Grape Phenolics Research Articles

Metabolites Are Key to Understanding Health Effects of Wine Polyphenolics1–3

Phenolic compounds in grapes and wine are grouped within the following major classes: stilbenes, phenolic acids, ellagitannins, flavan-3-ols, anthocyanins, flavonols, and proanthocyanidins. Consumption of foods containing phenolic substances has been linked to beneficial effects toward chronic diseases such as coronary heart disease and colorectal cancer. However, such correlations need to be supported by in vivo testing and bioavailability studies are the first step in establishing cause and effect. Class members from all phenolic groups can be glucuronidated, sulfated, and/or methylated and detected at low concentrations in the bloodstream and in urine. But the majority of phenolic compounds from grapes and wine are metabolized in the gastrointestinal tract, where they are broken down by gut microflora. This typically involves deglycosylation, followed by breakdown of ring structures to produce phenolic acids and aldehydes. These metabolites can be detected in bloodstream, urine, and fecal samples by using sophisticated instrumentation methods for quantitation and identification at low concentrations. The health effects related to grape and wine consumption may well be due to these poorly understood phenolic acid metabolites. This review discusses the known metabolism of each major class of wine and grape phenolics, the means to measure them, and ideas for future investigations.

Chardonnay grape seed procyanidin extract supplementation prevents high‐fat diet‐induced obesity in hamsters by improving adipokine imbalance and oxidative stress markers

Studies reported the effects of polyphenols but not for grape polyphenols towards obesity. We analysed the effects of a polyphenolic grape seed extract (GSE) on obesity and oxidative stress in hamsters receiving a high-fat diet (HFD). Three groups of hamsters received a standard diet (STD), or a HFD plus a daily gavage with water (Control, HFD) or a solution of GSE (HFD + GSE) for 12 wk. Plasma glucose, triglycerides (TG), insulin, leptin and adiponectin were measured. Oxidative stress was assessed by cardiac production of superoxide anion and NAD(P)H oxidase expression. After 12 wk, HFD increased abdominal fat as compared with standards. GSE avoided this feature. HFD led to higher plasma glucose, TG, insulin and greater insulin resistance (HOMA-IR) values. GSE prevented in part these effects, reducing insulinemia and leptinemia by 16.5 and 45%, respectively, whereas adiponectin level increased by 61% compared with obese controls. GSE lowered glycemia and HOMA-IR and strongly prevented cardiac production of superoxide by 74% and NAD(P)H oxidase expression by 30%. This is the first time that chronic consumption of grape phenolics is shown to reduce obesity development and related metabolic pathways including adipokine secretion and oxidative stress.

Grape phenolic impregnation by osmotic treatment: Influence of osmotic agent on mass transfer and product characteristics

Osmotic treatment (OT) is applied to obtain high quality intermediate moisture products impregnated with particular solutes, for instance phenolics from commercial grape seed extracts. To investigate how the nature of osmo-active solutes affects mass transfer of grape phenolics in a solid model food, sucrose, sodium chloride and glycerol were used as osmo-active solutes. Mass transfer of total and individual grape phenolics of low molecular weight were characterized by the diffusional approach and Peleg’s model. Of all the osmo-active solutes investigated, sodium chloride led to the highest phenolic infusion rate for each individual phenolic analyzed. With all the osmo-active solutes, the non esterified flavan-3-ol monomers showed a higher initial rate of phenolic mass transfer (1 /k 1) than their corresponding gallate esters and flavan-3-ol dimers. The phenolic content in the osmo-treated model food was similar or higher than that of the richest fruits and vegetables in all the conditions tested, thus increasing the antioxidant capacity of the product.

Direct Formulation of a Solid Foodstuff with Phenolic-Rich Multicomponent Solutions from Grape Seed: Effects on Composition and Antioxidant Properties

The aim of our work was to supplement a solid foodstuff with grape phenolics by osmotic treatment with an aqueous solution made of osmo-active agents (NaCl and sucrose) and a commercial grape seed extract. To investigate how the composition of the osmotic solution affected phenolic infusion, experimental conditions were set by a central composite design with two factors (the molality of NaCl and sucrose in the osmotic solution). In all experiments, the total phenolic content in the osmotic solution was kept constant (6300 +/- 45 mg gallic acid equivalents/kg), and the model food (an agar-agar gel) was processed for 8 h. Throughout the response surface, the osmo-treated model food was significantly supplemented with flavan-3-ols. At the central point of the experimental design, flavan-3-ol monomers and dimers were found in concentrations of 1334 +/- 126 and 486 +/- 55 mg/kg, respectively. Their penetration into the model food was limited by sucrose to a different extent. The Trolox equivalent antioxidant capacity of the osmo-treated gel was higher than that of fruits with a very high free radical scavenging activity.

Grape and wine phenolics: Observations and recent findings. Cien. Inv. Agr. 35(2):107-120.

What consumers taste in wine is the culmination of management practices from the vineyard to the glass. as researchers, in order to have control over the composition of wine at the time of consumption, it is important to understand how production practices affect wine chemistry. Because phenolic compounds are so important to the overall quality of wine, they are the subject of intense investigation throughout the world. this review is a summary of current knowledge and some recent findings that have taken place in this area. Lo que los consumidores prueban en el vino es la culminacion de practicas de manejo que parten en el vinedo y concluyen en la copa. Como investigadores, para tener un control sobre la composicion del vino al momento del consumo, es importante comprender como afectan las practicas de manejo la composicion quimica del vino. Debido a que los compuestos fenolicos tienen tal importancia sobre la calidad fi nal del vino, estos compuestos han sido objeto de una intensa investigacion mundial. Esta revision de literatura es un resumen del conocimiento actual y de algunos descubrimientos recientes que han ocurrido en esta area.

Using remote sensing to predict grape phenolics and colour at harvest in a Cabernet Sauvignon vineyard: Timing observations against vine phenology and optimising image resolution

Optical remote sensing can provide a synoptic view of grapevine photosynthetically-active biomass over entire vineyards both rapidly and cost-effectively. Such output offers viticulturists and winemakers a management tool of enormous potential with red grape varieties, especially if canopy architecture (defined in this way) can be linked to production of phenolics and colour in ripe grapes. Accordingly, this paper describes such associations for a Cabernet Sauvignon vineyard in Australia's cool-climate Coonawarra region. A link is established between physical descriptors of grapevine canopies (derived from remotely-sensed images), and subsequent measurements of grape phenolics and colour. High-resolution images were acquired on three occasions during each of two consecutive growing seasons and post-processed to a range of on-ground resolutions. The strength of correlation between those images and berry properties (both total phenolics, and colour levels at harvest), varied according to spatial resolution and vine phenology at the time of imaging. An image resolution corresponding approximately to row spacing resulted in the strongest correlations between berry constituents and image-based data on all occasions. Referenced to grapevine phenology, correlations were initially weak (insignificant) at bud-burst, reached maximum strength at veraison, then diminished somewhat as grapes ripened. Prospects for applying such remotely-sensed imagery (at an appropriate resolution and timing), to predict berry phenolics and colour at harvest, are discussed.

Prediction of Wine Color Attributes from the Phenolic Profiles of Red Grapes (Vitis vinifera)

Knowledge about the relation between grape and wine phenolics is of key interest for the wine industry with respect to being able to predict wine quality from analyses of grapes. Prediction of the phenolic composition and color of experimentally produced red wines from the detailed phenolic composition of the corresponding grapes was investigated using a multivariate approach. Grape extracts and wines were produced from 55 different grape samples, covering 8 different Vitis vinifera cultivars: Alicante, Merlot, Syrah, Cinsault, Grenache, Carignan, Cabernet Sauvignon, and Mourvedre. The phenolic composition of the grapes and wines showed that the average ratios between wine and grape phenolics ranged from 0.25 to 7.9 for the different phenolic compounds. Most interestingly, the average ratios were low for anthocyanins (0.31) and tannins (0.32), intermediate for (+)-catechin (0.75) and polymeric pigments (0.98), and high for gallic acid (7.9). Individual wine phenolics in general correlated well with several grape phenolics, indicating that a multivariate approach might be advantageous for prediction of wine phenolics from grape phenolics analysis. However the use of multivariate prediction of individual wine phenolics from the complete grape phenolic composition only improved the prediction of wine polymeric pigments, whereas wine anthocyanins were predicted with the same precision as from the direct relation with grape anthocyanins. Prediction of color attributes of pH normalized experimental wines from the phenolic profiles of grapes was accomplished using a multivariate approach. The correlation between predicted and measured total wine color was high ( r = 0.958) but was very similar to the correlation coefficient obtained for the direct relation between grape anthocyanins and total wine color ( r = 0.961). Color due to copigmentation, color due to anthocyanins, and color intensity were also predicted well.

Characterisation of the main enzymatic activities present in six commercial macerating enzymes and their effects on extracting colour during winemaking of Monastrell grapes

SummaryNumerous studies have reported on the use of enzymes in wineries to facilitate the extraction of grape phenolics and to aid colour stability, although no clear conclusions were reached. Information concerning the enzymatic activities of industrial preparations is very difficult to obtain despite its importance. The aim of this work was to characterise and quantify the activities of six macerating enzyme preparations to optimise their use, and to study their effect on the chromatic characteristics of a Monastrell wine. The results indicate that differences exist in the type of enzymatic activities present in the preparations and in their concentration. The chromatic characteristics of the resulting wines, both at the end of alcoholic fermentation and after 12 months of storage in stainless steel tanks, showed differences with the use of the different maceration enzymes when comparing with control wine, although very little differences were observed between the different enzyme treatments. The enzyme‐treated wines showed, at the end of alcoholic fermentation, a higher OD280 and tannin content, and after 12 months, a higher colour intensity too. The main effect of all the preparations was an increase in the total phenol content, probably by facilitating the release of skin tannins.

Mass Transfer during Osmotic Dehydration in a Multicomponent Solution Rich in Grape Phenolics with Antioxidant Activity

Osmotic dehydration has been assessed as an operation for obtaining solid foodstuffs supplemented with grape phenolics. However, mass transfer in multicomponent osmotic solutions during OD needs to be described appropriately if the infusion of target solutes, in this case phenolics with antioxidant activity, is to be better controlled. The effective diffusion coefficients of moisture, total phenolics, and the major individual phenolics of low-molecular-weight (caftaric acid, coutaric acid, caffeic acid, coumaric acid, ferulic acid, and rutin) were evaluated during the OD of a model food with a concentrated red grape must. An increase in the concentration of soluble solids above 50° Brix decreased the level of penetration of phenolics in the model food.

Solid Foodstuff Supplemented with Phenolics from Grape: Antioxidant Properties and Correlation with Phenolic Profiles

Osmotic dehydration was assessed as an operation for supplementing a solid foodstuff (a gel was used as the model food) with grape phenolics from a concentrated red grape must to increase its antioxidant properties. The model food was processed for up to 24 h, and the osmotic pressure was adjusted by diluting the concentrated red grape must. In all conditions tested, low molecular weight phenolics (<or=610 g/mol) and, in particular, trans-caftaric acid, trans-coutaric acid, ferulic acid, coumaric acid, caffeic acid (hydroxycinnamic acids), gallic acid (hydroxybenzoic acids), quercetin, and rutin (flavonols), were quantified in the red grape must and also in the osmo-dehydrated food. Other flavonoids such as (+)-catechin and (-)epicatechin (flavan-3-ols) were detected only in the red grape must. Trolox equivalent antioxidant activity (TEAC) and ferric reducing antioxidant power (FRAP) were determined in the osmo-dehydrated food. Under the conditions that maximized phenolic infusion, the total phenolic content of the gel was close to the values reported in some rich-in-phenolic fruits and vegetables, whereas TEAC was 3 times that of fresh fruit with the highest antioxidant capacity. Regression analysis showed that the individual phenolics analyzed significantly explain the antioxidant capacity of the osmo-dehydrated food.

Enriched ozone atmosphere enhances bioactive phenolics in seedless table grapes after prolonged shelf life

Abstract‘Autumn Seedless’ table grapes (Vitis vinifera L.) were stored for up to 60 days at 0 °C under ten different gas treatments. An additional simulated retail display period of 7 days in air at 15 °C was also applied in all cases. These postharvest treatments were tested as an alternative to the usual industrial SO2 application and included modified atmosphere packaging (MAP), with and without natural fungicides (hexanal and hexenal), controlled atmosphere (CA) and intermittent and continuous applications of ozone (O3). The sensory quality was preserved with MAP of 13–16 kPa O2 + 8–11 kPa CO2, CA of 5 kPa O2 + 15 kPa CO2 and both O3 treatments. Although O3 did not completely inhibit fungal development, its application increased the total flavan‐3‐ol content at any sampling time. Continuous 0.1 µL L−1 O3 application also preserved the total amount of hydroxycinnamates, while all treatments assayed maintained the flavonol content sampled at harvest. Total phenolics increased after the retail period in O3‐treated berries. MAP preserved the total polyphenol content, while a slight decrease was observed under the CA conditions used. Therefore the improved techniques tested for retaining the quality of ‘Autumn Seedless’ table grapes during long‐term storage seem to maintain or even enhance the antioxidant compound content. Copyright © 2007 Society of Chemical Industry

Structure and Properties of Wine Pigments and Tannins

Grape phenolics are structurally diverse, from simple molecules to oligomers and polymers that are usually designated “tannins,” referring to their ability to interact with proteins. Anthocyanin pigments and tannins are particularly important for red wine quality. Their extraction depends on their location in the berry and their solubility. All phenolic compounds are unstable and undergo numerous enzymatic and chemical reactions. Color and taste changes during red wine aging have been ascribed to anthocyanin-tannin reactions. The structures and properties of tannins and pigmented tannins from these reactions are often misunderstood. Current research on wine phenolic composition is reviewed, with emphasis on the following issues: (1) reactions of tannins yield both larger polymers and smaller species; (2) anthocyanin reactions can generate colorless species as well as polymeric and small various pigments; (3) some polymeric pigments undergo sulfite bleaching while some low molecular weight pigments do not; (4) polymers are both soluble and astringent, so the astringency loss during aging may involve cleavage rather than polymerization; and (5) sensory properties of anthocyanins and tannins are modulated by interactions with other wine components.

À la recherche des bilans sur Internet

In this study, the potentiality of Patatin (P), a protein extracted from potato, as must fining agent was investigated on musts obtained from two South Italy grape cultivars (Falanghina and Greco). Besides P, fining agents as bentonite (B) and potassium caseinate (C) were assayed at different concentrations. The rate of sedimentation, the decline of turbidity during time, the absorbance at 420 nm, the GRP (grape reaction products) and hydroxycinnamic acids (HCA) concentrations were determined.The comparative trials showed that P is a suitable fining agent to prevent browning and decrease haze during must settling because its effect on grape phenolics, brown pigments and turbidity is comparable and/or better than that detected for C. Its use as single fining agent or in combination with B depends on must characteristics.

Study of Anticancer Activities of Muscadine Grape Phenolics in Vitro

Muscadine grapes have unique aroma and flavor characteristics. Although a few studies reported high polyphenols content of muscadine grapes, little research has been conducted to evaluate the phenolic compounds bioactivities in any muscadine grape cultivar. The objective of this study was to evaluate the effect of phenolic compounds in muscadine grapes on cancer cell viability and apoptosis. Four cultivars of muscadine (Carlos, Ison, Noble, and Supreme) were assessed in this study. Phenolic compounds were extracted from muscadine skins and further separated into phenolic acids, tannins, flavonols, and anthocyanins using HLB cartridge and LH20 column. Some individual phenolic acids and flavonoids were identified by HPLC. Anthocyanin fractions were more than 90% pure. The effect of different fractions on the viability and apoptosis of two colon cancer cell lines (HT-29 and Caco-2) was evaluated. A 50% inhibition of cancer cell population growth for the two cell lines was observed at concentrations of 1-7 mg/mL for crude extracts. The phenolic acid fractions showed a 50% inhibition at the level of 0.5-3 mg/mL. The greatest inhibitory activity was found in the anthocyanin fraction, with a 50% inhibition at concentrations of approximately 200 microg/mL in HT-29 and 100-300 microg/mL in Caco-2. Anthocyanin fractions also resulted in 2-4 times increase in DNA fragmentation, indicating the induction of apoptosis. These findings suggest that polyphenols from muscadine grapes may have anticancer properties.

Effect of Soil Moisture Availability on Merlot: From Leaf Water Potential to Grape Composition

Grape phenolics are a relevant part of grape quality, and their metabolism in the berry may be modified by environmental factors. To determine the influence of different water regimes on the polyphenolic composition of berries, research was conducted for two years (2000 and 2001) on three-year-old <i>Vitis vinifera</i> cv. Merlot potted vines, comparing three water supply levels: (1) control (C), at ~80% of available water (aw); (2) moderate stress (M), at ~30% aw; and (3) severe stress (S), at ~15% aw. The treatments were applied in both years from veraison to fruit maturity. Predawn leaf water potential was reduced only in the S treatment in 2000, while in 2001 both M and S treatments had a lower value. Berry weight was reduced in M and S treatments, but no differences were observed in sugars, pH, and berry titratable acidity. Total skin and seed polyphenols were increased in S vines, but a probable increase of the structural complexity of phenolic compounds inside the berry (higher degree of polymerization) caused a lower extractability in winelike solution. Anthocyanins, which are monomers, were more concentrated and also more extracted in S berries. Water-stressed Merlot grapes (both S and M) will benefit from a longer maceration because a higher concentration of polymerized polyphenols could be extracted, stabilizing color and improving the mouthfeel properties of the resulting wines.

Effect of Soil Moisture Availability on Merlot: From Leaf Water Potential to Grape Composition

Grape phenolics are a relevant part of grape quality, and their metabolism in the berry may be modified by environmental factors. To determine the influence of different water regimes on the polyphenolic composition of berries, research was conducted for two years (2000 and 2001) on three-year-old <i>Vitis vinifera</i> cv. Merlot potted vines, comparing three water supply levels: (1) control (C), at ~80% of available water (aw); (2) moderate stress (M), at ~30% aw; and (3) severe stress (S), at ~15% aw. The treatments were applied in both years from veraison to fruit maturity. Predawn leaf water potential was reduced only in the S treatment in 2000, while in 2001 both M and S treatments had a lower value. Berry weight was reduced in M and S treatments, but no differences were observed in sugars, pH, and berry titratable acidity. Total skin and seed polyphenols were increased in S vines, but a probable increase of the structural complexity of phenolic compounds inside the berry (higher degree of polymerization) caused a lower extractability in winelike solution. Anthocyanins, which are monomers, were more concentrated and also more extracted in S berries. Water-stressed Merlot grapes (both S and M) will benefit from a longer maceration because a higher concentration of polymerized polyphenols could be extracted, stabilizing color and improving the mouthfeel properties of the resulting wines.

Evaluation of free radical-scavenging properties of commercial grape phenol extracts by a fast colorimetric method

Three commercial extracts of grape phenols (seeds, skin, whole) were used in this study. Each extract was divided by HPLC into five fractions of different polarities, and their free radical-scavenging activities were measured using the DPD ( N, N-diethyl- p-phenylenediamine) colorimetric method. Total phenol contents were determined using the Folin-Ciocalteu method to assess their contribution to the antiradical activity. The results showed that there was good correlation between total phenolic compound contents and free radical-scavenging activities of the different grape extracts. Moreover, the seed extract presented the most important free radical-scavenging properties (138 USP/mg extract), whereas the whole extract presented the lowest free radical-scavenging capacity (80.5 USP/mg extract). However, the free radical-scavenging properties, reported on the basis of content of phenolic compounds in each extract, showed that the free radical-scavenging activities of seed and whole extracts were not significantly different (171 versus 162 USP/mg phenol). In addition, free radical-scavenging activities of fractions from seed and skin extracts decreased as their polarities decreased.

Activity of grape polyphenols as inhibitors of the oxidation of fish lipids and frozen fish muscle

Grape phenolic compounds were obtained from grape ( Vitis vinifera) pomace by pressing and posterior maceration. Phenolics resulting of the crude grape extract were fractionated by preparative chromatography. The ability of fractions, containing flavanol monomers, oligomers (procyanidins) and glycosylated flavonols, for inhibiting oxidation of fish lipids was determined. The tests were conducted in fish oils, fish oil-in-water emulsions and in fatty fish species such as mackerel during frozen storage. Partitioning coefficients of grape phenolics showed high solubility in the aqueous media and low in oily media. The results suggest that an optimal combination of procyanidin, degree of polymerization and percentage galloylation may be related to the highest antioxidant efficacy of grape polyphenols in the different systems tested. Monomers were more effective in oily systems. Flavanol oligomers were the most potent inhibitors of oxidation in emulsions and in frozen fish muscle.

Alcohol, wine and platelet function.

Epidemiological studies have demonstrated an inverse correlation between moderate wine and alcohol consumption and morbidity and mortality from coronary heart disease. The protective effect has been associated with an increase in the plasma level of HDL cholesterol, as it is well recognized that plasma HDL is inversely correlated with CHD. In addition, it has become evident that blood platelets contribute to the rate of development of atherosclerosis and CHD through several mechanisms. In recent studies it has been shown that the level of HDL cholesterol can explain only 50% of the protective effect of alcoholic beverages; the other 50% may be partly related to a decrease in platelet activity. This anti-platelet activity of wine is explained by ethanol but also by the polyphenolic components with which red wines are richly endowed. Several studies carried out on humans and animals have shown that wine phenolics could exert their effects by reducing prostanoid synthesis from arachidonate. In addition, it has been suggested that wine phenolics could reduce platelet activity mediated by nitric oxide. Moreover, wine phenolics increase vitamin E levels while decreasing the oxidation of platelets submitted to oxidative stress. However, a rebound phenomenon of hyperaggregability is observed after an acute alcohol consumption which is not observed with wine consumption. This protection afforded by wine has been duplicated in animals with grape phenolics added to alcohol. The rebound phenomenon may explain ischemic strokes or sudden deaths known to occur after episodes of drunkenness. It appears that wine, and wine phenolics in particular, could have a more significant inhibitory effect on platelet aggregation and could explain, in part, the hypothesis that red wine is more protective against atherosclerosis and coronary heart disease.

Effect of principal polyphenolic components in relation to antioxidant characteristics of aged red wines.

Aged red wines possess significantly different polyphenolic composition compared with young ones, mainly due not only to formation of polymeric compounds but also because of oxidation, hydrolysis, and other transformations that may occur in native grape phenolics during aging. Representative Greek, single-variety, aged red wines were examined for total phenol, total flavanol, and total anthocyanin content using spectrophotometry, and attempts were made to establish correlations with the antiradical, reducing, and hydroxyl free radical scavenging activity. In addition, HPLC analyses were carried out, to ascertain whether individual polyphenols are actually responsible for the antioxidant effects of aged red wines. It was found that total flavanols are the class of polyphenols that account for hydroxyl free radical scavenging efficacy and to a lesser extent for antiradical and reducing ability, whereas there was a less significant link between the antioxidant properties and the total phenolics and only a weak relationship to total anthocyanin content. The correlation of the antioxidant properties with the principal polyphenols showed that individual compounds are weakly associated with all the antioxidant parameters, suggesting that the expression of antioxidant activity in aged red wines is rather a consequence of synergism between various phenolics, and it is not simply attributed to specific constituents.