Effect of vine foliar treatments on the varietal aroma of Monastrell wines

Wine Volatilome as Affected by Tartaric Stabilization Treatments: Cold Stabilization, Carboxymethylcellulose and Metatartaric Acid

The primary cause of bottled wine sediment is tartrate crystal precipitation. To prevent this, wines undergo a stabilization process before bottling. The most commonly used method is cold stabilization, which induces the precipitation of tartrate crystals that are then removed, thereby eliminating the excess ions that cause instability in wine. Another approach to tartaric stabilization is using enological stabilizers with a colloid protective effect, which prevents the formation of tartrate crystals. The most commonly used tartaric stabilizers are sodium carboxymethylcellulose (CMC) and metatartaric acid. However, both have drawbacks: they are semi-synthetic products, and metatartaric acid degrades over time, losing its stabilizing effect. This study aims to compare the effects of cold stabilization, stabilization with CMC, and metatartaric acid on the chemical composition, particularly the volatilome, of white, rosé, and red wines. Cold stabilization significantly impacted the wine volatilome, especially in white and rosé wines, by decreasing total alcohols and increasing total esters. It also reduced the color intensity of rosé and red wines by lowering monomeric anthocyanins. In contrast, enological stabilizers had minimal impact on the wines' phenolic composition, chromatic characteristics, and volatilome. The sensory impact of cold stabilization is complex; it can potentially enhance the aroma of white and rosé wines by increasing ester VOCs and decreasing higher alcohols, but it negatively affects the color of rosé and red wines.

Effect of Cluster-Zone Leaf Removal at Different Stages on Cabernet Sauvignon and Marselan (Vitis vinifera L.) Grape Phenolic and Volatile Profiles

This study investigated the effect of leaf removal at three stages of grape development on the phenolic and volatile profiles of Cabernet Sauvignon and Marselan grapevines for two consecutive years in the Jieshi Mountain region, an area of eastern China with high summer rainfall. The results indicated that cluster-zone leaf removal generally reduced the titratable acidity of both varieties, but did not affect the total soluble solids of grape berries. Leaf-removal treatments increased the anthocyanin and flavonol content of berries in both varieties. However, in Cabernet Sauvignon, leaf removal negatively affected the norisoprenoid compounds, with a more pronounced impact observed when the leaf removal was conducted at an early stage. This negative effect may be related to a decrease in the levels of violaxanthin and neoxanthin, potential precursors of vitisprine and β-damascenone. In contrast, the removal of leaves had no effect on the norisoprenoid aroma of Marselan grapes.

Volatile phenols in wine: overview of origin, formation, analysis, and sensory expression

Volatile phenols impart particular aromas to wine. Due to their distinctive aroma characteristics and low sensory thresholds, volatile phenols can easily influence and modify the aroma of wine. Since these compounds can be formed in wines in various ways, it is necessary to clarify the possible sources of each volatile phenol to achieve management during the winemaking process. The sources of volatile phenols in wine are divided into berry-derived, fermentation-derived, and oak-derived. The pathways and factors influencing the formation of volatile phenols from each source are then reviewed respectively. In addition, an overview of the sensory impact of volatile phenols is given, both in terms of the aroma these volatile phenols directly bring to the wine and their contribution through aroma interactions. Finally, as an essential basis for exploring the scientific problems of volatile phenols in wine, approaches to quantitation of volatile phenols and their precursors are discussed in detail. With the advancement of analytical techniques, more details on volatile phenols have been discovered. Further exploration is worthwhile to achieve more detailed monitoring and targeted management of volatile phenols in wine.

Applying rosemary extract and caffeic acid to modify the composition of Monastrell wines

This work studies the effect of applying rosemary extract and caffeic acid on the polyphenolic and aromatic composition of Monastrell wines, as well as the influence of traditional winemaking or incorporating prefermentative maceration. For this purpose, three treatments were carried out in triplicate. In one of them, rosemary extract was applied on the clusters 10 days before harvest, caffeic acid was applied in the same way in another, and, finally, this acid was applied to grape before crushing. Each treatment was run by both traditional vinification and vinification with prefermentative maceration. After making wines, they were monitored for 12 months after fermentation. The application of rosemary extract, and that of caffeic acid but to a lesser extent, increased the color, the concentration of anthocyanins, and the percentage of polymerized anthocyanins, while prefermentation maceration gave rise to wines with a higher concentration of condensed tannins and polyphenols. Applying rosemary extract and caffeic acid in the vineyard also increased the concentration of esters and other compounds that favor wine aromatic quality, which was also enhanced by prefermentative maceration.

Nutrient Management Effects on Wine Grape Tissue Nutrient Content

With limited research supporting local nutrient management decisions in North Carolina grape (Vitis vinifera) production, field studies (2015–17) were conducted to evaluate late season foliar nitrogen (N) application on leaf and petiole N concentration and yeast assimilable N (YAN) in the fruit. Foliar urea (1% v/v) was applied at different rates and application times beginning pre-and post-veraison. Compared to soil applied N, late season foliar N substantially enhanced petiole N and grape YAN. Smaller split N applications were generally more effective in increasing YAN than single larger N rates. These data demonstrate the value of assessing plant N content at full bloom with petiole N analysis or remote sensing to guide foliar N management decisions. Additional field studies (2008–11) were conducted to evaluate pre-bud soil applied phosphorus (P) and potassium (K) effects on petiole P and K nutrient status. Fertilizer P and K were initially broadcast applied (0–896 kg P2O5 ha−1; 0–672 kg K2O ha−1) prior to bud-break in 2008–09 and petiole P and K at full bloom soil test P and K were monitored for three to four years after application. Soil test and petiole P and K were significantly increased with increasing P and K rates, which subsequently declined to near unfertilized levels over the sampling time depending on site and P and K rate applied. These data demonstrate the value of annually monitoring petiole P and K levels to accurately assess plant P and K status to better inform nutrient management decisions.

The Opportunity of Valorizing Agricultural Waste, Through Its Conversion into Biostimulants, Biofertilizers, and Biopolymers

The problems arising from the limited availability of natural resources and the impact of certain anthropogenic activities on the environment must be addressed as soon as possible. To meet this challenge, it is necessary, among other things, to reconsider and redesign agricultural systems to find more sustainable and environmentally friendly solutions, paying specific attention to waste from agriculture. Indeed, the transition to a more sustainable and circular economy should also involve the effective valorization of agricultural waste, which should be seen as an excellent opportunity to obtain valuable materials. For the reasons mentioned above, this review reports and discusses updated studies dealing with the valorization of agricultural waste, through its conversion into materials to be applied to crops and soil. In particular, this review highlights the opportunity to obtain plant biostimulants, biofertilizers, and biopolymers from agricultural waste. This approach can decrease the impact of waste on the environment, allow the replacement and reduction in the use of synthetic compounds in agriculture, and facilitate the transition to a sustainable circular economy.

Bioactive Compounds from Vine Shoots, Grape Stalks, and Wine Lees: Their Potential Use in Agro-Food Chains

The winemaking sector is one of the most productive worldwide, and thus it also generates large amounts of by-products with high environmental impacts. Furthermore, global market trends and government regulations promote industrial alternatives based on sustainable production processes. As a result, several studies have focused their attention on the reuse of grape by-products in the agro-food chain. Vine shoots, grape stalks, and wine lees, although produced to a lesser extent than grape pomace, have increasingly been receiving attention for their applications in the food sector, since they are a good source of functional and bioactive compounds. In this framework, our review highlights the promising results obtained by exploiting the antioxidant and/or antimicrobial activity of vine shoots, grape stalks, and wine lees or their extracts to replace the most common oenological additives and to assay the activity against food pathogens. Further, innovative functional foods and sustainable food packaging have been formulated by taking advantage of polyphenols and fiber, as well as plant bio-stimulants, in order to obtain grapes and wines with high quality characteristics. Overall, these by-products showed the potential to be recycled into the food chain as functional additives for different products and applications, supporting the sustainability of the winemaking sector.

Review of the Effects of Grapevine Smoke Exposure and Technologies to Assess Smoke Contamination and Taint in Grapes and Wine

Grapevine smoke exposure and the subsequent development of smoke taint in wine has resulted in significant financial losses for grape growers and winemakers throughout the world. Smoke taint is characterized by objectional smoky aromas such as “ashy”, “burning rubber”, and “smoked meats”, resulting in wine that is unpalatable and hence unprofitable. Unfortunately, current climate change models predict a broadening of the window in which bushfires may occur and a rise in bushfire occurrences and severity in major wine growing regions such as Australia, Mediterranean Europe, North and South America, and South Africa. As such, grapevine smoke exposure and smoke taint in wine are increasing problems for growers and winemakers worldwide. Current recommendations for growers concerned that their grapevines have been exposed to smoke are to conduct pre-harvest mini-ferments for sensory assessment and send samples to a commercial laboratory to quantify levels of smoke-derived volatiles in the wine. Significant novel research is being conducted using spectroscopic techniques coupled with machine learning modeling to assess grapevine smoke contamination and taint in grapes and wine, offering growers and winemakers additional tools to monitor grapevine smoke exposure and taint rapidly and non-destructively in grapes and wine.

Advancement in analytical techniques for the extraction of grape and wine volatile compounds

The grape and wine aroma is one of the most determining factors of quality, therefore the study of their volatile composition is a very important topic in vitiviniculture. The range of concentrations in which many of these compounds are found is quite low, in concentrations of ng/L; due to this, a sample preparation stage is necessary before doing the chromatographic analysis of the volatile compounds. In this review, the main analytical techniques used for the extraction of volatile compounds in grapes and wines are studied. The techniques presented are liquid-liquid extraction (LLE), solid phase extraction (SPE), solid phase microextraction (SPME), stir bar sorptive extraction (SBSE), and thin film solid phase microextraction (TF-SPME). For each of these techniques, a description was made, and the different characteristics were numbered, as well as their main advantages and disadvantages. Furthermore, from the second technique, a comparison is made with the previous techniques, explaining the reasons why new techniques have emerged. Throughout the review it is possible to see the different techniques that have been emerging in the past years as an improvement of the classical techniques.

Aromatic Characterization of New White Wine Varieties Made from Monastrell Grapes Grown in South-Eastern Spain

The aromatic profile of a wine is one of the main characteristics appreciated by consumers. Due to climate change, vineyards need to adapt to new conditions, and one of the strategies that might be followed is to develop new white varieties from Monastrell and other cultivars by means of intervarietal crosses, since white varieties are a minority in south-eastern Spain. Such crosses have already been obtained and have been seen to provide quality white wines of high acidity and with a good aromatic composition. To confirm this, a quantitative analysis was carried out during two vintages (2018 and 2019) in order to study and compare the volatile composition of Verdejo (V) wine with the aromatic composition of several wines made from different crosses between Cabernet Sauvignon (C), Syrah (S), Tempranillo (T), and Verdejo (V) with Monastrell (M), by means of headspace SPME-GC-MS analysis. Wine volatile compounds (alcohols, volatile acids, ethyl esters, terpenes, norisoprenoids, and two other compounds belonging to a miscellaneous group) were identified and quantified using a HS-SPME-GS-MS methodology. An additional sensory analysis was carried out by a qualified tasting panel in order to characterize the different wines. The results highlighted how the crosses MT103, MC69, and MC180 showed significant differences from and better quality than the Verdejo wine. These crosses produced higher concentrations of several aromatic families analyzed, which was supported by the views of the tasting panel, thus confirming their excellent aromatic potential as cultivars for producing grapes well adapted to this area for making white wines.

An overview of plant-based natural biostimulants for sustainable horticulture with a particular focus on moringa leaf extracts

The horticulture sector is facing various challenges in the near future. Aside from maintaining or even improving yields, sustainable horticulture production is crucial to achieve food security. Reducing the reliance on agro-chemicals and/or increasing the efficiency of use under a changing climate is crucial. Natural biostimulants can play an important role in this regard, increasing production at a relatively low cost sustainably. Natural biostimulant feedstocks include leaf, root or seed extracts, either individually or in combination with others. Their positive effect on horticultural production is mostly due to plant growth-enhancing bioactive compounds such as phytohormones, amino acids, and nutrients. Here we review recent progress made in research and applications on plant-derived extracts with an emphasis on the use of these renewable biochemicals as biostimulants in sustainable horticulture. Moringa leaf extracts in particular have been shown to improve seed germination, plant growth and yield, nutrient use efficiency, crop and product quality traits (pre- and post-harvest), as well as tolerance to abiotic stresses. Although horticulture production relies on synthetic fertilisers to maintain and improve production, the use of plant-derived biostimulants such as moringa leaf extracts may be an option to reduce quantities needed and thus contribute in achieving global food security sustainably.

An Approach of the Madeira Wine Chemistry

Madeira wine is a fortified Portuguese wine, which has a crucial impact on the Madeira Island economy. The particular properties of Madeira wine result from the unique and specific winemaking and ageing processes that promote the occurrence of chemical reactions among acids, sugars, alcohols, and polyphenols, which are important to the extraordinary quality of the wine. These chemical reactions contribute to the appearance of novel compounds and/or the transformation of others, consequently promoting changes in qualitative and quantitative volatile and non-volatile composition. The current review comprises an overview of Madeira wines related to volatile (e.g., terpenes, norisoprenoids, alcohols, esters, fatty acids) and non-volatile composition (e.g., polyphenols, organic acids, amino acids, biogenic amines, and metals). Moreover, types of aroma compounds, the contribution of volatile organic compounds (VOCs) to the overall Madeira wine aroma, the change of their content during the ageing process, as well as the establishment of the potential ageing markers will also be reviewed. The viability of several analytical methods (e.g., gas chromatography-mass spectrometry (GC-MS), two-dimensional gas chromatography and time-of-flight mass spectrometry (GC×GC-ToFMS)) combined with chemometrics tools (e.g., partial least squares regression (PLS-R), partial least squares discriminant analysis (PLS-DA) was investigated to establish potential ageing markers to guarantee the Madeira wine authenticity. Acetals, furanic compounds, and lactones are the chemical families most commonly related with the ageing process.

Evaluation of Aroma Compounds in the Process of Wine Ageing with Oak Chips

Many modern alcoholic beverages are subjected to ageing processes during which compounds extracted from wood contribute decisively to the overall beverage character. Wines represent a perfect example of beverage in which ageing is a crucial technological manufacturing step. During winemaking, producers accelerate chemical changes in wine composition by traditional and alternative methods, such as the use of oak wood barrels and/or oak wood chips. Our research aimed to investigate the overall volatile composition and sensory quality of red wines aged for two timeframes, namely, 1.5 and 3 months, and with two technological variants, i.e., American and French oak wood chips. Red grapes from the Fetească neagră (Vitis vinifera) variety were harvested from a vineyard in the North-East region of Romania. Stir bar sorptive extraction and gas chromatography coupled with mass spectrometry (SBSE-GC-MS) was used to extract minor aromas present in wine samples. The results showed clear differences between wines treated with American and French oak chips. Furthermore, ageing for 3 months increased the concentration of cis-whiskey lactone and guaiacol in American oak-treated wine samples. For wines aged with French oak chips, we observed higher concentrations of furfural, 5-methylfurfural, 4-vinylguaiacol, and trans-whiskey lactone. The increased presence of chemical compounds in wine aged with French oak chips generated prominent smoky, licorice, and toasty aromas, whereas in wines aged with American oak chips, notes of vanilla, toasty, and cacao aromas were noticed. Moreover, red wines aged with American and French oak chips were discriminated by chemometric analysis, which confirmed the evolution of aroma compounds.

Evaluation of Volatile Metabolites Emitted In-Vivo from Cold-Hardy Grapes during Ripening Using SPME and GC-MS: A Proof-of-Concept

In this research, we propose a novel concept for a non-destructive evaluation of volatiles emitted from ripening grapes using solid-phase microextraction (SPME). This concept is novel to both the traditional vinifera grapes and the cold-hardy cultivars. Our sample models are cold-hardy varieties in the upper Midwest for which many of the basic multiyear grape flavor and wine style data is needed. Non-destructive sampling included a use of polyvinyl fluoride (PVF) chambers temporarily enclosing and concentrating volatiles emitted by a whole cluster of grapes on a vine and a modified 2 mL glass vial for a vacuum-assisted sampling of volatiles from a single grape berry. We used SPME for either sampling in the field or headspace of crushed grapes in the lab and followed with analyses on gas chromatography-mass spectrometry (GC-MS). We have shown that it is feasible to detect volatile organic compounds (VOCs) emitted in-vivo from single grape berries (39 compounds) and whole clusters (44 compounds). Over 110 VOCs were released to headspace from crushed berries. Spatial (vineyard location) and temporal variations in VOC profiles were observed for all four cultivars. However, these changes were not consistent by growing season, by location, within cultivars, or by ripening stage when analyzed by multivariate analyses such as principal component analysis (PCA) and hierarchical cluster analyses (HCA). Research into aroma compounds present in cold-hardy cultivars is essential to the continued growth of the wine industry in cold climates and diversification of agriculture in the upper Midwestern area of the U.S.

Effect of a grapevine-shoot waste extract on red wine aromatic properties

BACKGROUND

The use of a grapevine-shoot extract (VIN) is being studied as an alternative to sulfur dioxide (SO₂ ). VIN stabilizes anthocyanins and preserves polyphenolic compounds, and thus improves chromatic wine properties. In this study, selected aroma compounds (esters, C₁₃ -norisoprenoids, oxidation and vine-shoot-related compounds), sensory analysis and the olfactometric profile were determined in the wines treated with VIN at two concentrations.

RESULTS

Treatment with VIN hardly modified the content of esters and oxidation-related compounds in the wines. However, the high β-damascenone and isoeugenol contents and the increase in astringency at tasting in VIN wines were noteworthy, as were some odorant zones. All these were established as VIN markers after the chemometric data analysis.

CONCLUSION

These data revealed that only the lowest dose tested may be recommended as a suitable alternative to SO₂ . Although some aromatic properties of these wines may change, these changes are not considered to affect the quality of the wines negatively. These results are useful for wineries, which face having to discover the aroma-related processes in the challenge of producing SO₂ -free wines without detriment to their sensory properties. © 2018 Society of Chemical Industry.

Effect of sodium sulfite, tartaric acid, tannin, and glucose on rheological properties, release of aroma compounds, and color characteristics of red wine

In this study, we evaluated the effect of addition of non-volatile compounds (sodium sulfite, tartaric acid, tannin, and glucose) on the rheological properties, release of aroma compounds, and color of the red wine. While determining the rheological properties of the supplemented samples, non-Newtonian fluidic and shear-thinning behavior of samples was noticed. The viscosity of these samples was found in negative correlation with the dose of addition of various non-volatile substances. The aroma profile of red wine after additions showed the change in the release of the nine key aroma compounds. Among them ethyl hexanoate, phenylethyl alcohol, octanoic acid, diethyl succinate, and ethyl octanoate were profoundly increased. Further, the color of red wines was improved in the presence of tartaric acid and tannin. Overall, supplementation of various substances during storage period of three different wines could enormously affect the sensory characteristics in a dose dependent manner.

The Microvine, a plant model to study the effect of vine-shoot extract on the accumulation of glycosylated aroma precursors in grapes

BACKGROUND

The Microvine plant model displays unique reproductive organ behavior and is suitable for grapevine fruit physiological studies, allowing one to undertake studies up to five times more rapidly than the current situation with grapevines. Recently, vine-shoot aqueous extracts, which have an interesting phenolic and aroma composition, have been proposed as viticultural biostimulants, since their post-veraison foliar application to grapevines impacts the wine aroma profile. Using Microvines, the aim of this study was to determine the effect of vine-shoot extract foliar application on 21 stages of grape development. The application was carried out from BBCH 53 (inflorescences clearly visible) to BBCH 85 (softening of berries) to reveal stage-specific responses of the accumulation of glycosylated aroma precursors at BBCH 89 (berries ripe for harvest), the phenological stage selected to study the treatment effect.

RESULTS

Microvine use made it possible to carry out 15 sampling time points during 86 days of the experiment, which were established by the cumulative degree days (CDD) parameter. The results confirmed that vine-shoot extract treatment had a positive impact on total glycosylated compounds, especially aglycones such as alcohols, terpenes and C₁₃ -norisoprenoids, with a higher effect when the treatment was applied during ripening.

CONCLUSION

Extrapolation of the results to grapevines suggests that vine-shoot extract treatment could modulate the synthesis of grape glycosylated aroma precursors. © 2017 Society of Chemical Industry.

Application of a stir bar sorptive extraction method for the determination of volatile compounds in different grape varieties

BACKGROUND

Stir bar sorptive extraction (SBSE) has been employed for the analysis of aroma compounds directly from Spanish and Italian grape extracts. The extraction conditions have been optimized using a statistical approach, obtaining results that improve the current state of the art.

RESULTS

The proposed analytical conditions were: sample volume 40 mL, extraction time 80 min, 25% (w/v) NaCl and stirring speed 750 rpm using 20 mm × 0.5 mm stir bars. Performance characteristics of the SBSE procedure were further studied and showed correlation coefficients, detection and quantification limits, linear ranges, recoveries and precision values adequate for analysing these compounds in grapes. Twenty-four grape varieties (aromatic and non-aromatic) were analysed. Statistically significant differences (P < 0.05) according to geographical origin were found, being derived mainly from the terpenoid content. By principal component analysis it was possible to note that the terpenoids were more effective in the separation of the non-aromatic samples, showing negative and positive scores for Italian and Spanish grapes, respectively.

CONCLUSION

For non-aromatic grape varieties, the factor 'geographic location' was the most significant, thus corroborating the high influence of this parameter on the volatile composition of grapes and therefore on the genuineness of wines. © 2016 Society of Chemical Industry.

Moscatel vine-shoot extracts as a grapevine biostimulant to enhance wine quality

Non-aromatic vine-shoot extracts (Airén) has been recently proposed as "viticultural biostimulants" when applied to grapevine. In this paper, the application of extracts from non-toasted (MVS) and toasted (MVS_Toasted) vine-shoots from the well-known aromatic variety such Moscatel were applied on Airén grapevine leaves, observing an increased for grape yield and wines with a lower alcohol degree. All wines at the end of the alcoholic fermentation were characterized by their fruity and floral descriptors, especially MVS wines; and 4 months later, MSV and MVS_Toasted wines surprised by their higher spicy notes, which correspond with the highest OAVs values for compounds such as norisoprenoids (β-damascenone), vanillin derivatives (vanillin, acetovanillone) and volatile phenols (guaiacol, syringol), compared to control wine. Wine phenolic composition was affected positively over all by MVS in case of phenolic acids. These results confirm that Moscatel vine-shoot extracts foliar application into Airén non-aromatic grapevines produce an interesting enhance on wine quality.

Accumulation of guaiacol glycoconjugates in fruit, leaves and shoots of Vitis vinifera cv. Monastrell following foliar applications of guaiacol or oak extract to grapevines

Previous studies have shown that volatile compounds present within a vineyard during the growing season can be absorbed by grapevines, assimilated within grapes, and then released during fermentation to influence the final aroma of wine. For example, the accumulation of volatile phenols in glycoconjugate forms following grapevine exposure to bushfire smoke, and their subsequent release during winemaking. This study investigated the accumulation of guaiacol glycoconjugates in the fruit, shoots and leaves of Monastrell grapevines following foliar applications (at veraison) of either an aqueous solution of guaiacol or an aqueous oak extract. Fruit, shoot and leaf samples were then collected at 3 time points between veraison and maturity, and analysed by gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry, to quantify guaiacol and its glycoconjugates, respectively. Guaiacol glycoconjugates were observed in fruit and leaves in particular, demonstrating glycosylation occurred after grapevine treatment; however, different glycoconjugate profiles were apparent.

A gas-diffusion microfluidic paper-based analytical device (μPAD) coupled with portable surface-enhanced Raman scattering (SERS): facile determination of sulphite in wines

A novel facile method for on-site determination of sulphite in wine using a gas-diffusion microfluidic paper-based analytical device (μPAD) combined with surface-enhanced Raman spectroscopy (SERS) was explored.

Accumulation of Glycoconjugates of 3-Methyl-4-hydroxyoctanoic Acid in Fruits, Leaves, and Shoots of Vitis vinifera cv. Monastrell following Foliar Applications of Oak Extract or Oak Lactone

Grapevines are capable of absorbing volatile compounds present in the vineyard during the growing season, and in some cases, volatiles have been found to accumulate in fruits or leaves in glycoconjugate forms, that is, with one or more sugar moieties attached. The presence of oak lactone in wine is usually attributable to oak maturation, but oak lactone has been detected in wines made with fruit from grapevines treated with oak extract or oak lactone. This study investigated the accumulation of glycoconjugates of 3-methyl-4-hydroxyoctanoic acid (i.e., the ring-opened form of oak lactone) in the fruits, leaves, and shoots of Monastrell grapevines following foliar application of either oak extract or oak lactone at approximately 7 days postveraison. Fruits, leaves, and shoots were collected at three different time points, including at maturity. The oak lactone content of fruit was determined by gas chromatography-mass spectrometry, with declining concentrations observed in fruit from grapevines treated with oak lactone with ripening. The concentrations of a β-d-glucopyranoside of 3-methyl-4-hydroxyoctanoic acid in fruits, leaves, and shoots was determined by liquid chromatography-tandem mass spectrometry, with the highest oak lactone glucoside levels observed in leaves of grapevines treated with oak lactone. A glucose-glucose disaccharide was also tentatively identified. These results demonstrate both ring-opening and glycosylation of oak lactone occurred after experimental treatments were imposed.

Vine-shoot waste aqueous extracts for re-use in agriculture obtained by different extraction techniques: phenolic, volatile, and mineral compounds

Vine-shoots are an important waste in all viticulture areas that should be re-used with innovative applications. The aim of this work was to produce Airén waste vine-shoot aqueous extracts by four solid-liquid extraction techniques such as conventional solid-liquid extraction (CSLE), solid-liquid dynamic extraction (SLDE-Naviglio), microwave extraction (ME), and pressurized solvent extraction (PSE). Their chemical composition was studied in terms of phenolic, volatile, and mineral compounds. The highest concentrated extracts corresponded to CSLE and SLDE-Naviglio, independent of the conditions tested. The CSLE extracts had the highest flavanols, phenolic acids, and stilbenes contents. The volatile composition, quantified for first time in this work, shows that furanic compounds were the most abundant. All extracts showed an interesting mineral content, which may be assimilated by plants. These results show the agricultural potential of Airén vine-shoot waste aqueous extracts to be used as grape biostimulants and/or foliar fertilizer.