Potential opportunities of thinned clusters in viticulture: a mini review.

Crop thinning is a common practice performed in the vineyard consisting of whole clusters or individual fruits being removed after flowering is attained. Current studies have reported that unripe grape products as verjuice and sour grape sauce contain high content of bioactive compounds such as polyphenols, sugars, organic acids, nitrogenous compounds and sterols. This mini-review overviewed the bioactive components obtained from thinned unripe grapes such as phenolic compounds, sugars, organic acids, minerals, nitrogen compounds and sterols, and their use as antibrowning and whitening agents, natural catalysts, food preservative and food additive. In addition, their beneficial effects for human health also were reviewed, as well as the practices to maximize the extraction of antioxidant compounds. Therefore, revalorizing the waste from this management practice in viticulture can increase the vineyard sustainability and farmers' economic profits. © 2021 Society of Chemical Industry.

Effect of rootstocks on volatile composition of Merlot wines.

BACKGROUND: Scion physiology and grape quality are impacted by rootstock choice. There is little available information about the effects of rootstock on wine volatile composition, particularly when comparing grafted with own-rooted grapevines. This field trial was aimed at studying the influence of rootstock choice on volatile composition of Merlot wines. RESULTS: Wines made from grapes harvested from own-rooted grapevines had the lowest content of (E)-3-hexenol, diethyl succinate and total ethyl esters and the highest content of 1-pentanol, 1-hexanol, (Z)-3-hexenol, diethyl malate and acetovanillone. Rootstocks such as 99R and 140Ru led to a higher content of total ethyl esters in wines followed by 110R, 1103P and Gravesac. According to odor activity values, Merlot wines were characterized by roses, sweat, cheese and banana aromas. CONCLUSIONS: This work provides valuable information about the potential impact of rootstocks on wine volatile composition for Merlot wines. © 2020 Society of Chemical Industry.

Rootstock effects on grape anthocyanins, skin and seed proanthocyanidins and wine color and phenolic compounds from Vitis vinifera L. Merlot grapevines.

BACKGROUND: Rootstocks affect vegetative and reproductive parameters of the scion. However, limited knowledge exists on the effects of the adoption of a specific rootstock on grape and wine phenolic composition, which contribute to certain sensory attributes such as color, body and astringency of wine. These compounds are mainly affected by the variety, viticultural management and rootstock. The aim of this work was to study the influence of eight rootstocks on grape anthocyanin content, skin and seed proanthocyanidins and wine chromatic characteristics obtained from Merlot vines. RESULTS: Grapevines grafted onto SO4 rootstock, in general, presented a higher concentration of total proanthocyanidins in skins and seeds compared to the rest of the rootstocks, whereas grapevines grafted onto Gravesac presented a lower concentration of proanthocyanidins in skins and seeds. These differences were found in the wines developed from grapevines grafted onto SO4. Wines from grapevines grafted onto SO4, 140 Ruggeri, Gravesac and 4453 M rootstocks presented, in general, better chromatic characteristics and a higher anthocyanin and tannin content than the rest of the samples. CONCLUSION: This work gives additional information concerning the influence of rootstock on grape and wine phenolic composition. © 2018 Society of Chemical Industry.

Characterization of phenolic composition in Carignan noir grapes (Vitis vinifera L.) from six wine-growing sites in Maule Valley, Chile.

BACKGROUND: Among Chilean varieties, Carignan noir has had a major resurgence due to its rediscovered wine quality potential. For this, the aim of this study was to characterize phenolic composition of grapes grown in six sites from the Maule Valley. RESULTS: The data showed that myricetin-3-glc and catechin were the most important flavonol and flavanol, respectively. Anthocyanin and flavonol composition was correlated with biologically effective degree days, exhibiting a relationship with grape maturity. Flavanol and hydroxycinnamic acid composition was inversely correlated to the average maximum temperature of the warmest month, showing that their synthesis is favored by cooler temperatures during the warmest month. CONCLUSION: These results have enological and viticultural interest for grape growers as vineyard site selection for this cultivar can confer differentiable attributes in terms of grape composition and quality. On the other hand, understanding the effects of climate on the synthesis of phenolic compounds may be useful for managing the vineyards with the aim of improving grape quality. © 2017 Society of Chemical Industry.

Volatile composition of Carignan noir wines from ungrafted and grafted onto País (Vitis vinifera L.) grapevines from ten wine-growing sites in Maule Valley, Chile.

BACKGROUND: Carignan noir is one of the minor and ancient varieties from the Chilean wine scenario that has had a resurgence as a result of to its rediscovered oenological potential when cultivated under the conditions of the interior dryland area. Under these growing conditions Carignan noir wines stand out as fruit driven and fresh compared to those originating from other growing areas. On the other hand, it is well known that wine aroma composition depends mainly on variety, viticultural management and winemaking. Thus, the present study aimed to investigate the volatile composition of wines from Carignan noir grapes originating from ungrafted and grafted onto País grapevines, in ten sites of the Maule Valley (Chile) during two consecutive vintages. RESULTS: Higher alcohols were the most abundant volatile compounds, whereas ethyl esters and ß-damascenone were the most odoriferous compounds according to their odorant activity value. The dominant factor in Carignan noir wine volatile composition was season, whereas rootstock did not have a significant effect in differentiating the wines. In terms of climate, cold nights during the month prior to harvest correlated with higher linalool, α-terpineol and trans-3-hexen-1-ol content. The biologically effective degree-days index was inversely correlated with isoamyl acetate and 2-phenylethyl acetate content. Huglin's heliothermal and the average mean temperature of the warmest month indices were inversely correlated with ethyl vanillate, ethyl hexanoate and ethyl octanoate content. CONCLUSION: Site climate conditions were related to the accumulation of certain wine volatile compounds. This information may be useful for devising new Carignan noir vineyard management strategies when aiming to improve wine quality or adjust site selection approaches to maximize grape/wine volatile composition according to wine style. © 2018 Society of Chemical Industry.

Aroma Release in Wine Using Co-Immobilized Enzyme Aggregates.

Aroma is a remarkable factor of quality and consumer preference in wine, representing a distinctive feature of the product. Most aromatic compounds in varietals are in the form of glycosidic precursors, which are constituted by a volatile aglycone moiety linked to a glucose residue by an O-glycosidic bond; glucose is often linked to another sugar (arabinose, rhamnose or apiose). The use of soluble ß-glycosidases for aroma liberation implies the addition of a precipitating agent to remove it from the product and precludes its reuse after one batch. An attractive option from a technological perspective that will aid in removing such constraints is the use of immobilized glycosidases. Immobilization by aggregation and crosslinking is a simple strategy producing enzyme catalysts of very high specific activity, being an attractive option to conventional immobilization to solid inert supports. The purpose of this work was the evaluation of co-immobilized ß-glycosidases crosslinked aggregates produced from the commercial preparation AR2000, which contains the enzymes involved in the release of aromatic terpenes in Muscat wine (α-l-arabinofuranosidase and ß-d-glucopyranosidase). To do so, experiments were conducted with co-immobilized crosslinked enzyme aggregates (combi-CLEAs), and with the soluble enzymes, using an experiment without enzyme addition as control. Stability of the enzymes at the conditions of winemaking was assessed and the volatiles composition of wine was determined by SPE-GC-MS. Stability of enzymes in combi-CLEAs was much higher than in soluble form, 80% of the initial activity remaining after 60 days in contact with the wine; at the same conditions, the soluble enzymes had lost 80% of their initial activities after 20 days. Such higher stabilities will allow prolonged use of the enzyme catalyst reducing its impact in the cost of winemaking. Wine treated with combi-CLEAs was the one exhibiting the highest concentration of total terpenes (18% higher than the control) and the highest concentrations of linalool (20% higher), nerol (20% higher) and geraniol (100% higher), which are the most important terpenes in determining Muscat typicity. Co-immobilized enzymes were highly stable at winemaking conditions, so their reutilization is possible and technologically attractive by reducing the impact of enzyme cost on winemaking cost.

Non-Targeted Metabolite Profiles and Sensory Properties Elucidate Commonalities and Differences of Wines Made with the Same Variety but Different Cultivar Clones.

Grapes, one of the oldest agricultural crops, are cultivated to produce table fruits, dried fruits, juice, and wine. Grapevine variety is composed of clones that share common morphological traits. However, they can differ in minor genetic mutations which often result in not only notorious morphological changes but also in other non-visible sensorial distinctive attributes. In the present work, we identified three Vitis vinifera cv. Pinot noir clones grown under identical field conditions that showed different grape cluster types. Here, sensorial analysis together with non-targeted metabolite profiles by Ultra High performance Liquid Chromatography (UPLC) couples to Ultra High Resolution Mass Spectrometry (FT-ICR-MS) of wines elaborated from the three different grape cluster types was studied with the aim of (i) finding sensorial differences among these three types of wines, and, if there were, (ii) determining the molecular features (metabolites) associated with these sensorial attributes by a multivariate statistical approach.

Volatile composition and sensory characteristics of Carménère wines macerating with Colombian (Quercus humboldtii) oak chips compared to wines macerated with American (Q. alba) and European (Q. petraea) oak chips.

Different oak species or origins have been studied to find an alternative to traditional ones and Quercus humboldtii from Colombia is a candidate. Some studies analyse the composition of this oak, but no work has been found to study its use for wine treatment. The aim was to evaluate volatile composition of toasted Q. humboldtii oak chips and the wines treated with these chips. To evaluate its oenological potential Q. alba and Q. petraea have been included in this trial. The wines were subjected to a sensory analysis. Results indicated that oak chips and wines macerated for 90 days with toasted Colombian chips exhibited higher 5-methylfurfural, guaiacol, trans-isoeugenol and syringol concentrations than others, while the furfural and cis-ß-methyl-γ-octalactone content was lower. Sensory analysis showed that the wines treated with Colombian oak presented more notes of smoked and less of coconut. Therefore, this oak could probably be considered suitable for ageing.

Foliar nitrogen application in Cabernet Sauvignon vines: Effects on wine flavonoid and amino acid content.

Wine quality greatly depends on its chemical composition. Among the most important wine chemical compounds, flavonoids are the major contributors to wine organoleptic properties while amino acids have a huge impact on fermentation development and wine volatile profile. Likewise, nitrogen applications are known to have an impact on wine composition. Therefore, the aim of this work was to study the effects of foliar nitrogen applications on wine flavonoid and amino acid composition. The experiment involved five foliar nitrogen applications at veraison time: urea (Ur), urea plus sulphur (Ur+S), arginine (Arg), and two commercial fertilizers Nutrimyr Thiols (NT) and Basfoliar Algae (BA). The results showed that nitrogen foliar treatments decreased wine flavonoid content although the effect varied according to each treatment. This could be related to a low vine nitrogen requirement, since must yeast assimilable nitrogen (YAN) was above acceptable threshold values for all samples. With regard to wine amino acid content, all treatments except for Ur increased its values after the applications. Finally, foliar nitrogen treatments greatly influenced wine composition. Among them, urea seemed to exert the most negative effect on both phenolics and amino acids. In addition, an inverse relationship between wine amino acid content and flavonol concentration was exhibited.