Development of a new commercial phenolic analysis method for red grapes

Varietal thiols 3-sulfanylhexan-1-ol (3SH), 3-sulfanylhexyl acetate (3SHA) and 4-methyl-4-sulfanylpentan-2-one (4SMP) are essential for fruity aromas of Sauvignon Blanc wines. The concentration of varietal thiols in wines was thought to be related to the concentration of their precursors in grapes, however only a small proportion of precursors are released to varietal thiols during fermentation. New findings suggested that specific grape juice metabolites could significantly impact on the development of three major varietal thiols and other aroma compounds of Sauvignon Blanc wines.

This study aimed to validate a protocol and compare metrics for evaluating drought tolerance in two Vitis vinifera grapevine cultivars under field conditions. Various metrics were calculated to represent the physiological responses of plants to progressive water deficit. Data were collected from Sauvignon Blanc and Chardonnay plants subjected to three irrigation levels during the 2022-2023 season, along with data from three previous seasons. Hydro-escape areas were used to assess the plant’s ability to reduce water potential with decreasing soil water availability.

The phenological stage of the grapevine (Vitis vinifera L.) represents a fundamental element in vineyard management, since it determines key practices such as fertilization, irrigation, phytosanitary interventions and optimal harvest time (Mullins et al., 1992).

Winemaking grapes contain a diverse array of non-volatile precursors that become noticeable only after hydrolysis reactions or molecular rearrangements, during which aroma compounds are generated and released [1]. Among these, glycosidic precursors are the most abundant and play a key role in the development of wine aroma [2].

AIM Methyl salicylate (MeSA) has been reported as a potentially impactful compound in Verdicchio wines produced in central Italy. Lugana is another white wine produced in the north-east of Italy from a grape locally known as Trebbiano di Soave, sharing a very similar genetic background with Verdicchio. The aims of this study were evaluating MeSA occurrence in Lugana, assessing its aroma impact on white wines aroma and elucidating its biogenesis during vinification. METHODS Fifteen Lugana wines were analysed for methyl salycilate content in comparison with Verdicchio, Pinot grigio and Garganega wines. MeSA impact on white wine aroma was studied by means of triangular test, adding MeSA at different concentrations. Possible routes of MeSA formation by yeast were investigated by means of a high throughput assay in which S. cerevisiae cells were put in contact with precursor such as salicylic acid (esterification) or glycosidic extracts (glycosidase). Sub-fractions of Lugana glycosidic extracts were also obtained by HPLC fractionation, allowing further evaluation of precursors role.