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In this study, seeds, skins and stems of the red wine grape varieties Boğazkere, Cabernet Sauvignon, Merlot, Nero d’Avola, Sangiovese and Syrah grown in Turkey were analysed for their phenolic compounds. The highest total phenolic compound and DPPH were found in the stem of Boğazkere respectively as 62550 mg GAE/kg dw and 614 µmol/g dw; the highest ABTS, (+)-catechin, (–)-epicatechin were detected in the seed of Nero d’Avola respectively as 617 µmol trolox/g dw, 8650 mg/kg and 1902 mg/kg dw; the highest total anthocyanin and rutin were measured in the skin of Boğazkere respectively as 143.52 mg/kg dw and 9692 mg/kg dw; the highest quercetin was found in the seed of Boğazkere as 49.21 mg/kg dw and the highest trans-resveratrol was measured in the stem of Syrah as 61.56 mg/kg dw. Scientific Research Projects Coordinatorship of Ankara University - 11B4347003 WOS:000623982100002 Q4

Resveratrol, a phenolic compound possessing vital biological activities such as anti-cancer, is present abundantly in grape skin, a waste produced during the processing of grape juice. The objectives of this study were to prepare resveratrol-gold nanoparticles and a resveratrol nanoemulsion from grape skin and study their inhibition effects on pancreatic cancer cells BxPC-3. The spherical-shaped citrate gold nanoparticles (GNPs) and resveratrol-gold nanoparticles (R-GNPs) were, respectively, prepared with a surface plasmon resonance peak at 528 and 538 nm, mean particle size of 20.8 and 11.9 nm, and zeta-potential at −32.7 and −66.7 mV, by controlling an appropriate concentration of citrate/resveratrol and gold chloride as well as stirring time and temperature. The resveratrol nanoemulsion, composed of soybean oil, Tween 80, and sucrose fatty acid ester in glycerol and water, possessed a high storage stability with a mean particle size of 14.1 nm, zeta-potential of −49.7 mV, and encapsulation efficiency of 95.5%. An antiproliferation study revealed that both R-GNPs and resveratrol nanoemulsion could effectively inhibit the growth of pancreatic cancer cells BxPC-3, with the latter showing a higher inhibition effect. Western blot analysis implied that both can down-regulate expressions of cyclin A, cyclin B, CDK1, and CDK2 and up-regulate expressions of p53 and p21, accompanied by enhancing cytochrome C expression, decreasing BcL-2 expression, increasing Bax expression, and leading to the elevation of caspase-8, caspase-9, and caspase-3 activities for cell apoptosis execution. Future research is needed to study the inhibition of pancreatic tumors in vivo by R-GNPs and resveratrol nanoemulsions.

To explore the effect of pectolytic enzyme application on polysaccharide size and colloidal interactions, rosé wines were prepared from pressed Shiraz grape juice, and red wines were made from the same juice by the addition of skins and seeds from fresh pressings. A pectolytic enzyme preparation containing primarily polygalacturonase and side-activities of arabinase and pectin lyase was used. Enzyme treatment enhanced the contribution of high molecular weight (≈ 200 kDa) polysaccharides rich in mannose and glucose (mannoproteins) and removed arabinose-rich polysaccharides of intermediate (≈ 40 kDa) size. Enzyme application reduced the molecular weight average of a class of smaller polysaccharides of approximately 6 kDa (rhamnogalacturonan II). All wines had similar particle sizes, but enzyme treatment markedly reduced particle concentration in wines, particularly in rosé wines. Wine polysaccharides were purified and when reconstituted in model wine, showed reduced particle concentration in response to enzyme treatment. Aggregation of polysaccharide in the presence of seed tannin was also markedly reduced by enzyme treatment. The results indicated that changes in structure introduced by the enzyme affected wine colloidal properties, potentially increasing polysaccharide solubility.

Grape pomace is one of the most abundant solid by-products generated during winemaking. A lot of products, such as ethanol, tartrates, citric acid, grape seed oil, hydrocolloids, bioactive compounds and dietary fiber are recovered from grape pomace. Grape pomace represents a major interest in the field of fiber extraction, especially pectin, as an alternative source to conventional ones, such as apple pomace and citrus peels, from which pectin is obtained by acid extraction and precipitation using alcohols. Understanding the structural and functional components of grape pomace will significantly aid in developing efficient extraction of pectin from unconventional sources. In recent years, natural biodegradable polymers, like pectin has invoked a big interest due to versatile properties and diverse applications in food industry and other fields. Thus, pectin extraction from grape pomace could afford a new reason for the decrease of environmental pollution and waste generation. This paper briefly describes the structure and composition of grape pomace of different varieties for the utilization of grape pomace as a source of pectin in food industry.

EVALUATION OF THE TOTAL CONCENTRATION AND THE BIOACCESSIBLE FRACTION OF METALS IN SAMPLES OF GRAPE SKINS OF CULTIVARS TANNAT AND CABERNET SAUVIGNON BY MIP OES. This paper describes the evaluation of the total concentration of Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Mn, Pb e Zn and the bioaccessible fraction of Ba, Cu, Fe, Mn, Pb and Zn in samples of grape skins from different cultivars (Vitis Viníferas Tannat and Cabernet Sauvignon) by MIP OES. For the determination of total concentration, acid decomposition with a reflux system adapted to the digestion tubes in the oxidizing medium of HNO3 and H2O2 were used. The accuracy of the method was verified by recovery tests, whose values ranged from 80 to 120%, as well as through a comparative method in closed system. Bi, Cd and Cr showed values for total content below the LOD or below the values acceptable for health while Pb is higher than 0.2 mg kg-1, for both cultivars. To evaluate the bioacessible fraction, the gastrointestinal system was simulated using an in vitro procedure, and its performance was assessed considering the bioaccessible fraction (supernatant) and the non-bioaccessible fraction, whose sum should be closed to the total concentration, and the results obtained were between 81 and 120%. Both cultivars showed similar values for the bioaccessible fractions (~13.5 – 53% of the total content).

Grape seeds (GS) and grape skins (GK) are natural sources of polyphenols with featured antioxidant capacity. An experiment was conducted to investigate the effect of these polyphenol sources in diets formulated to contain the same total extractable grape polyphenol content on growth performance, protein and extractable polyphenol digestibility, plasma and meat α- and γ-tocopherol and thigh meat oxidation in broiler chickens. Five experimental diets were formulated: control, control + vitamin E (200 mg/kg), 30 g/kg GS diet, 110 g/kg GK diet, GS + GK diet (a mixture of 24.4 g/kg GS and 13.1 g/kg GK designed to simulate a reconstituted grape pomace). Feeding chickens with 110 g/kg GK reduced (p &lt, 0.001) daily weight gain, worsened (p &lt, 0.001) feed conversion ratio, increased (p &lt, 0.001) non-extractable polyphenol content in the ileum and in the excreta and decreased (p &lt, 0.05) ileal protein digestibility. Regardless of the grape polyphenol source used, the inclusion of grape byproducts in the diets led to an increase of total extractable polyphenol contents in the ileum (p &lt, 0.01) and the excreta (p &lt, 0.001), which resulted (p &lt, 0.001) in a decrease of extractable polyphenol digestibilities. Alpha- and gamma-tocopherol concentrations increased (p &lt, 0.001) in plasma and in seven-day stored meat in birds fed the diet combining GS and GK with respect to the control group. As it happened with the vitamin E supplementation, feeding the combination of GS and GK also reduced (p &lt, 0.001) the concentration of the lipid peroxidation marker (malondialdehyde) in the stored meat of chickens.

With the increasing needs of clean water supplies, the use of biomass wastes and residues for environmental remediation is essential for environmental sustainability. In this study, the residues from winery and citrus juice industries, namely grape skin and orange peel, respectively, were first converted to hydrochars by hydrothermal carbonization (HTC) and then a cationic dye (methylene blue) adsorption was studied on hydrochars. Hydrochars from both feedstocks were produced at three different temperatures (180, 220, and 250 °C) and a fixed residence time (1 h) to evaluate the hydrochar’s performance on the dye adsorption. The hydrochars were characterized in terms of their pH, pH at point of zero charge (pHPZC), surface functionalities, and surface area. A batch adsorption study of the dye was carried out with variable adsorbate concentration, pH, and temperature. Two adsorption isotherms namely Langmuir and Freundlich models were fitted at 4, 20, and 36 °C. The thermodynamic properties of adsorption (Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS)) were evaluated from the isotherms fittings. Results showed that the dye adsorption on both hydrochars was significant and followed Langmuir isotherm. The maximum adsorption capacity on citrus waste hydrochar was higher than the winery waste hydrochar at any corresponding HTC temperature. Although hydrochars showed the lowest surface area (46.16 ± 0.11 and 34.08 ± 1.23 m2/g for citrus and winery wastes, respectively) at 180 °C, their adsorption was the highest, owing to their maximum density of total oxygen functional groups (23.24 ± 0.22 and 32.69 ± 1.39 µmol/m2 for citrus and winery wastes, respectively), which decreased with the increase in HTC temperature. This research shows a sustainable route for the production of highly effective adsorbent materials at lower HTC temperatures from citrus and winery wastes.

In the past few years, research efforts have focused on plant exploitation for deriving some valuable compounds. Extraction has been usually performed using petrochemical and volatile organic solvents, but nowadays, increased recognition of environmental pollution has prompted the utilization of green solvents as alternatives. Therefore, the aim of the present study was to exploit deep eutectic solvents (DES) (choline chloride: citric acid and choline chloride: glucose) as solvents for extracting valuable phenolic antioxidants from grapes. Investigation was conducted on ten grape varieties, observing seeds and skin as different matrix. Total polyphenol content (TPC) was determined by Folin-Ciocalteu spectrophotometric microassay. Antioxidant activity was investigated using four different tests and results were combined in a unique Antioxidant Composite Index (ACI) to reveal comprehensive information about this biological activity. Polyphenol compounds were identified and quantified with the aim of HPLC-diode array detector (DAD). Overall results support that DES (particularly choline chloride: citric acid) were comparable to conventional solvent, and in most cases even outperformed acidified aqueous ethanol (concerning extraction efficiency and antioxidant activity). Regardless of varietal distinctions, grape seeds have higher antioxidant capacity compared to grape skin, and such findings are according to their phenol compound concentrations.

This work investigated the structural, biochemical, and molecular characteristics of grape skin cell wall during ripening, related to susceptibility to Botrytis cinerea. The comparative study between the two main grape cultivars in Champagne region, Pinot noir and Chardonnay, quantified: (1) the maturity and physical profile of grape skin, (2) the morphological characteristics, (3) soluble pectic polysaccharides located in grape skin cell walls, and (4) the gene expression of the two main degrading enzymes (VvPME1 and VvPG1) and PME activity. During the maturation period, the grape skins of the two cultivars appear different in their structure and composition. Chardonnay is characterized by higher relative humidity (RH) and level of VvPG1 expression, lower disease incidence and penetrometry values, and thicker cell walls than Pinot noir skins. Thus, the cell wall composition is sufficiently different between grape varieties from the same area to allow their discrimination and could be used to better manage the harvest date.

[EN] The determination of the detailed flavanol composition in food matrices is not a simple task because of the structural similarities of monomers and, consequently, oligomers and polymers. The aim of this study was the development and validation of an HPLC-MS/MS−multiple reaction monitoring (MRM) method that would allow the accurate and precise quantification of catechins, gallocatechins, and oligomeric proanthocyanidins. The high correlation coefficients of the calibration curves (>0.993), the recoveries not statistically different from 100%, the good intra- and interday precisions (

Benign prostatic hyperplasia (BPH) is a common chronic disease of the urinary system among elderly men. Especially, the metabolic imbalance of androgen in elderly men is one of the leading causes of BPH. Dihydrotestosterone (DHT) and converted testosterone by 5-&alpha, reductase type 2 (5AR2), binding with androgen receptor (AR), affect prostate proliferation and growth. In BPH, levels of androgen signaling-related protein expression are shown highly. Androgen signaling induces the overexpression of prostate-specific antigen (PSA) and cell proliferation factor such as proliferating cell nuclear antigen (PCNA) and cyclin D1. Grape skin anthocyanins are well known for their antioxidative, anti-cancer, anti-diabetes, anti-inflammatory, antimicrobial, and anti-aging activities. Polymerized anthocyanin (PA) downregulated the expression of androgen signaling-related proteins such as 5AR2, AR, and PSA in LNCaP cell lines. Furthermore, we investigated the effects on PA in testosterone propionate-induced BPH rat experiments. The oral administration of PA decreased the prostate weight in rats with TP-induced BPH. PA decreased the AR, 5AR2, SRC1, PSA, PCNA, and cyclin D1 expression in prostate tissues and the serum DHT levels, ameliorated the BPH-mediated increase of Bcl-2 expression, and increased the Bax expression. These results suggest that PA may be a potential natural therapeutic agent for BPH treatment.

To investigate the changes in wine chemical composition, sensory quality, and style induced by various levels of skin disruption and contact with oxygen during grape processing, five treatments were applied: whole grape cluster pressing in semi‐reductive conditions (WCP‐R), whole grape cluster pressing in standard conditions (WCP), standard grape mash pressing as a control (GMP), light (LOX), and heavy oxidation of grape juice (HOX). Produced wines were subjected to analysis of phenols (HPLC‐DAD) and volatiles (HS‐SPME‐GC/MS), as well as quantitative descriptive sensory analysis. WCP‐R wines stood out with the highest amounts of hydroxycinnamates and preserved aromas, and the highest intensities of positive sensory attributes. Both WCP and LOX treatments significantly reduced phenols when compared to GMP, while HOX treatment was detrimental in general. Apparently, the level of contact with oxygen exhibited a predominant effect on hydroxycinammates and aromas, while the level of grape skin disruption affected primarily hydroxybenzoic acids and flavan‐3‐ols.

Highly soluble maltodextrin-encapsulated grape skin phenolics comprising anthocyanins and less hydrophilic flavonoids were added as an ingredient to apple puree. Upon formulation, heat treatments were applied to achieve 3-14 decimal reductions (D) of the target microorganism (Alicyclobacillus acidoterrestris). A storage study was performed at 15-35°C for 1month. Monomeric anthocyanins were retained at 100% after the 3 D treatment, while anthocyanin retention decreased to 72% with increasing heating intensity until 14 D. During storage, the concentration of monomeric anthocyanins decreased following first-order kinetics (k25°C=34.4d(-1), activation energy=51.0kJ/mol). The flavanols were more stable than the monomeric anthocyanins. The hydroxycinnamic acid, dihydrochalcone and flavonol contents did not change. The fortified puree had a two-fold higher reducing capacity with respect to apple puree. Overall, this ingredient could meet the industrial demand for sustainable colouring agents and health promoting compounds.

Grape pomace is a winemaking by-product that can be used to extract oenological tannins. Recently, some grape skin tannins were shown to contain very high amounts of two polyfunctional thiol precursors (3-S-glutathionylhexan-1-ol, 3-S-cysteinylhexan-1-ol) whose free forms are responsible for appreciated tropical-like flavours. This study shows that an oxidative treatment (no SO2) of white grape pomace and the presence of grape leaves and stems can increase the content of the above mentioned precursors. Moreover, it shows significant differences between Sauvignon Blanc, Gewuerztraminer and Mueller-Thurgau grape pomace for the 3-mercaptohexan-1-ol precursors and 4-S-cysteinyl-4-methylpentan-2-one. The grape cultivar is crucial, but the technological ability of enhancing the level of the volatile thiol precursors simply by treating the grape marc in different ways is a promising and powerful tool for the production of potentially flavouring tannins intended for food and beverage industry.

Producción Científica, A bio-electronic tongue has been developed to evaluate the phenolic content of grape residues (seeds and skins) in a fast and easy way with industrial use in mind. A voltammetric electronic tongue has been designed based on carbon resin electrodes modified with tyrosinase combined with electron mediators. The presence of the phenoloxydase promotes the selectivity and specificity towards phenols. The results of multivariate analysis allowed discriminating seeds and skins according to their polyphenolic content. Partial least squares (PLS) has been used to establish regression models with parameters related to phenolic content measured by spectroscopic methods i.e., total poliphenol content (TPC) and Folin–Ciocalteu (FC) indexes. It has been shown that electronic tongue can be successfully used to predict parameters of interest with high correlation coefficients (higher than 0.99 in both calibration and prediction) and low residual errors. These values can even be improved using genetic algorithms for multivalent analysis. In this way, a fast and simple tool is available for the evaluation of these values. This advantage may be due to the fact that the electrochemical signals are directly related to the phenolic content., Ministerio de Ciencia Innovación y Universidades-FEDER (grants RTI2018-097990-B-100 and BES-2016-077825), Junta de Castilla y León-FEDER (grant VA275P18) y (Infraestructuras Red de Castilla y León (INFRARROJOS) UVA01)

U ovom je radu ispitana mogućnost uporabe osam različitih imidazolijevih ionskih kapljevina kao novih otapala za ekstrakciju flavonoida iz pokožice grožđa, te su rezultati uspoređeni s konvencionalnom ekstrakcijom pomoću organskog otapala. Struktura aniona, kationa i koncentracije ionskih kapljevina značajno su utjecali na iskorištenje ekstrakcije. Najveća koncentracija proantocijanidina dobivena je pomoću 2,5 mol/L 1-butil-3- -metilimidazolijevog bromida [C4mim][Br], a antocijana pomoću 2,5 mol/L 1-etil-3- -metilimidazolijeva bromida [C2mim]. Statistički bitno veće koncentracije ukupnih i svih slobodnih antocijana dobivene su ekstrakcijom pomoću 2,5 mol/L [C2mim][Br] i 2,5 mol/L 1- -metilimidazolijevog hidrogen sulfata [HM][HSO4], u usporedbi s konvencionalnim otapalom. Nadalje, 2,5 mol/L [C4mim][Br] i 2.5 mol/L 1-(4-sulfobutil)-3-metilimidazolijevog hidrogen sulfata [S4mim][HSO4] imali su znatno veću selektivnost prema antocijanin-3-O- -acetilmonoglukozidu i antocijanin-3-(6-O-p-kumaril)monoglikozidu., In this study, eight different types of imidazolium-based ionic liquids (ILs) were applied as new solvents in the extraction of flavonoids from grape skin, and compared to the conventional organic solvent extraction that was not reported earlier. The structure of anions, cations and concentration of ILs significantly affected extraction yields. The highest mass fractions of proanthocyanidins and anthocyanins were obtained with 2.5 mol/L of 1-butyl-3-methylimidazolium bromide [C4mim][Br] and 2.5 mol/L of 1-ethyl-3-methylimidazolium bromide [C2mim][Br], respectively. The studied ILs provided an excellent preliminary result in the extraction of anthocyanins. Significantly higher mass fractions of total and all free anthocyanins were extracted with 2.5 mol/L of [C2mim][Br] and 2.5 mol/L of 1-methylimidazolium hydrogen sulfate [mim][HSO4] than with conventional solvent with the exception of anthocyanin-3-O-acetylmonoglucosides in the latter. On the other hand, 2.5 mol/L of [C4mim][Br] and 2.5 mol/L of 1-(4-sulfobutyl)-3-methylimidazolium hydrogen sulfate [sC4mim][HSO4] showed significantly higher selectivity towards anthocyanin-3-O-acetylmonoglucosides and anthocyanin-3-(6-O-p-coumaroyl)monoglucosides.

The goal of this study was to investigate the characteristics of grape skin extract (GSE) spray dried with different carriers: maltodextrin (MD), gum Arabic (GA) and skim milk powder (SMP). The grape skin extract was obtained from winery by-product of red grape variety Prokupac (Vitis vinifera L.). The morphology of the powders, their thermal, chemical and physical properties (water activity, bulk and tapped densities, solubility), as well as release studies in different pH conditions were analyzed. Total anthocyanin content and total phenolic content were determined by spectrophotometric methods. MD and GA-based microparticles were non-porous and spherical, while SMP-based ones were irregularly shaped. The process of spray drying Prokupac GSE using these three carriers produced powders with low water activity (0.24-0.28), good powder characteristics, high yields, and solubility higher than 90%. The obtained dissolution/release profiles indicated prolonged release of anthocyanins and phenolic compounds in different mediums, especially from GSE/GA microparticles. These results have shown that grape skin as the main by-product of wine production could be used as a source of natural colorants and bioactive compounds, and microencapsulation as a promising technique for the protection of these compounds, their stabilization in longer periods and prolonged release.

In this research, we propose a novel concept for a non-destructive evaluation of volatiles emitted from ripening grapes using solid-phase microextraction (SPME). This concept is novel to both the traditional vinifera grapes and the cold-hardy cultivars. Our sample models are cold-hardy varieties in the upper Midwest for which many of the basic multiyear grape flavor and wine style data is needed. Non-destructive sampling included a use of polyvinyl fluoride (PVF) chambers temporarily enclosing and concentrating volatiles emitted by a whole cluster of grapes on a vine and a modified 2 mL glass vial for a vacuum-assisted sampling of volatiles from a single grape berry. We used SPME for either sampling in the field or headspace of crushed grapes in the lab and followed with analyses on gas chromatography-mass spectrometry (GC-MS). We have shown that it is feasible to detect volatile organic compounds (VOCs) emitted in-vivo from single grape berries (39 compounds) and whole clusters (44 compounds). Over 110 VOCs were released to headspace from crushed berries. Spatial (vineyard location) and temporal variations in VOC profiles were observed for all four cultivars. However, these changes were not consistent by growing season, by location, within cultivars, or by ripening stage when analyzed by multivariate analyses such as principal component analysis (PCA) and hierarchical cluster analyses (HCA). Research into aroma compounds present in cold-hardy cultivars is essential to the continued growth of the wine industry in cold climates and diversification of agriculture in the upper Midwestern area of the U.S.

Conventional extraction techniques for plant phenolics are usually associated with high organic solvent consumption and long extraction times. In order to establish an environmentally friendly extraction method for grape skin phenolics, deep eutectic solvents (DES) as a green alternative to conventional solvents coupled with highly efficient microwave- assisted and ultrasound-assisted extraction methods (MAE and UAE, respectively) have been considered. Initially, screening of five different DES for proposed extraction was performed and choline chloride-based DES containing oxalic acid as a hydrogen bond donor with 25% of water was selected as the most promising one, resulting in more effective extraction of grape skin phenolic compounds compared to conventional solvents. Additionally, in our study, UAE proved to be the best extraction method with extraction efficiency superior to both MAE and conventional extraction method. The knowledge acquired in this study will contribute to further DES implementation in extraction of biologically active compounds from various plant sources.

Microwave-assisted extraction (MAE) was investigated for recovering of total phenolic compounds from dried waste grape skins using a domestic microwave oven. Influence of vessel geometry, irradiation cycles, irradiation power and time was investigated. The results in terms of phenolics yield, antioxidant capacity and energy consumption were compared with a reference solid–liquid extraction (SLE) carried out for 2 h at 60°C. Equivalent yield of total phenolics as in SLE was achieved with a MAE extraction time of 1,033 sec (corresponding to 83 sec of irradiation at 900 W, 83% saving in extraction time compared to SLE and with a 70% energetic efficiency). Pre-maceration of samples and solvent pre-heating are proposed for large-scale industrial processes to enhance phenolics extraction and process efficiency.

In this study free and bound volatile compounds of Aglianico and Uva di Troia grape skins and pulp juices were extracted and concentrated by Solid Phase Extraction (SPE) technique. 26 grape aroma compounds were monitored and quantified by gas chromatography–mass spectrometry (GC-MS) in selective ion monitoring modality (SIM). Aglianico showed a higher total level of free and bound volatile fraction than Uva di Troia grapes. The aroma of the two red grape varieties was carried out by grouping volatile compounds into seven aromatic series. The free volatile fraction of the two grape varieties was essentially dominated by herbaceous and floral series. The herbaceous series does not differentiate the two grape varieties, while the floral series is two times higher in Uva di Troia grape skin than in Aglianico. The bound volatile fraction, representing aroma potential of the two grape cultivars, differentiated them. Aglianico grapes were characterized mainly by fruity and sweet and were not characterized by spicy and toasty series. On the contrary, spicy series result enough importance in Uva di Troia grapes' aroma profile.

In this study seven published methods of extraction of skin free and bound volatile compounds have been compared. The free and bound volatiles were separated by solid phase extraction (SPE) and then analysed by gas chromatography coupled with mass spectrometry (GC–MS). The results showed that the extraction of volatile compounds from grapes is highly affected by extraction solution features. The solution at pH 3.2 and 0% ethanol resulted the most effective as it led to the extraction of a higher number and amount of free and glycosilated volatile compounds. The selected extraction method of grape skin and the process of pulp juice were validated for quantitative determination of a wide range of grape aroma compounds. A total of 37 free and bound grape aroma compounds were quantified by GC–MS in selective ion monitoring modality (SIM). Among them, 26 volatile compounds resulted validated in grape skin and pulp juice.

Correspondance auteur: Doco T. E-mail: doco@supagro.inra.fr; International audience; Polysaccharide modification is the most fundamental factor that affects firmness of fruit during ripening. In grape, because of the lack of information on the modifications occurring in cell wall polysaccharides in skins, but also because this tissue contains large amounts of organoleptic compounds for winemaking, a study was performed on the evolution and extractability of polysaccharides from grape skins of Shiraz cultivar throughout ripening, A HEPES/phenol extraction technique was used to analyze Shiraz grape cell wall material isolated from skins of berries harvested from one to ten weeks after veraison. Total amounts in cell wall polysaccharides remained constant during ripening (4.2 mg/berry). A slight decrease in galactose content of insoluble polysaccharides was observed, as well as a significant de-esterification of methoxylated uronic acids, indicating that some modifications occur in cell wall polysaccharides. The water-soluble fraction represented a very small fraction of the whole polysaccharides, but its amounts increased more than 2-fold between the first and the last sample. Isolated cell walls were also analyzed for their protein composition. Last, hydroalcoholic extractions in model-wine solution were also performed on fresh skins. This extracted fraction was very similar to the water-soluble one, and increased during the entire period. By comparison with polysaccharide modifications described in flesh cell wall in previous works, it can be assumed that the moderate skin polysaccharide degradation highlights the protective role of that tissue

L'aspect physico-chimique et microbiologique du compostage des pellicules de raisins a été étudié. Il est démontré qu'au cours du processus, ce sont surtout les matières organiques facilement métabolisables qui sont dégradéesIl a été possible de déterminer la succession des populations microbiennes. Les micro-organismes intervenant dès le début du processus sont des moisissures et des levures. Puis dès que la température augmente et que le pH se basifie, ceux-ci disparaissent et laissent la place à une flore bactérienne, responsable en grande partie de la dégradation de la matière organique.

International audience; Quantitative and qualitative modifications of tannins and anthocyanins in grape skin were investigated at different dates of harvest, from berries sorted on the basis of their density. Free anthocyanins accumulated until 170 g/L of sugars in pulp before undergoing a slight decrease. Changes in anthocyanin composition were observed with increasing sugar levels in the pulp that reflected structural differences between classes of anthocyanins. The proportion of methoxylated anthocyanins continued to increase in the skin as sugar accumulated while the proportion of coumaroylated anthocyanins initially increased (up to 200 g/L of sugars in the pulp) and then rapidly decreased. In comparison, no major quantitative nor qualitative change was observed for tannins, except for a slight increase of the mean degree of polymerization. Whatever the physiological stage of the pulp, the extraction yield of skin phenolics into hydroalcoholic solution for 5 h was lower than 77% for anthocyanins and 38% for proanthocyanidins. For both classes of compounds, no clear evolution in these extraction yields could be observed as sugars accumulated in pulp (from 162.6 to 275.0 g/L). Nevertheless, some structural features within each family of compounds significantly influenced extractability, for example, a lower extraction yield for coumaroylated anthocyanins and for tannins with a high degree of polymerization. Finally, no direct relationship could be found in extraction media between the amounts of all red pigments (measured in acidic conditions) and the color intensity at 520 nm (measured in wine-like model solutions).

Pigments resulting from the direct condensation of anthocyanins and flavanols are usually associated with reactions taking place during processing and storage of plant-derived foods and beverages and have been particularly studied in aged red wines. In this paper, small amounts of flavanol-anthocyanin condensed pigments are found in different plant extracts. Structures are suggested for 10 such condensed pigments detected in extracts of strawberry, runner beans, purple corn and grape skins, based on their MS" fragmentation patterns, following analyses by electrospray tandem mass spectrometry. All of them correspond to dimers containing a flavan-3-ol [either (epi)afzelechin, (epi)catechin or (epi)gallocatechin] as the upper unit carbon-carbon linked to a lower anthocyanin unit consisting of different delphinidin, cyanidin, pelargonidin, peonidin or malvidin derivatives. The detection of these pigments in plant extracts may suggest that they are natural pigments and not products exclusively formed during storage and ageing of processed foods and beverages, as was previously assumed. Comissão Europeia (Fundo Social Europeu) e Governo Português através do Programa PRODEP (III) - ref.ª 5.3/N/199.006/00-Doutoramento.

Grape seed powders, byproducts of either winemaking or grape processing, were prepared from Vitis vinifera (Merlot and Chardonnay) and Vitis rotundifolia (Muscadine) species. Water, methanol, acetone and ethanol were tested as extractants on Muscadine seed powder. Antioxidant activities of grape seeds and skins were determined as oxygen radical absorbance capacity with phycoerythrin (ORACPE) for both grape species. The results indicated that aqueous solutions of ethanol, methanol or acetone were better than a single-compound solvent system for extraction of total phenols from Muscadine seed powder. Antioxidant capacities of Chardonnay, Merlot and Muscadine grape seeds were 638, 345 and 311 μmol Trolox equivalent (TE)/g dry weight in decreasing order (P

International audience; The fractionation of a grape skin extract by multilayer countercurrent chromatography coupled with step gradient elution allowed the preparation of a fraction almost devoid of free anthocyanins. This fraction appeared to be almost exclusively polymeric, as judged by liquid chromatographic-mass spectrometric (LC-MS) analysis, color-bleaching tests with sulfur dioxide, and thiolysis. Electrospray mass spectrometric analysis indicated that the pigmented material in this fraction was chiefly composed of direct condensation products of anthocyanin extending up to trimers. With regard to their linkages, the anthocyanin units in the oligomers were possibly linked by either an A-type (by both carbon-carbon and ether bonds) or B-type (by carbon-carbon bond) linkage, like proanthocyanidins. The terminal anthocyanin unit of the oligomers is consistently in the flavylium form but the extension units are in the flavan form for the A-type oligomers and in the flavene form for the B-type oligomers. Although their linkages still need to be defined rigorously, this is the first mass spectrometric evidence confirming the existence of anthocyanin oligomers in the grape skin extract

Aims: The changes that skin tannins undergo during ripening, which are crucial for their extractability and transfer to wine, were followed in Monastrell grape skins. To elucidate whether the commonly used analytical method involving extraction with 70 % acetone overestimates the quantity of tannins that could be extracted during the winemaking process, the extraction with aqueous 12.5 % ethanol was also monitored throughout the ripening period.Methods and results: When 70 % acetone was used as extraction solvent, the results showed that skin tannin concentration decreased towards maturity. When tannins were extracted with 12.5 % ethanol, their concentration during the first part of maturation was much higher than that obtained with the acetone extraction. However, both methods gave similar quantitative results for the last sampling dates, although the mean degree of polymerization (mDP) of the extracted tannins was significantly lower using the ethanol method.Conclusions: The acetone method provides, for ripe grapes, an accurate prediction of what may be quantitatively extracted by a fermenting medium, although it overestimates the tannin mDP.Significance and impact of the study: The structural composition of tannins (and not only their concentration) might be essential for defining the sensorial characteristics of the wine and the differences observed in tannin mDP between the acetone and the ethanol method may be of importance when predicting wine organoleptic characteristics.

This study was conducted to investigate the effect of dietary grape skin on lipid peroxidation and antioxidant defense system in rats fed high fat diet. The Sprague-Dawley rats were fed either control (5% fat) diet or high fat (25% fat) diet which was based on AIN-93 diet for 2 weeks, and then they were grouped as control group (C), control + 5% grape skin group (CS), high-fat group (HF), high fat + 5% grape skin group (HFS) with 10 rats each and fed corresponding diets for 4 weeks. The hepatic thiobarbituric acid reacting substances (TBARS) were increased in high fat group as compared with control group, but reduced by grape skin. The serum total antioxidant status, and activities of hepatic catalase and superoxide dismutase, xanthine oxidase and glucose-6-phosphatase were increased by supplementation of grape skin. Glutathione peroxidase activity was significantly higher in CS group than in C group. Grape skin feeding tended to increase the concentration of total glutathione, especially in control group. The ratio of reduced glutathione to oxidized glutathione was lower in high fat groups than in control groups. The ratio was increased by dietary supplementation of grape skin in control group. These results suggest that dietary supplementation of grape skin would be effective on protection of oxidative damage by lipid peroxidation through improvement of antioxidant defense system in rats fed high fat diet as well as rats with low fat diet.

Background The objective of the present study was to determine the phytochemical content and the protective effect of red grape skin extract (RGSE) against fructose-mediated protein oxidation. In addition, RGSE was screened for its potential as an antioxidant using various in vitro models. Methods Antioxidant activity was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl radical scavenging activity, superoxide radical scavenging activity, trolox equivalent antioxidant capacity, ferric reducing antioxidant power (FRAP), ferrous ion chelating power. The total phenols content was measured by Folin–Ciocalteu assay, the flavonoids content by the AlCl3 colorimetric method. Antiglycation activity was determined using the formation of AGE fluorescence intensity, Nϵ-(carboxymethyl)lysine, and the level of fructosamine. The protein oxidation was examined using the level of protein carbonyl content and thiol group. Results The results showed that the content of total phenolics, flavonoids and total anthocyanins in RGSE was 246.3 ± 0.9 mg gallic acid equivalent/g dried extract, 215.9 ± 1.3 mg catechin equivalent/g dried extract, and 36.7 ± 0.8 mg cyanidin-3-glucoside equivalent/g dried extract, respectively. In the DPPH radical scavenging activity, hydroxyl radical scavenging activity, and superoxide radical scavenging activity, RGSE had the IC50 values of 0.03 ± 0.01 mg/ml, 5.40 ± 0.01 mg/ml, and 0.58 ± 0.01 mg/ml, respectively. In addition, RGSE had trolox equivalent antioxidant capacity assay (395.65 ± 1.61 mg trolox equivalent/g dried extract), ferric reducing antioxidant power (114.24 ± 0.03 mM FeSO4/g dried extract), and ferrous ion chelating power (3,474.05 ± 5.55 mg EDTA/g dried extract), respectively. The results showed that RGSE at different concentrations (0.031–0.500 mg/ml) has significantly inhibited the formation of AGEs in terms of the fluorescence intensity of glycated BSA during 4 weeks of study. The RGSE markedly decreased the level of fructosamine, which is directly associated with the reduction of AGE formation and Nϵ-(carboxymethyl)lysine (CML). The results demonstrated the significant effect of RGSE on preventing protein oxidative damages, including effects on the thiol and protein carbonyl oxidation. Conclusions The present study revealed that RGSE would exert beneficial effects by virtue of its antioxidants and antiglycation. The findings could provide a new insight into the naturally occurring antiglycation properties of RGSE for preventing AGE-mediated diabetic complication.

The aim of this work was to study the effect of the daily ingestion of a purified anthocyanin extract from red grape skin on rat serum antioxidant capacity (ORAC) and its safety for the intestinal epithelium. The study was carried out in rats orally administered with the extract for 10 days in either normal physiological conditions or exposed to a pro-oxidant chemical (CCl4). The oral administration of the extract significantly (P