Aromatic and polyphenolic quality of grapes and wines

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Current changes of ecoclimatic indicators may cause significant variation in grapevine phenology and grape ripening. Climate change modifies several abiotic factors (e.g. temperature, sunlight radiation, water availability) during the grapevine growth cycle, having a direct impact on the phenological stages of the grapevine, modulating the metabolic profile of berries and activating the synthesis and accumulation of diverse compounds in the skin of berries, with consequences on the composition of the grapes. The increase in average and extreme temperatures of summer months, as a major consequence of climate change, as well as changes of rainfall patterns during the ripening phase, leads to a higher concentration of sugar and a general change of the acidic profile of grapes, but also to the modification of secondary metabolites profiles.

Therefore, in several viticulture areas, ripening occurs, when both colour and aroma profile can be adversely affected which in wine is translated to a loss of typicity and terroir expression. Due to climate change, a mismatch is also noted between the different parameters of technological, phenolic, and aromatic quality as they are regulated by different biosynthetic pathways and therefore are influenced differently.Significant variations observed in temperature and rainfall patterns or conditions of limited water availability and high temperature, that lately are characterizing the second part of berry development may cause the rapid development of individual berries during the hottest part of the season, which can adversely affect may affect the secondary metabolites that detrmine color and aroma thus grape and wine quality. 

 

Solutions

Radiation and temperature

  • Early light exposure before veraison : Carotenoids, Flavonoids were amongst the most affected compounds by higher levels of radiation. The fruit environment strongly regulates the production of carotenoids, flavonoids and early exposure has been found to have a greater impact on their concentrations than treatments performed at or after véraison. 

 

  • Avoid defoliation in the period of high T°:   Whilst higher carotenoids, flavonoids and selected free aroma compounds were observed in defoliated treatments thus in higher radition conditions, higher temperatures appear to have been detrimental to the adaptation of berries by limiting production of these compounds and increasing their rate of degradation, which further stresses the need to perform activities such as defoliation when temperatures are still mild.

 

  • Avoid bunch extremely high T° in the last stage of ripening:   Previous research indicated that microclimate conditions, which vary according to vintage, vineyard aspect and vine vigour may affect the timing of the peak concentration of norisoprenoid precursors whereas high temperature during the last stages of grape ripening, evidently leads to a decrease of the total norisoprenoids . Extremly high radiation and temperature may have negative effects the grape is also subject to burns if exposed directly to the sun, negative effects mostly for free Terpenes,  in aromatic varieties, while overipening and possible withering, favour the accumulation of terpenes in glycosidic form, which will be released slowly during aging. Leave a few more leaves to protect the bunches
  •  biostimulants,  cover products

    In a context of climate change and excessive use of agrochemical products, sustainable approaches for environmental and human health such as the use of bio stimulants in viticulture represent a potential option, against abiotic and biotic threats. Bio stimulants are organic compounds, microbes, or a combination of both, that stimulate plant's vital processes, allowing high yields and good quality products. The application of these natural compounds has effects on plant physiology, pathogens development and leads to a diverse expression of plant genes responsible for triggering metabolic pathways and plant defense responses. In vines, may trigger an innate immune response leading to the synthesis of secondary metabolites, key compounds for the organoleptic properties of grapes and wines.Bio stimulants thus, may improve the aromatic  parameters of the grapes, but their effect is different based on the product, the frequency and the timing of the application, the chemical class of the compounds involved and the cultivar examined.

    cover products such Kaolin may protected the berry exocarp from light stress

     

     

    may enchance  polyphenolic and /or aromatic content: Methyl Jasmonate, absiscic acid, chitosan, yeast extract

     


     

Water stress 

 

  • avoid water stress: to mantain free terpenes n Moscato  maintain the correct grassing under the row and in the row. In the sub-row if there is humidity  leave more grass, if there is greater siccity, remove it. The plant must feed on water in a balanced way. Work the soil between the rows is another important aspect: for example to keep it soft when cutting the grass “reshuffles” it into the earth so that it becomes a nourishing element
  • increase Organic substance content in the soil, and with the presence and abundance of mycorrhizae, i.e. symbiosis between the roots and some fungi, which function as an extension of the root system, or by an consortium of microrganisms 

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References

Mori, K., Goto-Yamamoto, N., Kitayama, M., and Hashizume, K. (2007). Loss of anthocyanins in red-wine grape under high temperature. Journal of experimental botany 58, 1935–1945.

De Orduna, R. M. (2010). Climate change associated effects on grape and wine quality and production. Food Research International 43, 1844–1855.

van Leeuwen, C., and Darriet, P. (2016). The impact of climate change on viticulture and wine quality. Journal of Wine Economics 11, 150–167.

Asproudi, A., Petrozziello, M., Cavalletto, S., and Guidoni, S. (2016). Grape aroma precursors in cv. Nebbiolo as affected by vine microclimate. Food chemistry 211, 947–956.

Asproudi, A., Ferrandino, A., Bonello, F., Vaudano, E., Pollon, M., and Petrozziello, M. (2018). Key norisoprenoid compounds in wines from early-harvested grapes in view of climate change. Food Chemistry 268, 143–152. doi: 10.1016/j.foodchem.2018.06.069.

van Leeuwen, C., Barbe, J.-C., Darriet, P., Geffroy, O., Gomès, E., Guillaumie, S., et al. (2020). Recent advancements in understanding the terroir effect on aromas in grapes and wines. OENO One 54, 985. doi: 10.20870/oeno-one.2020.54.4.3983.

Monteiro, E.; Gonçalves, B.; Cortez, I.; Castro, I. The Role of Biostimulants as Alleviators of Biotic and Abiotic Stresses in Grapevine: A Review. Plants (2022), 11, 396

Cataldo E. Fucile M., Mattii G. B. Biostimulants in Viticulture: A Sustainable Approach against Biotic and Abiotic Stresses. Review Plants (2022), 11, 162. Colla G.; Rouphael, Y., Biostimulants in horticulture. Sci. Hortic. (2015), 196, 1–134 

Written by Andriani Asproudi

This is a work in progress...


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