Influence of seaweed foliar application to Tempranillo grapevines on grape and wine phenolic compounds over two vintages

The study of seaweeds is increasing in viticulture due to their implications on plant protection and grape quality. This trial aimed to study the effects of foliar applications of an Ascophyllum nodosum extract at low (0.25%, v v-1) and high (0.50%, v v-1) dosages on grape and wine phenolic compounds in 2017 and 2018. In grapes, seaweed biostimulation increased the content of malvidin-3-glc, myricetin-3-glc and myricetin-3-gal in 2017 season. Moreover, both treatments improved the synthesis of trans-piceid and total stilbenes in both seasons. Sensory analysis revealed that 2017 wines had more color than the 2018 wines, which coincided with color intensity parameters. Therefore, seaweed applications to grapevines improved stilbenes content in grapes independently of the season and its effects on the rest of phenolic compounds in grapes and wines depended strongly of season factor.

Seaweed foliar applications at two dosages to Tempranillo blanco (Vitis vinifera L.) grapevines in two seasons: Effects on grape and wine volatile composition

The effects of seaweed applications to grapevines on grape and wine volatile composition are currently unknown. The aim of this work was to study the influence of seaweed foliar applications (Ascophyllum nodosum) to a Tempranillo blanco vineyard on grape and wine volatile composition. A low (Ld) and a high dosage (Hd) of the seaweed fertilizer was applied in two consecutive seasons (2017-2018). The most abundant family of varietal volatile compounds in Tempranillo blanco grapes was C13 norisoprenoid. Hd treatment tended to increase the concentration of certain C6 compounds in grapes in both seasons, whereas Ld application tended to decrease 2-phenylethanol and 2-phenylethanal content in grapes with a season dependence. Season factor affected to the concentration of most of the volatile compounds in grapes due to the differences on rainfall, which affected to the weight of 100 berries and physico-chemical parameters. Yeast assimilable nitrogen (YAN) in musts could have affected the concentration of most of the wine volatile compounds. According to odor activity values (OAV), Tempranillo blanco wines were characterized as floral, fruity, banana, pear, among others aroma compounds.

Riboflavin applications to grapevine leaves and berries blue-light post-harvest treatments modifies grape anthocyanins and amino acids contents

Light is an energy source and key environmental factor for plants. Out of the different light wavelengths, blue-light is one of the most relevant spectral regions because of its relation to anthocyanins biosynthesis. Among the compounds present in grapes, anthocyanins determine their main organoleptic and healthy properties; while a minimum concentration of ammonium and amino acids is necessary for a desirable development of the alcoholic fermentation. Moreover, amino acids are precursors of several volatile compounds synthetized during the fermentation. The aim of this study was to assess the influence of riboflavin (vitamin B2) applications, at harvest and one week later,to grapevine leaves in combination with post-harvest blue-light irradiation on Tempranillo (Vitis vinifera L.) grape anthocyanins and amino acidscomposition. The combination of blue-light irradiation and two riboflavin doses as well as theseindividual factors affected both grape anthocyanins and amino acidsconcentrations. After one week of storage, anthocyanins concentration diminished when clusters were irradiated with blue-light; while for amino acids content, the trend to increase or decrease is dependent on the riboflavin dose applied in vines and the storage time.

Grape and wine amino acid composition from Carignan noir grapevines growing under rainfed conditions in the Maule Valley, Chile: Effects of location and rootstock

Nitrogen compounds play a key role on grape and wine quality. Their composition in grapes depends mainly on variety, viticultural management, and terroir, and affects fermentation kinetics and the volatile compound formation. The aim of this work was to study grape and wine amino acid composition of ungrafted or grafted onto cv. País Carignan grapevines growing under rainfed conditions in ten sites of the Maule Valley (Chile). The results showed that proline was the most abundant amino acid in grapes and wines. In general, Carignan noir grapevines grafted over País showed lower grape amino acid content respect to ungrafted vines. Cool night index (CI) was inversely correlated to several amino acids, showing that their plant synthesis or accumulation increased with lower minimum temperatures during the last month before harvest. Truquilemu (Tru) and Ciénaga de Name (Cdn) sites showed the highest concentration for several amino acids and total amino acid content in grapes, which led to a faster alcoholic fermentation.

Chitosan and Laminarin as Alternatives to Copper for Plasmopara viticola Control: Effect on Grape Amino Acid

Copper fungicide use is limited by the European regulation; therefore, new strategies have been developed to prevent grapevine downy mildew (GDM). However, there is poor information about their effects on grape amino acid composition. This field trial aimed to evaluate the effect on grape amino acid composition of chitosan and of a mixture of laminarin and Saccharomyces extracts (LamE), applied in different strategies with copper hydroxide. The results showed that all the treatments applied to grapevines decreased the concentration of several amino acids. Moreover, treatments that have mostly decreased these compounds are those with copper hydroxide, especially when applied individually. LamE applied individually or alternately with copper hydroxide had the least negative effect on grape amino acid content. These results provide further information about the negative effects of copper on grape quality, which can be reduced when it is used in strategy with LamE or chitosan in GDM control.

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.