Grape Amino Acid Research Articles

Influence on wine biogenic amine composition of modifications to soil N availability and grapevine N by cover crops.

Vineyard soil management can modify the nitrogen soil availability and, therefore, grape amino acid content. These compounds are precursors of biogenic amines, which have negative effects on wine quality and human health. The objective was to study whether the effect of conventional tillage and two cover crops (barley and clover) on grapevine nitrogen status could be related to wine biogenic amines. Over 4 years, soil NO3- -N, nitrogen content in leaf and wine biogenic amine concentration were determined. Barley reduced soil NO3- -N availability and clover increased it. In 2011, at bloom, nitrogen content decreased with barley treatment in both blade and petiole. In 2012, nitrogen content in both leaf tissues at bloom was greater with clover than with tillage and barley treatments. Also, total biogenic amines decreased in barley with respect to tillage and clover treatments. There were correlations between some individual and total biogenic amine concentrations with respect to nitrogen content in leaf tissues. Wine biogenic amine concentration can be affected by the grapevine nitrogen status, provoked by changes in the soil NO3- -N availability with both cover crop treatments. © 2017 Society of Chemical Industry.

Effect of two doses of urea foliar application on leaves and grape nitrogen composition during two vintages

Nitrogen affects grapevine growth and also yeast metabolism, which have a direct influence on fermentation kinetics and the formation of different volatile compounds. Throughout the grapevine cycle, soil nitrogen availability and grape nitrogen composition can vary because of different factors. Nitrogen foliar applications can contribute toward enhancing grapevine nitrogen status and minimize the problem of leaching that traditional nitrogen-soil applications can provoke. The present study aimed to evaluate the influence of urea foliar applications on grapevine nitrogen status and grape amino acid content. Accordingly, two different doses of urea were applied over the leaves of a 'Tempranillo' vineyard. The highest urea doses affected nitrogen content on blade leaf tissues after veraison. Must amino acid profiles were modified by urea application and some of the compounds increased their concentrations. The effect of year on the increase of must total amino acid concentrations was more important than the effect of the doses applied. Urea foliar applications can be an interesting tool for decreasing grapevine nitrogen deficiencies. This method of nitrogen implementation in the vineyard could avoid sluggish fermentation problems during winemaking, enhance must nitrogen composition, and contribute to improving wine quality. © 2016 Society of Chemical Industry.

Effect of methyl jasmonate application to grapevine leaves on grape amino acid content

Over the last few years, considerable attention has been paid to the application of elicitors to vineyard. However, research about the effect of elicitors on grape amino acid content is scarce. Therefore, the aim of this study was to evaluate the influence of foliar application of methyl jasmonate on must amino acid content. Results revealed that total amino acid content was not modified by the application of methyl jasmonate. However, the individual content of certain amino acids was increased as consequence of methyl jasmonate foliar application, i.e., histidine, serine, tryptophan, phenylalanine, tyrosine, asparagine, methionine, and lysine. Among them, phenylalanine content was considerably increased; this amino acid is precursor of phenolic and aromatic compounds. In conclusion, foliar application of methyl jasmonate improved must nitrogen composition. This finding suggests that methyl jasmonate treatment might be conducive to obtain wines of higher quality since must amino acid composition could affect the wine volatile composition and the fermentation kinetics.

Study of the effects of proline, phenylalanine, and urea foliar application to Tempranillo vineyards on grape amino acid content. Comparison with commercial nitrogen fertilisers

The aim of this work was to study the influence of foliar application of different nitrogen sources on grape amino acid content. The nitrogen sources applied to Tempranillo grapevines were proline, phenylalanine, urea, and two commercial nitrogen fertilisers, both without and with amino acids in their formulations. All treatments were applied at veraison and one week later. Proline treatment did not affect the must nitrogen composition. However, phenylalanine and urea foliar application enhanced the plants’ synthesis of most of the amino acids, producing similar effects. In addition, the spray of commercial nitrogen fertilisers over leaves also induced a rise in grape amino acid concentrations regardless of the presence or absence of amino acids in their formulation. The most effective treatments were phenylalanine and urea followed by nitrogen fertilisers. This finding is of oenological interest for improved must nitrogen composition, ensuring better fermentation kinetics and most likely enhancing wine quality.

Study of polyamines and their precursor amino acids in Grenache noir and Syrah grapes and wine of the Rhone Valley

Polyamines and their amino acid precursors were determined in Grenache and Syrah grapes and in wines made from these grapes. The compounds analysed were the polyamines putrescine, spermidine, and spermine, in addition to their precursors, ornithine, agmatine and arginine. The analytes were determined by reversed-phase high performance liquid chromatography (HPLC) with fluorescence detection using FMOC (fluorenylmethylchloroformate) as a pre-column derivatising agent Grape clusters were sampled from flowering to full maturity at different developmental stages. In addition, different berry parts were analysed separately from half veraison onwards. It appears that at berryset there is a decrease in the concentration of arginine, whereas polyamine concentrations remain constant at this stage. Concentrations of polyamines increased from must to alcoholic to malolactic fermentation; putrescine was the most abundant in wine (mean concentration after malolactic fermentation, MLF was 4.93 mg/l) followed by spermidine and then spermine (mean concentrations after MLF were 1.84 and 0.17 mg/l, respectively). In three of the four fermentation sites concentrations of all three compounds were greater in Syrah than in Grenache wines. In both varieties, it appears that polyamine biosynthesis occurs preferentially from arginine via agmatine. In all cases, concentrations of polyamines found in these grapes and wines were significantly below the levels typically found in other fermented foods.

Changes in the free amino acid composition with maturity of the noble cultivar of Vitis rotundifolia Michx. grape.

The changes in amino acid composition that occur with maturity of the Noble cultivar of the Vitis rotundifolia Michx. (muscadine) grape were determined by HPLC. Eighteen amino acids were identified. Histidine was the most prominent amino acid followed by alanine. The concentrations of most of the major amino acids (alanine, glycine, histidine, valine, isoleucine, aspartic acid, and serine) were highest at verasion. Glutamine and threonine contents dropped sharply after fruit set, while those of arginine and proline increased gradually with maturity and ripening. Tyrosine content increased gradually with maturity and ripening following a slight drop after fruit set. In ripe grapes, seeds contained most of the amino acids in mature grapes (50%) followed by the pulp (23%), the juice (15%), and the skin (11%). Alanine, histidine, and arginine were the principal amino acids identified in the juice. Alanine, histidine, arginine, valine, glutamine, aspartic acid, proline, serine, and threonine accounted for about 90% of the amino acids in the pulp. In seeds, alanine, proline, asparagine, and histidine accounted for over 55% of the amino acids, while alanine and histidine were found to be the predominant free amino acids in the skin. The profile indicates some differences in the changes in amino acid composition with berry maturity and relative amounts of amino acids present in muscadine compared to those in nonmuscadine grape species.

Profiles of free amino acids in grapes of grafted Chardonnay grapevines

Chardonnay grapes from a rootstock trial in the Murray Valley region of South Australia were sampled for two seasons and concentrations of free amino acids in grape extract (‘juice’) were determined. The lowest concentrations of free assimilable amino-N were measured in Chardonnay grapes from vines on 140 Ruggeri and 101–14 rootstocks, and the highest concentrations were in grapes from vines on their own roots, Schwarzmann and K51–40. Free assimilable amino-N concentrations were sufficient to sustain fermentation through to completion. Arginine concentrations were generally too low to expect significant concentrations of urea in the wine. Amino-S concentrations were much lower and varied less than amino-N concentrations. The effect of any particular rootstock on the concentration of total free amino acids in Chardonnay grape ‘juice’ did not appear to be related to the known effects of those rootstocks on the NO3-N status of petioles at flowering. The concentrations of leucine, iso-leucine, valine, threonine, tyrosine and phenylalanine were generally higher in Chardonnay grapes grafted onto K51–40 in comparison to grapes from Chardonnay vines grafted on the other rootstocks. Any of these amino acids may be associated with the presence of specific higher alcohols in wine.

Peptidase activity and the ability of wine yeasts to utilise grape must proteins as sole nitrogen source

Abstract Peptidase activity of 14 Saccharomyces cerevisiae wine strains was tested with API ZYM kits LRA ZYM AP‐III and LRA ZYM AP‐IV, each containing 10 different enzymatic substrates. The ability of the yeast strains to utilise grape must proteins directly as sole nitrogen source was also examined by growth and fermentation tests in synthetic nutrient medium without additional nitrogen compounds, using a washed alcoholic precipitate of grape must. These observations strongly support the existence of an extracellular grape must protein hydrolytic enzymatic system in wine yeasts. Free amino acid content evolution in clarified and unclarified Chardonnay and Cortese pressed and free‐run juices, with or without growing yeast cells, was investigated by high‐performance liquid chromatography. Clarification does not seem to affect the grape amino acid contents. These remained almost constant from 0 to 8 h of contact with suspended solids when no growing yeast cells were detected. No grape proteolytic activity o...

Effect of Vineyard Locations, Varieties, and Rootstocks on the Juice Amino Acid Composition of Several Cultivars

Several grape varieties grown in Napa Valley and Davis and certain samples from other locations were analyzed for amino acids at the beginning of fermentation. Amino acid contents of two grape varieties grown on nine different rootstocks in the Santa Ynez Valley were analyzed for the effects of rootstock on the juice amino acid composition. Key grape amino acids prior to fermentation and at the end of fermentation were related to fermentation times of Chardonnay juices from two different locations.