Effects of partial dehydration techniques on the metabolite compositionin ‘Refošk’ grape berries and wine*

Abstract

IntroductionGrape quality is reflected in a balanced composition of primary and secondary metabolites, which constitute different parts of the fresh berries during their development and ripening. The accumulation of these metabolites within the berries is affected by genetic characteristics, cultivation practices, and climate conditions (Jackson and Lombard, 1993).The phenolic compounds in the skins of red berry grapevine varieties are mostly anthocyanins, hydroxycinnamic acids, stilbenoids, flavanols, and flavonols, which are also the building blocks of the grapes' and wines' sensorial properties (Jackson and Lombard, 1993;Gonzalez-Alvarez et al., 2013). In red grapes, anthocyanins are responsible for the red color of the skins and consequently define the color and quality of the must and wine (Liang et al., 2008). Other polyphenols, such as flavonols and flavanols, mostly contribute to wine flavor and astringency (Li et al., 2009). Phenolic compounds are biosynthesized through the phenylpropanoid and flavonoid pathways and originate from the amino acid precursor, phenylalanine. These pathways are among the most studied and thoroughly described secondary metabolic pathways in plants (Yang et al., 2012). Polyphenolic compounds play an important role in the sensorial quality of grapes and wines. Their transformation during the vinification process directly or indirectly influences the quality of the wine: its structure and sensorial properties (Cheynier, 2005;Noguerol-Pato et al., 2013).In order to change the composition of fresh berries and improve the quality of the wines produced from these, different canopy techniques, especially training systems, bunch thinning, defoliation, dehydration etc., have been introduced in viticulture ( Kyraleou et al., 2015;Liu et al., 2015). Grape dehydration, used for the production of late harvest, botrytized, and ice wines, represents a measure applied for the production of sweeter wines in general, in which the contents of soluble solids, phenolics, and aroma

Optimization of extraction time and temperature for natural antioxidants of öküzgözü grape pomace using various solvent ratios

“…Highest values of all anthocyanins were found to be at ethanol: 0.1% citric acid (50:50). It is determined that the selected optimum parameters for this study, are similar to other studies (Mikulic-Petkovsek et al, 2017;Cebrian et al, 2017;Karacabey et al, 2013;Riquelme et al, 2019;Çetin et al, 2011). In addition, similar results were obtained by Corrales et al (2008) who have reported that 50:50 ethanol concentration were chosen for the extraction.…”

On‐vine withering process of ‘Moscato bianco’ grapes: effect of cane‐cut system on volatile composition

“…Rusjan and Mikulic‐Petkovsek observed that Merlot berries from cane‐cut vines reached significantly higher soluble acid levels and titratable acidity values in comparison to control berries at harvest. Other studies performed on Refosk, Istrian Malvasia, and Rebula grape berries exhibited a significant increase in titratable acidity, tartaric acid, and malic acid when the cane‐cut on‐vine technique was applied to the vineyard compared to the control. This behavior was affected by the season in Istrian Malvasia.…”

“…After the cut, the berries are left on‐vine until technological ripeness and / or overripeness is reached. The different level of ripeness of the grapes treated with this technique with respect to other normally ripened grapes was technically called double‐reasoned maturation (DMR) . Studies of the cane‐cut on‐vine procedure as an overripening technique have demonstrated the capability of this technique to produce changes in the soluble solids, organic acids, and phenolic compounds in grape berries .…”

“…Studies of the cane‐cut on‐vine procedure as an overripening technique have demonstrated the capability of this technique to produce changes in the soluble solids, organic acids, and phenolic compounds in grape berries . The cane‐cut on‐vine overripe technique was applied to several cultivars such as Raboso Piave, Istrian Malvasia, Refosk, Rebula and Vitovxka or Merlot showing a positive impact on grape and wine composition, mainly involving phenolic compounds. However, to the best of our knowledge, studies of the effect of this technique on the volatile composition of grapes have never been performed to date.…”

“…The different level of ripeness of the grapes treated with this technique with respect to other normally ripened grapes was technically called double-reasoned maturation (DMR). [11][12][13][14] Studies of the cane-cut on-vine procedure as an overripening technique have demonstrated the capability of this technique to produce changes in the soluble solids, organic acids, and phenolic compounds in grape berries. 13 The cane-cut on-vine overripe technique was applied to several cultivars such as Raboso Piave, 13 Istrian Malvasia, 15 Refosk, 14 Rebula and Vitovxka 16 or Merlot 17 showing a positive impact on grape and wine composition, mainly involving phenolic compounds.…”