Investigation of Brazilian grape juice metabolomic profile changes caused by methyl jasmonate pre‐harvest treatment

Abstract

Grape juice is a major source of potential health-promoting bioactive polyphenols, especially for children and those who do not consume wine. Since the subtropical climate may negatively affect the concentrations of grape polyphenols, especially anthocyanins, elicitors such as methyl jasmonate (MeJa) could be used to promote polyphenol biosynthesis. This work aimed at investigating the impact of MeJa treatment on grape juice produced via a traditional low-cost process from two Vitis labrusca cultivars and in two Brazilian regions. The untargeted LC-MS analytical protocol demonstrated that Isabel Precoce juices strongly benefited from MeJa treatment, especially regarding their anthocyanic profile, regardless of the cultivation region. Known MeJa markers in wine and V. vinifera grapes (flavanols, flavonols and stilbenes) in this experiment had mixed behaviours depending on the region/variety/cultivation. Moreover, it was found that all the detected hydroxycinnamates were influenced by the treatment, especially the concentration of their glucosides, which was increased. Glutathione, 2-S-glutathionyl caftaric acid and indole lactic acid glucoside were identified for the first time as MeJa treatment biomarkers in grape products, indicating a possible positive effect on juice antioxidant properties.

Improvement of Stilbene Content in Concord and Isabel Precoce Grapes and Juice through Methyl Jasmonate Application

“…labrusca and its hybrids, ‘Isabel Precoce’ presents lower anthocyanin content and color intensity. ,, Regarding the MJ treatment effect on the chromatic characteristics, no significant difference was observed in comparison with CT juices. These results disagree with previous reports, in which an increase in color intensity is observed in the wine and anthocyanin content from MJ-treated grapes. , Additionally, it has been reported that MJ applications positively affect the bioactive compound composition. ,− , The treatments not only promote the activation of additional regulatory pathways involving the upregulation of the MYB family but also stimulate positive feedback on their own MJ biosynthesis. , …”

“…vinifera grapes cultivated in Europe, a positive response was observed regarding the secondary metabolism ,− of grapes and their corresponding wine. ,, Our group’s previous work demonstrated that a similar response was observed in Vitis labrusca L. grapes grown under Brazilian climate conditions, regarding volatile compounds and flavonoid and nonflavonoid compounds, such as anthocyanins, flavonols, hydroxycinnamic acids, flavanols, and stilbenes . In Isabel Precoce and Concord juice, MJ application improves anthocyanins and promotes a positive impact on hydroxycinnamics, respectively. − …”

“…18,33 Additionally, it has been reported that MJ applications positively affect the bioactive compound composition. 17,[24][25][26]36 The treatments not only promote the activation of additional regulatory pathways involving the upregulation of the MYB family but also stimulate positive feedback on their own MJ biosynthesis. 13,37 These different responses observed in our research might be related to the differences between the grape skin contacts during the process.…”

“…In general, our results are in agreement with the literature reports on grape juice elaborated with Vitis labrusca L. varieties. 5,26 3.2. Stilbene Content.…”

Vine Foliar Treatments at Veraison and Post-Veraison with Methyl Jasmonate Enhanced Aromatic, Phenolic and Nitrogen Composition of Tempranillo Blanco Grapes

“…Finally, trans -fertaric acid content in grapes increased significantly after the foliar application of MeJ, with the highest concentration of this hydroxycinnamic acid being obtained for MeJ-Post. Figure 2 i shows that the total concentration of hydroxycinnamic acids in the samples increased with both MeJ treatments, in agreement with Moro et al [ 46 ], who observed higher concentrations of these compounds in juices after MeJ application. Hydroxycinnamic acids can act as precursors of vinylphenols during wine ageing in oak barrels [ 47 ] and, therefore, can be responsible for a depreciating wine sensory characteristic.…”