Amino Acid Profile of Must and Aromatic Potential of 30 Minor Grape Varieties Grown in Alcalá de Henares (Spain)

Amino acid composition and nitrogen quantification in grape must are of great importance given their usefulness for varietal characterization, influence on fermentation processes and identification of the aromatic potential of musts. The objective of this work was to determinate the amino acid and nitrogen compound profiles of 30 minority varieties of potential use in winemaking, all grown in the same ampelographic collection in Alcalá de Henares. The concentrations of 31 amino acids in must were identified and quantified using high-performance liquid chromatography (HPLC) during four seasons (2020 to 2023), and the average values of total free amino acids (TAN), yeast assimilable nitrogen (YAN) and aromatic precursor nitrogen (APN) were calculated for each variety. ‘Tazazonal’, a minority red grape variety, was found to exhibit high concentrations of yeast assimilable nitrogen (YAN), total amino nitrogen (TAN) and ammonia nitrogen (APN), comparable to those observed in ‘Tempranillo’ and ‘Garnacha Tinta’. These two cultivars are representative of traditional Spanish red grapevine varieties and are among the most widely cultivated in the country. In the case of white varieties, ‘Albillo del Pozo’, ‘Pintada’ and ‘Verdejo Serrano’ showed higher concentrations of these parameters than ‘Malvar’ and ‘Airén’, which are also widely grown in Spain. The results revealed distinct amino acid profiles for each variety, enabling their classification and supporting the identification of variants within the autochthonous germplasm. This approach aimed to highlight minority varieties of potential interest for future studies, given their relevance to both regional and national viticulture.