Effect of artificial shading on the tannin accumulation and aromatic composition of the Grillo cultivar (Vitis vinifera L.)

Abstract

BackgroundWhite wine quality, especially in warm climates, is affected by sunlight and heat stress. These factors increase the probability that ambering processes will occur and reduce the potential flavour compounds. This study aimed to investigate the effect of sunlight reduction on the accumulation of polyphenolic and aromatic compounds.ResultsThis study was conducted in a commercial vineyard containing V. vinifera L. cv Grillo. Opaque polypropylene boxes (100% shading) and high-density polyethylene (HDPE) net bags (50% shading) were applied at fruit set. The effect of the shaded treatments was compared to the exposed fruit treatment. The shaded treatments resulted in heavier berries and lower must sugar contents than the exposed treatments. Proanthocyanidins and total polyphenol levels were similar in the exposed and bagged grapes; however, the levels were always lower in the boxed fruit. At harvest, the highest aroma level was measured in the boxed fruits.ConclusionsThe boxed fruit had less sugar, fewer proanthocyanidins and more flavours than the exposed grapes.The reduction in flavanols reactive to p-dimethylamino-cinnamaldehyde as (+)-catechin equivalents and total skin proanthocyanidins is an important result for the white winemaking process. In addition, the higher level of aromatic compounds in shaded grapes at harvest is an important contribution to the development of different wine styles.

Impact of agronomic practices on grape aroma composition: a review

“…By contrast, in a study conducted in Sicily on the white cv. Grillo, shading increased concentrations of free and glycosylated terpenes, C 13 ‐norisoprenoids, benzenoids and C 6 ‐alcohols . This result possibly occurred due to the warm climate conditions and possible heat stress on the grapes.…”

“…Most of them have focused their research on the main aroma molecules: glycosylated aroma precursors, free aroma volatiles, C 13 ‐norisoprenoids, terpenes, and methoxypyrazines. Although the removal of basal leaves around a bunch is usually chosen to increase the exposure to light, some authors have used artificial shading (e.g., boxes) …”

“…The influence of light on the concentration of free and/or bound terpenols has been extensively studied . Most of the authors applied artificial shading to the bunches, but one of them applied a leaf‐removal treatment .…”

Application of exogenous 24-epibrassinolide enhances proanthocyanidin biosynthesis in Vitis vinifera ‘Cabernet Sauvignon’ berry skin

“…Many factors may influence the PAs composition of grapes, such as genotype, climatic conditions (Lorrain et al 2011), and cultural and technological practices. Recent studies have focused on and compared the effects of different viticultural technologies, such as water deficit (Bucchettia et al 2011), ultraviolet (UV) light irradiation , and artificial shading (Scafidi et al 2013), that impact on the PAs content in grapes. Plant hormones also influence the PAs accumulation in grapes.…”

Characterization of rhizosphere bacterial community and berry quality of Hutai No.8 (Vitis vinifera L.) with different ages, and their relations

“…Generally, grape quality is distinguished by a number of factors, such as berry maturity, vineyard productivity, plant vigor, health, floor and canopy management, rootstock, growing environment, tree-ages, and so on. [7][8][9][10][11][12][13] Like other living plants, grapevine roots both release many kinds of substances into the soil and absorb moisture, mineral salts and other nutrients from the soil. Plant rhizosphere, where material exchange occurs between roots and soil, is the soil nearest to the plant root system.…”