White Wine Grape Research Articles

Phenolic Compound Profiles in Skins of White Wine and Table Grape Cultivars Grown in the National Grape Germplasm Resource Nursery of China

The phenolic compound profiles in the skins of white grapes, containing ten wine grape and six table grape cultivars grown in the National Grape Germplasm Resource Nursery at the Zhengzhou Fruit Research Institute of China, were investigated using ultra-high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS/MS). The objective of this study was to evaluate if phenolic compound profiles can be used as indictors to differentiate the quality of wine and table grape cultivars. Significant differences in phenolic compound profiles were observed among these grape cultivar skins. The highest content of total hydroxybenzoic acids, total hydroxycinnamic acids, total flavan-3-ols, total flavones and flavonols and total stilbenes was observed in the skin of the Canada Muscat, Rommel, Kadin parmac, Bacchus and Silvaner cultivars respectively. A great compositional difference was observed among these grape cultivars regarding the individual hydroxycinnamic acids and flavonols. Cluster analysis showed that three table grape cultivars, namely Canada Muscat, Rommel and Kadin parmac, possessed significantly different phenolic compound profiles compared to the other grape cultivars. These results suggested that phenolic compound patterns and contents played important roles in evaluating the quality of table and wine grapes and might provide useful information on grape breeding and winemaking in China.

Ethanol Content in Must Grape by Alcohol Dehydrogenase Biosensors Based on Doped - Polyaniline Modified Screen Printed Electrodes

The presence of ethanol in wine grapes is an important parameter for the evaluation of their quality in winemaking. In this study we report the development of an amperometric biosensor for the determination of ethanol in must grape based on the alcohol dehydrogenase enzyme immobilized on polyaniline doped with poly(2-acrylamido-2-methyl-1-propane) sulfonic acid polymer. The doped polymer was able to detect βnicotinamide-adenine dinucleotide, reduced at low potential with a linear range from 0.005-2 mM and a sensitivity of 653.15 μA M −1 . Under optimized conditions, the alcohol dehydrogenase biosensor showed a limit of detection of 0.001 %vol ethanol and a sensitivity of 3551 nA %vol −1 . Finally, the ethanol biosensor was used for ethanol determination in must from red and white wine grapes and matrix effect was evaluated.

Influence of Short-Term Postharvest Ozone Treatments in Nitrogen or Air Atmosphere on the Metabolic Response of White Wine Grapes

Grapes were exposed to ozone gas in air (GO) or in nitrogen atmosphere (GNO) for 12 h at 10 °C and then kept in normal atmosphere for 1 day at room temperature. Grapes kept at 10 °C, for 12 h without ozone treatment plus 1 day at room temperature, were considered as the control sample (GC). Low temperature induced a great change of ripening features only in GC with reduction of weight, loss of sugars (about 20 %) and increase in titratable acidity but, above all, 15 % of increase in malondialdehyde (MDA). The use of ozone in air or in nitrogen neither altered the fruit quality attributes nor modified MDA concentration. Ozone provoked a high decrease of hydroxycinnamic acids, compared to the harvest grapes, overall in GNO samples (caftaric acid −38.8 %; coutaric acid −26.1 %). Cold storage treatment without ozone enhanced antiradical capacity. Three main flavonols, named hyperoside (quercetin-3-O-galactoside), rutin (quercetin-3-O-rutinoside), and kaempferol-3-O-glucoside were found in all grape extracts analyzed, and the total flavonol content increased significantly (p < 0.008) in all the samples starting from 1.79 mg/g dry matter of grapes at harvest (GH sample) up to 2.13 mg/g of GNO one. Both cold storage and ozone in air treatments significantly increased catechin content compared to that in the grapes at harvest (+54.6 and +35.7 % for GC and GO, respectively; p < 0.008). The interrelationships between the parameters analyzed and the different postharvest treatments, as well as the relationships among variables, were investigated by principal component analysis. Component loadings showed significant groupings for concentrations of hydroxycinnamic acid derivates and flavonols, which appeared as good candidates to be further considered as biomarkers of the physiological status of grapes. Similarly, the component scores grouped according to the different postharvest treatments, highlighting hyperoside as a useful indicator of the ozone effect on the grape’s physiology.

Biological performance of grape varieties in Eastern Hungary

Eurasian and interspecific grape varieties and candidates were inspected for biological productivity in the variety collection of the University of Debrecen at the Horticultural Experimental Station in Pallag. In this paper, data are reported on yields (kg/stock), cane production (kg/ stock) and use-up index of wood yield of each cultivar in the experimental years 2011-2012. From the range of Eurasian (Vitis vinifera L.) white wine-grape qualified cultivars and candidates ’Ezerfürtû’, ’Generosa’, ’Jubileum 75’, ’Müller Thurgau’, ’Zöld veltelíni’,’B-11’, ’CSFT-92’, ’Pintes’, from the range of Eurasian (Vitis vinifera L.) red wine-grape qualified cultivars and candidates ’Kármin’, ’Pinot noir’, ’Alicante Bouschet’ and ’Rubintos’ were highlighted. Promising data of interspecific ’Aletta’, ’Csillám’, ’Kunleány’, ’Orpheus’, ’Refrén’, ’Taurus’, ’Viktória gyöngye’, ’Alföld 100’, ’Reform’, ’RF38/32’, ’Toldi’ white, and ’Dunagyöngye’ ’Pannon frankos’ red wine-grape cultivars and candidates were emphasized. Published data refer only to the biological performance of the cultivars. The thorough evaluation of varieties needs respect to data on resistance to fungal disease and climatic extremities, and other characteristics concerning production technology and oenological parameters.

Research on the quality of the wine grapes in corridor area of China

The corridor area of Gansu Province is one of the most important wine grape growing regions in China, and this strip of land results in a significant difference in terms of terroir between its regions. Chemical composition and antioxidant capacity of the main wine grape varieties (Vitis vinifera L.) cultivated in the corridor area of Gansu Province in northwest China were compared. Three regions (Zhangye, Wuwei, and Jiayuguan) were selected to explain the influence of soil and climate conditions on the quality of wine grapes. This study aims to investigate the effect of different regions on berry composition and antioxidant capacity, providing a general evaluation of red and white wine grapes quality in the corridor area of China. The results showed that ‘Merlot’ grapes grown in Zhangye had the best quality among the different varieties in the three regions of Gansu evaluated. The moderate temperature and nitrogen deficiency were associated with improved fruit quality. It was identified that the most suitable grape variety from Zhangye is ‘Merlot’, and that ‘Cabernet Sauvignon’ and ‘Italian Resling’ are the most suitable varieties from Wuwei and Jiayuguan, respectively.

Seasonal variation in amino acid and phenolic compound profiles of three Turkish white wine grapes

Abstract: Changes in amino acids and phenolic compounds in Emir, Narince, and Sultaniye grapes were monitored by high-performance liquid chromatography for two consecutive seasons. Seasonal and varietal variations in amino acid content were observed among the cultivars. Arginine, histidine, and alanine were the most prominent amino acids in all 3 cultivars in both years, with arginine being the highest found in the Sultaniye cultivar, varying between 910 and 955 mg/L. The phenolic contents also showed seasonal and varietal variations. Of the phenolic compounds identified, catechin was the most abundant in all three cultivars, with the highest found in Narince ranging between 106 and 109 mg/kg. Procyanidin B1 and gallic acid were the second most prominent.

Xenia and metaxenia in grapes: differences in berry and seed characteristics of maternal grape cv. 'Narince' (Vitis vinifera L.) as influenced by different pollen sources.

Literature investigations indicate that the grapes have quite complex fertilisation biology. This complexity necessitates extensive investigations to obtain reliable knowledge for both well-organised hybridisation studies and maximising grape yield. Therefore, this study was conducted to investigate the influences of self-, free- and cross-pollination on berry and seed characteristics in grape. Five different pollination treatments were applied to 'Narince', the most widely known and popular white wine grape in Turkey. Pollen tests indicated that all the cultivars had satisfactory in vitro pollen viability percentages. Free-pollination produced a significantly higher percentage berry set. Among the pollinizers, the use of pollen of 'Thompson Seedless' and 'Cardinal' varieties resulted in higher berry set percentage in 'Narince'. The free-pollination was also superior in giving the highest weight, length and width of the berry, as well as number of seeds per berry. These findings revealed that there were strong xenial and metaxenial effects in the studied grape cultivars. Among the pollinizer cultivars, the most effective pollinator was 'Thompson Seedless'. Hence, for better berry set and quality, the use of 'Thompson Seedless' as a pollinizer may be an attractive option in both grape production and breeding studies.

Influence of Ecoclimatic and Ecopedological Conditions on Quality of White Wine Grape Varieties from North-West of Romania

Viticulture is one of the cultures occupying large proportions of the cultivated area on the Globe. It is practiced, in particular, to produce table grapes, juice and other derivatives, and especially (about 70% of the total) to obtain different categories of quality wine and wine-based beverages. Wine can be produced everywhere, as long as the grapes ripen, but not all conditions for ripening the grapes are favorable for the production of quality wines (Teodorescu et al., 1987). If the area where vine is grown is large, the one objective is to evaluate the ecoclimatic and ecopedological conditions of three culture areas (Baia Mare (BM), Ažimleul Silvaniei (SS) and Turulung Vii (TUR)) in north-western Romania and their inIluence on the quality of the varieties: E»FeteascAƒ albAƒE¼, E»FeteascAƒ regalAƒE¼, E»Riesling italianE¼. The genetic soil types from these locations are: aluvosoil in Baia Mare, luvosoil in Ažimleul Silvaniei and preluvosoil in Turulung Vii. 2013 was a year with higher average temperatures than the annual average in Baia Mare and Turulung Vii, but lower in Ažimleul Silvaniei, but the precipitations were lower in the same areas, compared to the multiannual average. The higher amount of sugar was accumulated in E»FeteascAƒ albAƒE¼ in Ažimleul Silvaniei and the lowest in E»FeteascAƒ regalAƒE¼ in Baia Mare, the acidity falling between a normal interval for wine varieties.

Comparison of methods for the quantification of botrytis bunch rot in white wine grapes

Background and Aims: Quantification of botrytis bunch rot (BBR) in wine grapes, caused by Botrytis cinerea , is commonly done by visual estimation of the proportion of the area of individual bunches affected by BBR. Visual estimation was compared with four other quantification methods: digital image analysis, near-infrared and mid-infrared spectroscopy, and quantitative real-time polymerase chain reaction. Methods and Results: Visual estimation was found to vary significantly ( P P Conclusions: Near-infrared and mid-infrared spectroscopy require further calibration to quantify accurately BBR of low severity. Quantitative real-time polymerase chain reaction was the most accurate method but is unsuitable for routine use in the vineyard. RotBot was the most suitable and practical alternative to visual estimation, requiring no specialised equipment. Significance of the Study: Visual estimation was demonstrated to be prone to assessor bias. RotBot software is a suitable alternative that can be implemented immediately for objective quantification of BBR severity in white wine grapes. RotBot could be developed further and deployed in mobile devices for rapid sensing in the vineyard and easy collection of disease assessment data by wineries.

Effect of moderate alcohol consumption on fetuin-A levels in men and women: post-hoc analyses of three open-label randomized crossover trials

BackgroundFetuin-A, a liver-derived glycoprotein that impairs insulin-signalling, has emerged as a biomarker for diabetes risk. Although moderate alcohol consumption has been inversely associated with fetuin-A, data from clinical trials are lacking. Thus, we evaluated whether moderate alcohol consumption decreases circulating levels of fetuin-A.MethodsWe analyzed data of three separate open-label, randomized, crossover trials: 1) 36 postmenopausal women consuming 250 ml white wine (25 g alcohol) or white grape juice daily for 6 weeks, 2) 24 premenopausal women consuming 660 ml beer (26 g alcohol) or alcohol-free beer daily for 3 weeks, and 3) 24 young men consuming 100 ml vodka (30 g alcohol) orange juice or only orange juice daily for 4 weeks. After each treatment period fasting blood samples were collected.ResultsCirculating fetuin-A concentrations decreased in men after vodka consumption (Mean ± SEM: 441 ± 11 to 426 ± 11 μg/ml, p = 0.02), but not in women after wine (448 ± 17 to 437 ± 17 μg/ml, p = 0.16) or beer consumption (498 ± 15 to 492 ± 15 μg/ml, p = 0.48) compared to levels after each corresponding alcohol-free treatment. Post-hoc power analyses indicated that the statistical power to detect a similar effect as observed in men was 30% among the postmenopausal women and 31% among the premenopausal women.ConclusionsIn these randomized crossover trials, moderate alcohol consumption decreased fetuin-A in men but not in women. This sex-specific effect may be explained by the relatively short intervention periods or the low statistical power in the trials among women.Trials registrationClinicalTrials.gov ID no’s: NCT00285909, NCT00524550, NCT00918918.

Grape expectations: how the proportion of white grape in Champagne affects the ratings of experts and social drinkers in a blind tasting

Champagnes (or sparkling wines that are made using the ‘methode champenoise’) are composed of white and/or red wine grapes. Their relative proportions are thought to contribute to a sparkling wine’s distinctive flavour profile, but this has not yet been tested empirically. We, therefore, conducted a blind tasting experiment in which the participants had to report the perceived proportion of white grapes in a range of seven sparkling wines (including six Champagnes). The participants, including four expert, six intermediate, and five novice Champagne tasters, were unable to accurately judge the percentage of white grapes in the wines. Instead, the perceived proportion of white grape was correlated with the dosage and alcohol content of the wines. The hedonic ratings for the Champagnes did not correlate with price. Further, the more expensive Champagnes were only appreciated by the expert tasters. Dosage and alcohol content appear to be the two attributes that tasters rely on when judging the contribution that different grape types make to the distinctive flavour of a sparkling wine. In the case of Champagne, flavour perception relies on a complex combination of factors including alcohol content, dosage, price expectancy, and experience with the product. The present results have implications for marketing Champagnes; they might be better if focused on the distinctive characteristics of each cuvee, or simplicity (blends versus non-blends), since these might be easier characteristics to detect than the proportion of white versus red grapes.

Near and Mid-Infrared Spectroscopy for the Quantification of Botrytis Bunch Rot in White Wine Grapes

Botrytis bunch rot (BBR), one of the most important diseases of wine grapes, is usually quantified in the vineyard by visual estimation of percentage disease severity on individual grape bunches. This method is prone to assessor error and there is a need for a more objective quantification method that is cost-effective and practical. Near infrared (NIR; 800–2690 nm) and mid-infrared (mid-IR; 2510–25, 770 nm) spectroscopy were investigated as alternatives to visual estimation. Partial least squares (PLS) analysis of the NIR and mid-IR spectra from near-ripe grape bunches from Tasmanian vineyards was used to generate prediction models from both raw data and data pre-processed using the Savitzky–Golay derivative. The entire spectral range for each spectral region was analysed first, after which specific spectral ranges were analysed based on their influence on the initial PLS analysis. The spectral range of 1260–1370 nm with Savitzky–Golay smoothing and first derivative pre-processing produced the PLS model with the highest predictive ability in the NIR spectral region, with a ratio of standard error of prediction to standard deviation ( RPD) of 2.2. The spectral range of 8760–9520 nm with Savitzky–Golay smoothing and first derivative pre-processing produced the PLS model with the highest predictive ability in the mid-IR spectral region, with a RPD of 1.7. Both methods demonstrated the potential for spectroscopic quantification of BBR. However, further calibration is required to increase the accuracy of these models, particularly at low BBR severities, if they are to be considered suitable for use in the vineyard.

Red wine, white wine, rosé wine, and grape juice inhibit angiotensin-converting enzyme in human endothelial cells

Background: Beneficial effects of wine on cardiovascular disease have been shown previously, but the mechanism is still unknown. The renin-angiotensin system is an important mechanism in the body concerning regulation of blood pressure, fluid, and electrolyte balance, and the angiotensin-converting enzyme (ACE) is a key enzyme in this system. Aims: The aim of this study was to investigate the effect of red wine, white wine, rosι wine, and alcohol-free grape juice on somatic ACE-1 activity. The effects of the stilbene resveratrol and its glycoside, resveratrol-3-glycoside were also tested on ACE activity and concentration of nitric oxide (NO). Materials and Methods: Cultured endothelial cells from human umbilical veins (HUVEC) were incubated with wine, grape juice, resveratrol, or resveratrol-3-glycoside. Ethanol was used as control in the corresponding concentration (13%). Results: After incubation, a significant inhibition of ACE activity was seen with all the wines tested and the red grape juice. This inhibition was of a similar magnitude except for a lesser inhibition with the rosι wine. No significant inhibition was seen with the white grape juice, resveratrol, resveratrol-3-glycoside, or ethanol alone, and neither did resveratrol nor resveratrol-3-glycoside affect the concentration of NO. Conclusions: The effect of wine and grape juice on ACE activity in HUVEC is dependent on the amount of flavonoids and not on the content of alcohol or resveratrol.

Analysis of grapevine phenology in the region of Sremski Karlovci

A comprehensive analysis of phenological timing and growth intervals for eight red and thirteen white wine grape cultivars in the region of Sremski Karlovci was performed using a long-term (1986-2011) data set. Four phenological stages of grapevine were examined: beginning of budburst, beginning of flowering, beginning of veraison and harvest. The phenological stages studied exhibited a 30 to 51 day variation between the earliest and latest years for red cultivars and 29 to 49 day variation for white cultivars. The beginning of flowering exhibited the least, while harvest showed the highest inter-annual variation. The difference between red and white cultivars was the greatest for harvest - the mean harvest date averaged over all red cultivars was 24 September and over all white cultivars 14 September. The beginning of flowering to the beginning of veraison interval showed the smallest and budburst to harvest interval the greatest year-toyear variability. The beginning of budburst to harvest period for the cultivars examined averaged 165 days for red and 156 days for white cultivars, with the mean interval range of 58 days for red and 55 days for white cultivars. In addition, it was found that a variability of the onset and duration of phenological phases was greater between years for a single cultivar than among cultivars within individual years, meaning that climatic factors are more important than genetic characteristics of cultivars for phenological timing.

Plant-Parasitic Nematodes Associated with Grapevines, Vitis vinifera , in Washington and Idaho

Surveys were conducted in eastern Washington and Idaho to determine the plant-parasitic nematodes associated with winegrape (Vitis vinifera) vineyards. The most commonly encountered plant-parasitic nematodes in eastern Washington and Idaho winegrape vineyards were Meloidogyne hapla, Paratylenchus spp., and Xiphinema spp. (detected in >50% of sampled vineyards) with Pratylenchus spp. and Helicotylenchus spp. also commonly detected in Idaho. The frequency of occurrence of these plant-parasitic nematodes was consistently greater in Idaho compared to eastern Washington, except for M. hapla, which had a similar frequency of occurrence in both states. The types of groundcover or irrigation method used in vineyards and estimates of previous crop yields did not influence nematodes present in soil, but differences in plant-parasitic nematode communities were found among geographical areas (American Viticultural Areas, AVAs). Xiphinema spp. was more commonly associated with vineyards in the Horse Heaven Hills and Snake River Valley AVAs than in the Yakima Valley and Columbia Valley AVAs. Twenty-seven juice grape (Vitis labruscana) vineyards were sampled to enable a comparison of plant-parasitic nematode communities among red and white winegrapes (V. vinifera) and juice grape varieties. Meloidogyne hapla and Xiphinema spp. were more commonly found in red and white winegrape vineyards than in juice grape vineyards, while Mesocriconema xenoplax and Paratylenchus spp. were more commonly associated with white wine and juice grape vineyards than with red winegrape vineyards. While plant-parasitic nematodes were commonly found in eastern Washington and Idaho vineyards, the impact of these plant-parasitic nematodes on winegrape productivity in this region remains to be determined.

Antioxidant and Vasodilatory Effects of Blackberry and Grape Wines

In contrast to the well-described various biological effects of grape wines, the potential effects of commonly consumed blackberry wine have not been studied. We examined in vitro antioxidant and vasodilatory effects of four blackberry wines and compared them with the effects of two red and two white grape wines. Although some blackberry wines had lower total phenolic content relative to the red grape wines, their antioxidant capacity was stronger, which may be related to a higher content of non-flavonoid compounds (most notably gallic acid) in blackberry wines. Although maximal vasodilation induced by blackberry wines was generally similar to that of red wines, blackberry wines were less potent vasodilators. Vasodilatory activity of all wines, in addition to their flavonoid and total phenolic content, was most significantly associated with their content of anthocyanins. No association of vasodilation with any individual polyphenolic compound was found. Our results indicate the biological potential of blackberry wines, which deserves deeper scientific attention.

Grapevine Genotype Susceptibility toXylella fastidiosadoes not Predict Vector Transmission Success

For vector-borne diseases, interactions between vector, host, and pathogen can influence patterns of disease spread. In particular, previous studies suggest that host genotype may influence disease dynamics because of differences in susceptibility to the pathogen and, therefore, subsequent vector transmission efficiency from these plants. We tested this hypothesis by using the pathogenic bacterium Xylella fastidiosa, the etiological agent of Pierce's disease in grapevines, and its leafhopper vector Homalodisca vitripennis (Germar). Pathogen infection level and transmission efficiency among several widely cultivated red and white wine, table, and raisin grape cultivars, were compared with the expectation that vector transmission rate would differ among cultivars, because of underlying differences in susceptibility to infection. The 14 grapevine genotypes evaluated showed significant differences among cultivars in the populations of X. fastidiosa that developed in petioles. 'Flame seedless' hosted the highest bacterial populations, between 1.81 and 2.05 times higher than the least susceptible 'Merlot', 'Crimson seedless', 'Grenache Noir', and 'Rubired'. Although the transmission rate of X. fastidiosa by H. vitripennis varied substantially (zero to 33%), it was not significantly different among cultivars. These results suggest that either the relationship between vine infection level and transmission is weaker than previously reported, or innate differences in vector preference among cultivars confounded any effects of vine susceptibility to infection.

Varietal Relationship between Instrumental Skin Hardness and Climate for Grapevines (Vitis vinifera L.)

The main aims of this work were to classify 30 colored and white wine grape varieties according to the berry skin hardness, to assess the influence of annual variations in climate on the berry skin hardness, and to establish significant relationships among berry skin mechanical properties and some climatic-bioclimatic indices calculated for different grape-ripening periods, close to the harvest date. The results obtained show that the most influential bioclimatic indices on the skin mechanical attributes were temperature parameters. In the same season, the influence of the production area was also evaluated, precipitation parameters being the best correlated with the berry skin hardness. This first work has permitted us to know the relationship among skin texture characteristics and seasonal climatic indices.

Nutrient content and in vitro digestibility of Turkish grape pomaces

During harvest of grapes for wine production in Turkey, a total of 28 fresh grape pomace samples from white and red wine grape varieties were collected from wine production facilities. Samples were classified by grape color and the pomace from red grapes was separated manually into stalk, skin plus pulp and seed fractions. Nutrient contents were determined for total samples and for fractions. Assays included dry matter (DM), crude protein (CP), ether extract (EE), neutral detergent fiber (NDF), acid detergent fiber (ADF) and ash. To estimate ruminal digestion, in vitro disappearance of DM and NDF were determined using ruminal fluid collected at a local slaughterhouse. Color of grape altered (P<0.05) DM, CP, NDF and ADF content of the grape pomace. Although in vitro disappearance of DM and NDF at 48h was similar for pomace from both white and red grapes, DM disappearance was higher at short incubation times for pomace from red grapes. Nutrient content generally differed among the fractions of pomace assayed, and in vitro disappearance of DM at 48h was higher for skin plus pulp and for seed than for the stalk fraction of the pomace. Fresh grape pomace, particularly pomace from red grapes rich in skin and seed, should be a suitable feed for ruminants and to nonruminants with extensive cecal fermentation.

Chemical composition of dietary fiber and polyphenols of five different varieties of wine grape pomace skins

The skins of two white wine grape pomace (WWGP) and three red wine grape pomace (RWGP) from US Pacific Northwest were analyzed for their dietary fiber (DF) and phenolic composition. DF was measured by gravimetric–enzymatic method with sugar profiling by HPLC–ELSD. Insoluble DF composed of Klason lignin (7.9–36.1% DM), neutral sugars (4.9–14.6% DM), and uronic acid (3.6–8.5% DM) weighed more than 95.5% of total DF in all five WGP varieties. WWGP was significantly lower in DF (17.3–28.0% DM) than those of RWGP (51.1–56.3%), but extremely higher in soluble sugar (55.8–77.5% DM vs. 1.3–1.7% DM) ( p < 0.05). Soluble polyphenols were extracted by acidified 70% acetone and measured spectrophotometrically. Compared with WWGP, RWGP had higher values in total phenolic content (21.4–26.7 mg GAE/g DM vs. 11.6–15.8 mg GAE/g DM) and DPPH radical scavenging activity (32.2–40.2 mg AAE/g DM vs. 20.5–25.6 mg AAE/g DM) ( p < 0.05). The total flavanol and proanthocyanidin contents were ranged from 31.0 to 61.2 mg CE/g DM and 8.0 to 24.1 mg/g DM, respectively for the five WGP varieties. This study demonstrated that the skins of WGP can be ideal sources of DF rich in bioactive compounds.