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

Changes in Tannin Composition of Syrah Grape Skins and Seeds during Fruit Ripening under Contrasting Water Conditions

Tannin accumulation and composition were determined in skins and seeds isolated from Vitis vinifera cv. Syrah grapes submitted to contrasting water regimes under semiarid climatic conditions. Three irrigation treatments were conducted, starting at berry set through harvest of two growing seasons, 2011 and 2012: irrigation at 100% of crop evapotranspiration ETc (FI), irrigation at 50% of ETc (DI) and non-irrigated (NI). Seed total tannins did not vary with maturity but those of skins underwent a progressive decline (especially in 2011), expressed both on a fresh weight and on a per berry basis. Skin total tannin concentration and content per berry were increased under NI and DI conditions, mainly in 2012. In contrast, seed total tannins (in 2012) and flavan-3-ol monomers and tannin oligomers (both years) were higher in the fully irrigated vines (FI). Skin polymer size increased during ripening, NI and DI skins showing higher mean degree of polymerization (mDP) compared to FI at harvest. NI was also associated with a lower percentage of galloylation (%G) in skin oligomeric fraction (in 2012) and a lower percentage of prodelphinidins in the skin polymeric fraction (both years) at harvest. The mDP and %G of seed extracts did not vary during ripening and were higher in NI but only in 2012. According to the results, management of vine water status was shown to influence tannin amount and composition of Syrah grapes grown under semiarid conditions.

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.

Effect of harvest time on physico-chemical properties and bioactive compounds of pulp and seeds of grape varieties

In this study, physicochemical properties and bioactive compounds of three grape varieties (Cardinal, Müşküle and Razaki) harvested at the three different harvest times (on time, one and two weeks earlier) were investigated. The highest antioxidant activity, total phenolic and flavonoid contents were observed in Razaki pulp and these were 82.854%, 127.422 mg/100 g, 3.873 mg/g, respectively. The contents of bioactive compounds in grape seeds were found higher than those in pulps. Similarly, seed of Razaki had higher antioxidant activity (91.267%) and total phenolic content (477.500 mg/100 g) when compared to results of other varieties. The key phenolic compounds of all grape variety and seeds were gallic acid, 3,4-dihydroxybenzoic acid, (+)-catechin ve 1,2-dihydroxybenzene. The oil content of grape seeds ranged from 8.50% (Razaki harvested one week ago) to 19.024% (Müşküle harvested one week ago). The main fatty acids of grapeseed oils were linoleic, oleic and palmitic acids. In addition, the oil of Razaki seeds was rich in tocopherols when compared to the other varieties.

Addressing Facts and Gaps in the Phenolics Chemistry of Winery By-Products

Grape and wine phenolics display a noticeable structural diversity, encompassing distinct compounds ranging from simple molecules to oligomers, as well as polymers usually designated as tannins. Since these compounds contribute critically to the organoleptic properties of wines, their analysis and quantification are of primordial importance for winery industry operators. Besides, the occurrence of these compounds has been also extensively described in winery residues, which have been pointed as a valuable source of bioactive phytochemicals presenting potential for the development of new added value products that could fit the current market demands. Therefore, the cumulative knowledge generated during the last decades has allowed the identification of the most promising compounds displaying interesting biological functions, as well as the chemical features responsible for the observed bioactivities. In this regard, the present review explores the scope of the existing knowledge, concerning the compounds found in these winery by-products, as well as the chemical features presumably responsible for the biological functions already identified. Moreover, the present work will hopefully pave the way for further actions to develop new powerful applications to these materials, thus, contributing to more sustainable valorization procedures and the development of newly obtained compounds with enhanced biological properties.

Influence of genetic and vintage factors in flavan-3-ol composition of grape seeds of a segregating Vitis vinifera population

BACKGROUND

Flavan-3-ol compounds are important secondary metabolites which show high antioxidant activity and are responsible for bitterness and astringency of food products. The aim of this work was to evaluate the potential for selecting grape materials with higher seed flavanol content from a breeding population. The composition and content of flavan-3-ols from 151 genotypes obtained from crossing wine grape varieties was evaluated by UPLC in three consecutive years.

RESULTS

Chromatograms of flavan-3-ol compounds showed the same 12 compounds for all samples, but quantitative differences were observed between genotypes as well as parental varieties. The most abundant compounds were (-)-epicatechin and (+)-catechin followed by proanthocyanidins A2 and B2. Progeny showed higher values than the parental genotypes for every detected compound indicating directional transgressive segregation. With these results genotypes with as much as five times more flavanols than their parents could be identified. The year effect was significant; however, high correlations between years for each compound indicated that there is a strong genetic component in the determination of flavanol content.

CONCLUSION

Higher contents of seed flavan-3-ols can be obtained by hybridisation, and those genotypes could be used for extracting healthy phytochemicals, adding value to seeds as a sub-product in wine elaboration. © 2016 Society of Chemical Industry.

Long-term effects of abscisic acid (ABA) on the grape berry phenylpropanoid pathway: Gene expression and metabolite content

ABA has been proposed as the main signal triggering the onset of the ripening process in grapes, and modulating the secondary metabolism in grape berry skins. To determine the effect of ABA on secondary metabolism in berries, clusters of Carménère were sprayed with 0 μLL(-1) ABA; 50 μLL(-1) ABA and 100 μLL(-1) ABA during pre-véraison, and the gene expression of the transcription factors and enzymes of the phenylpropanoid pathway were assessed from véraison to 70 days after véraison (DAV). Additionally, flavonols, tannins and anthocyanins were assessed from véraison until harvest (110 DAV). ABA accelerated sugar and anthocyanin accumulation at véraison. The grape transcript abundance of VvDFR, VvANS, VvUFGT and VvMybA1, all peaking around véraison mimicked the concentration of ABA throughout the season. The highest anthocyanin concentration occurred 35 DAV for all treatments, but higher pigment concentrations were observed in ABA-treated berries at véraison and from 60 to 70 DAV to harvest. VvPAL was also increased by treatment at the higher concentration of ABA from véraison to 40 DAV. Regarding flavanol synthesis, VvLAR2 and VvMyb4A decreased from véraison until 40 DAV and then increased again until 70 DAV. Compared to the control, both ABA treatments resulted in a less-than-proportional reduction of the expression of both genes compared to the control and, after 40 DAV, in a more-than-proportional increase compared to the control, suggesting a long-term effect of the pre-véraison ABA spray on the berries. A concomitant increase in flavanols was observed in berries after 40 DAV, and this occurred at a higher extent in berries treated with the highest ABA concentration.

Trying to set up the flavanolic phases during grape seed ripening: A spectral and chemical approach

Grape seeds were collected in ten different dates and classified in seven groups according to their individual hyperspectral imaging characteristics. Proanthocyanidin composition was studied using HPLC-MS for oligomers and acid catalyzed cleavage for polymers characterization. The combination of both analysis provided a complete description of the flavanols. Chemometric analysis was performed to summarize the analytical results. None of the considered variables presented statistical differences among all groups. From one to five groups were found for each variable, while three was the most frequent value, consequently three putative stages might be considered the real number of different analytical stages since it is the number of statistically significant groups for the majority of the compounds. This classification could be considered as the first step to optimize the use of seeds in winemaking to minimize the gap between sugar and phenolic maturities, consequence of the global climate change, mainly observed in warm climate.

Use of organic acids for prevention and removal of Bacillus subtilis biofilms on food contact surfaces

The efficacies of organic acid (citric, malic, and gallic acids) treatments at 1% and 2% concentrations on prevention and removal of Bacillus subtilis biofilms were investigated in this study. The analyses were conducted on microtitration plates and stainless steel coupons. The biofilm removal activities of these organic acids were compared with chlorine on both surfaces. The results showed that citric acid treatments were as powerful as chlorine treatments for prevention and removal of biofilms. The antibiofilm effects of malic acid treatments were higher than gallic acid and less than citric acid treatment. When the antibiofilm effects of these acids and chlorine on the two surfaces were compared, the prevention and removal of biofilms were measured higher on microtitration plates than those on stainless steel coupons. Higher reductions were obtained by increasing concentrations of sanitizers on 24-hour biofilm with 20-minute sanitizer treatments for removal of biofilms.

Determination of phenolic compounds content and antioxidant activity in skin, pulp, seed, cane and leaf of five native grape cultivars in West Azerbaijan province, Iran

In the present work, the phenolic compounds content and antioxidant activity in the skin, pulp, seed, cane and leaf of one international (Muscat) and five native (Hosseini, Ghara Shira, Agh Shani, Ghara Shani and Ghara Ghandome) grape cultivated in West Azerbaijan, Iran were investigated. Ghara Shani grape skin was found to contain the highest content of total phenolic and anthocyanin and cane of Ghara Shani contains the highest amount of flavonoid. A remarkable DPPH radical scavenging activity up to 95% and consequently, the lowest IC50 was found for skin of Ghara Shani. According to RP-HPLC experiments, the highest concentration of phenolic compounds was identified as catechin (945 μg/g), epicatechin (482 μg/g), gallic acid (319 μg/g) and resveratrol (29.8 μg/g) in skin of Ghara Shani, quercetin in cane of Ghara Shani (956 μg/g), rutin in skin of Ghara Shira (298 μg/g) and caffeic acid in cane of Ghara Shira (17.4 μg/g).

Effect of Three Training Systems on Grapes in a Wet Region of China: Yield, Incidence of Disease and Anthocyanin Compositions of Vitis vinifera cv. Cabernet Sauvignon

Grapevine training systems determine the suitability for grape varieties in a specific growing region. We evaluated the influence of three training systems, Single Guyot (SG), Spur-pruned Vertical Shoot-Positioned (VSP), and Four-Arm Kniffin (4AK), on the performance of grapes and vines of Vitis vinifera L. cv. Cabernet Sauvignon in the 2012 and 2013 growing seasons in a wet region of central China. 4AK was the most productive system in comparison to SG and VSP. SG and VSP had lower disease infections of leaves and berries, especially in the mid- and final stage of berry ripening. Three training systems had no impact on berry maturity. PLS-DA (Partial Least Squares-Discriminant) analysis showed that the relatively dry vintage could well discriminate three training systems, but the wet vintage was not. A wet vintage of 2013 had more accumulation of 3′5′-substituted and acylated anthocyanins, including malvidin-3-O-(6-O-acetyl)-glucoside, malvidin-3-O-glucoside, and petunidin-3-O-(cis-6-O-coumaryl)-glucoside, etc. With regard to the effect of training systems, 4AK grapes had the lowest concentrations of total anthocyanins and individual anthocyanins, SG and VSP differed according to the different vintages, and showed highest concentration of total individual anthocyanins in 2012 and 2013, respectively. Generally, VSP benefited the most, contributing to significantly highest levels of total individual anthocyanins, and major anthocyanin, including malvidin-3-O-glucoside and malvidin-3-O-(6-O-acetyl)-glucoside, and the grapes obtained from VSP presented significantly highest proportion of 3′5′-substituted anthocyanins. With regard to the ratios of 3′5′/3′-substituted, methoxylated/non-methoxylated and acylated/non-acylated anthocyanins, the significantly higher levels were also shown in VSP system. In summary, VSP was the best training system for Cabernet Sauvignon to accumulate relatively stable individual anthocyanins in this wet region of China and potentially in other rainy regions.

Polyphenolic Contents and Antioxidant Activities of Underutilized Grape (Vitis vinifera L.) Pomace Extracts

Grape pomace is an abundant source of underutilized winery by-products. Polyphenols were extracted from grape pomace using cellulase and gluco-amylase enzymes. 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Folin-Ciocalteu's assays were used to measure antioxidant activity and total polyphenolic contents. Both cellulase, and gluco-amylase digested grape pomace showed efficient radical scavenging activity. In addition, the total polyphenolic contents of cellulase digested grape pomace showed lower concentrations were effective compared to higher concentrations, whereas gluco-amylase enzyme did not show remarkable variations. The DPPH radical scavenging activity and total polyphenolic contents were significantly higher in the cellulase digested grape pomace compared to the gluco-amylase digested and the not digested grape pomace. It is notable that enzymatic digestions were efficient for extracting polyphenols from grape pomace. The underutilized grape pomace polyphenols can be further used for food safety as a natural antioxidant.

Kaempferol and inflammation: From chemistry to medicine

Inflammation is an important process of human healing response, wherein the tissues respond to injuries induced by many agents including pathogens. It is characterized by pain, redness and heat in the injured tissues. Chronic inflammation seems to be associated with different types of diseases such as arthritis, allergies, atherosclerosis, and even cancer. In recent years natural product based drugs are considered as the novel therapeutic strategy for prevention and treatment of inflammatory diseases. Among the different types of phyto-constituents present in natural products, flavonoids which occur in many vegetable foods and herbal medicines are considered as the most active constituent, which has the potency to ameliorate inflammation under both in vitro and in vivo conditions. Kaempferol is a natural flavonol present in different plant species, which has been described to possess potent anti-inflammatory properties. Despite the voluminous literature on the anti-inflammatory effects of kaempferol, only very limited review articles has been published on this topic. Hence the present review is aimed to provide a critical overview on the anti-inflammatory effects and the mechanisms of action of kaempferol, based on the current scientific literature. In addition, emphasis is also given on the chemistry, natural sources, bioavailability and toxicity of kaempferol.

Phenolic composition and antioxidant capacity of pomaces from four grape varieties (Vitis vinifera L.)

BACKGROUND

Phenolic compounds are widely distributed secondary metabolites in plants usually conferring them with unique taste, flavour and health-promoting properties. In fruits of Vitis vinifera L., phenolic composition is highly dependent on grape variety. Differential extraction of these compounds from grapes during winemaking is critically associated with wine quality. By-products of winemaking, such as grape pomace, can contain significant amounts of polyphenols. However, information concerning the varietal effect on wine grape pomace is scarce. In this study, pomaces from Sauvignon Blanc (SB), Chardonnay (CH), Cabernet Sauvignon (CS) and Carménère (CA) grape varieties were characterized spectroscopically and by HPLC-DAD analysis.

RESULTS

White grape pomaces (SB and CH) presented higher antioxidant capacities and higher contents of total phenols and total proanthocyanidins compared with red grape pomaces (CS and CA), whereas the latter showed much higher anthocyanin levels and colour intensities. Concentrations of monomeric proanthocyanidins and low-molecular-weight phenols in the four grape pomace varieties were significantly different.

CONCLUSION

Grape pomaces from four varieties showed high but diverse contents of polyphenols and antioxidant capacities. Thus grape pomaces represent an important potential source of polyphenols, which could be useful for nutritional and/or pharmacological purposes.

Monitoring trans-Resveratrol in Grape Berry Skins During Ripening and in Corresponding Wines by HPLC

Trans-resveratrol (3,5,4'-trihydroxy-trans-stilbene) is naturally present in the skin of grapes and therefore is expected to occur in grape products. Recently, there has been a renewal of interest in wine as medical treatment for various disorders. In this study, berry skins of five red grape varieties were analysed at weekly intervals for trans-resveratrol production, during 2012 and 2013 harvest. The obtained wines were also evaluated. Quantification of trans-resveratrol in grape skin extracts and wines was carried out by high-performance liquid chromatography. Favourable viticultural climate during harvest in 2012 resulted in a higher content of trans-resveratrol. The highest trans-resveratrol content was in Pinot Noir and Feteasca Neagra grape varieties, both in berry skins and wines, while the lowest amounts were identified in Cabernet Sauvignon variety. We can conclude that there was a significant correlation between the content of trans-resveratrol in grape skins and that in the respective wine.

Extraction kinetics of anthocyanins from skin to pulp during carbonic maceration of winegrape berries with different ripeness levels

The evolution of the content and profile of anthocyanins was studied in the skin and pulp of Gamay winegrapes during twelve days of carbonic maceration. The ripening effect was also investigated using berries belonging to two density classes (A=1094-1100 kg/m(3) and B=1107-1115 kg/m(3)). The ripest berries showed a higher extraction yield, even though the differences among density classes tended to decline towards the end of the process, and few significant differences were found in the anthocyanin profile. The maceration time influenced strongly not only the content and extraction yield, but also the qualitative composition of anthocyanins towards the predominance of malvidin derivatives. Finally, the extraction yield of anthocyanins was positively related with the ethanol formed and the skin mechanical properties using linear regression models, which showed that the skin hardness is likely to be an important variable in modelling daily anthocyanin extraction during carbonic maceration, particularly from the sixth day.

Phenolic composition and mouthfeel characteristics resulting from blending Chilean red wines

BACKGROUND

The blending of wine is a common practice in winemaking to improve certain characteristics that are appreciated by consumers. The use of some cultivars may contribute phenolic compounds that modify certain characteristics in blended wines, particularly those related to mouthfeel. The aim of this work was to study the effect of Carménère, Merlot and Cabernet Franc on the phenolic composition, proanthocyanidin profile and mouthfeel characteristics of Cabernet Sauvignon blends.

RESULTS

Significant differences in chemical composition were observed among the monovarietal wines. Separation using Sep-Pak C₁₈ cartridges revealed differences in the concentration but not in the proportion of various proanthocyanidins. Blending reduced polyphenol concentration differences among the various monovarietal wines. Although no major overall differences were observed after blending the monovarietal wines, this oenological practice produced clear differences in mouthfeel characteristics in such a way that the quality of the perceived astringency was different.

CONCLUSION

This study showed that the use of a particular wine variety (Cabernet Sauvignon) in a higher proportion in wine blending produced blends that were less differentiable from the monovarietal wine, owing to a suppression effect, producing an apparent standardization of the wines regarding chemical composition.

Factors affecting skin tannin extractability in ripening grapes

The acetone-extractable (70% v/v) skin tannin content of Vitis vinifera L. cv. Cabernet Sauvignon grapes was found to increase during late-stage ripening. Conversely, skin tannin content determined following ethanol extraction (10, 20, and 50% v/v) did not consistently reflect this trend. The results indicated that a fraction of tannin became less extractable in aqueous ethanol during ripening. Skin cell walls were observed to become more porous during ripening, which may facilitate the sequestering of tannin as an adsorbed fraction within cell walls. For ethanol extracts, tannin molecular mass increased with advancing ripeness, even when extractable tannin content was constant, but this effect was negligible in acetone extracts. Reconstitution experiments with isolated skin tannin and cell wall material indicated that the selectivity of tannin adsorption by cell walls changed as tannin concentration increased. Tannin concentration, tannin molecular mass, and cell wall porosity are discussed as factors that may influence skin tannin extractability.

A novel method for evaluating flavanols in grape seeds by near infrared hyperspectral imaging

Chemical composition of seeds changes during grape ripening and this affects the sensory properties of wine. In order to control the features of wines, the condition of seeds is becoming an important factor for deciding the moment of harvesting by winemakers. Sensory analysis is not easy to carry out and chemical analysis needs lengthy procedures, reagents, and it is destructive and time-consuming. In the present work, near infrared hyperspectral imaging has been used to determine flavanols in seeds of red (cv. Tempranillo) and white (cv. Zalema) grapes (Vitis vinifera L.). As reference measurements, the flavanol content was estimated using the p-dimethylaminocinnamaldehyde (DMACA) method. Not only total flavanol content was evaluated but also the quantity of flavanols that would be extracted into the wine during winemaking. A like-wine model solution was used for this purpose. Calibrations were performed by partial least squares regression and they provide coefficients of determination R(2)=0.73 for total flavanol content and R(2)=0.85 for predicting flavanols extracted with model solution. Values up to R(2)=0.88 were reached when cultivars were considered individually.

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.

Simultaneous determination of 14 phenolic compounds in grape canes by HPLC-DAD-UV using wavelength switching detection

The paper described a novel chromatographic method for the simultaneous determination of phenolic compounds such as gallic, protocatechuic, vanillic, caffeic, syringic, p-coumaric and salicylic acid, (+)-catechin, (‒)-epicatechin, rutin, morin, quercetin, coumarin and trans-resveratrol at their maximum absorbance wavelengths (MAW) employing reverse-phase high performance liquid chromatography combined with DAD and UV detection via detection wavelength switching. The method was based on MAW acquisition by DAD and quantification by UV. The separation process was performed on a Shim-Pack VP-ODS C₁₈ column (250 mm × 4.6 mm, 5 μm) held at 30 °C, utilizing 3.0% acetic acid and acetonitrile as mobile phase at a flow rate of 0.8 mL/min in the gradient elution mode. The method was fully validated in terms of linearity (r² > 0.9990, 10‒350 mg/L), precision (both intra-day and inter-day RSD < 4.22%), accuracy (97.31%‒104.66%), specificity, robustness (0.59% < RSD < 2.86%), limit of detection and quantification. The switching method significantly improved the sensitivities of most phenolics studied in comparison with the standard constant wavelength detection (280 nm). The proposed method has been successfully applied to the determination of 14 phenolic compounds in 89 varieties of one-year-old Chinese grape one-year-canes. Grape canes contain many phenolics, especially trans-resveratrol, (‒)-epicatechin, and (+)-catechin.

Use of instrumental acoustic parameters of winegrape seeds as possible predictors of extractable phenolic compounds

The use of instrumental acoustic parameters produced during a compression test as reliable predictors of the extractable phenolic composition in intact winegrape seeds, determined by reference chemical methods, was evaluated by means of the analytical performance of calibration models. These models were developed only for those phenolic compounds most significantly and strongly correlated with the acoustic parameters. The analytical performance of the models was expressed in terms of standard error of cross-validation (SECV) and residual predictive interquartile amplitude (RPIQ), among other statistics. Several acoustic parameters showed satisfactory predictive accuracy for the percentage of galloylation in the terminal units, the content of (-)-epicatechin, and the mean degree of polymerization. Most of the reliable models developed are fairly recommended not for quantitative purposes but for fast screening (SECV% < 19, 1.6 < RPIQ < 2.1).

Effect of inert gas and prefermentative treatment with polyvinylpolypyrrolidone on the phenolic composition of Chilean Sauvignon blanc wines

BACKGROUND

Sauvignon blanc wines are produced under a wide variety of winemaking conditions, some of which include different fruit-ripening levels, cold soaks and the use of fining agents and inert gases. Anecdotal evidence suggests that sensory variations among these wines may have to do with their phenolic composition and concentration. Therefore the aim of this work was to study the effects of different winemaking conditions typically used in Chile on the phenolic composition and concentration of Sauvignon blanc wines.

RESULTS

The use of an inert gas (CO2) in winemaking produced differences in the proportion of proanthocyanidin fractions. A higher concentration of flavan-3-ol monomers resulted from winemaking in the presence of inert gas. This condition also produced a higher content of total phenols and low-molecular-weight phenolic compounds. Low doses of polyvinylpolypyrrolidone (PVPP) in the prefermentative treatments produced wines with a higher content of phenolic compounds. Under these conditions a higher content of polymeric proanthocyanidins was observed.

CONCLUSION

Different winemaking conditions modified the concentration and proportion of proanthocyanidin fractions and the global phenolic composition of the resulting white wines. This should be taken into account by the wineries producing these wines.

Evolution of analysis of polyhenols from grapes, wines, and extracts

Grape and wine phenolics are structurally diverse, from simple molecules to oligomers and polymers usually designated as tannins. They have an important impact on the organoleptic properties of wines, that's why their analysis and quantification are of primordial importance. The extraction of phenolics from grapes and from wines is the first step involved in the analysis. Then, several analytical methods have been developed for the determination of total content of phenolic, while chromatographic and spectrophotometric analyses are continuously improved in order to achieve adequate separation of phenolic molecules, their subsequent identification and quantification. This review provides a summary of evolution of analysis of polyphenols from grapes, wines and extracts.

Effect of rain-shelter cultivation of Vitis vinifera cv. Cabernet Gernischet on the phenolic profile of berry skins and the incidence of grape diseases

Rain-shelter cultivation is an effective cultural method to prevent rainfall damage during grape harvest and widely applied in the Chinese rainy regions. In this study we investigated the effect of rain-shelter cultivation on grape diseases and phenolic composition in the skins of Vitis vinifera cv. Cabernet Gernischet grape berries through the comparison with open-field cultivation at two vintages (2010 and 2011). The results showed that rain-shelter cultivation reduced the incidence of grape diseases significantly and delayed the maturation of Cabernet Gernischet fruits. With regards to most of the phenolic compounds identified in this study, their content in grape samples under rain-shelter cultivation was decreased compared to those under open-field cultivation. However, rain-shelter cultivation stimulated the accumulation of dihydroquercetin-3-O-rhamnoside in grape skins during grape maturation. These were related with micrometeorological alterations in vineyards by using plastic covering under rain-shelter cultivation. It suggests the rain-shelter cultivation makes possible the cultivation of “Cabernet Gernischet” grapes in an organic production system, for providing a decrease in the incidence of diseases and the dependence on chemical pesticides in the grape and wine industry.

Optimization of a method based on the simultaneous measurement of acoustic and mechanical properties of winegrape seeds for the determination of the ripening stage

An instrumental texture analysis method has been optimized for the differentiation of grape ripening stages based on the simultaneous determination of mechanical and acoustic parameters of the seeds. Two factorial central composite design was used to optimize the most influencing operative conditions (speed and deformation) on mechanical and acoustic measurements. This experimental design in combination with response surface methodology showed that the most responsive parameters to changes in seeds during ripening were Young's modulus of elasticity, many acoustic parameters measured with instrumental gain set to 0 (acoustic energy, linear distance, and number of peaks) and others measured at 24 dB gain (linear distance, number of peaks, and average pressure level). However, the optimal operative conditions depended on the texture parameter used. A correlation study between texture parameters and phenolic compounds of the seeds revealed that acoustic parameters like the average pressure level could be proposed as phenolic maturity indices.

Phenolic compositions of grapes and wines from cultivar cAbernet Sauvignon produced in Chile and their relationship to commercial value

The phenolic composition of wine depends on, among other factors, the grapes used to make it. In this sense, knowledge of the chemical composition of grapes and its association with the resulting wines is an important tool to determine if there is a relationship between the phenolic composition of grapes and the price that these wines obtain in the market. For this purpose, grape skins and seeds from the cultivar Cabernet Sauvignon from the central region of Chile, in 2009 and 2010 vintages from two ripening points, were subjected to chemical and phenolic analyses, as were the wines made from these grapes. Grapes and the corresponding wines from three retail price wine categories, U.S. $6-8, U.S. $28-30, and U.S. $150-160, were evaluated. No differences were found across the price categories in the chemical analysis of grapes. Berry skins and wines from the higher price categories presented a higher concentration only of total tannins, and the differences in their concentrations were only among the different fractions of proanthocyanidins in the skins, seeds, and wines; there were no differences in their proportions. A seasonal effect influenced the concentrations of certain compounds in grapes and led to a decrease in the concentration of total phenols, total tannins, and total anthocyanins between sampling dates as harvesting moved toward the common commercial grape harvest in Chilean viticulture.

Varietal differences among the phenolic profiles and antioxidant properties of four cultivars of spine grape (Vitis davidii Foex) in Chongyi County (China)

Spine grape (Vitis davidii Foex) is an important wild plant species in South China. To provide sufficient experimental evidence for the strong antioxidant activity of spine grapes, four cultivars from Chongyi County, China, including three red varieties (Junzi #1, Junzi #2, and Liantang) and one white variety (Baiyu) were evaluated. The Junzi #1 had the highest phenolic content (total phenolic, flavonoids, flavanols, and anthocyanins) and the strongest antioxidant capacity (DPPH radical-scavenging capacity, cupric-reducing capacity and hydroxyl radical-scavenging activity) among the four varieties. HPLC analysis of spine grapes revealed that the (+)-catechin was the most abundant phenolics and the hydroxycinnamic acids were the major phenolic acids in the four varieties. Hierarchical cluster analysis showed that the Junzi #1 belongs to the group with high phenolic content and strong antioxidant power. The results suggest the Junzi #1 has the best health promoting properties, and the higher utilization value and potential for development.