Amino acids content in 'Tempranillo' must from three soil types over four vintages

Amino acids are the main grape nitrogen compounds and the principal source of N for yeasts, being precursors of several volatile compounds. Therefore, N compound concentrations in musts can affect sensorial characteristics of wines. The aim of this study was to analyse the influence of N-NO3- and N-NH4+ contents from different soils on profile and content of amino acids in 'Tempranillo' grapes. In order to determine this soil influence on must quality, three plots were selected in AOC Rioja, classified as Fluventic Haploxerepts, Typic Calcixerepts, and Petrocalcic Palexerolls. The results showed that amino acids and yeast assimilable nitrogen (YAN) content allowed us to differentiate samples from the three soils, and in each soil type, samples of each season. In general, must contents of total amino acids and some of them, as alanine, threonine, and tyrosine, were more influenced by soil type; YAN, proline, histidine, serine, and glycine concentrations mainly depended on the interaction soil-vintage. In conclusion, free amino acids concentration could be a tool to differentiate musts coming from different soils.