Prefermentative CO₂ saturation of grape must to obtaining white wines with low SO₂ content

Arbuscular mycorrhizal fungi (AMF) symbiosis is probably the most widespread beneficial interaction between plants and microorganisms. AMF has been widely reported to promote grapevine growth, water and nutrient uptake as well as both biotic and abiotic stress tolerance[1]. However, the impact of AMF on grape composition has been less studied. The aim of this work was to evaluate the effects of the association between two commercial grapevine cultivars (Tempranillo and Cabernet Sauvignon grafted onto 110 rootstock) and AMF on the anthocyanin, flavonol and amino acid concentrations and profiles of grapes.

Table grapes, being consumed as fresh, raisins, and transformed products are among the most appreciated fruits worldwide. Its popularity is increasing also due to its organoleptic and nutritional qualities that meet the consumers’ interest in healthier foods. Recent data from International Organization of Vine and Wine (OIV) revealed that table grape production has doubled in the last twenty years, and varietal availability has increased thanks to the several breeding programs.
To maintain the socio-economic impact of this sector, new challenges need to be addressed.

Wine production is a complex biochemical process that involves a heterogeneous microbiota consisting of different microorganisms such as yeasts, bacteria, and filamentous fungi. Among these microorganisms, yeasts play a predominant role in the chemistry of wine, as they actively participate in alcoholic fermentation, a biochemical process that transforms the sugars in grapes into ethanol and carbon dioxide while producing additional by-products. The quality of the final product is greatly influenced by the microbiota present in the grape berry, and the demand for indigenous yeast starters adapted to specific grape must and reflecting the biodiversity of a particular region is increasing. This supports the concept that indigenous yeast strains can be associated with a “terroir”.

Atypical aging (ATA) is a white wine fault characterized by the appearance of notes of wet rag, acacia blossoms and naphthalene, along with the vanishing of varietal aromas. 2-aminoacetophenone (AAP) – a degradation compound of indole-3-acetic acid (IAA) – is regarded as the main sensorial and chemical marker responsible for this defect. About the origin of ATA, a stress reaction occurring in the vineyard has been looked as the leading cause of this defect. Agronomic, climatic and pedological factors are the main triggers and among them, drought stress seems to play a crucial role.[1]

Rootstocks are used in vineyards worldwide and have been the focus of many studies. However, rootstock performance varies based on regional climates and soil types. As Oregon experiences warmer seasons and variable precipitation patterns, growers are interested in rootstocks with more drought tolerance than the commonly planted rootstocks: 3309C, Riparia Gloire, and 101-14 Mgt. In Oregon’s Willamette Valley, annual precipitation is typically sufficient to make dry-farming possible and use of irrigation is limited.