Study of must and wine amino acids composition after seaweed applications to Tempranillo blanco grapevines.

Recently, A.O.C. Rioja have selected and enlisted the Tempranillo blanco as a new grapevine variety to be cultivated in this area. This is the first report that studies amino acid and ammonium composition of grape juice and wine from Tempranillo blanco. The aim was to study the effect of foliar application of a seaweed extract to a Tempranillo blanco vineyard on must and wine amino acids and ammonium content. The results suggested that Tempranillo blanco behaved as an arginine accumulator variety. Biostimulation after seaweed applications at a high dosage (Hd) to the grapevines increased the concentration of several amino acids in the 2017 season, while scarcely affected their content in 2018. Phenylalanine, precursor of several volatile and phenolic compounds, was increased in both seasons after Hd applications. Season was the most important factor in the variability of the must and wine amino acids concentration, followed by treatment and its interaction.

The impacts of temperature, alcoholic degree and amino acids content on biogenic amines and their precursor amino acids content in red wine.

The aim was to study how factors such as temperature, alcoholic degree, and amino acids supplementation are able to influence the content of tyramine, histamine, 2-phenylethylamine, tryptamine and their precursor amino acids in winemaking process. Biogenic amines and amino acids were quantified at the beginning, middle and end of alcoholic fermentation, and at the end of malolactic fermentation. In general, samples produced with amino acid supplementation did not show the highest concentrations of biogenic amines, except for histamine, which content increased with the addition of the four amino acids. The synthesis of tyramine was mainly affected by the temperature and alcoholic degree, the formation of phenylethylamine was largely influenced by alcoholic degree, and tryptamine synthesis principally depended on temperature. Interestingly, there was interaction between these three factors for the biogenic amines studied. In conclusion, winemaking conditions should be established depending on the biogenic amine which synthesis is required to be controlled.

Vine-shoot waste aqueous extract applied as foliar fertilizer to grapevines: Effect on amino acids and fermentative volatile content.

The aim of this work was to study the influence of foliar applications of different wood aqueous extracts on the amino acid content of musts and wines from Airén variety; and to study their relationship with the volatile compounds formed during alcoholic fermentation. For this purpose, the foliar treatments proposed were a vine-shoot aqueous extract applied in one and two times, and an oak extract which was only applied once. Results obtained show the potential of Airén vine-shoot waste aqueous extracts to be used as foliar fertilizer, enhancing the wine amino acid content especially when they were applied once. Similar results were observed with the aqueous oak extract. Regarding wine fermentative volatile compounds, there is a close relationship between musts and their wines amino acid content allowing us to discuss about the role of proline during the alcoholic fermentation and the generation of certain volatiles.

Factors influencing the formation of histaminol, hydroxytyrosol, tyrosol, and tryptophol in wine: Temperature, alcoholic degree, and amino acids concentration.

The validation of a HPLC-PDA-MS/MS chromatographic method for the quali/quantitative characterization of histaminol, hydroxytyrosol, tyrosol, and tryptophol in wine has been described and discussed. Four standards showed a good linearity with high correlation coefficient values (over 0.9989) and LOD and LOQ were 0.001-0.015 mg/L and 0.004-0.045 mg/L, respectively. Furthermore, this study reported how factors such as temperature, alcoholic degree, and amino acids concentration are able to influence the formation of these four alcohols in Monastrell wines. The quantification values of these alcohols has been detected both at the half and end of alcoholic fermentation, and at the end of malolactic fermentation. In relation to interactions between factors, several significant variations emerged (p ⩽ 0.001). The impact of amino acids supplementation in Monastrell must it has been demonstrated, mainly in regards to histaminol and tryptophol.