Characterization of Vitis vinifera L. Cv. Carménère grape and wine proanthocyanidins

Protein extracts from amaranth and quinoa as novel fining agents for red wines

Due to allergenic concerns, only pea, potato, and wheat proteins have been approved as alternatives for replacing animal-based fining agents in wines. In pursuit of other substitutes, this work aimed to determine the fining ability of amaranth (Amaranthus caudatus L.) proteins (AP) in red wine, compared to quinoa (Chenopodium quinoa Willd.) (QP) and a commercial pea protein. Phenolic and volatile composition, as well as color characteristics, were analyzed. AP was as effective as QP at decreasing condensed tannins, with AP at 50 g/hL being the most effective treatment (25.6% reduction). QP and AP produced a minor or no statistical change in the total anthocyanins and wine color intensity. They reduced the total ester concentration, but the total alcohols remained unchanged. The outcomes of AP and QP were similar, and sometimes better than the pea proteins, thus suggesting that they could be promising options for the development of novel fining agents.

Different physicochemical interactions between varietal wines and human saliva: Correspondence with astringency

Astringency corresponds to the sensation of dryness and roughness that is experienced in the oral cavity in association with the interaction between salivary proteins and food polyphenols. In this study, the phenolic composition of seven varietal wines, the intensity of astringency they evoke and the physicochemical reactivity of these wines with whole human saliva were evaluated. Phenolic composition of wines was characterized by spectrophotometry and HPLC chromatography. Intensity of astringency was evaluated by trained sensory panels. Saliva from a single volunteer subject was used to assess wine-saliva interactions. To this end, binary mixtures were produced at different v/v wine/saliva ratios and each of them assayed for the ability of the salivary protein to diffuse on a cellulose membrane (diffusion test) and to remain in solution (precipitation test). Physicochemical reactivities between wine components and the protein fraction of saliva were contrasted against the astringency and the phenolic profile of each varietal wine. The study supports the view that astringency depends on physicochemical interactions between two complex matrices -wine and saliva- and not between some of their particular components.

Enhanced Polyphenols Recovery from Grape Pomace: A Comparison of Pressurized and Atmospheric Extractions with Deep Eutectic Solvent Aqueous Mixtures

Deep eutectic solvents (DES) are emerging as potent polyphenol extractors under normal atmospheric conditions. Yet, their effectiveness in hot pressurized liquid extraction (HPLE) must be studied more. We explored the ability of various water/DES and water/hydrogen bond donors (HBDs) mixtures in both atmospheric solid liquid extraction (ASLE) and HPLE (50%, 90 °C) for isolating specific polyphenol families from Carménère grape pomace. We assessed extraction yields based on total polyphenols, antioxidant capacity, and recovery of targeted polyphenols. The HBDs ethylene glycol and glycerol outperformed DES in atmospheric and pressurized extractions. Ethylene glycol exhibited a higher affinity for phenolic acids and flavonols, while flavanols preferred glycerol. Quantum chemical computations indicated that a high-water content in DES mixtures led to the formation of new hydrogen bonds, thereby reducing polyphenol-solvent interactions. HPLE was found to be superior to ASLE across all tested solvents. The elevated pressure in HPLE has caused significant improvement in the recovery of flavanols (17-89%), phenolic acids (17-1000%), and flavonols (81-258%). Scanning electron microscopy analysis of post-extraction residues suggested that high pressures collapse the plant matrix, thus easing polyphenol release.

Chemical Diversity of Flavan-3-Ols in Grape Seeds: Modulating Factors and Quality Requirements

Grape seeds are a rich source of flavan-3-ol monomers, oligomers, and polymers. The diverse profile of compounds includes mainly B-type procyanidins (especially C4→C8 linked molecules) and the key monomers, catechin, and epicatechin that are positively implicated in the 'French Paradox'. Today grape seed nutraceuticals have become a multi-million-dollar industry. This has created incentives to elucidate the variations in chemistry across cultivars, to identify signs of adulteration, and to understand the intrinsic and extrinsic factors controlling the expression of metabolites in the seeds' metabolome. This review provides a critical overview of the existing literature on grape seed chemistry. Although the biosynthetic pathways for polymeric procyanidins in seeds have not yet been explained, abiotic factors have been shown to modulate associated genes. Research of extrinsic factors has demonstrated that the control of procyanidin expression is strongly influenced, in order of importance, by genotype (species first, then variety) and environment, as claimed anecdotally. Unfortunately, research outcomes on the effects of abiotic factors have low certainty, because effects can be specific to genotype or variety, and there is limited control over physical metrics in the field. Thus, to gain a fuller understanding of the effects of abiotic factors and biosynthetic pathways, and realise potential for optimisation, a more fundamental research approach is needed. Nevertheless, the current synthesis offers insight into the selection of species or varieties according to the profile of polyphenols, as well as for optimisation of horticultural practices, with a view to produce products that contain the compounds that support health claims.

Improved hemocompatibility for gelatin-graphene oxide composite aerogels reinforced with proanthocyanidins for wound dressing applications

Aerogels based on gelatin and graphene oxide (GO) were synthesized by microwave-assisted reactions, incorporating grape skin extracts -high in proanthocyanidins (PAs)- to develop a hemostatic device with improved properties. The effects of incorporating PAs into the aerogels were investigated in relation to their physicochemical properties, absorption ability, clotting activity and cytotoxicity in human dermal fibroblast (HDF) cells. The aerogels presented highly resistant porous structures, capable of absorbing more than 50 times their weight when in contact with a phosphate saline solution (PBS) and fresh human blood. Interestingly, the addition of PAs increased the negative surface charges and the blood absorption ability of the aerogels, which may make them suitable for hemostasis. The incorporation of 5% and 10% (w/w) of extracts into the aerogels increased the total coagulated blood content by 36.6% and 24.5% compared with gelatin-GO aerogel, respectively. These improvements in the hemostatic properties of the aerogels were greater with the inclusion of 5% (w/w) of grape skin extracts into the aerogels. The aerogels were also able to adhere red blood cells onto their surfaces, which could favor the formation of stable fibrin networks to promote hemostasis. Their clotting activity suggested the activation of alternative routes based on complement coagulation systems. Finally, the aerogels were non-toxic for HDF cells and the PAs were successfully released from their matrices. Thus, gelatin-GO aerogels reinforced with PAs are promising as topical phytodrug delivery systems, with great potential for wound healing processes.

Chemical Properties of Vitis Vinifera Carménère Pomace Extracts Obtained by Hot Pressurized Liquid Extraction, and Their Inhibitory Effect on Type 2 Diabetes Mellitus Related Enzymes

Grape pomace polyphenols inhibit Type 2 Diabetes Mellitus (T2DM)-related enzymes, reinforcing their sustainable recovery to be used as an alternative to the synthetic drug acarbose. Protic co-solvents (ethanol 15% and glycerol 15%) were evaluated in the hot pressurized liquid extraction (HPLE) of Carménère pomace at 90, 120, and 150 °C in order to obtain extracts rich in monomers and oligomers of procyanidins with high antioxidant capacities and inhibitory effects on α-amylase and α-glucosidase. The higher the HPLE temperature (from 90 °C to 150 °C) the higher the total polyphenol content (~79%, ~83%, and ~143% for water-ethanol, water-glycerol and pure water, respectively) and antioxidant capacity of the extracts (Oxygen Radical Absorbance Capacity, ORAC), increased by ~26%, 27% and 13%, while the half maximal inhibitory concentration (IC₅₀) decreased by ~65%, 67%, and 59% for water-ethanol, water-glycerol, and pure water extracts, respectively). Water-glycerol HPLE at 150 and 120 °C recovered the highest amounts of monomers (99, 421, and 112 µg/g dw of phenolic acids, flavanols, and flavonols, respectively) and dimers of procyanidins (65 and 87 µg/g dw of B1 and B2, respectively). At 90 °C, the water-ethanol mixture extracted the highest amounts of procyanidin trimers (13 and 49 µg/g dw of C1 and B2, respectively) and procyanidin tetramers of B2 di-O-gallate (13 µg/g dw). Among the Carménère pomace extracts analyzed in this study, 1000 µg/mL of the water-ethanol extract obtained, at 90 °C, reduced differentially the α-amylase (56%) and α-glucosidase (98%) activities. At the same concentration, acarbose inhibited 56% of α-amylase and 73% of α-glucosidase activities; thus, our grape HPLE extracts can be considered a good inhibitor compared to the synthetic drug.

Metabolic elicitors of Pseudomonas fluorescens N 21.4 elicit flavonoid metabolism in blackberry fruit

BACKGROUND

The beneficial rhizobacterium, Pseudomonas fluorescens N 21.4, and its metabolic elicitors were inoculated in commercial cultivars of blackberry plants (Rubus cv. Loch Ness). Phenolic compounds present in red and black fruit and the expression of structural marker genes of the phenylpropanoid pathway during fruit ripening were studied.

RESULTS

An inverse relationship between gene expression and accumulation of metabolites was seen, except for the RuDFR gene, which had a direct correlation with cyanidin 3-O-glucoside synthesis, increasing its content 1.3 times when RuDFR was overexpressed in the red fruit of plants inoculated with the metabolic elicitors of P. fluorescens N 21.4, compared with red fruit of plants inoculated with N 21.4. The RuCHS gene also had a fundamental role in the accumulation of metabolites. Both rhizobacterium and metabolic elicitors triggered the flavonoid metabolism, enhancing the catechin and epicatechin content between 1.1 and 1.6 times in the case of red fruit and between 1.1 and 1.8 times in the case of black fruit. Both treatments also boosted the anthocyanin, quercetin, and kaempferol derivative content, highlighting the effects of metabolic elicitors in red fruit and the effects of live rhizobacterium in black fruit.

CONCLUSION

The metabolic elicitors' capacity to modulate gene expression and to increase secondary metabolites content was demonstrated. This work therefore suggests that they are effective, affordable, easily manageable, and ecofriendly plant inoculants that complement, or are alternatives to, beneficial rhizobacteria. © 2020 Society of Chemical Industry.

How does water stress affect the low molecular weight phenolics of hydroSOStainable almonds?

Water scarcity is a threat for food production because, water, is more and more limited and force farmers to use new deficit irrigation (DI) strategies without affecting fruit yield and quality. No information exists on almond polyphenols and proanthocyanidins (PAs) produced under DI. The present work studied the effect of 2 regulated DI (RDI) and one sustained (SDI) on the low molecular weight phenolics together with the antioxidant activity (AA) in almonds. Fifteen phenolic compounds were identified (13 flavonoids and 2 non-flavonoids) and 10 PAs. Kaempferol-3-O-galactoside was the predominant compound in almond skin and whole kernel but it was not found in deskinned kernels. The use of moderate RDI significantly increased the total phenolic content in skin (∼9.8%), PAs, and the AA. Consequently, after one season the application of DI positively affected the almond cv. Vairo phenols, however, several seasons must be evaluated in order to corroborate the present results.

Effect of extraction time on content, composition and sensory perception of proanthocyanidins in wine-like medium and during industrial fermentation of Cabernet Sauvignon

BACKGROUND

The research objectives focused on the extraction of grape tannins during extended maceration. Skins and seeds were extracted separately in a wine-like medium. In parallel, the same grapes were fermented in industrial tanks. The content and structural characteristics of extractable proanthocyanidins (PAs) were determined spectrophotometrically and using UHPLC-DAD-MS/MS, respectively. Skin, seed extracts and fermented wines were characterized in chemical and sensorial terms after different extraction durations.

RESULTS

The extraction of high molecular-weight PAs (HMWPs) from seeds increased for up to 20 days, whereas low molecular-weight PAs (LMWPs) reached a plateau earlier. The extraction of HMWPs and LMWPs from skins reached a maximum at the first sampling. Sensory evaluation confirmed greater astringency and bitterness of seed extracts with increasing time. Neither seed nor skin extracts differed statistically in terms of the mean degree of polymerization (mDP) and percentage of galloylation (%G) on different extraction days (except for seeds at the first sampling). During industrial maceration, HMWPs and LMWPs increased up to 12.7% alcohol (9 days of maceration); thereafter, the increase was not significant, whereas the mDP, %G and percentage of prodelphinidins did not significantly change after 11.4% alcohol. There were positive correlations with the wine astringency and PA content.

CONCLUSION

Looking at both simulated and industrial maceration, it can be concluded that, with a longer maceration time, the increase in HMWP content was more evident than PA structural changes. The increasing content of tannins from seeds played an important role in the greater astringency and bitterness of Cabernet Sauvignon macerated at length. © 2019 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Glycerol as Alternative Co-Solvent for Water Extraction of Polyphenols from Carménère Pomace: Hot Pressurized Liquid Extraction and Computational Chemistry Calculations

Glycerol is a co-solvent for water extraction that has been shown to be highly effective for obtaining polyphenol extracts under atmospheric conditions. However, its efficacy under subcritical conditions has not yet been studied. We assessed different water-glycerol mixtures (15%, 32.5%, and 50%) in a hot pressurized liquid extraction system (HPLE: 10 MPa) at 90 °C, 120 °C, and 150 °C to obtain extracts of low molecular weight polyphenols from Carménère grape pomace. Under the same extraction conditions, glycerol as a co-solvent achieved significantly higher yields in polyphenols than ethanol. Optimal extraction conditions were 150 °C, with 32.5% glycerol for flavonols and 50% for flavanols, stilbenes, and phenolic acids. Considering gallic acid as a model molecule, computational chemistry calculations were applied to explain some unusual extraction outcomes. Furthermore, glycerol, methanol, ethanol, and ethylene glycol were studied to establish an incipient structure-property relationship. The high extraction yields of gallic acid obtained with water and glycerol solvent mixtures can be explained not only by the additional hydrogen bonds between glycerol and gallic acid as compared with the other alcohols, but also because the third hydroxyl group allows the formation of a three-centered hydrogen bond, which intensifies the strongest glycerol and gallic acid hydrogen bond. The above occurs both in neutral and deprotonated gallic acid. Consequently, glycerol confers to the extraction solvent a higher solvation energy of polyphenols than ethanol.

Role of anthocyanin traits on the impact of oenological tannins addition in the first stage of red winegrape skin simulated maceration

In winemaking, exogenous tannins are added before maceration to improve future wine color characteristics derived from extracted grape anthocyanins. The study aimed to investigate the relation between different grape varieties, selected according to their anthocyanin profile, and the effect of five exogenous tannin formulations differing in origin and chemical features. Anthocyanin content, polymeric pigments, and color traits were assessed during a 72-hour skin simulated maceration. Grape skin-derived tannins increased color intensity (up to one unit) and polymeric pigments formation (up to 6.5%) in malvidin-prevalent Merlot and Cabernet sauvignon, with different extent depending on the anthocyanin richness. Grape seed-derived and ellagic formulations favored the pigment polymerization, the first in Nebbiolo and Sangiovese (up to 8.2%), which are characterized by high ratios of disubstituted anthocyanins, and the latter in malvidin-rich Syrah and Aglianico (up to 5%). A positive effect of quebracho regarded the defense of anthocyanin forms, particularly in Sangiovese and Nebbiolo.

Design and Characterization of Chitosan-Graphene Oxide Nanocomposites for the Delivery of Proanthocyanidins

Introduction

In the last years, the utilization of phytomedicines has increased given their good therapeutic activity and fewer side effects compared to allopathic medicines. However, concerns associated with the biocompatibility and toxicity of natural compounds, limit the phytochemical therapeutic action, opening the opportunity to develop new systems that will be able to effectively deliver these substances. This study has developed a nanocomposite of chitosan (CS) functionalized with graphene oxide (GO) for the delivery of proanthocyanidins (PAs), obtained from a grape seed extract (Ext.).

Methods

The GO-CS nanocomposite was covalently bonded and was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM) and by dynamic light scattering (DLS). The loading and release of Ext. from the GO-CS nanocomposite were performed in simulated physiological, and the cytotoxicity of the raw materials (GO and Ext.) and nanocomposites (GO-CS and GO-CS-Ext.) was determined using a human kidney cell line (HEK 293).

Results

The chemical characterization indicated that the covalent union was successfully achieved between the GO and CS, with 44 wt. % CS in the nanocomposite. The GO-CS nanocomposite was thermostable and presented an average diameter of 480 nm (by DLS). The Ext. loading capacity was approximately 20 wt. %, and under simulated physiological conditions, 28.4 wt.% Ext. (g) was released per g of the nanocomposite. GO-CS-Ext. was noncytotoxic, presenting a 97% survival rate compared with 11% for the raw extract and 48% for the GO-CS nanocomposite at a concentration of 500 µg mL-1 after 24 hrs.

Conclusion

Due to π–π stacking and hydrophilic interactions, GO-CS was reasonably efficient in binding Ext., with high loading capacity and Ext. release from the nanocomposite. The GO-CS nanocomposite also increased the biocompatibility of PAs-rich Ext., representing a new platform for the sustained release of phytodrugs.

Grape Flavonoid Evolution and Composition Under Altered Light and Temperature Conditions in Cabernet Sauvignon (Vitis vinifera L.)

The evolution of flavonoids under altered temperature and light conditions in the fruit zone was followed in Cabernet Sauvignon (Vitis vinifera L.) grapes during ripening. The study was conducted over two consecutive seasons in 2010/2011 and 2011/2012 comprising two main treatments in which the light quantity was manipulated in the bunch zone: (1) standard (STD) with no lateral shoot or leaf removal and (2) leaf removal west (LRW) treatment with leaf removal on the western side of the bunch zone. Furthermore, the light quality was altered by installing ultraviolet B-suppression sheets within the bunch zone in both seasons. Tannin evolution was dependent on the prevailing light quality/quantity and temperatures during berry development in a particular season. Grape seed tannin accumulation coincided with seed development and commenced at the early stages of berry development. Seed proanthocyanidin composition was not influenced by the treatments. The largest impact on proanthocyanidin accumulation and structure in the skin was due to seasonal variations highlighting the complex interaction between light quality and/or quantity across the two growing seasons and eventually the complex interaction with temperature. Flavonol accumulation was significantly influenced by the light quality, which is known to be the main abiotic driver of flavonol biosynthesis regulation. Anthocyanin concentration and content were largely dependent on the temperature and light quality in a particular season. Anthocyanin composition was altered by the season rather than the treatment.

Diploid Genome Assembly of the Wine Grape Carménère

In this genome report, we describe the sequencing and annotation of the genome of the wine grape Carménère (clone 02, VCR-702). Long considered extinct, this old French wine grape variety is now cultivated mostly in Chile where it was imported in the 1850s just before the European phylloxera epidemic. Genomic DNA was sequenced using Single Molecule Real Time technology and assembled with FALCON-Unzip, a diploid-aware assembly pipeline. To optimize the contiguity and completeness of the assembly, we tested about a thousand combinations of assembly parameters, sequencing coverage, error correction and repeat masking methods. The final scaffolds provide a complete and phased representation of the diploid genome of this wine grape. Comparison of the two haplotypes revealed numerous heterozygous variants, including loss-of-function ones, some of which in genes associated with polyphenol biosynthesis. Comparisons with other publicly available grape genomes and transcriptomes showed the impact of structural variation on gene content differences between Carménère and other wine grape cultivars. Among the putative cultivar-specific genes, we identified genes potentially involved in aroma production and stress responses. The genome assembly of Carménère expands the representation of the genomic variability in grapes and will enable studies that aim to understand its distinctive organoleptic and agronomical features and assess its still elusive extant genetic variability. A genome browser for Carménère, its annotation, and an associated blast tool are available at http://cantulab.github.io/data.

Maximizing Polyphenol Content to Uncork the Relationship Between Wine and Cancer

Studies have revealed conflicting results regarding the risk of cancer from alcohol consumption. Furthermore, some studies have suggested that wine may have benefits that separate it from other alcoholic beverages. As wine contains a significant amount of chemicals, specifically polyphenols like anthocyanins and proanthocyanidins (PA), that can affect cellular function and promote health, this hypothesis is reasonably supported by recent research. Polyphenols promote several anticancer cellular pathways, including xenobiotic metabolism, support of innate antioxidant production, and stimulation of phase I and II detoxification of carcinogens. However, the multitude of growing and production conditions of grapes, including temperature, water availability, soil type, maceration, and aging can result in a remarkably varying final product based on the available literature. Thus, we hypothesize that wines produced from grapes cultivated between steady daily temperatures at 15–25°C with moderate sun exposure from flowering to harvest, lower vine-water status, resulting either from lower precipitation, and irrigation practices or more permeable soil types, limitation of fertilizers, extended maceration, and aging in oak will impact the concentration of anthocyanins and PA in the finished wine and may have a differential impact on cancer. This higher concentration of polyphenols would, in theory, create a healthier wine, thus explaining the conflicting reports on the benefits or harms of wine.

Estimation of polyphenols by using HPLC-DAD in red and white wine grape varieties grown under tropical conditions of India

Grapes are well known for their high content of phenolic compounds. Polyphenols are classified into flavonoids and non-flavonoids by their primary chemical structures of hydroxybenzene. Flavonoids mainly consist of anthocyanins, flavonoids, and flavonols whereas non-flavonoids include hydroxycinnamic and hydroxybenzoic acids. In the present study, sixteen phenolic compounds from ten red and nine white grape wine varieties were quantified using high-performance liquid chromatography. Gallic acid, Vanillic acid, Rutin hydrate, Ellagic acid, Chlorogenic acid, Sorbic acid, Catechin hydrate, Epicatechin, p-coumaric acid, Quercetin, Myricetin, Kaempferol, Piceatannol, and Resveratrol were major compounds found in red wine grapes. Among the varieties, Petit Verdot, Cabernet Franc showed maximum quantitative phenolics, whereas Cabernet Sauvignon, Niellucio, Cinsaut, and Syrah showed least quantitative phenolics in grape berries. Phenolic profile of white wine grapes showed lower concentration of phenolics than that of red wine grapes. The variety Gros Meseng showed maximum phenolics followed by Sauvignon, while the variety Colombard and Chenin Blanc showed least phenolics.

Modeling of the Nanoparticles Absorption Under a Gastrointestinal Simulated Ambient Condition

Proanthocyanidins (PAs) have several bioactivities, but they are unstable in the digestive tract and possess low bioavailability. Nanoencapsulation stabilizes these compounds for oral administration. The intestinal absorption of grape seed and skin extracts, and the poly-lactic acid (PLA) nanoparticles loaded with such extracts was modeled, taking into consideration physicochemical process parameters, evaluating the PAs concentration profile in the human small intestine. Density (ρ), solubility, viscosity (μ), diffusion coefficient (D), and the global mass transfer coefficient (K) for both substrates were estimated, simulating their passing from the intestine into the blood at 37°C. For the seed and skin extracts encapsulated in PLA the physicochemical parameters were: D = 1.81 × 10^^-5 and D = 5.72 × 10^^-5 cm²/s; K = 3.4 × 10^^-3 and K = 2.47 × 10^^-4 cm/s, respectively. Lower resistance was offered by the seed extract than by skin extracts (nanoencapsulated), which was explained by differences in structural composition, and average molecular weight of the two kinds of extracts, which should be more favorable to the mass transfer in comparison to the raw extracts. The concentration profile of grape extracts in the small intestine was modeled through a pure convection model, and the encapsulated extract on PLA nanoparticles using a mixed regime model, which described the process of dissolution and absorption of the grape extracts from the intestine to the blood stream. The absorbed fraction predicted by the model was 42.7 and 24.2% for seed and skin extracts, respectively. Those values increased to 100% for both extracts after the simulation with the nanoencapsulated extracts. Consequently, extract encapsulation should produce a significant increase in intestinal absorption.

Polyphenols of Carménère Grapes

Carménère is the emblematic grape of Chile. Recent studies indicate that it has a different polyphenolic profile than other commercial varieties of grape among other factors, due to its long maturation period. The grape and wine of Carménère stand out for having high concentrations of anthocyanins (malvidin), flavonols (quercetin and myricetin) and flavanols (catechin, epicatechin and epigallocatechin). These compounds are related to the distinctive characteristic of Carménère wine regarding astringency and color. In vivo and in vitro models suggest some positive effects of these polyphenols in the treatment and prevention of chronic diseases, such as atherosclerosis and cancer. Therefore, there is a high level of interest to develop scalable industrial methods in order to obtain and purify Carménère grape polyphenol extracts that could be used to improve the characteristics of wines from other varieties or produce nutraceuticals or functional foods for preventing and treating various chronic diseases.

Comparison of Aquitaine and Rioja Red Wines: Characterization of Their Phenolic Composition and Evolution from 2000 to 2013

Wine chemical analysis was carried out on 194 commercial blended red wines produced by two major wine-growing areas—the Aquitaine (France) and Rioja (Spain) regions—in order to compare the wines of both regions. Anthocyanins and derived pigments, tannins and derivatives were identified and quantified by HPLC-DAD-ESI-MS/MS (high pressure liquid chromatography coupled to diode array detector and mass spectrometry using the electrospray ionization interface). Mean degree of polymerization (mDP) was determined. The influence of the wine-growing region and the predominance of the properties of some grape varieties used are confirmed by the significant differences observed between both regions. Rioja and Bordeaux “generic” (Bordeaux and Bordeaux-Supérieur appellations) red wines showed the highest anthocyanic content and the highest mDP, as these wines are in a majority made from Merlot (Bordeaux “generic”) and Tempranillo (Rioja). On the contrary, Bordeaux “specific” regions (Blayais, Médoc, Graves, and Libournais) showed the red wines with the highest total phenolic content and tannin concentration, as the predominant grape variety used is Cabernet Sauvignon. A principal component analysis (PCA) and a hierarchical ascendant classification (HAC) suggesting patterns between the chemical parameters and the distribution of the red wines in three groups were proposed. The comparison of the two wine-growing areas also reveals some similarities between the various grape varieties used. A general effect of a progressive decrease in anthocyanins, anthocyanin-derived pigment and tannins is observed for older wines.

Characterization of polyphenols and antioxidant potential of white grape pomace byproducts (Vitis vinifera L.)

A detailed assessment of the total phenolic and total tannin contents, the monomeric and oligomeric flavan-3-ol composition, the proanthocyanidin profile, and the antioxidant potential of the grape pomace byproducts (considered as a whole, both skins and seeds), derived from four white grape varieties (Vitis vinifera L.), was performed. Significant differences (p < 0.05) of the total phenolic content, total tannin content, and antioxidant capacity of grape pomace byproducts were observed among the different grape varieties studied. For the first time in the literature, the particular flavan-3-ol composition of the four grape varieties investigated was described for the whole fraction of their grape pomace byproducts. The phenolic composition and antioxidant capacity of grape pomaces were compared to those of their corresponding stems. The global characterization of these white grape varieties provided a basis for an integrated exploitation of both winemaking byproducts as potential, inexpensive, and easily available sources of bioactive compounds for the pharmaceutical, cosmetic, and food industries.

Taste and mouthfeel properties of red wines proanthocyanidins and their relation to the chemical composition

The aim of this work is to assess the relationship between the in-mouth sensory properties of proanthocyanidins (PAs) and its chemical composition. To achieve such a goal, the proanthocyanidin fraction from six different young commercial red wines was obtained by gel permeation chromatography. A sensory panel, selected on the basis of their PROP status and trained in taste and mouthfeel sensations, described both the wines and fractions. MALDI-TOF-MS and UPLC-MS were used to identify thoroughly the polyphenolic composition of each proanthocyanidin fraction. The results showed that the PAs fractions were exclusively described as astringent and persistent. The astringent subqualities studied (velvety and puckering/drying) were mainly related to the quantity of proanthocyanidins and the proportion of the extension flavanol units linked to proanthocyanidins. A significant negative correlation was found between both of the astringencies (velvety and puckering/drying). Furthermore, both subqualities appeared to contribute to the persistence. A significant correlation was observed between the astringency and the persistence data of the wines and fractions. Significant multiple linear regressions were found between the sensory astringency data and the chemical compounds analyzed. The concentration of proanthocyanidins present in young red wines is the major determinant of the differences perceived in the astringency. Additionally, the extension flavanol units linked to the proanthocyanidins seem to have a different impact on the astringent subqualities.

Relationship between the sensory-determined astringency and the flavanolic composition of red wines

The relationship between the proanthocyanidin profile and the perceived astringency was assessed in 13 commercial Tempranillo red wines. The concentration and compositional information were obtained by liquid chromatography with diode array detection coupled to electrospray ionization mass spectrometry after acid-catalyzed depolymerization of wine proanthocyanidins in the presence of excess phloroglucinol. Statistical analysis of the results showed significant correlations between sensory and chemical determinations. Astringency was more affected by the subunit composition than by the total concentration or the average degree of polymerization of wine proanthocyanidins. Higher proportions of epicatechin (EC) subunits in extension positions and gallocatechin (GC) subunits in terminal positions were shown to increase astringency. On the contrary, the amount of epigallocatechin (EGC) in both extension and terminal positions was negatively correlated with the perceived astringency.

Detailed characterization of proanthocyanidins in skin, seeds, and wine of Shiraz and Cabernet Sauvignon wine grapes (Vitis vinifera)

The distribution of proanthocyanidin (PA) polymer lengths, proanthocyanidin concentration at each polymer length, and polymer composition were determined in the seed, skin, and wine of Shiraz and Cabernet Sauvignon grape berries grown in southeast Australia. PA was fractionated by semipreparative high performance liquid chromatography (HPLC) and analyzed by phloroglucinolysis and HPLC to report the degree of polymerization (DP), concentration, and composition at 11 DP values in seed and wine and 21 DP values in skin. In skin, the highest PA concentration was observed at a DP of 31 in Shiraz and 29 in Cabernet Sauvignon representing 15% of the total PA in both varieties. The distribution of seed PA had the highest concentration at a DP of 7 in Shiraz and 6 in Cabernet Sauvignon representing around 30% of the total PA. In the wine PA distribution, the highest concentration was observed at a DP of 11 in Shiraz and 9 in Cabernet Sauvignon representing around 26 and 32% of the distribution, respectively. A second peak in wine PA concentration was observed at the largest DP of 18 in Shiraz and 15 in Cabernet Sauvignon representing around 20% of the distribution. The composition in wine did not vary at different DP, but the proportion of epicatechin gallate varied in seed PA less than 4 DP. The proportion of epigallocatechin increased with increasing DP in skin PA. Wine PA had a DP range and composition similar to the distribution of skin PA between DP 4 and 18 suggesting that larger skin PAs are not extracted into wine. This study provides information that could be used to target the important PA fractions in grapes that need to be measured to understand (or predict) PA extraction into wine and eventual mouthfeel.

Phenolics composition and antioxidant activity of wine produced from spine grape (Vitis davidii Foex) and Cherokee rose (Rosa laevigata Michx.) fruits from South China

Wines made from 3 spine grape (Vitis davidii Foex) genotypes-Junzi 1# (JZ 1#), Junzi 2# (JZ 2#), and Liantang (LT)-and Cherokee rose (Rosa laevigata Michx., CR) were evaluated for their phenolics composition and antioxidant activities by several assays, including 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS scavenging capacity, cupric ion reducing antioxidant capacity, and metal-chelating capacity). The results showed that CR wine had higher contents of total phenolics, total flavonoids, and oligomeric proanthocyanidins than the 3 spine grape genotype wines and Cabernet Sauvignon (CS) wine. Among the 3 varieties of spine grape wines, JZ 1# had higher contents than the 2 other genotypes. Moreover, the total monomeric anthocyanins in JZ 1# was about 4.5-fold higher than those in CS wine and CR wine. A significance analysis demonstrated that the antioxidant capacity (as measured by the ABTS scavenging capacity and cupric ion reducing antioxidant capacity) of CR wine was significantly higher than that of the control and spine grape wines. With respect to metal-chelating capacity, the CR wine was the strongest amongst all the wine samples tested, followed by JZ 1#. This indicates that CR and JZ 1# wines can potentially be considered as wild fruit wines with abundant phenolic compounds and antioxidant activities.

PRACTICAL APPLICATION

Spine grape (Vitis davidii Foex) and Cherokee rose (Rosa laevigata Michx.) are 2 species of important wild plants in South China. However, they have not yet been effectively developed and utilized. Recently, some researchers attempted to convert their juice to wine. We anticipate that this research will provide sufficient experimental evidence for their good antioxidant activity and potential for further development and utilization.

Relationship between red wine grade and phenolics. 2. Tannin composition and size

Commercial red wines ( Vitis vinifera L. cv. Shiraz) produced during the 2009 vintage underwent winemaker assessment for allocation grade soon after production. The wines were then subjected to phenolic analysis to measure wine color (total anthocyanin, SO(2) nonbleachable pigment, and wine color density) and tannins (concentration, composition, and average degree of polymerization). A positive relationship was found between wine phenolic concentration and projected bottle price. Tannin compositional analysis suggested that there was specifically a relationship between wine grade and skin-derived tannins. These results suggest that maximization of skin tannin concentration and/or proportion is related to an increase in projected wine bottle price.

Chemical and sensory evaluation of Bordeaux wines (Cabernet-Sauvignon and Merlot) and correlation with wine age

Wine quality study was carried out with 24 vintages of Cabernet-Sauvignon (CS) and 7 vintages of Merlot (M) produced by two different Bordeaux wine-growing areas. Proanthocyanidin monomers and oligomers were identified and quantified by HPLC-UV-Fluo. Percentage of galloylation (%G), of prodelphinidins (%P) as well as mean degree of polymerisation (mDP) were also determined. Total phenolic compounds, total anthocyanins, total tannins, hue, CI (colour intensity), titratable acidity, ethanol level and pH were evaluated. Sensory analysis concerning astringency and bitterness intensity was also performed. Total phenolic compounds, total anthocyanins, total tannins, tannin monomers, hue, CI, % G, % P, mDP and astringency intensity differentiate both wines (M and CS) according to vintage. Correlations between wine age and: mDP, hue, astringency and tannin monomers (C+EC) are obtained. Qualitative tannin characterisation is established by correlation between astringency and mDP (R(2)=0.509, p=0.051, CS; R(2)=0.780, p=0.000M). In addition, mDP decreases significantly during ageing (R(2)=0.796, p=0.000; CS and R(2)=0.946, p=0.000; M). Scale patterns between wine mDP and tannin perception (astringency) are proposed.

Comparative study of the phenolic composition of seeds and skins from Carménère and Cabernet Sauvignon grape varieties (Vitis vinifera L.) during ripening

The phenolic composition of skins and seeds from Vitis vinifera L. cv. Carménère and Cabernet Sauvignon grapes during ripening was evaluated by high-performance liquid chromatography-diode array detection and spectrophotometric analysis. As compared to Cabernet Sauvignon grape skins, Carménère grape skins presented higher contents of total anthocyanins, monomeric flavan-3-ols, and total flavonoids, a higher mean degree of polymerization, a higher percentage of galloylation, a higher average molecular weight of the flavanol fraction, and a higher color intensity. As compared to Cabernet Sauvignon grape seeds, Carménère grape seeds presented a lower content of monomeric flavan-3-ols, a higher mean degree of polymerization, a higher percentage of galloylation, a higher average molecular weight of the flavanol fraction, a lower content of (+)-catechin, and higher contents of (-)-epicatechin, epicatechin-3-O-gallate, gallic acid, and dimeric procyanidins esterified with gallic acid. Altogether, we conclude that Carménère grapes present a differential composition and evolution of phenolic compounds when compared to Cabernet Sauvignon grapes.

Grape skin and seed proanthocyanidins from Monastrell x Syrah grapes

In this study, the grape skin and seed proanthocyanidin profiles from Monastrell x Syrah grape (Vitis vinifera L.) crosses were determined. Concentration and compositional information in extracts was determined by reversed-phase HPLC after acid-catalyzed cleavage in the presence of excess phloroglucinol. In general, the proanthocyanidin compositions of crosses were qualitatively similar to those of Monastrell and Syrah, but, quantitatively, differences were observed. Consistent with transgressive segregation, the proanthocyanidin concentration in some crosses exceeded that in either parent. To the best of the authors' knowledge, this is the first study to provide information on the inheritance of proanthocyanidin features from V. vinifera cultivars. The overall objective of this study is to develop new varieties that are well-adapted to our agro-ecological conditions, as Monastrell is, and with a proanthocyanidin profile that will result in high-quality wines.

Proteomic and selected metabolite analysis of grape berry tissues under well-watered and water-deficit stress conditions

In order to investigate the unique contribution of individual wine grape (Vitis vinifera) berry tissues and water-deficit to wine quality traits, a survey of tissue-specific differences in protein and selected metabolites was conducted using pericarp (skin and pulp) and seeds of berries from vines grown under well-watered and water-deficit stress conditions. Of 1047 proteins surveyed from pericarp by 2-D PAGE, 90 identified proteins showed differential expression between the skin and pulp. Of 695 proteins surveyed from seed tissue, 163 were identified and revealed that the seed and pericarp proteomes were nearly completely distinct from one another. Water-deficit stress altered the abundance of approximately 7% of pericarp proteins, but had little effect on seed protein expression. Comparison of protein and available mRNA expression patterns showed that 32% pericarp and 69% seed proteins exhibited similar quantitative expression patterns indicating that protein accumulation patterns are strongly influenced by post-transcriptional processes. About half of the 32 metabolites surveyed showed tissue-specific differences in abundance with water-deficit stress affecting the accumulation of seven of these compounds. These results provide novel insights into the likely tissue-specific origins and the influence of water-deficit stress on the accumulation of key flavor and aroma compounds in wine.

Grape variety effect on proanthocyanidin composition and sensory perception of skin and seed tannin extracts from bordeaux wine grapes (Cabernet Sauvignon and Merlot) for two consecutive vintages (2006 and 2007)

Grape variety [Cabernet Sauvignon (CS) and Merlot (M)] effect on the proanthocyanidin composition and sensory perception of wine grapes from Bordeaux vineyards for two successive vintages (2006 and 2007) is reported. The flavan-3-ol monomers [(+)-catechin = C, (-)-epicatechin = EC, (-)-epicatechin-O-gallatte = ECG] and the proanthocyanidin oligomers [dimers B1, B2, B3, and B4 and trimer Cat-Cat-Epi (T)] in grape seed and skin tannin extracts were identified and quantified at harvest. Proanthocyanidin subunit compositions, percentage of galloylation (%G), and percentage of prodelphinidins (%P) as well as mean degree of polymerization (mDP) of the proanthocyanidin fraction were determined. Sensory analysis concerning the astringency and bitterness intensity of the proanthocyanidins of skin and seed tannin extracts was also performed. The results showed that proanthocyanidin composition can be greatly affected by grape variety. For both vintages between CS and M, significant differences were found on mDP (p < 0.05) in seed tannin extracts, whereas in skin tannin extracts, significant differences were observed for %G and %P (p < 0.05). Sensory analysis showed that grape variety influenced neither astringency nor bitterness intensity perception for both skin and seed tannin extracts for the two successive vintages studied. A positive correlation was found between astringency intensity, mDP, and B3 content in skin tannin extracts.

Chemical synthesis of proanthocyanidins in vitro and their reactions in aging wines

Proanthocyanidins are present in many fruits and plant products like grapes and wine, and contribute to their taste and health benefits. In the past decades of years, substantial progresses has been achieved in the identification of composition and structure of proanthocyanidins, but the debate concerning the existence of an enzymatic or nonenzymatic mechanism for proanthocyanidin condensation still goes on. Substantial attention has been paid to elucidating the potential mechanism of formation by means of biomimetic and chemical synthesis in vitro. The present paper aims at summarizing the research status on chemical synthesis of proanthocyanidins, including non-enzymatic synthesis of proanthocyanidin precursors, chemical synthesis of proanthocyanidins with direct condensation of flavanols and stereoselective synthesis of proanthocyanidins. Proanthocyanidin-involved reactions in aging wines are also reviewed such as direct and indirect reactions among proanthocyanidins, flavanols and anthocyanins. Topics for future research in this field are also put forward in this paper.

Berry integrity and extraction of skin and seed proanthocyanidins during red wine fermentation

In this study, microscale fermentations were conducted on Vitis vinifera L. cv. Merlot. Five treatments were established varying from 0-100% crushed fruit (25% increments x 5 replicates). Caps were kept submerged throughout the experiment, and fermentation temperatures were maintained at 25 degrees C. Samples were collected throughout fermentation and from the free run and press wine at the time of pressing. Proanthocyanidins were determined by acid-catalyzed depolymerization in the presence of phloroglucinol, followed by reversed phase, high performance liquid chromatography (RP-HPLC). Total proanthocyanidin extraction increased with time in all treatments. In addition, crushing increased the rate at which proanthocyanidins were extracted. When the extraction of skin and seed proanthocyanidins were monitored separately, skin proanthocyanidin extraction rate exceeded that for seed proanthocyanidins and followed a Boltzmann sigmoid extraction model. The highest proanthocyanidin concentration for skin (435 mg/L) and seed (344 mg/L) was observed for the 75% crushed fruit treatment at the time of pressing (17 days). The highest skin proanthocyanidin proportion (79%) was observed for the 75% crushed fruit treatment on day 9 with a total proanthocyanidin concentration of 439 mg/L. For all treatments, skin proanthocyanidin extraction reached a plateau concentration prior to pressing, with the plateau concentration increasing with crushing. Seed proanthocyanidin concentration increased throughout maceration.

Effect of micro-oxygenation on color and anthocyanin-related compounds of wines with different phenolic contents

Several factors may affect the results obtained when micro-oxygenation is applied to red wines, the most important being the moment of application, the doses of oxygen, and the wine phenolic characteristics. In this study, three red wines, made from Vitis vinifera var. Monastrell (2005 vintage) and with different phenolic characteristics, were micro-oxygenated to determine as to how this technique affected the formation of new pigments in the wines and their chromatic characteristics. The results indicated that the different wines were differently affected by micro-oxygenation. In general, the micro-oxygenated wines had a higher percentage of new anthocyanin-derived pigments, being that this formation is more favored in the wines with the highest total phenol content. These compounds, in turn, significantly increased the wine color intensity. The wine with the lowest phenolic content was less influenced by micro-oxygenation, and the observed evolution in the degree of polymerization of tannins suggested that it might have suffered overoxygenation.