Targeted metabolomics of anthocyanin derivatives during prolonged wine aging: Evolution, color contribution and aging prediction

Metabolomics analysis based on UHPLC-QqQ-MS/MS to discriminate grapes and wines from different geographical origins and climatological characteristics

With the proliferation of the consumer's awareness of wine provenance, wines with unique origin characteristics are increasingly in demand. This study aimed to investigate the influence of geographical origins and climatological characteristics on grapes and wines. A total of 94 anthocyanins and 78 non-anthocyanin phenolic compounds in grapes and wines from five Chinese viticultural vineyards (CJ, WH, QTX, WW, and XY) were identified by UHPLC-QqQ-MS/MS. Chemometric methods PCA and OPLS-DA were established to select candidate differential metabolites, including flavonols, stilbenes, hydroxycinnamic acids, peonidin derivatives, and malvidin derivatives. CCA showed that malvidin-3-O-glucoside had a positive correlation with mean temperature, and quercetin-3-O-glucoside had a negative correlation with precipitation. In addition, enrichment analysis elucidated that the metabolic diversity in different origins mainly occurred in flavonoid biosynthesis. This study would provide some new insights to understand the effect of geographical origins and climatological characteristics on phenolic compounds in grapes and wines.

GC/MS-based untargeted metabolomics reveals the differential metabolites for discriminating vintage of Chenxiang-type baijiu

The "outstanding and unique aged aroma" of Chinese Chenxiang-type baijiu (CXB)-Daoguang 25 (DG25) mainly originates from a "extraordinary storage technology" of Mujiuhai (a wooden container), so it is mysterious and interesting. In this study, an untargeted GC/MS-based metabolomics was used to reveals the volatile differential metabolites for discriminating six different vintages of DG25 combing with chemometrics. A total of 100 volatile metabolites (including unknowns) were extracted and identified, including esters (41%), alcohols (10%) and acids (7%) so on. Finally, 33 differential metabolites were identified as aging-markers. Among them, 25 aging-markers showed a downtrend, including 17 esters such as ethyl acetate, ethyl hexanoate and ethyl palmitate so on. Moreover, it was interesting and to further study that furans showed a significant downtrend. Statistically speaking, ethyl benzoate played an important role in discriminating vintage of 1Y and 3Y, and the other 24 differential metabolites with downtrend discriminating the unstored (0Y-aged) DG25. Eight differential metabolites, such as ethyl octanoate, benzaldehyde, 3-methylbutanol and 1,1-diethoxyaccetal so on increased during aging of DG25, and they played a statistical role in discriminating the 5Y-, 10Y- and 20Y-aged DG25. This study provides a theoretical basis way for the formation mechanism of aging aroma for CXB.

Research of 2D-COS with metabolomics modifications through deep learning for traceability of wine

To tackle the difficulty of extracting features from one-dimensional spectral signals using traditional spectral analysis, a metabolomics analysis method is proposed to locate two-dimensional correlated spectral feature bands and combine it with deep learning classification for wine origin traceability. Metabolomics analysis was performed on 180 wine samples from 6 different wine regions using UPLC-Q-TOF-MS. Indole, Sulfacetamide, and caffeine were selected as the main differential components. By analyzing the molecular structure of these components and referring to the main functional groups on the infrared spectrum, characteristic band regions with wavelengths in the range of 1000-1400 nm and 1500-1800 nm were selected. Draw two-dimensional correlation spectra (2D-COS) separately, generate synchronous correlation spectra and asynchronous correlation spectra, establish convolutional neural network (CNN) classification models, and achieve the purpose of wine origin traceability. The experimental results demonstrate that combining two segments of two-dimensional characteristic spectra determined by metabolomics screening with convolutional neural networks yields optimal classification results. This validates the effectiveness of using metabolomics screening to determine spectral feature regions in tracing wine origin. This approach effectively removes irrelevant variables while retaining crucial chemical information, enhancing spectral resolution. This integrated approach strengthens the classification model's understanding of samples, significantly increasing accuracy.

Metabolomics and HS-SPME-GC-MS-based analysis of quality succession patterns and flavor characteristics changes during the fermentation of Lycium barbarum and Polygonatum cyrtonema compound wine

This work set out to investigate how the physicochemical markers, volatiles, and metabolomic characteristics of mixed fermented the fermentation of Lycium barbarum and Polygonatum cyrtonema compound wine (LPCW) from S. cerevisine RW and D. hansenii AS2.45 changed over the course of fermentation. HS-SPME-GC-MS combined with non-targeted metabolomics was used to follow up and monitor the fermentation process of LPCW. In total, 43 volatile chemical substances, mostly alcohols, esters, acids, carbonyl compounds, etc., were discovered in LPCW. After 30 days of fermentation, phenylethyl alcohol had increased to 3045.83 g/mL, giving off a rose-like fresh scent. The biosynthesis of valine, leucine, and isoleucine as well as the metabolism of alanine, aspartic acid, and glutamic acid were the major routes that led to the identification of 1385 non-volatile components in total. This study offers a theoretical foundation for industrial development and advances our knowledge of the fundamental mechanism underlying flavor generation during LPCW fermentation.

Enhancement of pyranoanthocyanin formation in blueberry wine with non-Saccharomyces yeasts

The development of blueberry wine provides an alternative method for maintaining the nutritional value and extending the shelf life of blueberries. However, anthocyanin loss and off-flavor compound generation during fermentation impair blueberry wine color and quality. Hydroxycinnamate decarboxylase from yeast can catalyze the conversion of hydroxycinnamic acids to vinylphenols, which later may condense with anthocyanins to form more stable vinylphenolic pyranoanthocyanins. In this study, 10 non-Saccharomyces yeasts from Daqu that showed hydroxycinnamate decarboxylase activity were screened. Among the 10 strains, Wickerhamomyces anomalus Y5 showed the highest consumption (34.59%) of the total tested phenolic acids and almost no H2S production. Furthermore, Y5 seemed to produce four vinylphenol pyranoanthocyanins (cyanidin-3-O-galactoside/glucoside-4-vinylcatechol, cyanidin-3-O-galactoside/glucoside-4-vinylsyringol, malvidin-4-vinylguaiacol, and malvidin-4-vinylcatechol) during blueberry wine fermentation, which may improve the color stability of blueberry wine. These findings provide new insights for improving the quality of blueberry wine using non-Saccharomyces yeasts.

Advancements in the promotion of pyranoanthocyanins formation in wine: A review of current research

Pyranoanthocyanin (PACN) is a class of anthocyanin (ACN)-derived pigments found in aged red wines, which has certain advantages over the prototype ACN in terms of stability, and biological activity. However, the efficiency and yield of PACNs in the natural fermentation system are low. This article summarizes five frequently employed physical processing techniques that can accelerate the formation of PACN. From a mechanistic standpoint, these techniques can produce large amounts of active substances, further promoting the extracellular release of phenolics and the formation of some cofactors and PACNs' pyran rings. Precursor substances and environmental factors affecting PACN yields are also pointed out. It mainly included the parent ring substitution in ACNs, the type and quantity of glycosides, the electron donating ability and concentration of cofactors, etc. Thus, this article aims to provide an overview of the advancements in processing techniques, thereby facilitating their wider utilization in the food and beverage industry.

A Review of Quantitative and Topical Analysis of Anthocyanins in Food

Anthocyanins, a subclass of flavonoids known for their vibrant colors and health-promoting properties, are pivotal in the nutritional science and food industry. This review article delves into the analytical methodologies for anthocyanin detection and quantification in food matrices, comparing quantitative and topical techniques. Quantitative methods, including High-performance Liquid Chromatography (HPLC) and Mass Spectrometry (MS), offer precise quantification and profiling of individual anthocyanins but require sample destruction, limiting their use in continuous quality control. Topical approaches, such as Near-infrared Spectroscopy (NIR) and hyperspectral imaging, provide rapid, in situ analysis without compromising sample integrity, ideal for on-site food quality assessment. The review highlights the advancements in chromatographic techniques, particularly Ultra-high-performance Liquid Chromatography (UHPLC) coupled with modern detectors, enhancing resolution and speed in anthocyanin analysis. It also emphasizes the growing importance of topical techniques in the food industry for their efficiency and minimal sample preparation. By examining the strengths and limitations of both analytical realms, this article aims to shed light on current challenges and prospective advancements, providing insights into future research directions for improving anthocyanin analysis in foods.

Metabolomic analysis to unravel the composition and dynamic variations of anthocyanins in bayberry-soaked wine during the maceration process

In this work, we employed a global untargeted metabolomics technique to explore the intricate composition of anthocyanin constituents in bayberry wine and elucidate their alteration during the maceration process. Our analysis uncovered 20 distinct forms of anthocyanins in bayberry wine, including cyanidin-type, delphinidin-type, peonidin-type, malvidin-type, and other-type. 'Dongkui' (DK) bayberry wine was characterized by a predominance of glycoside forms of cyanidin-type and delphinidin-type anthocyanins, while 'Shuijing' (SJ) bayberry wine mainly contained other-type anthocyanins. Additionally, differential anthocyanins analyses conducted across various maceration periods demonstrated the different fate of the components in the wine, with a conspicuous decline in most glycosidic form anthocyanins. Moreover, correlation analysis revealed that the red hue of bayberry wine was primarily associated with cyanidin-3-O-glucoside, cyanidin-3-O-rhamnoside, delphinidin-3-O-arabinoside, and delphinidin-3-O-galactoside. This research contributes to our understanding of the anthocyanin composition and the dynamic variations in bayberry wine, opening avenues for further exploration and optimization of production techniques in the future.

Leaching and evolution of anthocyanins and aroma compounds during Cabernet Sauvignon wine fermentation with whole-process skin-seed contact

This study explores the leaching and evolution of anthocyanins and aroma compounds during wine-making, using an industrial-scale vinification of Cabernet Sauvignon with whole-process skin-seed contact. The results indicated that compounds within the same class displayed similar evolutionary patterns during fermentation. The extraction of anthocyanins, C6 aldehydes, and β-damascenes occurred continuously during cold soak, accompanied by the conversion of C6 aldehydes into alcohols and hydrolytic release of glycosidic β-damascenone. During alcoholic fermentation, pyranoanthocyanins, polymeric pigments, esters, benzene compounds, higher alcohols, and acids were generated. The concurrent occurrence of malolactic fermentation and prolonged maceration led to aromas associated with lactic acid bacteria metabolism. Finally, a comparison between free-run wine and pressed wine revealed high concentrations of C6 compounds and polymeric pigments with flavanol dimers in the pressed wine. These results can be used as a reference to optimize the vinification process to enhance the red due and fruity aromas of the wine.

Effects of Phenolic Evolution on Color Characteristics of Single-Cultivar Vitis vinifera L. Marselan and Merlot Wines during Vinification and Aging

The loss of red hue in dry red wine has been a persistent issue for wine enterprises in western China. We investigated the changes in anthocyanins and non-anthocyanin phenols during the industrial-scale fermentation and one-year bottle aging of Vitis vinifera L. Merlot and Vitis vinifera L. Marselan, respectively, using the grapes in the Ningxia region. We also examined their correlation with color characterization. The study found that both anthocyanins and non-anthocyanin phenolics were rapidly extracted from grapes during alcohol fermentation. However, their concentrations decreased rapidly during malolactic fermentation. On the other hand, Vitisin A and Vitisin B were formed during alcoholic fermentation and decreased slowly from malolactic fermentation to storage period. Directly polymerized pigments (F-A and A-F), bridged polymerized pigments (A-e-F), and flavanyl-pyranoanthocyanins (A-v-F) from the reactions of anthocyanins (A) and flavan-3-ols (F), as well as pinotins were generated during the later stages of alcoholic fermentation, and remained at a high level throughout malolactic fermentation and bottle storage. Partial least squares regression and Pearson correlation analyses revealed that the red hue (a* value) of 'Merlot' and 'Marselan' wines was closely associated with monomeric anthocyanins and F-A type pigments. Furthermore, four pinotin components were positively correlated with the red hue (a* value) of 'Merlot' wine. These primary red components of the two varieties had a positive correlation with the level of flavan-3-ols. The data suggest that elevating the flavan-3-ol concentration during fermentation aids in improving the color stability of red wine.

Anthocyanins degradation mediated by β-glycosidase contributes to the color loss during alcoholic fermentation in a structure-dependent manner

Anthocyanins deteriorate during fermentation to varying degrees depending on the structure of the anthocyanin, thus affecting the sensory quality of the wine, and the degradation of anthocyanins is closely associated with the β-glycosidase. In this study, the alcoholic fermentation systems containing cyanidin-3-O-glucoside (C3G), peonidin-3-O-glucoside (Pn3G), delphinidin-3-O-glucoside (D3G), petunidin-3-O-glucoside (Pt3G), and malvidin-3-O-glucoside (M3G) incubated for eight days. Our results indicated that the color of the systems containing different anthocyanins saw significant and dissimilar changes during fermentation, in relation to anthocyanin degradation. The five anthocyanins showed varying degradation degrees, which are relevant to theβ-glycosidase produced by yeast. Enzyme kinetics and molecular docking analysis showed the affinity between anthocyanins and β-glucosidase: C3G < M3G < Pn3G < Pt3G < D3G. This study demonstrated that β-glycosidase had distinct effects on anthocyanins with diverse structures, resulting in different color changes in fermentation systems. It provided a potential strategy for sensory quality improvement during the fermentation of fruit wines rich in anthocyanins.

Adjusting the pomace ratio during red wine fermentation: Effects of adding white grape pomace and juice runoff on wine flavoromics and sensory qualities

Adding pomace or juice runoff during maceration is a traditional winemaking process. To mitigate the negative effects of rainfall during harvest and examine the effects of adjusting the pomace ratio during fermentation on the flavor profile of Marselan grape wines, the prefermentation addition of Petit Manseng grape pomace (PAP) and prefermentation juice runoff (PJR) was determined. The phenolic and volatile compounds were investigated using HPLC-MS and GC-MS. PAP enriched the flavanols and PJR enriched the pigment and copigment matrix. Approximate 10% increase in the ratio of pomace promoted the formation of anthocyanin derivatives. The increased pomace ratio reduced the concentration of volatile compounds without impacting the aroma quality. Sensory analysis revealed PAP wines scored higher for acidity and astringency and PJR wines scored higher for color. In conclusion, an appropriate increase in the pomace ratio of approximately 10% can enhance the color and mouthfeel of the wine while having a limited influence on aroma.

Obtaining and characterizing polyphenol extracts based on anthocyanins from Melinis minutiflora inflorescences and Plinia cauliflora fruits and application in gelatins

Anthocyanins are a class of compounds potentially used as food dyes. Thus, this study aimed to obtain and characterize natural extracts from Melinis minutiflora inflorescence (M), Plinia. cauliflora peel (JP) and P. cauliflora peel and seeds (JPS) and apply them as natural food dyes in gelatins. The extracts did not show statistically significant differences in pH values and water activity. The M and JPS extracts showed similar values of anthocyanins and total phenolic compounds and were higher than those from the JP extract. The M and JPS extracts showed a bathochromic effect, which was not observed for the JP extract. The bathochromic effect may indicate a possible complexation of anthocyanins. The color composition analysis revealed that the JP extract has a higher absorbance at a wavelength of 520 nm, indirectly suggesting the presence of more monomeric anthocyanins in its composition. The extract application test in gelatin did not change the texture properties of the gelatins. In addition, our findings revealed that the JPS extract had the best color stability after ten days of analysis, indicating that anthocyanin complexation with the phenolic compounds of P. cauliflora seeds contributed more effectively to anthocyanin stability in the model used.

The key role of vineyard parcel in shaping flavonoid profiles and color characteristics of Cabernet Sauvignon wines combined with the influence of harvest ripeness, vintage and bottle aging

Recently, revealing the terroir influence on wine chemical features has drawn increasing interest. This study aimed to explain how wine flavonoid signatures were altered by vineyard parcel, harvest ripeness, vintage and bottle aging. Six commercial Cabernet Sauvignon vineyards were selected in the Manas region to produce wines at three harvest ripeness in three seasons (2019-2021) and aged for three years. The six vineyards had little difference in mesoclimate conditions while varying greatly in soil composition. Results showed high vineyard pH (> 8.5) could accelerate grape ripening rate and increase wine flavonol concentration. Vineyards with moderate nutrition produced wines with abundant anthocyanin derivatives and maintained color characteristics during aging. The role of detailed anthocyanin derivatives in regulating wine color was clarified. As the harvest ripeness elevated, wine's flavonoid profiles were altered and gained a higher red color intensity. This work provides chemical mechanisms underlying single-vineyard wines and a theoretical basis for targeted wine production.

Widely targeted metabolomic analysis reveals that volatile metabolites in cigar tobacco leaves dynamically change during fermentation

Changes in volatile metabolites during cigar tobacco leaves fermentation as well as the metabolic pathways of metabolites with significant differences were investigated to determine the influence of cigar tobacco leaves fermentation on its flavor. The volatile substances in cigar tobacco leaves at different stages were detected by headspace-solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS), and the main differences in volatile substances in cigar tobacco leaves at different fermentation stages of Yunxue1 in Yuxi production area were analyzed by principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). The results show that in the process of cigar tobacco leaves fermentation (YXF0, YXF1, YXF2, YXF3, YXF4, YXF5), a total of 613 volatile metabolites were detected, and a significant difference was found in 263 kinds of metabolites. Among them, the main upregulated differential metabolites were 1,3,6,10-Cyclotetradecatetraene, 3,7,11-trimethyl-14-(1-methylethyl)-, [S-(E,Z,E,E)]-, Benzoic acid, Benzaldehyde, etc. While the main downregulated differential metabolites included beta.-Myrcene, trans-Farnesol, etc. The metabolites with significant differences are mainly concentrated in the biosynthesis of monoterpenes, diterpenes, sesquiterpenes and triterpenes, the degradation metabolism of amino acids, such as valine, leucine and isoleucine, and the biosynthesis of phenylpropyl. There were 8 different metabolites in 5 groups, including 4- (1-methylethyl) -1-cyclohexene-1-formaldehyde、2, 4-dihydroxyacetophenone、2-methylbutyl 3-methylbutyrate and methylpyrazine, all of which showed upregulation trend during fermentation. In the fermentation process, volatile metabolites participate in various synthesis and degradation pathways. The biosynthesis pathway of terpenes and amino acid synthesis and degradation pathway are connected to produce various terpenes, aldehydes and other substances, such as 1,3,6,10-Cyclotetradecatetraene, 3,7,11-trimethyl-14-(1-methylethyl)-, [S-(E,Z,E,E)]-、benzaldehyde and 4-hydroxybenzaldehyde, which are conducive to the overall flavor and quality of cigar tobacco leaves.

Non-enzymatic browning of wine induced by monomeric flavan-3-ols: A review

Non-enzymatic browning occurs widely in both white and red wines, and it has a huge impact on the color evolution and aging potential. Previous studies have proved that phenolic compounds, especially those with catechol groups, are the most important substrates involved in browning reactions of wine. This review focus on the current knowledge of non-enzymatic browning in wine resulting from monomeric flavan-3-ols. First, some relevant aspects of monomeric flavan-3-ols are introduced, including their structures, origins, chemical reactivities, as well as potential impacts on the organoleptic properties of wine. Second, the mechanism for non-enzymatic browning induced by monomeric flavan-3-ols is discussed, with an emphasis on the formation of yellow xanthylium derivatives, followed by their spectral properties and effects on the color change of wine. Finally, attentions are also be given to the factors that influence non-enzymatic browning, such as metal ions, light exposure, additives in winemaking, etc.

A Metabolomics and Big Data Approach to Cannabis Authenticity (Authentomics)

With the increasing accessibility of cannabis (Cannabis sativa L., also known as marijuana and hemp), its products are being developed as extracts for both recreational and therapeutic use. This has led to increased scrutiny by regulatory bodies, who aim to understand and regulate the complex chemistry of these products to ensure their safety and efficacy. Regulators use targeted analyses to track the concentration of key bioactive metabolites and potentially harmful contaminants, such as metals and other impurities. However, the metabolic complexity of cannabis metabolic pathways requires a more comprehensive approach. A non-targeted metabolomic analysis of cannabis products is necessary to generate data that can be used to determine their authenticity and efficacy. An authentomics approach, which involves combining the non-targeted analysis of new samples with big data comparisons to authenticated historic datasets, provides a robust method for verifying the quality of cannabis products. To meet International Organization for Standardization (ISO) standards, it is necessary to implement the authentomics platform technology and build an integrated database of cannabis analytical results. This study is the first to review the topic of the authentomics of cannabis and its potential to meet ISO standards.

Manipulating the severe shoot topping delays the harvest date and modifies the flavor composition of Cabernet Sauvignon wines in a semi-arid climate

This study aimed to mitigate the adverse effects of global warming by applying severe shoot topping (SST) to grapevines in a semi-arid climate. A three-year study (2018-2020) was performed to investigate the impact of SST on wine flavor composition. Results showed that SST effectively delayed the grape harvest date, which was more evident in the dry and warm vintage (7-11 d). SST significantly increased the concentration of myricetin-based flavonols in wines which were 18% higher than in untreated wines. Through orthogonal partial least squares discriminant analysis (OPLS-DA), SST wines were characterized by more abundant phenolic compounds and higher sensory scores. The carry-over effect of applying SST in consecutive years in the same vines could be reflected in wine color. The correlations among wine metabolites, color and aroma parameters, and sensory parameters were evaluated through multiple analyses. This study provided an idea for delaying grape ripening in a semi-arid climate.

Untargeted metabolomics analysis based on LC-IM-QTOF-MS for discriminating geographical origin and vintage of Chinese red wine

Identifying wine geographical origin and vintage is vital due to the abundance of fraudulent activity associated with wine mislabeling of region and vintage. In this study, an untargeted metabolomic approach based on liquid chromatography/ion mobility quadrupole time-of-flight mass spectrometry (LC-IM-QTOF-MS) was used to discriminate wine geographical origin and vintage. Wines were well discriminated according to region and vintage with orthogonal partial least squares-discriminant analysis (OPLS-DA). The differential metabolites subsequently were screened by OPLS-DA with pairwise modeling. 42 and 48 compounds in positive and negative ionization modes were screened as differential metabolitesfor the discrimination of different wine regions, and 37 and 35 compounds were screened for wine vintage. Furthermore, new OPLS-DA models were performed using these compounds, and the external verification trial showed excellent practicality with an accuracy over 84.2%. This study indicated that LC-IM-QTOF-MS-based untargeted metabolomics was a feasible tool for wine geographical origin and vintage discrimination.

Cholesterol-Lowering Activity of Vitisin A Is Mediated by Inhibiting Cholesterol Biosynthesis and Enhancing LDL Uptake in HepG2 Cells

Pyranoanthocyanins have been reported to possess better chemical stability and bioactivities than monomeric anthocyanins in some aspects. The hypocholesterolemic activity of pyranoanthocyanins is unclear. In view of this, this study was conducted to compare the cholesterol-lowering activities of Vitisin A with the anthocyanin counterpart Cyanidin-3-O-glucoside(C3G) in HepG2 cells and to investigate the interaction of Vitisin A with the expression of genes and proteins associated with cholesterol metabolism. HepG2 cells were incubated with 40 μM cholesterol and 4 μM 25-hydroxycholeterol with various concentrations of Vitisin A or C3G for 24 h. It was found that Vitisin A decreased the cholesterol levels at the concentrations of 100 μM and 200 μM with a dose-response relationship, while C3G exhibited no significant effect on cellular cholesterol. Furthermore, Vitisin A could down-regulate 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (HMGCR) to inhibit cholesterol biosynthesis through a sterol regulatory element-binding protein 2 (SREBP2)-dependent mechanism, and up-regulate low-density lipoprotein receptor (LDLR) and blunt the secretion of proprotein convertase subtilisin/kexin type 9 (PCSK9) protein to promote intracellular LDL uptake without LDLR degradation. In conclusion, Vitisin A demonstrated hypocholesterolemic activity, by inhibiting cholesterol biosynthesis and enhancing LDL uptake in HepG2 cells.

Metabolomic fingerprinting based on network analysis of volatile aroma compounds during the forced aging of Huangjiu: Effects of dissolved oxygen and temperature

Introduction

Huangjiu is an important Chinese alcoholic beverage, usually prepared from rice. Although its unique flavor improves with prolonged storage in traditional pottery jars, knowledge of the aging mechanism, necessary for commercialization of an optimum product, remains unclear.

Methods

Here, volatile aroma compounds from forced aged samples exposed to different temperatures and oxygen treatments were measured by GC/MS. After retention time alignment and normalization, the peak vectors were compared over storage time using Pearson's correlation, and a correlation network was established. Marker compounds, representative of traditionally aged Huangjiu, were then monitored and compared to similar compounds in the forced aged product.

Results and discussion

Correlation network analysis revealed the following: Temperature had little effect on most aroma compounds; alcohols, acids, and esters all increased with increasing dissolved oxygen, while polyphenols, lactones, and ketones were readily oxidized; aldehydes (e.g., furfural and benzaldehyde) were highly dependent on both temperature and dissolved oxygen. Dynamic changes in the targeted aging-markers showed that a higher initial oxygen concentration intensified the "aging-aroma" of Huangjiu in the early and middle stages of storage. Consequently, careful control of oxygen supplementation and storage temperature could be beneficial in controlling the desirable flavor of Huangjiu in the artificially aged product.

Specification and Simplification of Analytical Methods to Determine Wine Color

The color of wine is an important quality parameter essential for the first impression of consumers. The International Organization of Vine and Wine (OIV) recommends two methods to describe wine color: color calculation according to Glories and the determination of coordinates in the CIE L*a*b* color space. The measurement of wine color is often not feasible for winemakers because the required instrumentation is expensive and bulky. In this study, the influence of photometer settings on the calculated color was investigated based on 14 wines. Furthermore, the CIE L*a*b* and Glories system were compared using 56 red and 56 white wines. Photometer settings were found to influence the reproducibility of color determination. In addition, CIE L*a*b* system do not correlate in all wines with the Glories system and Glories probably provides less information about wine color. Using interpolation, CIE L*a*b* coordinates were calculated from single wavelength measurements taken by a small-sized and inexpensive portable analysis system, which could be used by winemakers in the future.

The effects of regions and the wine aging periods on the condensed tannin profiles and the astringency perceptions of Cabernet Sauvignon wines

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Thirty-two commercial red wines of Cabernet Sauvignon produced in five continuous vintages (2015–2019) and collected from four production regions were statistically different for the analyzed condensed tannin profiles.

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Cabernet Sauvignon wines from four regions were rich in the (–)-epicatechin as the extension subunit.

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Condensed tannin profiles could be used to distinguish some of the production region, but the different vintage samples were not well differentiated.

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A negative correlation of ageing periods and condensed tannin concentration of Cabernet Sauvignon wines was observed.

This study sought to determine the effects of wine-producing regions and aging periods on the astringency and chemistry of condensed tannins of Cabernet Sauvignon dry red wines. A wine quality study was performed with 5 vintages of 32 Cabernet Sauvignon wines produced in four Chinese wine-producing regions, Hebei (H), Xinjiang (X), Inner Mongolia (NM), and Ningxia (NX). Condensed tannin profiles were assessed by high-performance liquid chromatography coupled with a diode array detector (HPLC-DAD). The (–)-epicatechin as the terminal subunit (tEC) is the major differential component between regions. Correlation analysis revealed that condensed tannin concentration and composition significantly affected the sensory evaluation of astringency. Condensed tannin concentrations were significantly and negatively correlated with wine aging periods. However, no significant correlation was found between aging periods and condensed tannin subunits (as mole%) composition. The current findings enhance the understanding of condensed tannins' chemical and astringency characteristics in Cabernet Sauvignon wines.

Cluster spatial positions varied the phenolics profiles of 'Cabernet Sauvignon' grapes and wines under a fan training system with multiple trunks

The fan training system with multiple trunks (F-MT) is widely used in the northern China winegrape region with high yield and convenience for burying soil to prevent winter cold. However, the wide distribution of clusters under F-MT usually leads to variations in berry compositions. In two consecutive years, clusters from different spatial positions were collected to determine the phenolic composition in grapes and resultant wines by HPLC-QqQ-MS/MS. Results showed that light exposure promotes the accumulation of flavonols and 3'-hydroxylated anthocyanins in berries. Wines made from upper clusters had higher alcohol degree, lightness, monomeric anthocyanins and flavonols, whereas wines made from lower clusters had relatively higher total acidity, red color component, polymeric anthocyanin and total flavanols. Most of the wine parameters were also significantly affected by vintage. In conclusion, the quality of grapes and wines varied from different cluster positions, graded harvesting helps to maximize the characteristics of grape berries.

Red wine coloration: A review of pigmented molecules, reactions, and applications

Color is one of the most distinctive qualities of red wine. Despite new knowledge in the field of pigment identification, copigmentation, and oxidation being forthcoming, there is still a large gap between the fundamental research and practical winemaking outcomes. A state-of-art review from these two aspects is, therefore, necessary. This review first introduces updated knowledge about the primary pigments in wine, with emphasis on their physicochemical properties. Then, the mechanisms of copigmentation and oxidation are elucidated in detail, along with their relative contributions to wine color. Finally, the practical effects of copigmentation and micro-oxygenation (MOX) in winemaking are summarized and discussed. In general, wine coloration is ultimately determined by the anthocyanin flavylium cation, which is greatly influenced by wine pH. In young red wine, grape-derived anthocyanins and nonanthocyanin polyphenols (as copigments) are the foundation for wine coloration. During aging and storage, anthocyanin derivatives are formed via various chemical reactions, where moderate oxidation plays a vital role, whereas copigmentation constantly decreases. The essence of wine color evolution relates to the changes of physicochemical properties of primary pigments in wine, where the hydration equilibrium gradually diminishes. In practice, the effects of copigment addition and MOX during real vinification can be viewed as somewhat controversial, considering that many studies showed different effects on wine color and pigment concentration. Universal features can be summarized but some phenomena still remain unclear and deserve further exploration.

The combined influence of rootstock and vintage climate on the grape and wine flavonoids of Vitis vinifera L. cv. Cabernet Sauvignon in eastern China

Rootstocks are commonly utilized owing to their resistance to abiotic and biotic stress in viticulture. This study evaluated the effects of three rootstocks (1103P, SO4, and 5A) on the Cabernet Sauvignon (CS) vine growth, and their berries and wines flavonoids profiles in four consecutive vintages. The results showed that 1103P increased the pruning weight of CS and decreased the anthocyanin concentration in berries and wines, especially in the vintages with more rainy and cloudy days. 5A tended to decrease the pruning weight of CS and increase the anthocyanin concentration in berries and wines. Orthogonal partial least squares discriminant analysis (OPLS-DA) showed that the concentrations of total anthocyanins, F3'H-anthocyanins, malvidin-3-O-glucoside (Mv-glu), and malvidin-3-O-acetylglucoside (Mv-acglu) were the key substances affected by the rootstocks in CS berries and were significantly decreased by 1103P. Total anthocyanins, pinotins, Mv-glu, epicatechin, and vitisins were the rootstock-sensitive compounds that commonly differed in wines among the three comparison groups in the two vintages. Furthermore, 1103P brought more brightness to the wine and 5A gave the wine more red tones. In conclusion, rootstock 5A was recommended in the rainy and cloudy climate regions with regard to the berry flavonoids accumulation and the wine color.

Grape UV-C irradiation in the postharvest period as a tool to improve sensorial quality and anthocyanin profile in 'Cabernet Sauvignon' wine

Anthocyanins are important compounds in grapes and wine and significantly influence their characteristics. Ultraviolet light-C (UV-C) can be used as a tool to induce secondary metabolism, and in this study, it was used in 'Cabernet Sauvignon' grapes in the postharvest period to improve the anthocyanin profile and sensory attributes in wine produced with irradiated grapes. Grapes in the postharvest period were exposed to 0, 2, or 3 kJ m^-2 UV-C radiation. After winemaking and storage time (6 months), physicochemical and color analyses, anthocyanin quantification and identification (HPLC-PDA-MS/MS), and sensory analyses were carried out. 'Cabernet Sauvignon' wine produced with grapes irradiated with 3 kJ m^-2 UV-C showed increased spectrophotometric color, which is likely due to a 22.5% increase in total anthocyanin monomers, 59.3% of pyranoanthocyanins, 92.3% of direct condensation products, and 62.8% of acetaldehyde-mediated condensation products. In addition, this irradiated dose presented higher perception scores for visual color, aroma, taste, and was preferred by the tasters over the wine produced with non-irradiated grapes. This study is the first of its kind to show that the UV-C radiation treatment of grapes in the postharvest period can be a promising tool to improve the anthocyanin profile and sensorial quality of 'Cabernet Sauvignon' wine.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-021-05191-5.

Identification of characteristic volatiles and metabolomic pathway during pork storage using HS-SPME-GC/MS coupled with multivariate analysis

Previous researches have been conducted evaluating the volatile compounds of pork. However, data regarding the changes in volatiles and metabolic pathways during pork storage were inadequately investigated. Herein, a headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC/MS) coupled multivariate analysis was proposed for characterizing the profiles of volatile compounds and metabolic pathways during pork storage. A total of 37 metabolites, including aldehydes, ketones, alcohols etc. were successfully identified. Multivariate statistical analysis revealed a substantial variation in metabolite phenotype among samples over the pork storage period, with 12 characteristic metabolites and 5 potential characteristic metabolites screened as biomarkers. Moreover, three metabolomic pathways analysis and transformation between each other (thermal reactions, lipid metabolism and amino acid metabolism) reveals the underlying mechanisms of metabolites change of pork. Therefore, the present study may provide insight into future understanding of the variation in the pork metabolite profiles.

Grape Pomace Valorization by Extraction of Phenolic Polymeric Pigments: A Review

In recent years there has been a growing concern about environmental pollution linked to the generation of agroindustrial waste. The wine industry generates approximately 8.49 million tons of grape pomace per year worldwide; this residue can be used to obtain compounds with biological activity. Grape pomace is a source of anthocyanins, pigments that have antioxidant properties and help prevent cardiovascular disease. The development of sustainable extraction, purification and identification techniques constitutes an important step in adding value to this waste. Therefore, the present research has focused on presenting a review of works carried out in the last years.

Reactivity comparison of three malvidin-type anthocyanins forming derived pigments in model wine solutions

Malvidin-3-O-glucoside (MvG), malvidin-3-O-(6-O-acetyl)-glucoside (MvAG), and malvidin-3,5-O-diglucoside (MvDG) are three representative malvidin-type anthocyanins in red wine. In this study, the influence of structural differences on the formation efficiency of two types of derived pigments ((-)-epicatechin-ethyl-anthocyanins and pyranoanthocyanins) was investigated in model solutions using UHPLC-MS. The results showed that the yields of MvAG were higher than those of MvG to form both types of derived pigments, and the formation rate of pyranoanthocyanin was also relatively higher. In contrast, acetylation slowed the formation of (-)-epicatechin-ethyl-anthocyanins, indicating that the rate of covalent reactions may be linked to the affinity of (-)-epicatechin to copigment with anthocyanins. The condensation rate of MvDG with (-)-epicatechin, mediated by acetaldehyde, was much lower than that of the two monoglucosidic anthocyanins and also exhibited lower yields. In addition, pyranoanthocyanin was not generated from MvDG due to the absence of a free hydroxyl group at the C5 position.

Impact of three phenolic copigments on the stability and color evolution of five basic anthocyanins in model wine systems

Phenolic copigments have important influence on red wine color. In this study, UV-visible spectrophotometer and UHPLC-Q-TOF-MS were combined to investigate the effects of three types of phenolic copigments (gallic acid, (-)-epicatechin, and quercetin-3-O-glucoside) on the stability and color properties of five common 3-O-monoglucosidic anthocyanins in model wine solutions. Results showed low concentrations (0.5 mM) of gallic acid and (-)-epicatechin protected anthocyanins from degradation, whereas high concentrations (8 mM) of them had the opposite effect. Quercetin-3-O-glucoside always improved the stability of anthocyanins despite its additive amount (0.1 mM or 0.4 mM). Even small quantity of (-)-epicatechin led to obvious yellow hue into the solution, and xanthylium derivatives generated from (-)-epicatechin were detected. Antagonistic effect among the three copigments was observed, probably as a result of competition of intermolecular copigmentation. Additionally, the stability of anthocyanins was significantly influenced by their structures: cyanidin-3-O-glucoside, peonidin-3-O-glucoside, and malvidin-3-O-glucoside were more stable than delphinidin-3-O-glucoside and petunidin-3-O-glucoside.

Distal leaf removal made balanced source-sink vines, delayed ripening, and increased flavonol composition in Cabernet Sauvignon grapes and wines in the semi-arid Xinjiang

Leaf removal applied in the upper canopy of modified vertical shooting positioning trellis system has been proposed as an effective strategy to mitigate the adverse effects of global warming on grape and wine quality. In this study, we removed the upper leaves of Cabernet Sauvignon canopy in a semi-arid climate for three consecutive years (2018-2020). About one-third of the whole canopy leaves were removed at the beginning of véraison (LR1) and post-véraison (LR2). All leaf removal treatments included two schemes: (i) leaf removal in the same vines in all vintages to investigate the carry-over effects (1-LR1 and 1-LR2); (ii) leaf removal in different vines in each vintage as repeated experiments among vintages (2-LR1 and 2-LR2). Results showed that leaf removal treatments significantly decreased total soluble solids accumulation in grapes without affecting titratable acidity and pH. LR1 treatments could delay ripening to 6.6 days on average, which was 2.6 days longer than LR2 treatments. LR treatments did not affect the yield but decreased soluble sugar content in canes. Leaves net assimilation rate showed no compensation for the loss of leaves. For phenolic composition, LR treatments increased flavonol concentration in both wines and grapes while had inconsistent effects on anthocyanins and flavanols over three seasons. Principal component analysis (PCA) showed that different LR treatment stages (LR1s vs LR2s) and whether LR in the same vines over consecutive years (1-LRs vs 2-LRs) had limited effects on phenolic profiles. In conclusion, LR in consecutive years at the upper canopy of grapevines was a practical strategy to face global warming in Xinjiang.

Influence of Berry Ripening Stages over Phenolics and Volatile Compounds in Aged Aglianico Wine

The harvest time of grapes is a major determinant of berry composition and of the wine quality, and it is usually established through empirical testing of main biochemical parameters of the berry. In this work, we studied how the ripening stage of Aglianico grapes modulates key secondary metabolites of wines, phenolics and volatile compounds. Specifically, we analyzed and compared four berry ripening stages corresponding to total soluble solids of 18, 20, 22, and 25 °Brix and related aged wines. Wine color intensity, anthocyanins level and total trans-resveratrol (free + glycosidic form) increased with grape maturity degree. Wines obtained from late-harvested grapes significantly differed from the others for a higher content of aliphatic alcohols, esters, acetates, α-terpineol and benzyl alcohol. The content of glycosidic terpene compounds, such as nerol, geraniol and α-terpineol, was higher in wines obtained with grapes harvested at 25 °Brix compared to the earlier harvests. Our work indicated that the maturity of the grape is a determining factor in phenolic and volatile compounds of red Aglianico wines. Moreover, extending grape ripening to a sugar concentration higher than 22 °Brix improves the biochemical profile of aged wine in terms of aroma compounds and of phytochemicals with known health-related benefits.

Using untargeted metabolomics to profile the changes in roselle (Hibiscus sabdariffa L.) anthocyanins during wine fermentation

In this study, an UHPLC-QE-MS approach in combination with multivariate statistical analyses was used to investigate the metabolic profiles, especially the anthocyanin profiles, during the fermentation of roselle wine. Overall, a large number of different metabolites (e.g., phenols, lipids, carbohydrates, amino acids and peptides, and others) were identified in the fermentation processes. Eight anthocyanin metabolites were identified in roselle wine for the first time, of which six were identified in the main fermentation process and two in the post-fermentation process. In addition, we identified several metabolic pathways during the fermentation process, and the metabolic pathways of anthocyanins in roselle wine are mainly related to flavonoid biosynthesis and to anthocyanin biosynthesis. These findings are expected to be useful for further studies on wine chemistry and yeast metabolism.

Development of a Wine Metabolomics Approach for the Authenticity Assessment of Selected Greek Red Wines

Wine metabolomics constitutes a powerful discipline towards wine authenticity assessment through the simultaneous exploration of multiple classes of compounds in the wine matrix. Over the last decades, wines from autochthonous Greek grape varieties have become increasingly popular among wine connoisseurs, attracting great interest for their authentication and chemical characterization. In this work, 46 red wine samples from Agiorgitiko and Xinomavro grape varieties were collected from wineries in two important winemaking regions of Greece during two consecutive vintages and analyzed using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QToF-MS). A targeted metabolomics methodology was developed, including the determination and quantification of 28 phenolic compounds from different classes (hydroxycinnamic acids, hydroxybenzoic acids, stilbenes and flavonoids). Moreover, 86 compounds were detected and tentatively identified via a robust suspect screening workflow using an in-house database of 420 wine related compounds. Supervised chemometric techniques were employed to build an accurate and robust model to discriminate between two varieties.

Comparison of Three Accelerated Oxidation Tests Applied to Red Wines with Different Chemical Composition

Background: Three accelerated oxidation tests were proposed to simulate red wine oxidation thus providing information useful to correctly manage moderate oxygen exposure of wine during aging in regard to phenolic composition and wine color. Since the results of the tests have never been compared on wines with different initial composition, the aim of this study was to find a suitable method to simulate oxidation of any still red wine. Methods: Aglianico, Barbera, Gaglioppo, Magliocco, and Nerello wines were treated with (1) three cycles of air saturation, (2) the addition of hydrogen peroxide, and (3) the addition of acetaldehyde. Changes in chromatic characteristics and phenolic composition were determined by spectrophotometric and HPLC methods. Results: Important differences in the behavior of the different wines were detected: the highest formation of polymeric pigments was observed in Barbera and Aglianico wines. In contrast, Gaglioppo and Magliocco wines showed a lower variability before and after the oxidation probably due to the lower anthocyanin/tannin ratio. Among the accelerated oxidation tests applied, no significant differences in color parameters and phenolic composition were detected in samples treated with the addition of H₂O₂ and the air saturation method. Conclusion: The study demonstrated that H₂O₂ addition is a successful tool to predict the evolution of different phenolic compounds during the air saturation treatment of wines.

Liquid Chromatography-Mass Spectrometry-Based Metabolomics for Understanding the Compositional Changes Induced by Oxidative or Anoxic Storage of Red Wines

The aim of this work was to study the physicochemical changes of eight red wines stored under conditions differing in O₂ exposure and temperature and time under anoxia. The methods used to analyze the wines included the measurement of volatile sulfur compounds, color, tannin (T) polymerization, and liquid chromatography-mass spectrometry untargeted metabolomic fingerprint. After 3 months, the color of the oxidized samples evolved 4-5 times more intensively than in wines stored under anoxia. The major metabolomic differences between oxidative and anoxic conditions were linked to reactions of acetaldehyde (favored in oxidative) and SO₂ (favored in anoxia). In the presence of oxygen, the C-4 carbocation of flavanols delivered ethyl-linked tannin-anthocyanin (T-A) and tannin-tannin (T-T) adducts, pyranoanthocyanins, and sulfonated indoles, while under reduction, the C-4 carbocation delivered direct linked T-A adducts, rearranged T-T adducts, and sulfonated tannins. Some of these last reactions could be related to the accumulation of reduced species, eventually ending with reductive off-odors.