Understanding the impact of rising temperatures due to climate change on aromatic compositions in Malbec wines from Mendoza, Argentina

The growing interest in minority grape varieties is due to their potential for adaptation to global warming and their oenological capabilities. However, the cultivation of these varieties has often been limited due to their low economic efficiency. One such example is Maturana Blanca, a recently recovered and authorized minority grape variety in the DOCa Rioja region, known for its remarkable oenological potential but low productivity. This study aimed to increase the yield of Maturana Blanca by implementing the vertical cordon training system, which allowed for a higher number of buds per plant and an increased cluster count per vine.

The ongoing climate change implies an increasing mean air temperature, which is signified by weather extremes or sudden changes between drought and local heavy rainfalls. These changing conditions are especially challenging for the established grapevine varieties growing under cool climate conditions due to an increased risk for fungal diseases like downy mildew (DM) and Botrytis bunch rot (BBR) as well as for grape sunburn. To meet that demand, the scope of most grapevine breeding programs is the selection of mildew fungus-resistant and climatic adapted grapevines with balanced, healthy yield and outstanding wine quality.

Light is a fundamental part at sales points which influences in the conservation of wines, particularly in those that are sold in transparent glass bottles such as rosé wines and increasingly white wines. The photochemical effect known as “light-struck taste” can cause changes in the aromatic characteristics of the wine. This “light-struck taste” is due to reactions triggered by the photochemical sensitivity of riboflavin (RBF).

Wine contains secondary metabolites derived from aromatic amino acids (AADC), which can determine quality, stability and bioactivity. Several yeast species, as well as some lactic acid bacteria (LAB), can contribute in the production of these aromatic compounds. Winemaking should be studied as a series of microbial interactions, that work as an interconnected network, and can determine the metabolic and analytical profiles of wine. The aim of this work was to select microorganisms (yeast and LAB) based on their potential to produce AADC compounds, such as tyrosol and hydroxytyrosol, and design a microbial consortium that could increase the production of these AADC compounds in wines.

Ultra High-Pressure Homogenization (UHPH) is a high-pressure pumping at 300 MPa (>200 MPa) with a subsequent depressurization against a highly resistant valve made of tungsten carbide covered by ceramic materials or carbon nanoparticles. The intense impact and shear efforts produce the nano-fragmentation of colloidal biopolymers including the elimination of microorganism (pasteurization or sterilization depending on in-valve temperature) and the inactivation of enzymes.