Grape and wine polymeric polyphenols: Their importance in enology

Phenolic compounds are important constituents of red wine, contributing to its sensory properties and antioxidant activity. Owing to the diversity and structural complexity, study of these compounds was mainly limited, during the last three decades, on their low-molecular-mass compounds or simple phenolic compounds. Only in recent years, much attention has been paid to highly polymerized polyphenols in grape and red wines. The reason for this is largely due to the development of analytical techniques, especially those of HPLC-ESI-MS, permitting the structural characterization of highly polymerized polyphenols. Furthermore, the knowledge on the biological properties of polymeric polyphenols of red wine is very limited. Grape polyphenols mainly consist of proanthocyanidins (oligomers and polymers) and anthocyanins, and low amount of other phenolics. Red wine polyphenols include both grape polyphenols and new phenolic products formed from them during winemaking process. This leads to a great diversity of new polyphenols and makes wine polyphenol composition more complex. The present paper summarizes the advances in the research of polymeric polyphenols in grape and red wine and their important role in Enology. Scientific results indicate that polymeric polyphenols, as the major polyphenols in grape and red wine, play a major role in red wine sensory properties, color stability and antioxidant activities.     

Profiles of Phenolic Acids and Flavan‐3‐ols for Select Chinese Red Wines: A Comparison and Differentiation According to Geographic Origin and Grape Variety

The profiles of phenolic acids and flavan‐3‐ols for the selected Chinese red wines and the potential of using phenolic acids and flavan‐3‐ols to differentiate the geographic origin and grape variety of wines from China are investigated in this study. Significant differences and markers could be found according to the geographical origin and grape variety. Through a canonical discriminant analysis a good differentiation was developed according to the geographic origin or grape variety, and the accuracy of the discriminant model was 88.9% and 100%, respectively. According to the phenolic acid and flavan‐3‐ols profiles of the wine samples and good differentiation in the region and the variety discriminant analysis, minimal fraudulent claims were noted for the Chinese red wines investigated.     

Microwave Maceration of Pinot Noir Grape Must: Sanitation and Extraction Effects and Wine Phenolics Outcomes

Pinot noir grapes have a unique phenolic profile which can impinge on the extraction and stabilisation of compounds such as anthocyanins and tannins which contribute to the colour and mouthfeel of red wine. This study examined the concentration of phenolic compounds in Pinot noir grape must and wine following application of a novel microwave maceration treatment for red grape must. Microwave maceration was shown to be highly effective for extraction of phenolics from grape solids into grape juice. When juices were fermented to wine, ultraviolet–visible spectrophotometry showed microwave maceration was associated with significantly higher concentrations of total phenolics, anthocyanin, tannin and pigmented tannin in wine at 18 months bottle age, compared with control wine. Mean tannin concentration in microwave treatment wine was 0.60 gm/L at 18 months, compared with 0.14 gm/L in control wine. The microwave treatment was also associated with a substantial and rapid decrease in the grape-associated yeast population, compared with control maceration, and a shorter lag phase at the outset of alcoholic fermentation. Based on this study, microwave maceration warrants further investigation as a potential industrial-scale application in red winemaking.     

Screening grape seeds recovered from winemaking by‐products as sources of reducing agents and mammalian α‐glucosidase and α‐amylase inhibitors

Grape seeds collected from vinification of various grape varieties were extracted by supercritical CO₂ for oil recovery. The defatted residues thus obtained were considered as a re‐utilisable co‐product and assessed for phenolic content, reducing capacity and inhibitory activities against mammalian α‐amylase and α‐glucosidase enzymes. Supercritical CO₂ treatment led to higher recovery of anthocyanins. Reducing capacity of phenolic extracts reached up to ~2200 mmolFe(II) kg^?1, much higher than that of various natural phenolic sources. The anthocyanin‐rich extracts showed the highest inhibitory effectiveness towards α‐glucosidase (I₅₀ value equal to ~40 μg gallic acid equivalents (GAE)/mL ~ half than acarbose). Inhibitory effectiveness towards α‐amylase activity was similar among grape varieties, with I₅₀ values comparable to that of acarbose and correlated with proanthocyanidin contents. These results could pave the way for an efficient processing of grapes, including cascade processes, namely: winemaking, oil extraction from recovered grape seeds and phenolic extraction from defatted grape seeds as potential cost‐effective nutraceuticals.     

Acceptability of wine produced with an increased content of grape seeds and stems as a functional food

Owing to a globally increased interest in the relationship between nutrition and health, the development of new functional food products is gaining more importance. The aim of this research was to evaluate the quality and acceptability of a wine produced with increased amounts of grape seeds and stems as a functional beverage. Sensory properties of the wines produced were evaluated and the market potential of this product was estimated through a survey carried out among wine consumers in Novi Sad, Serbia. It was shown that addition of enhanced amounts of grape seeds in the pomace had a greater influence on the phenolic composition and antioxidant capacity towards DPPH and hydroxyl radicals than supplementation with stems. Flavan‐3‐ols and their monomers [(+)‐catechin and (?)‐epicatechin], as predominant phenolic compounds extracted from grape seeds, showed a high positive correlation with antioxidant activity (r ≥ 0.950). Based on the best relationship between phenolic composition and sensory acceptability, the addition of 80 g seeds per kilogram of pomace has been suggested as the most acceptable quantity. The survey showed the necessity for promoting the health‐beneficial effects of catechins through various channels, despite the high percentage of respondents (68%) who were willing to pay up to two times more for this functionally enhanced wine. The major obstacle to the official acceptance of this wine as a functional beverage in Serbia is the insufficiently examined question of the effect of moderate alcohol intake on health. Copyright © 2014 The Institute of Brewing & Distilling     

Comparison of fining red wines with purified grape pomace versus commercial fining agents: effect on wine chromatic characteristics and phenolic content

The large quantity of grape pomace (seeds, skin, and peduncle) produced during the winemaking process can be a problem and the search for procedures which could permit their valorisation is considered an important issue. This study investigates the use of purified grape pomace as a fining agent for reducing the level of some wine phenolic compounds, especially tannins. For this, purified grape pomace was applied to three young red wines of different phenolic composition and the results were compared with the effect of some common commercial fining agents. The results demonstrated that grape pomace can be used to decrease the wine tannin content with similar results to those obtained with casein, while also reducing anthocyanin content although to a similar extent to when bentonite is used. The effect of purified Monastrell grapes pomace is similar in the three different studied wines although it affected the most to wines with high monomeric anthocyanin content.     

Wine tartrate stabilization by different levels of cation exchange resin treatments: impact on chemical composition,phenolic profile and organoleptic properties of red wines

The aim of this work was to evaluate the impact of cation exchange resin, on tartrate stabilization, chemical composition, general phenolic composition, individual anthocyanin and different proanthocyanidin fraction content of a red wine made from a mixture of three Portuguese red grape varieties. Additionally, the influence of this tartrate stabilization process on organolpetic properties was another aim of this work. The cation exchanged red wines were mixed in different proportions with the untreated red wine. The results showed that the application of a cation exchange resin used was useful to adjust the pH and total acidity and revealed a good capacity to retain potassium and calcium. In addition, the cation exchange resin treatment caused a significant decrease in the contents of individual anthocyanins well as in the different fractions of proanthocyanidins (especially in monomeric fraction). Finally, considering the organoleptic properties, the most highly evaluated wine, especially considering taste parameters, was the control wine. These results confirm that cation exchange is an interesting in red winemaking to improve tartaric stability, but at same time it is important analyze potential effects on phenolic content and organoleptic properties of red wines.     

Applications of Wine Pomace in the Food Industry: Approaches and Functions

Winemaking generates large amounts of wine pomace, also called grape pomace. This by‐product has attracted the attention of food scientists and the food industry, due to its high content in nutrients and bioactive compounds. This review mainly focuses on the different published approaches to the use of wine pomace and its functions in the food industry. Traditionally, wine pomace has been used to obtain wine alcohol, food colorings, and grape seed oil. More recently, research has focused in the production of other value‐added products, such as extracts of bioactive compounds, mainly phenols, recovery of tartaric acid, and the making of flours. The most common functions associated with wine pomace products are their use as antioxidants, followed by their use as fortifying, coloring, and antimicrobial agents. These products have mainly been applied to the preparation of meat and fish products and to, a lesser extent, cereal products.     

New perspectives in safety and quality enhancement of wine through selection of yeasts based on the parietal adsorption activity

The present article aims to review research papers that focus on the parietal adsorption activity of wine yeast and on its contribution to the enhancement of wine safety and quality. There is a great diversity among yeasts for their parietal adsorption activity: the outermost layer of the cell wall has a chemical composition that notably varies from yeast to yeast. Parietal mannoproteins can contain phosphate, pyruvate, or glucuronic acid, which impart negative charges, modifying the electrostatic and ionic interactions with wine components. The following could give a good reason to propose a specific selection of wine yeasts based on their parietal adsorption activity to improve wine safety and quality: (a) ochratoxin A content of wines is greatly reduced by expressly selected yeasts, sequestering the toxin during winemaking; (b) yeast influences concentration and composition of phenolic compounds in wine, above all by adsorbing them on cell wall; (c) among grape pigments, anthocyanins, in particular, may be adsorbed by yeast cell wall; and (d) yeast can also interact with wine colour producing anthocyanin-beta-d-glucosidase, pyruvic acid, and acetaldehyde or releasing mannoproteins and different polysaccharides. Genomic strategies could also be used to obtain a further enhancement of the adsorption/non-adsorption activity of wine yeasts. Based on winemaking requirements and on parietal adsorption activity, a specific selection of yeasts might be performed: (a) to protect wine colour during red winemaking, (b) to remove residual wine colour during white winemaking, (c) to selectively remove ochratoxin A, and (d) to protect phenolic compounds responsible for antioxidant activity.     

Evaluation of the bioactive compounds and the antioxidant capacity of grape pomace

Grape pomace is an agro‐industrial residue produced worldwide and mainly employed for animal feed or as a fertiliser. Several studies have shown that grape pomace is a rich source of bioactive compounds, such as phenolic compounds, polysaccharides, fatty acids and others. Three varieties of grape pomace were evaluated in this study. Antioxidant activity was determined by three different methods, namely, DPPH˙, ABTS and ferrous ion assays. Fatty acids and phenolic compounds were identified, respectively, by gas and liquid chromatography. Results showed that grape pomace is a rich source of polyunsaturated fatty acids and phenolic compounds. Cabernet Sauvignon pomace revealed higher values of total phenolic compounds, total flavonoids and total monomeric anthocyanin, and presented the lowest value of EC₅₀, and thus a higher antioxidant activity among the samples analysed.     

葡萄酒酿造过程中氨基酸含量变化的研究

应用HPLC对我国4个产区多个品种葡萄酒酿造过程样品中氨基酸含量变化趋势进行了研究,结果表明,L-脯氨酸是所有葡萄汁中氨基酸的主体,也是各样品含量差异最大的氨基酸;红葡萄酒中含脯氨酸、苏氨酸、赖氨酸等20种氨基酸,其中以脯氨酸含量最高,发现不同葡萄品种之间游离氨基酸种类和含量有差别,这与葡萄品种、气候、发酵工艺有关。     

The Influence of Prefermentative Addition of Gallic Acid on the Phenolic Composition and Chromatic Characteristics of Cabernet Sauvignon Wines

In this study, the prefermentative addition of gallic acid in Cabernet Sauvignon red winemaking was performed. The influence of gallic acid addition on wine phenolic composition, the ratio of copigmentation, and the color parameters were monitored throughout the winemaking process. The results showed that the prefermentative addition of gallic acid enhanced the extraction of total anthocyanins and the copigmentation effect, producing wines with more darkness, redness, yellowness, and saturation. Moreover, the addition of gallic acid contributed to the concentration of total phenolic acids. However, it had a negative effect on the concentrations of flavonols and flavan‐3‐ols in the final wines. Thus, the prefermentative addition of gallic acid at appropriate levels might be a promising enological technology to obtain wines with high color quality and aging potential.     

Phenolic profile of blackberry wine produced using Korean winemaking techniques in earthenware jars

This research evaluated the winemaking potential of ‘Natchez’ and ‘Triple Crown’ blackberries grown in Oklahoma and examined the phenolic composition of blackberry wines made using modified Korean traditional winemaking techniques. The winemaking variables were fermentation temperature (21.6 vs 26.6°C), and fermentation type (yeast inoculation vs wild fermentation). High‐performance liquid chromatography was used to examine the phenolic compounds in blackberry juice and wine. The phenolic compounds consisted of anthocyanins (kuromanin, keracyanidin, delphinidin) and phenolic acids (gallic acid, catechin, caffeic acid, epicatechin, p‐coumaric acid). The ‘Natchez’ berries had higher concentrations of anthocyanins (kuromanin) while ‘Triple Crown’ berries had higher levels of phenolic acids (p‐coumaric acid). For many compounds, a higher fermentation temperature generally corresponded to higher concentrations of the phenolic compound in the wine after three months aging, but this was not universally observed. Accordingly, fermentation temperature may best be matched with individual cultivars via experimentation in order to maximise extraction and retention of phenolic compounds in the finished wines. Overall, the Korean traditional winemaking technique may be a good technique to add value to wines made from blackberries suited for production in a mid‐continental climate such as the central USA. © 2018 The Institute of Brewing & Distilling     

Phenolic profile and free radical‐scavenging activity of Cabernet Sauvignon wines of different geographical origins from the Balkan region

BACKGROUND: The phenolic profile, determined by the relative proportions of different phenolic compounds, is characteristic for each grape variety and its corresponding wine. The aim of this study was to determine the phenolic and hydroxycinnamate acid, flavan‐3‐ol and flavonol contents and free radical‐scavenging activity of single‐cultivar (Cabernet Sauvignon) wines from selected Balkan vineyard regions by spectrophotometric methods and high‐performance liquid chromatography with photodiode array and fluorescence detection. RESULTS: The contents of phenolic compounds varied depending on the agroclimatic factors and oenological practices of the vineyard region. The antioxidant activity of wine samples was estimated by their ability to scavenge the stable 2,2′‐diphenyl‐1‐picrylhydrazyl free radical (DPPH). All wines showed high DPPH‐scavenging activity (70.03–83.53%, mean 73.76%). Significant correlations between catechin (R² = 0.8504) and quercetin (R² = 0.8488) concentrations and DPPH‐scavenging ability of the wines were found. CONCLUSION: The concentrations of the main components catechin and quercetin can be used as biochemical markers for the authentication of red grape cultivars and their corresponding single‐cultivar wines. Copyright © 2010 Society of Chemical Industry     

Simple determination of main organic acids in grape juice and wine by using capillary zone electrophoresis with direct UV detection

An accurate, simple and rapid capillary zone electrophoresis (CZE) method with direct UV detection has been set up for the determination of main organic acids in grape juice and wine. The determination of tartaric, malic, and citric acids in grape juices and tartaric, malic, succinic, acetic, lactic and citric acids in wines can be achieved in less than 3 min with only a simple dilution and filtration treatment of the sample. Validation parameters of the method as detection and quantification limits, linearity, precision (intraday and interday analysis) and recovery were also studied in grape juice, white wine, rose wine and red wine, separately. The proposed method decreases the analysis times of the previous reported CZE methods and allows the rapid control of the grape maturity, the winemaking processes and the detection of wine alterations and/or illnesses.     

Application of high‐power ultrasounds during red wine vinification

Wine colour is one of the main organoleptic characteristics influencing its quality. It is of special interest in red vinifications due to the economic resources that wineries have to invest for the extraction of the phenolic compounds responsible for wine colour, compounds that are mainly located inside the skin cell vacuoles, where the volatile compounds are also found. The transfer of phenolic compounds from grapes to must during vinification is closely related to the type of grapes and the winemaking technique. During traditional winemaking, grapes are crushed and skin macerated for several days, with pumps overs to facilitate the colour extraction. To increase this extraction, some chemical (maceration enzymes) or physical technologies (thermovinification, cryomaceration, flash‐expansion) can be applied. In this work, a new methodology has been tested. This methodology consists in the application of high‐power ultrasounds to crushed grapes to increase the extraction of phenolic compounds. Crushed grapes were treated with this non‐thermal technology and vinified, with 3, 6 and 8 days of skin maceration time, and the results were compared with a control vinification, where crushed grapes were not subjected to any treatment and were skin macerated during 8 days. The wine chromatic characteristics (determined spectrophotometrically) and the individual phenolic compounds (anthocyanins and tannins, determined by HPLC) were followed during the maceration period, at the end of alcoholic fermentation and after two months in bottle. Also, the wine volatile compounds were determined by GC‐MS. The wines made with ultrasound‐treated grapes showed differences with the control wine, especially regarding total phenol content and tannin content. The wines elaborated with sonicated grapes and with only three days of skin maceration time presented similar concentration of anthocyanins and twice the concentration of tannins than control wines elaborated with 8 days of skin maceration.     

Grape by‐product extracts against microbial proliferation and lipid oxidation: a review

The wine industry is responsible for the production of million tons of waste, such as grape skin, stalk, sludge and seeds, which can be considered inexpensive sources of phenolic compound owing to incomplete extraction during wine production. Phenolic compounds, also called polyphenols, comprise the most abundant bioactive compounds in grape and are recognized by their antioxidant and antimicrobial potential. Because of their functional properties, extracts obtained from grape wastes, which are rich in phenolic compounds, can be employed in the development of many products, ranging from medical to food applications, decreasing the growth of spoilage and pathogenic microorganisms and inhibiting lipid oxidation. These characteristics are motivating the research for alternative sources of natural antioxidant and antimicrobial agents, aimed at decreasing the use of artificial additives, which have been associated with some toxic effects. This article provides a review of the use of grape by‐product extracts and their bioactive compounds as natural antioxidant and antimicrobial agents in food products. © 2016 Society of Chemical Industry     

ANTIOXIDANT AND CALMODULIN-INHIBITORY ACTIVITIES OF PHENOLIC COMPONENTS IN FRUIT WINES AND ITS BIOTECHNOLOGICAL IMPLICATIONS

Fruits are rich sources of anthocyanins, flavonoids and phenols that are important nutraceutical components. Processed products of various fruits such as wines and juices, also contain these nutraceuticals, and have been proposed to be the primary components that provide health-beneficiary effects to the cardiovascular system. In the present study, we have evaluated the antioxidant and calmodulin-inhibitory effects of three fruit wines and a red grape wine to provide a comparison in their nutraceutical properties. Using in vitro systems that generate superoxide radicals and hydroxyl radicals, all the wines and their partially purified phenolic extracts were demonstrated to possess strong superoxide and hydroxyl radical scavenging properties. On the basis of specific phenolic content, the summer cherry, blackberry and blueberry wines were 30–40% more efficient in superoxide radical scavenging than red grape wine. Similarly, blueberry wine demonstrated considerably high hydroxyl radical scavenging efficiency than the other wines. The flavonoid aglycones such as catechin and naringenin, were as efficient or more in scavenging superoxide radicals, as ascorbate. As well, these compounds also scavenged hydroxyl radicals, as or more effectively than melatonin, a known hydroxyl radical scavenger. All the wines had components that inhibited calcium and calmodulin-promoted phosphodiesterase activity, indicating their potential to interfere with the calcium second messenger function. Blueberry, blackberry and red wine components were more effective in the inhibition of calmodulin-promoted phosphodiesterase than those from summer cherry wine. Active oxygen scavenging or calmodulin-inhibitory properties appear to be associated with a variety of wine components that may provide synergistic action than any single components in them. This study paves way for the potential use of fermentation biotechnology to optimize the enzymatic release and levels of nutritionally important phenolic components in fruit wines.     

Characterisation and evolution of grape polyphenol profiles of Vitis vinifera L. cv. Tannat during ripening and vinification

Background and Aims: Changes in different polyphenol families during grape ripening and vinification were determined in Tannat grapes. This was done to establish a polyphenol profile for Tannat grapes during ripening and for young wines. Methods and Results: We demonstrated, by high‐performance liquid chromatography with diode array detection and mass spectrometry (HPLC‐DAD‐MS) analysis, that the content of flavan‐3‐ols in Tannat seeds was higher than that reported for a large number of other grape varieties analysed. Forty per cent of the total flavan‐3‐ols in seeds were galloylated compounds, whereas the flavan‐3‐ol profile in skins was characterised by the absence of galloylated forms. Prodelphinidins in skins ranged between 30 and 35% with very low values for epigallocatechin. Epicatechin gallate was not detected in Tannat wine and galloylated forms represented a low percentage of total flavan‐3‐ols. Tannat grapes had very high concentrations of anthocyanins in skins with levels increasing during ripening. Eleven phenolic acids were identified in Tannat grape skins and wines, but only gallic and protocatechuic acids were found in the seeds. Conclusions: Tannat wines were shown to have one of the highest levels of phenolic compounds reported for vinifera grape varieties. The profiles for different polyphenol families present in Tannat grapes (skins and seeds) and wines were determined. Significance of the Study: The results presented will help to better understand the phenolic winemaking potential of this variety and its functional properties within food chemistry.     

ANTIOXIDANT AND CALMODULIN-INHIBITORY ACTIVITIES OF PHENOLIC COMPONENTS IN FRUIT WINES AND ITS BIOTECHNOLOGICAL IMPLICATIONS

Fruits are rich sources of anthocyanins, flavonoids and phenols that are important nutraceutical components. Processed products of various fruits such as wines and juices, also contain these nutraceuticals, and have been proposed to be the primary components that provide health-beneficiary effects to the cardiovascular system. In the present study, we have evaluated the antioxidant and calmodulin-inhibitory effects of three fruit wines and a red grape wine to provide a comparison in their nutraceutical properties. Using in vitro systems that generate superoxide radicals and hydroxyl radicals, all the wines and their partially purified phenolic extracts were demonstrated to possess strong superoxide and hydroxyl radical scavenging properties. On the basis of specific phenolic content, the summer cherry, blackberry and blueberry wines were 30-40% more efficient in superoxide radical scavenging than red grape wine. Similarly, blueberry wine demonstrated considerably high hydroxyl radical scavenging efficiency than the other wines. The flavonoid aglycones such as catechin and naringenin, were as efficient or more in scavenging superoxide radicals, as ascorbate. As well, these compounds also scavenged hydroxyl radicals, as or more effectively than melatonin, a known hydroxyl radical scavenger. All the wines had components that inhibited calcium and calmodulin-promoted phosphodiesterase activity, indicating their potential to interfere with the calcium second messenger function. Blueberry, blackberry and red wine components were more effective in the inhibition of calmodulin-promoted phosphodiesterase than those from summer cherry wine. Active oxygen scavenging or calmodulin-inhibitory properties appear to be associated with a variety of wine components that may provide synergistic action than any single components in them. This study paves way for the potential use of fermentation biotechnology to optimize the enzymatic release and levels of nutritionally important phenolic components in fruit wines.