniques to analyze the dynamics of the (intra- and extracellular) metabolomes and/or transcriptomes of representative strains of S. cerevisiae, S. uvarum, S. kudriavzevii, and hybrids.

Climate change is introducing a high variability on grape ripening, causing uncertainty, excessive spending on pesticides and eventually frustrating results in terms of the quality of the vintage, with the increasingly frequent appearance of aromatic problems associated with overripeness, raisining and greenness, which sometimes only appear in bottled wines.