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Grapevines may require the input of nitrogen to grow and to guarantee an appropriate grape composition. Recently there has been a growing interest in foliar fertilization, which entails a fast and efficient assimilation of the products. The aim of this work was to study the influence of foliar applications of phenylalanine and urea, at two different doses, on grape anthocyanins, flavonols, flavan-3-ols, phenolic acids, and stilbenes. All treatments were applied at veraison and one week later at doses of 0.9 and 1.5 kg N/ha. The results showed that the synthesis of phenolic compounds was favoured by foliar applications of phenylalanine and urea. The application of the lowest dose of urea was the most effective treatment, increasing the content of several anthocyanins and flavonols. Moreover, none of the foliar treatments worsened the grape phenolic composition. In conclusion, foliar application of phenylalanine and especially urea, could be an interesting management tool for improving grape quality and their health-promoting properties. [ABSTRACT FROM AUTHOR] more...

In this work the influence of the foliar application of proline, phenylalanine, urea and two commercial nitrogen fertilizers, with and without amino acids, on grape aroma composition was studied. The treatments were applied in a Tempranillo vineyard, at a dose of total N of 900 g/ha, at veraison and a week later. Enological parameters and volatile compound content were determined in grapes. The results showed that terpenoids synthesis decreased with all treatments carried out in the vineyard, and there were not significant differences either in the amount of C 13 norisoprenoids or in esters between treated and control samples. The treatment with phenylalanine increased the presence of benzenoid compounds and decreased C6 compounds. Therefore, this treatment could be considered the best from the point of view of grape aroma composition. The treatments with the commercial nitrogen fertilizers did not affect the total compound content present in the samples. [ABSTRACT FROM AUTHOR] more...

Highlights: [•] Effect of different nitrogen foliar treatments to vineyard on grape amino acid content. [•] Proline treatment did not affect the must nitrogen composition. [•] Phenylalanine and urea applications favoured the synthesis of the most amino acids. [•] Regardless of the formulation, nitrogen fertilizers improved grape amino acid content. [•] Enological interest to enhance amino acid content and a tool to improve wine quality. [Copyright &y& Elsevier] more...

Abstract: The aim of this work was to study the influence of pulsed electric field (PEF) treatments on the volatile composition of three grape varieties. In order to do this, grapes were crushed and destemmed, and four PEF treatments were applied. The process was carried out continuously using a semi-industrial equipment. Volatile compounds were analyzed by SPME-GC–MS. The results showed that the effect of PEF treatment was different depending on variety. However, the aromatic profile of the studied varieties was not affected in any case. PEF enhanced the aromatic composition of Grenache, increasing the quantity of monoterpenoids. Moreover, a positive effect was observed in the amount of β-ionone, total esters and benzenoid compounds, and little difference was observed between treatments for C6 compounds. However, the volatile composition of Tempranillo and Graciano was not favored by PEF. In conclusion, from the point of view of the volatile composition and taking into account the treatments used in this study, it can be concluded that PEF is an appropriate technology to improve the aromatic quality of Grenache variety. Industrial relevance: Pulsed electric field is a non-thermal technology that enhances the volatile content in Grenache. Consequently, this technology could be used in the food industry to improve the aromatic quality of Grenache must and therefore the overall quality of Grenache wine, as this variety is one of the most widely grown in the world. [Copyright &y& Elsevier] more...