Development and validation of a free solvent UHPLC/MS-MS method to analyse melatonin and its precursors in Spanish commercial wines  

Nitrogen (N) is quite important nutrient in grapevine development and must quality, but under Mediterranean climatic conditions, available soil water (ASW) during grapevine development can also influence vigour and must quality. The aim was to determine the influence of soil nitrate (NO3-) availability on N foliar, yield, and must quality in vineyards with similar available water holding capacity (AWC). For this purpose, four cv. Tempranillo (Vitis vinifera L.) vineyards were selected. All of them are placed in Uruñuela municipality (La Rioja, Spain), separated less than 2.5 km and in a slope <1 %, in soils with similar soil chemistry properties and with similar rooting depth (ranging between 105 cm and 110 cm).

Enzymatic browning[1] is an oxidation process that occurs in many foods that increases the brown colour[2]. This problem is especially harmful in the wine industry[3]. especially when the grapes are infected by grey rot since this fung release the oxidative enzyme laccase[4]. In the particular case of red wines, the presence of laccase implies the deterioration of the red colour and can even cause the precipitation of the coloring matter (oxidasic haze)[5].

Vine growth circumstances are becoming warmer and drier because of climate change. Higher temperatures advance ripening to a point in the season less conducive to the production of fine wine, while drought reduces yields (Van Leeuwen et al., 2019). Several wine-producing regions around the world have already recognized threats to their viticultural viability (Santos et al., 2020). An economical and cost-effective strategy for adaptation is the employment of late-ripening, drought-resistant plant material (varieties, clones, and rootstocks).

Ultra-High Pressure Homogenization (UHPH) is an innovative, efficient and non-thermal technology that can be applied at different stages in winemaking in order to reduce or avoid the use of sulphites. During 2022 vintage, a batch of Xarel·lo must was processed by UHPH at 300 MPa with an inlet temperature (Ti) of 4 ºC. In order to verify the influence of the UHPH treatment in wine characteristics, alcoholic fermentations with this must (UHPH) were carried out and compared with a control batch (without SO2 addition (C)) and a sulphited batch, in which 60 mg/L of total SO2 (SO2) were added.

The plant rhizosphere microbial communities are an essential component of plant microbiota, which is crucial for sustaining the production of healthy crops. The main drivers of the composition of such communities are the growing environment and the planted genotype. Recent viticulture studies focus on understanding the effects of these factors on soil microbial composition since microbial biodiversity is an important determinant of plant phenotype, and of wine’s organoleptic properties. Microbial biodiversity of different wine regions, for instance, is an important determinant of wine terroir.