Mass spectrometry in the study of wood compounds released in the barrel-aged wine and spirits.

Aging of wines and spirits in wooden barrels is an industrial process used to stabilize the color, to improve the limpidity and to enrich the sensorial characteristics of the products. In red wines, the oxygen that permeates through the wood staves promotes the oxidization of polyphenols and the formation of new pigments with consequent stabilization of the wine color. Barrel aging of spirits, such as brandy, whisky, rum, and grappa is finalized to enrich their aroma and improve their sensorial characteristics by the contribute of the compounds released by the wood. Oak is the wood type mostly used in making barrels; however, an increasing interest in the use of chestnut, cherry, acacia, and in less extent, ash and mulberry, has been observed in the recent years. Gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry are the main techniques used to characterize respectively the volatile and polar metabolites released by the wood barrels in the products. In this article are reported the recent advancements in this field.

Metabolomic profiling of different clones of vitis vinifera L. cv. "Glera" and "Glera lunga" grapes by high-resolution mass spectrometry.

INTRODUCTION: Prosecco wine production has been strongly extended in the last decade and several new clones have been introduced. "Glera" (minimum 85%) and "Glera lunga" are grape varieties of great economic impact used to produce Prosecco wines. Study of grape berry secondary metabolites is effective in the classification of vine varieties and clones. High-resolution mass spectrometry provides complete panorama of these metabolites in single analysis and coupling to statistical multivariate analysis is successfully applied in vine chemotaxonomy. OBJECTIVES: update and deepen the knowledge on the "Glera" and "Glera lunga" berry grapes chemotaxonomy and investigate some of the most produced and marketed clones by using the modern analytical and statistical tools. METHODS: five clones of "Glera" and two of "Glera lunga" grown in the same vineyard with same agronomical practices were studied for three vintages. Grape berry metabolomics was characterized by UHPLC/QTOF and multivariate statistical analysis was performed on the signals of main metabolites of oenological interest. RESULTS: "Glera" and "Glera lunga" showed different monoterpene profiles ("Glera" is richer in glycosidic linalool and nerol) and differences in polyphenols (catechin, epicatechin and procyanidins, trans-feruloyltartaric acid, E-ε-viniferin, isorhamnetin-glucoside, quercetin galactoside). Vintage affected the accumulation of these metabolites in berry. No statistical differentiation among the clones of each variety, was found. CONCLUSIONS: Coupling HRMS metabolomics/statistical multivariate analysis enabled clear differentiation between the two varieties. The examined clones of same variety showed similar metabolomic profiles and enological characteristics, but vineyard planting using different clones can result in more consistent final wines reducing the vintage variability linked to genotype × environment interaction.

Coupling between high-resolution mass spectrometry and focalized data-analysis methods provides the identification of new putative glycosidic non-anthocyanic flavonoids in grape.

INTRODUCTION: The biochemical diversity of flavonoids is based on glycosylation, methylation, acylation, and many other modifications of the flavonoid backbone. Liquid chromatography coupled to high-resolution mass spectrometry demonstrated to be a powerful approach to gain new insights into the flavonoid composition of many plant species, including grapes. OBJECTIVES: Among different metabolomic approaches, suspect screening analysis relies on the construction of a specific database and on ultra-high performance liquid chromatography/quadrupole time-of-flight (UHPLC/QTOF) analysis to find new compounds of oenological interest. METHODS: A homemade database containing mass data information retrieved from the literature specific for plant flavonoid derivatives (GrapeFlavMet) was constructed. Tandem mass spectrometry analysis of V. vinifera and hybrid grape extracts was performed, and MS/MS fragmentation allowed to assign the putative flavonoid chemical structure to various identification levels, as established by the Metabolomics Standard Initiative. RESULTS: By this approach, putative flavonoid derivatives with different glycosylation and acylation patterns were identified. They include three pentoside derivatives of tetrahydroxy-flavone, tetrahydroxy-flavanone and myricetin isomers, a putative dihydrorhamnetin hexoside derivative, three cinchonain isomers (phenylpropanoid-substituted flavan-3-ols with antidiabetic properties), and two syringetin isomer derivatives (acetyl- and p-coumaroyl-hexoside). Two acetyl-hexoside derivatives of dihydrorhamnetin and pentahydroxy-methoxy-flavanone, and three derivatives of tetrahydroxy-dimethoxy-flavanone (acetyl, p-coumaroyl, and caffeoyl-hexoside) were tentatively annotated. CONCLUSIONS: Most of the compounds were identified in grape for the first time, while two putative syringetin derivatives previously proposed in the literature were confirmed. These findings deepen the current knowledge on grape flavonoids, suggesting more connections at the biochemical level.

First investigation on polyphenols and glycosidic aroma precursors in a spontaneous colour mutant of 'Glera', the principal grape variety of Prosecco sparkling wine.

BACKGROUND: Somatic mutations in Vitis spp. are relatively frequent and can generate new agronomically interesting phenotypes. We report the discovery, genetic and chemical characterization of 'Glera rosa', a mutant for the berry skin colour of 'Glera', the main white cultivar used to produce Prosecco wine. RESULTS: We ascertained the relationship between the skin colour of 'Glera rosa' and the polymorphisms in the Myb-gene transcription factors involved in polyphenol biosynthesis. We established that VvMybA1 was homozygous (VvMybA1a/VvMybA1a) in 'Glera' but heterozygous (VvmybA1a/VvmybA1b) in the 'Glera rosa' mutant. We verified that the VvMybA1a non-functional allele contained Grapevine Retrotransposon 1 (Gret1), while in the VvmybA1b allele Gret1 was missing, and the gene function was partially restored. The effects of mutation on 'Glera rosa' grape metabolites were studied by high-resolution mass spectrometry and gas chromatography/mass spectrometry analysis. Fifteen anthocyanins and five unique flavonols were found in the 'Glera rosa' mutant. The mutation also increased the contents of trans-resveratrol and its derivatives (i.e., piceatannol, E-ε-viniferin, cis- and trans-piceid) and of some flavonols in grape. Finally, the mutation did not significantly affect the typical aroma precursors of Glera grape such as glycosidic monoterpenes, norisoprenoids and benzenoids. CONCLUSION: 'Glera rosa' could be an interesting genetic source for the wine industry to produce Prosecco DOC rosé typology (made by adding up to 15% of 'Pinot Noir'), which was introduced to the market in 2020 with a worldwide massive success. © 2022 Society of Chemical Industry.

Influence of Non-Saccharomyces on Wine Chemistry: A Focus on Aroma-Related Compounds.

Wine fermentation processes are driven by complex microbial systems, which comprise eukaryotic and prokaryotic microorganisms that participate in several biochemical interactions with the must and wine chemicals and modulate the organoleptic properties of wine. Among these, yeasts play a fundamental role, since they carry out the alcoholic fermentation (AF), converting sugars to ethanol and CO2 together with a wide range of volatile organic compounds. The contribution of Saccharomyces cerevisiae, the reference organism associated with AF, has been extensively studied. However, in the last decade, selected non-Saccharomyces strains received considerable commercial and oenological interest due to their specific pro-technological aptitudes and the positive influence on sensory quality. This review aims to highlight the inter-specific variability within the heterogeneous class of non-Saccharomyces in terms of synthesis and release of volatile organic compounds during controlled AF in wine. In particular, we reported findings on the presence of model non-Saccharomyces organisms, including Torulaspora delbrueckii, Hanseniaspora spp,Lachancea thermotolerans, Metschnikowia pulcherrima, Pichia spp. and Candida zemplinina, in combination with S. cerevisiae. The evidence is discussed from both basic and applicative scientific perspective. In particular, the oenological significance in different kind of wines has been underlined.

Effects of Traditional and Modern Post-Harvest Withering Processes on the Composition of the Vitis v. Corvina Grape and the Sensory Profile of Amarone Wines.

In the Valpolicella area (Verona, Italy) Vitis vinifera cv. Corvina is the main grape variety used to produce Amarone wine. Before starting the winemaking process, the Corvina grapes are stored in a withering (i.e., dehydrating) warehouse until about 30% of the berry weight is lost (WL). This practice is performed to concentrate the metabolites in the berry and enrich the Amarone wine in aroma and antioxidant compounds. In compliance with the guidelines and strict Amarone protocol set by the Consorzio of Amarone Valpolicella, withering must be carried out by setting the grapes in a suitable environment, either under controlled relative air humidity (RH) conditions and wind speed (WS)-no temperature modification is to be applied-or, following the traditional methods, in non-controlled environmental conditions. In general, the two processes have different dehydration kinetics due to the different conditions in terms of temperature, RH, and WS, which affect the accumulation of sugars and organic acids and the biosynthesis of secondary metabolites such as stilbenes and glycoside aroma precursors. For this study, the two grape-withering processes were carried out under controlled (C) and non-controlled (NC) conditions, and the final compositions of the Corvina dried grapes were compared also to evaluate the effects on the organoleptic characteristics of Amarone wine. The findings highlighted differences between the two processes mainly in terms of the secondary metabolites of the dried grapes, which affect the organoleptic characteristics of Amarone wine. Indeed, by the sensory evaluation, wines produced by adopting the NC process were found more harmonious, elegant, and balanced. Finally, we can state how using a traditional system, grapes were characterised by higher levels of VOCs (volatile compounds), whilst wines had a higher and appreciable complexity and finesse.

Flavonoid and Non-Flavonoid Compounds of Autumn Royal and Egnatia Grape Skin Extracts Affect Membrane PUFA's Profile and Cell Morphology in Human Colon Cancer Cell Lines.

Grapes contain many flavonoid and non-flavonoid compounds with anticancer effects. In this work we fully characterized the polyphenolic profile of two grape skin extracts (GSEs), Autumn Royal and Egnatia, and assessed their effects on Polyunsaturated Fatty Acid (PUFA) membrane levels of Caco2 and SW480 human colon cancer cell lines. Gene expression of 15-lipoxygenase-1 (15-LOX-1), and peroxisome proliferator-activated receptor gamma (PPAR-γ), as well as cell morphology, were evaluated. The polyphenolic composition was analyzed by Ultra-High-Performance Liquid Chromatography/Quadrupole-Time of Flight mass spectrometry (UHPLC/QTOF) analysis. PUFA levels were evaluated by gas chromatography, and gene expression levels of 15-LOX-1 and PPAR-γ were analyzed by real-time Polymerase Chain Reaction (PCR). Morphological cell changes caused by GSEs were identified by field emission scanning electron microscope (FE-SEM) and photomicrograph examination. We detected a different profile of flavonoid and non-flavonoid compounds in Autumn Royal and Egnatia GSEs. Cultured cells showed an increase of total PUFA levels mainly after treatment with Autumn Royal grape, and were richer in flavonoids when compared with the Egnatia variety. Both GSEs were able to affect 15-LOX-1 and PPAR-γ gene expression and cell morphology. Our results highlighted a new antitumor mechanism of GSEs that involves membrane PUFAs and their downstream pathways.

Thiol precursors in Vitis mould-tolerant hybrid varieties.

BACKGROUND: Over recent years, a new wave of disease-tolerant to mildew varieties has flooded the viticulture sector, for reasons of human safety and economic expediency. These hybrid grape cultivars are selected mainly on the basis of their intrinsic capability to counter the attack of the main fungal diseases that affect grape production, such as downy mildew and powdery mildew. However, their organoleptic and oenological characteristics have not yet been studied in depth for purposes of both juice and wine production, due to the high number of newly proposed germplasms and the lack of information about their adaptability to different environments. This work examines the thiol aroma precursors concentration in 64 red and white disease-tolerant hybrid varieties in the vine germplasm collections of Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria-Viticulture and Enology Research Center and Fondazione Edmund Mach, both from the north-east of Italy. RESULTS: All cultivars showed the presence of 3-mercaptohexan-1-ol (3MH) precursors, ranging from 4.4 to 1141 µg kg-1 for 3-S-glutathionyl hexan-1-ol (GSH-3MH), and from 0.3 to 136 µg kg-1 for 3-S-cysteinyl 3-hexan-1-ol. The concentration of GSH-3MH exceeded 600 µg kg-1 in eight varieties, with values comparable to those of the richest Vitis vinifera reported so far. On average, red grapes showed higher concentrations of 3MH precursors than white ones did. Only two hybrids had 4-mercapto-4-methylpentan-2-one (4MMP) precursors over the limit of quantification, albeit with a much higher concentration than those normally reported in Sauvignon Blanc. CONCLUSION: This is the first detailed survey of 3MH and 4MMP precursors carried out taking into account a considerable number of hybrid grape varieties. The results show that some of these varieties could be interesting for the production of tropical juices or tropical-aromatic wines and soft drinks, through the enzymatic liberation of thiol aromas, as well as for the production of aromatizing tannins to be used in the food industry. © 2020 Society of Chemical Industry.

High-resolution mass spectrometry metabolomics of grape chemical markers to reveal use of not-allowed varieties in the production of Amarone and Recioto wines.

INTRODUCTION: Grape varieties allowed to produce Amarone della Valpolicella and Recioto DOCG wines are strictly regulated by their disciplinary of production. These are Corvina Veronese and Corvinone grapes, to a lesser extent also Rondinella can be used. The use of other varieties, is not allowed. OBJECTIVES: To identify chemical markers suitable to reveal addition of two not allowed grape varieties to the Corvina/Corvinone blend, such as Primitivo or Negro Amaro. METHODS: The identification of the secondary metabolites of the four grape varieties was conducted by high-resolution mass spectrometry (HRMS) metabolomics. By using the signals of these metabolites the indexes able to identify the presence of Primitivo or Negro Amaro grapes in the Corvina/Corvinone 1:1 blend were calculated. RESULTS: Indexes of laricitrin (Lr), delphinidin (Dp), and petunidin (Pt) signals were effective to identify the use of 10% Primitivo, while α-terpineol pentosyl-hexoside and linalool pentosyl-hexoside reveal the presence of Negro Amaro in the grape blend. CONCLUSIONS: Varietal markers useful to detect the presence of Primitivo and Negro Amaro in the grape blend were identified by HRMS metabolomics, a method suitable to check the identity of grapes on arrival at the winery, as well as the fermenting musts. The effectiveness of the identified markers in the final wines have to be confirmed. Potentially, a similar approach can be used to reveal analogous frauds performed on other high-quality wines.

Effect of pre-bloom leaf removal on grape aroma composition and wine sensory profile of Semillon cultivar.

BACKGROUND: Early leaf removal at pre-bloom is an innovative viticultural practice for regulating yield components and improving grape quality. The effects of this technique on vine performance, grape composition and wine sensory profile of Semillon variety were assessed. RESULTS: Pre-bloom leaf removal enhanced canopy porosity, total soluble solids in musts and reduced cluster compactness. This practice had a strong effect on glycoside aroma precursors, in particular by increasing glycoside terpenols and norisoprenoids. Metabolites of linalool were the most responsive to leaf removal. Wine produced from defoliated vines was preferred in tasting trials for its more intense fruity notes and mouthfeel attributes. CONCLUSION: Pre-bloom leaf removal is a powerful technique for modifying canopy microclimate, vine yield, grape composition and wine quality. The increase of glycoside aroma compounds in treated grapes has potential positive effect in improving the sensory profile of the resulting wines. © 2017 Society of Chemical Industry.

Insights on the stilbenes in Raboso Piave grape (Vitis vinifera L.) as a consequence of postharvest vs on-vine dehydration.

BACKGROUND: Grape withering is a process used to produce reinforced wines and raisins. Dehydration is usually carried out postharvest by keeping ripe grapes in special warehouses in controlled conditions of temperature, relative humidity (RH) and air flow. Alternatively, grape clusters can be left on the vines after the canes have been pruned. In general, dehydration increases stilbenes in grape, but there are few studies on the effects of on-vine withering. The stilbene profiles of Raboso Piave grape during postharvest and on-vine dehydration were studied here. RESULTS: High-resolution mass spectrometry (MS) was used to identify 19 stilbenes, including resveratrol monomers, dimers (viniferins), oligomers and glucoside derivatives. The two dehydration methods generally had different effects on the above nutraceuticals in grape. The samples kept in warehouses revealed significant increases in Z-ω-viniferin, E-ϵ-viniferin, δ-viniferin and another resveratrol dimer which were not observed in the plants. Trans-Resveratrol increased significantly only in samples dehydrated in the warehouse at 21 °C and 60-70% RH. CONCLUSION: The findings increase knowledge of stilbene composition in grapes subjected to withering on-vine. The choice of dehydration method affects the contents of these nutraceuticals in the grape and consequently in wines. Reasonably, it could also affect other secondary metabolites important for wine quality. © 2017 Society of Chemical Industry.

Putative identification of new p-coumaroyl glycoside flavonoids in grape by ultra-high performance liquid chromatography/high-resolution mass spectrometry.

RATIONALE: Grape polyphenols are antioxidant compounds, markers in vine chemotaxonomy, and involved in color stabilization of red wines. Sugar acylation usually confers higher stability on glycoside derivatives and this effect is enhanced by an aromatic substituent such as p-coumaric acid. Until now, only p-coumaroyl anthocyanins have been found in grape. METHODS: A method of 'suspect screening analysis' by ultra-high-performance liquid chromatography/high-resolution mass spectrometry (UHPLC/QTOFMS) has recently been developed to study grape metabolomics. In the present study, this approach was used to identify new polyphenols in grape by accurate mass measurement, MS/MS fragmentation, and study of correlations between fragments observed and putative structures. RESULTS: Three putative p-coumaroyl flavonoids were identified in Raboso Piave grape extract: a dihydrokaempferide-3-O-p-coumaroylhexoside-like flavanone, isorhamnetin-3-O-p-coumaroylglucoside, and a chrysoeriol-p-coumaroylhexoside-like flavone. Accurate MS provided structural characterization of functional groups, and literature data indicates their probable position in the molecule. A fragmentation scheme is proposed for each compound. CONCLUSIONS: Compounds were identified by overlapping various analytical methods according to recommendations in the MS-based metabolomics literature. Stereochemistry and the definitive position of substituents in the molecule can only be confirmed by isolation and characterization or synthesis of each compound. These findings suggest addressing research of acylated polyphenol glycosides to other grape varieties.

Characterization of Non-Anthocyanic Flavonoids in Some Hybrid Red Grape Extracts Potentially Interesting for Industrial Uses.

Previous studies showed that hybrid grapes often have qualitatively and quantitatively higher polyphenolic contents than the common V. vinifera grape varieties. In general, these compounds are studied for grape chemotaxonomy and for nutraceutical purposes due to their relevant antioxidant activity. Non-anthocyanic flavonoid composition of five red hybrid grape varieties produced by crossing of V. vinifera, V. aestivalis, V. cinerea, V. berlandieri, V. labrusca, V. lincecumii, and V. rupestris were studied by liquid chromatography/high-resolution mass spectrometry. Thirty-one compounds were identified, including methylnaringenin, a tetrahydroxy-dimethoxyflavanone-hexoside, two flavonols (quercetin and a pentahydroxyflavone isomer), 20 glycoside flavonols (four quercetin, two myricetin, two kaempferol, three isorhamnetin, one laricitrin, two syringetin, one kaempferide and two dihydroflavonol derivatives; myricetin-glucoside-glucuronide; myricetin-diglucoside; syringetin-dihexoside), three flavan-3-ols (-)-epicatechin, (+)-catechin, (-)-epicatechin gallate) and four proantocyanidins (procyanidin B1, procyanidin B2, procyanidin B3 or B4/B5, procyanidin T2 or T3/T4/C1). Seibel 19881, Seyve Villard 12-347 and Seyve Villard 29-399 were particularly rich in polyphenols. These findings emphasize that these grapes are especially interesting for the production of antioxidant extracts for nutraceutical and pharmaceutical uses.

Applications of solid-phase microextraction and gas chromatography/mass spectrometry (SPME-GC/MS) in the study of grape and wine volatile compounds.

Volatile compounds are responsible for the wine "bouquet", which is perceived by sniffing the headspace of a glass, and of the aroma component (palate-aroma) of the overall flavor, which is perceived on drinking. Grape aroma compounds are transferred to the wine and undergo minimal alteration during fermentation (e.g., monoterpenes and methoxypyrazines); others are precursors of aroma compounds which form in winemaking and during wine aging (e.g., glycosidically-bound volatile compounds and C13-norisoprenoids). Headspace solid phase microextraction (HS-SPME) is a fast and simple technique which was developed for analysis of volatile compounds. This review describes some SPME methods coupled with gas chromatography/mass spectrometry (GC/MS) used to study the grape and wine volatiles.

Study of Glycosidically Bound Volatile Precursors as Variety Markers to Reveal Not-Allowed Practices in White Wines Winemaking.

Liquid chromatography/high-resolution mass spectrometry (LC/HRMS) can provide identification of grape metabolites which are variety markers. White grapes are poorer in polyphenolics, and the main secondary metabolites which contribute the sensorial characteristics of wines are the glycosidically bound volatile precursors and their aglycones. The profiles of three white grape juices (Pinot grigio, Garganega, and Trebbiano) were characterized by LC/HRMS, and 70 signals of putative glycosidic terpenols, norisoprenoids, and benzenoids were identified. Four signals found only in Pinot grigio corresponded to a norisoprenoid hexose-hexose, 3-oxo-α-ionol (or 3-hydroxy-ß-damascone) rhamnosyl-hexoside, monoterpene-diol hexosyl-pentosyl-hexoside, and hexose-norisoprenoid; three signals were found only in Garganega (putative isopropyl alcohol pentosyl-hexoside, phenylethanol rhamnosyl-hexoside, and norisoprenoid hexose-hexose isomers), and a monoterpenol pentosyl-hexoside isomer only in Trebbiano. These variety markers were then investigated in juice blends of the three varieties. This approach can be used to develop control methods to reveal not-allowed grape varieties and practices in white wines winemaking.

Monoglucoside versus Diglucoside Anthocyanin Evolution of Red Wine Produced Using a Fungus-Resistant Grape Cultivar (Downy Mildew and Powdery Mildew) under Oxidative Conditions.

The need to reduce the use of pesticides in viticulture is increasing the interest in wines produced using fungal-resistant grapevine varieties, which are characterized by relevant contents of both monoglucoside and diglucoside anthocyanins. Aging in wooden barrels induces oxygen permeation into wine, but little is known about diglucoside anthocyanin evolution. Cabernet cortis wine was subjected to addition of oxygen and oak chips, and the anthocyanin changes were followed for 1 month. Decreases of 90% total monoglucosides, 80% acylated monoglucosides, 65% diglucosides, and 90% acylated diglucosides were observed. Monoglucosides formed pyranoanthocyanins, and the lower steric hindrance favored their polymerization with flavanols. Instead, the decrease in diglucosides was correlated to the number of hydroxyl groups of ring B, indicating the predominant oxidation of aglycones. However, three flavonol-anthocyanin-diglucoside derivatives named (epi)catechin-ethyl-Mv-dihexoside, (epi)catechin-ethyl-Pn-dihexoside, and (epi)catechin-Mv-dihexoside A-type were identified in wine for the first time. These research findings are useful for tuning suitable oenological practices to stabilize the color of these wines (type of barrel, aging times, oxygenation practices) and lower the malvin content, which currently is recommended by the OIV at a maximum of 15 mg/L and is a critical issue for their commercialization.

Advanced knowledge of three important classes of grape phenolics: anthocyanins, stilbenes and flavonols.

Grape is qualitatively and quantitatively very rich in polyphenols. In particular, anthocyanins, flavonols and stilbene derivatives play very important roles in plant metabolism, thanks to their peculiar characteristics. Anthocyanins are responsible for the color of red grapes and wines and confer organoleptic characteristics on the wine. They are used for chemotaxonomic studies and to evaluate the polyphenolic ripening stage of grape. They are natural colorants, have antioxidant, antimicrobial and anticarcinogenic activity, exert protective effects on the human cardiovascular system, and are used in the food and pharmaceutical industries. Stilbenes are vine phytoalexins present in grape berries and associated with the beneficial effects of drinking wine. The principal stilbene, resveratrol, is characterized by anticancer, antioxidant, anti-inflammatory and cardioprotective activity. Resveratrol dimers and oligomers also occur in grape, and are synthetized by the vine as active defenses against exogenous attack, or produced by extracellular enzymes released from pathogens in an attempt to eliminate undesirable toxic compounds. Flavonols are a ubiquitous class of flavonoids with photo-protection and copigmentation (together with anthocyanins) functions. The lack of expression of the enzyme flavonoid 3',5'-hydroxylase in white grapes restricts the presence of these compounds to quercetin, kaempferol and isorhamnetin derivatives, whereas red grapes usually also contain myricetin, laricitrin and syringetin derivatives. In the last ten years, the technological development of analytical instrumentation, particularly mass spectrometry, has led to great improvements and further knowledge of the chemistry of these compounds. In this review, the biosynthesis and biological role of these grape polyphenols are briefly introduced, together with the latest knowledge of their chemistry.

LC-MS methods combination for identification and quantification of trans-sinapoylquinic acid regioisomers in green coffee.

The present study aims to both identify and quantify trans-sinapoylquinic acid (SiQA) regioisomers in green coffee by combined UHPLC-ESI-QqTOF-MS/MS and UHPLC-ESI-QqQ-MS/MS methods. Among the various mono-acyl chlorogenic acids found in green coffee, SiQA regioisomers are the least studied despite having been indicated as unique phytochemical markers of Coffea canephora (known as Robusta). The lack of commercially available authentic standards has been bypassed by resorting to the advantages offered by high-resolution LC-MS as far as the identification is concerned. SiQA regioisomers have been identified in several samples of Robusta and Coffea arabica (known as Arabica) commercial lots from different geographical origin and, for the first time, in different samples of coffee wild species (Coffea liberica and Coffea pseudozanguebariae). Quantification (total SiQA ranging from 3 to 5 mg/100 g) let to reconsider these chlorogenic acids as unique phytochemical markers of Robusta being present in the same quantity and distribution in C. liberica as well. Gardeniae Fructus samples (fruits of Gardenia jasminoides) have additionally been characterized as this matrix is recognized as one of the few naturally occurring SiQA sources. The SiQA regioisomer content (total SiQA about 80 mg/100 mg) fully supports the proposal to use this matrix as a surrogate standard for further studies.

The pivotal role of high-resolution mass spectrometry in the study of grape glycosidic volatile precursors for the selection of grapevines resistant to mildews.

A breeding program to produce new grape varieties tolerant to main vine fungal pathogens (Plasmopara viticola and Erysiphe necator) is carrying out by crossing Vitis vinifera cv. "Glera" with resistant genotypes such as "Solaris," "Bronner," and "Kunleany." Firstly, resistance gene-based markers analyses allowed the identification of five genotypes, which have inherited the resistance loci against mildews. To select those that also inherited the phenotype as close as possible to 'Glera' suitable to be introduced in the Prosecco wine production protocols, the grape glycosidic derivatives were studied by UHPLC/QTOF mass spectrometry. Targeted identification of the metabolites was performed using a database expressly constructed by including the glycosidic volatile precursors previously identified in grape and wine. A total of 77 glycosidic derivatives including many aroma precursors and some variety markers, were identified. Original resistant genotypes had distinct metabolomic profiles and different to 'Glera', while the crossings showed varying similarity degrees to V. vinifera parent. Findings demonstrated the Glera × Bronner and Glera × Solaris crossings are more suitable to produce high-sustainable Prosecco wines. Coupling of glycosidic volatile precursors profiling to multivariate statistical analysis was effective for phenotypic characterization of grapes and to evaluate their enological potential.

Corrigendum: Correlation between antioxidant and anticancer activity and phenolic profile of new Apulian table grape genotypes (V. Vinifera L.).

[This corrects the article DOI: 10.3389/fpls.2022.1064023.].