Effects of foliar application of inactivated yeast on the phenolic composition of <em>Vitis vinifera</em> L. cv. Agiorgitiko grapes under different irrigation levels

Abstract

Recent climate changes have caused the rising of average growing season temperatures leading to the advancement of vine phenological stages and to earlier harvests. This could result in the production of grapes with advanced berry sugar accumulation, but incomplete phenolic ripeness, thereby jeopardizing wine quality. This study aims to evaluate the effects of the application of a new product consisting of yeast derivatives on the phenolic maturity and composition of Agiorgitiko grapes and wines, under contrasting water conditions. The experiment was arranged as a 2×2 factorial design in a commercial vineyard situated in southern Greece, combining foliar spraying with LalVigne ® Mature (two applications after veraison and an untreated control) and water conditions (deficit irrigation and nonirrigated). Irrigation accelerated berry sugar accumulation, increased berry weight and anthocyanin content, and decreased skin tannin concentration. Spraying with yeast derivatives did not affect phenolic content of berry components, and it had no effect on must attributes. Foliar application of yeast derivatives resulted in a higher phenolic potential of the produced wines, only when combined with irrigation.

Explore the Rare—Molecular Identification and Wine Evaluation of Two Autochthonous Greek Varieties: “Karnachalades” and “Bogialamades”

“…Comparing total phenols and anthocyanins levels, “Bogialamades” grapes had higher values than “Karnachalades”. The grapes coming from “Karnachalades” variety had relatively lower levels of total phenols and anthocyanins than “Agiorgitiko” grapes [ 29 ] while grapes from the “Bogialamades” variety had relatively higher total phenols and anthocyanins than “Agiorgitiko”. Gambouti et al [ 30 ] showed that the higher the condensed tannin; the proanthocyanid content of the grapes is the greater the perceived astringency could be.…”

How Pre-Harvest Inactivated Yeast Treatment May Influence the Norisoprenoid Aroma Potential in Wine Grapes

“…In the literature, it is well documented that the use of elicitors (i.e., methyl jasmonate, chitosan, yeast extracts) stimulates plant defense mechanisms and consequently activates the enzymes responsible for the biosynthesis of secondary metabolites, such as phenolic compounds [16,31]. YE caused an accumulation of anthocyanins, stilbenes, and flavonoids in wine grapes without varying their phenological maturation [18,32,33]. Since there was no significant difference in maturation indexes between YE and C samples (Tables 2 and 3), the effect of treatment on ∆C variation could be attributed to the activation of enzymes catalyzing either the biosynthesis of carotenoids (as proved by the highest values being in YE grapes at véraison) or their degradation (as confirmed by the lowest values being in YE grapes at harvest) (Figure 4).…”