Factors influencing the production of the antioxidant hydroxytyrosol during alcoholic fermentation: Yeast Assimilable Nitrogen and Sugar content.

Carbon dioxide (CO2) is the gaseous species responsible for the sparkle in all sparkling wines, influencing their visual appearance, aromas and mouthfeel.

Grapevine is subject to multiple stresses, either biotic or abiotic, frequently in combination. These stresses may negatively impact the health status of plants and reduce yields. For biotic stress, grapevine is affected by numerous pest and diseases such as downy and powdery mildews, grey mold, black rot, grapevine fanleaf virus and trunk diseases (namely GTDs). The interaction between grapevine and pathogens is relatively complex and linked to various pathogenicity factors including cell-wall-degrading enzymes (especially CAZymes) and phytotoxic secondary metabolites, growth regulators, effectors proteins, and fungal viruses.

Copper in white wine can be associated with Cu(II) organic acids (Cu fraction I), Cu(I) thiol species (Cu fraction II), and Cu sulfides (Cu fraction III). The first two fractions are associated with the repression of reductive aromas in white wine, but these fractions gradually decrease in concentration during the normal bottle aging of wine. Although exposure of white wine to fluorescent light is known to induce the accumulation of volatile sulfur compounds, causing light-struck aroma, the influence on the loss of protective Cu fractions is uncertain. Riboflavin is known to be a critical initiator of photochemical reac-tions in wine, but the rate of its decay under short-term light exposure in different coloured bottles and for wine of different oxygen concentrations is not well understood.

The components and the methodology for characterization of the terroir in Spain have been described by Gómez-Miguel et al.

Rotundone, the pepper aroma compound, has been detected in wines made from a large number of grape varieties. However, given the fact that analyzed wines were sourced from different winegrowing regions and seasons, made using different winemaking techniques and at different scales, it remains difficult to assess the real variety potential to produce rotundone.