Grape Phenolics Research Articles

Evaluation of passive samplers as a cost-effective method to predict the impact of wildfire smoke in grapes and wines

Wildfire smoke exposure alters grape composition, potentially resulting in “smoke tainted” wines. This has been correlated with elevated levels of smoke-derived volatile phenols (VPs) in grapes and wines. This work sought to create a predictive tool that could correlate levels of VPs in smoke with concentrations in grapes and wines. Therefore, passive samplers and Cabernet Sauvignon grapes were intentionally exposed to various smoke intensities, and wines were made thereafter. As expected, concentrations of VPs in grapes and wines were positively associated with the intensity of smoke exposure. Interestingly, levels of guaiacol in the passive samplers had a strong positive correlation with concentrations in grapes (R2 = 0.9999) and wines (R2 = 0.9998). The passive samplers were able to accurately predict guaiacol levels in smoke exposed grapes and wines with percent errors ranging from 0.08 to 11.3 %. These results suggest the capability of passive samplers to act as a monitoring system in vineyards during smoke events.

A novel method for ultra-fast determination of phenolics with performance comparable to UPLC/DAD: Method development and validation on analysis of seedless table grapes

Grapes are well-known for the rich content of phenolics with benefits for human health. The reliable identification of phenolics in grapes is essential to explore the related bioactivity, highlighting the value of the grape source. In this work, an ultra-fast method for determining phenolic compounds in HPLC-DAD using a Rapid Resolution High Throughput-RRHT column (RP-C18 4.6 ×50 mm, 1.8 µm) was developed and validated and nine seedless table grapes produced in the São Francisco Valley, Brazil were analyzed. The method showed good sensitivity (LOD≤ 0.65 mg/L and LOQ< 1.12 mg/L), high linearity (R2 > 0.998), selectivity, precision (CV%< 6.82). The recovery (81.5–105.6 %) was adequate for the desired purpose. A total of 41 phenolics were separated in 20 min, rending a resolution equivalent to UPLC-DAD. Thirty-four phenolics were quantified in grapes, including eight phenolic acids, two stilbenes, one phenolic aldehyde, three isoflavones, four flavanols, three proanthocyanidins, five flavonols, and eight anthocyanins. Patented grapes presented a high content of mono glucoside anthocyanins. Brazilian registered grapes presented high anthocyanin content and the presence of 3,5-diglucoside anthocyanins. The validated method is an alternative for rapid identification of phenolics and maybe useful to stablish procedures for identifying compounds in determining the markers in fruit.

Effect of Cluster-Zone Leaf Removal at Different Stages on Cabernet Sauvignon and Marselan (Vitis vinifera L.) Grape Phenolic and Volatile Profiles.

This study investigated the effect of leaf removal at three stages of grape development on the phenolic and volatile profiles of Cabernet Sauvignon and Marselan grapevines for two consecutive years in the Jieshi Mountain region, an area of eastern China with high summer rainfall. The results indicated that cluster-zone leaf removal generally reduced the titratable acidity of both varieties, but did not affect the total soluble solids of grape berries. Leaf-removal treatments increased the anthocyanin and flavonol content of berries in both varieties. However, in Cabernet Sauvignon, leaf removal negatively affected the norisoprenoid compounds, with a more pronounced impact observed when the leaf removal was conducted at an early stage. This negative effect may be related to a decrease in the levels of violaxanthin and neoxanthin, potential precursors of vitisprine and β-damascenone. In contrast, the removal of leaves had no effect on the norisoprenoid aroma of Marselan grapes.

From grape to wine - Muscat Ottonel from Blaj-Târnave vineyard chemical and sensory analysis

Following the global trend of selling high-quality wines, those produced in Blaj vineyard must be superior due to a highly competitive market and consumer tastes and demands. Because the quality of wine is given by both sensory and chemical properties this work presents the phenolic fingerprint, the general chemical characteristics, and the sensory properties of the 2021 Blaj Muscat Ottonel wine as well as the phenolic composition of the grapes from which this wine was produced. Grape phenolics were represented by flavanols (73%), flavonols (14%), hydroxybenzoic acids (9.08 %) and hydroxycinnamic acids (4%), while wine phenolics by flavanols (42%), hydroxycinnamic acids (33%) and hydroxybenzoic acids (15%). Catechin and procyanidin dimer B1 were identified both in grapes and in wine. More than half of the grapes’ procyanidin dimer B1 (3.638 mg/g out of 6.379 mg/g) and more than one-tenth of grapes’ catechin (1.570 mg/g out of 9.298 mg/g) were found in wine. As the general and sensory qualities of the Blaj Muscat Ottonel wine were kept within the limits of a Protected Designation of Origin (PDO) demi-sweet wine, the presence of resveratrol glucoside, catechin, and procyanidin in its content supports the idea of classifying this wine as a potential nutraceutical ‘functional wine’.

A combination of thiophenols and volatile phenols cause the ashy flavor of smoke taint in wine

Grapes exposed to wildfire smoke can develop reduce wine quality, imparting unpleasant smokey and ashy flavors. Research has primarily focused on the increased concentration of volatile phenols (VPs) in grapes and wine acquired from smoke. This study was undertaken to determine the chemical compounds that cause the ashy flavor in wines produced from smoke exposed grapes. The chemical composition of a tasting standard produced from charred leeks was determined using UPLC-QToF/MS. Several thiol derivatives were identified. Analyses of smoke-impacted wines and grapes revealed the presence of thiophenols, napthalene thiols, and additional thiol-derived compounds. LC-MS/MS of wines produced from smoke-exposed grapes showed higher concentrations of thioguaiacol and thiocresols. Chemical causation of smoky and ashy flavors by these compounds was investigated using sensory descriptive analysis. Wines with both thiophenols and VPs were described as ashy and smokey, contributing to more than 90% total variance for each wine.

Chromosome-scale genomics, metabolomics, and transcriptomics provide insight into the synthesis and regulation of phenols in Vitis adenoclada grapes.

Vitis adenoclada is a wild grape unique to China. It exhibits well resistance to heat, humidity, fungal disease, drought, and soil infertility. Here, we report the high-quality, chromosome-level genome assembly of GH6 (V. adenoclada). The 498.27 Mb genome contained 221.78 Mb of transposable elements, 28,660 protein-coding genes, and 481.44 Mb of sequences associated with 19 chromosomes. GH6 shares a common ancestor with PN40024 (Vitis vinifera) from approximately 4.26-9.01 million years ago, whose divergence occurred later than Vitis rotundifolia and Vitis riparia. Widely-targeted metabolome and transcriptome analysis revealed that the profiles and metabolism of phenolic compounds in V. adenoclada varieties significantly were differed from other grape varieties. Specifically, V. adenoclada varieties were rich in phenolic acids and flavonols, whereas the flavan-3-ol and anthocyanin content was lower compared with other varieties that have V. vinifera consanguinity in this study. In addition, ferulic acid and stilbenes content were associated with higher expressions of COMT and STSs in V. adenoclada varieties. Furthermore, MYB2, MYB73-1, and MYB73-2 were presumably responsible for the high expression level of COMT in V. adenoclada berries. MYB12 (MYBF1) was positively correlated with PAL, CHS, FLS and UFGT.Meanwhile, MYB4 and MYBC2-L1 may inhibit the synthesis of flavan-3-ols and anthocyanins in two V. adenoclada varieties (YN2 and GH6). The publication of the V. adenoclada grape genome provides a molecular foundation for further revealing its flavor and quality characteristics, is also important for identifying favorable genes of the East Asian species for future breeding.

Influence of grapevine age on general physicochemical and phenolic parameters of Rabigato (Vitis viniferaL.) white variety: Results from three vintages

The preservation of the old vine heritage, combined with the fact that old vines could present greater resistance to biotic and abiotic factors, has led to an increase in research studies about the contribution of vine age on grape and wine quality. Thus, the main goal of this work was to evaluate the potential influence of grapevine age on several general physicochemical and phenolic parameters during grape maturation of a Rabigato white grape variety. Therefore, grapes from two adjacent vineyards, with an age difference of 30 years (one with 20 years and the other with 50 years, at the beginning of this study) were studied. At technological maturation, the results obtained for the three consecutive vintages studied (2019 to 2021), and for the general physicochemical parameters analysed, do not seem to indicate a clear differentiation between the grape musts obtained from the younger and the older vineyards. However, for grape phenolics, the results suggest that vine age could be a potential factor on phenolic content, nevertheless not totally confirmed by the results at technological maturation during the three consecutive vintages considered. With this work we will contribute to expand the knowledge about the potential impact of the vine age on grape composition.

Investigating the Relation between Skin Cell Wall Composition and Phenolic Extractability in Cabernet Sauvignon Wines

In this study, phenolic extractability of Cabernet Sauvignon grapes from two California regions (Sonoma County and Central Coast) and its relation with skin cell wall composition was investigated. Phenolic grape composition, wine phenolic content as well as berry and pomace cell wall composition of three sites per region were determined. Grape cell wall material (CWM) composition, and thus pomace CWM composition, was impacted by the growing region. The process of fermentation modified CWM composition, solubilizing some of the compounds such as pectin and polysaccharides making pomace CWM composition from different sites more similar in the case of Sonoma County and more different for the samples grown in the Central Coast. Growing region had a significant impact on grape phenolics, particularly on flavan−3-ols and polymeric phenols, whereas polymeric pigments and anthocyanin contents were more similar among samples. Wines made from Sonoma County grapes showed higher anthocyanin and polymeric phenol content when compared to wines made from Central Coast grapes. Comparing wine to grape phenolic composition suggests a large difference in extractability based on region. Of all the CWM components analyzed, only lignin and the amount of cell wall isolated were found to have a significant impact on phenolic extractability.

Effects of grape phenolics, myricetin and piceatannol, on bovine granulosa and theca cell proliferation and steroid production in vitro

Myricetin (a flavonol) and piceatannol (a stilbenoid) are naturally occurring phenolic compounds in red wine with cardio-protective and anti-carcinogenic effects, but their potential reproductive effects have not been investigated. Thus, the present study was designed to determine if myricetin and piceatannol can directly affect ovarian function using bovine granulosa cells (GC) and theca cells (TC) as in vitro model systems to evaluate effects on cell proliferation and steroid production. In Experiment 1 and 2, myricetin and piceatannol at 30 μM blocked insulin-like growth factor 1 (IGF1)-induced progesterone production by GC without affecting GC numbers. In contrast, myricetin stimulated IGF1-induced estradiol production, whereas piceatannol at 30 μM inhibited IGF1-induced estradiol production by 90% in GC. In Experiment 3 and 4, TC androstenedione and progesterone production and TC proliferation was inhibited by myricetin and piceatannol at 30 μM. In Experiment 5, piceatannol (30 μM) reduced the Fusarium mycotoxin, beauvericin (6 μM)-induced inhibition on progesterone production and cell proliferation. Myricetin (30 μM) reduced the inhibitory effect of beauvericin on estradiol but not progesterone production or cell proliferation. In conclusion, the red wine phenols, myricetin and piceatannol, directly affected GC and TC steroidogenesis, and were able to reduce some of the inhibitory effects of beauvericin on GC function.

Improving the Phenolic Content of Tempranillo Grapes by Sustainable Strategies in the Vineyard.

Wine phenolics are of considerable interest due to their implication in the organoleptic appreciation of wines and due to their bioactive functions as antioxidants. In this work, the effects of sustainable strategies in the vineyard, regulated deficit irrigation treatments (RDI) and crop load level (CL) on Tempranillo grape phenolics over two seasons was studied. Rainfed (T), early (EDI) and late (LDI) regulated deficit irrigation was applied. Cluster thinning (TH) and control (C) without cluster removal were also applied under each irrigation treatment. The effect of CL remained independent of RDI for all compounds, except for phenolic acids. The RDI influence on the grape skin phenolic profile was higher than CL in the dry season (2009); however, in 2010, the effect of CL was greater. In 2009, a tendency to increase anthocyanin and hydroxycinnamic acid content in grape skins was registered in EDI with respect to T. However, significant decreases in hydroxycinnamic and flavanol compounds were found in LDI. In 2010, the wettest year, CL increased all phenolic families’ content. Thus, it can be concluded that the effects of RDI and cluster thinning treatments depend on the family of compounds considered and the meteorological conditions of the year.

Effects of gibberellin and cytokinin on phenolic and volatile composition of Sangiovese grapes

Cytokinin and gibberellin are plant growth regulators (PGRs) used to increase berry size in seedless table grapes but their effects on wine grape phenolics and volatiles was not studied. In the current study, gibberellic acid (GA3) and synthetic cytokinin forchlorfenuron (CPPU) and their combination were applied to fruitlets of Sangiovese and berries were sampled 79 days following application. All the treatment significantly increase berry diameter and berry weight and CPPU containing treatment increased skin thickness. All treatments reduced sugar accumulation and color development but did not have an effect on acid levels. HPLC analysis showed that total flavan-3-ols level was increased by CPPU, GA containing treatments reduced the levels of flavonols and anthocyanins were significantly reduced in all the treatment (≈50%). Phloroglucinol analysis showed that proanthocyanidins level were significantly increased whereas the mean degree of polymerization was reduced from 40 to ≈21 by all the treatments. GC–MS analysis of berries showed a decrease in fatty acid derived volatile compounds by all treatments with potential impact on flavor. Analysis of wine phenolics in subsequent harvest was in general agreement with the previous results. In summary, this study provides new information on how PGRs can change berry composition and subsequently wine attributes.

Glycosylation of Volatile Phenols in Grapes following Pre-Harvest (On-Vine) vs. Post-Harvest (Off-Vine) Exposure to Smoke.

Taint in grapes and wine following vineyard exposure to bushfire smoke continues to challenge the financial viability of grape and wine producers worldwide. In response, researchers are studying the chemical, sensory and physiological consequences of grapevine smoke exposure. However, studies involving winemaking trials are often limited by the availability of suitable quantities of smoke-affected grapes, either from vineyards exposed to smoke or from field trials involving the application of smoke to grapevines. This study compared the accumulation of volatile phenol glycosides (as compositional markers of smoke taint) in Viognier and Cabernet Sauvignon grapes exposed to smoke pre- vs. post-harvest, and found post-harvest smoke exposure of fruit gave similar levels of volatile phenol glycosides to fruit exposed to smoke pre-harvest. Furthermore, wines made from smoke-affected fruit contained similar levels of smoke-derived volatile phenols and their glycosides, irrespective of whether smoke exposure occurred pre- vs. post-harvest. Post-harvest smoke exposure therefore provides a valid approach to generating smoke-affected grapes in the quantities needed for winemaking trials and/or trials that employ both chemical and sensory analysis of wine.

Incorporation of phenolic-rich ingredients from integral valorization of Isabel grape improves the nutritional, functional and sensory characteristics of probiotic goat milk yogurt

This study elaborated different probiotic goat milk yogurt formulations with addition of a low-calorie Isabel “Precoce” grape preparation and flour from derived solid by-products. Physicochemical characteristics, probiotic counts, phenolic and protein/peptide molecular weight profile, antioxidant capacity (AC) and sensory acceptance of different yogurt formulations were evaluated. Yogurts with Isabel grape ingredients (IGI) had high nutritional value, distinct phenolic profile and high AC. High counts of probiotic Lactobacillus acidophilus La-05 were found in yogurts during storage. AC of yogurts with IGI increased during a simulated gastrointestinal digestion with breakdown of high molecular weight proteins and release of protein-bound phenolics. AC of yogurts with IGI should be linked to goat milk peptides and Isabel grape phenolics. Yogurts with IGI had enhanced sensory acceptance. Incorporation of Isabel grape preparation and derived by-product flour into probiotic goat milk yogurt resulted in an added-value product with multifunctional characteristics and improved sensory characteristics.

Correlation between Skin Cell Wall Composition and Polyphenol Extractability of Pinot noir and Cabernet Sauvignon Grapes

The composition of skin cell wall material from Pinot noir and Cabernet Sauvignon grape berries from four different regions in California was investigated to determine relationships between cell wall composition and phenolic extractability observed under winemaking conditions. Multiple vineyards (sites) per region were studied. Cell wall composition analysis included determining total soluble sugars, proteins, noncellulosic glucose, cellulose, lignin, lipids, total polyphenolic content, soluble polysaccharides, and uronic acid, as well as isolation efficiency. Results indicated that cell wall material (CWM) composition is mainly site-specific, with some effect due to variety and little to no effect from the growing region. Grape phenolics analyzed included monomeric flavan-3-ols, anthocyanins, polymeric phenols, and polymeric pigments and could be used to distinguish between varieties. Grapes grown in the same region exhibited similar phenolic extractability, indicating a significant effect of the growing area, as well as a synergistic effect between CWM composition and grape phenolics. CWM composition analysis indicated that demethylation of pectin favored the release of phenolics, while lignin content correlated negatively with the phenolics extracted. Proteins showed a negative correlation with polymeric phenols, whereas no correlation was found with polymeric pigments. Anthocyanin extractability was highly affected by its content within grape skins, more so than other phenolics that are present in both the skins and seeds.

Phenolics composition and contents, as the key quality parameters of table grapes, may be influenced obviously and differently in response to short-term high temperature

Although the grape surface appears to be normal under high temperature during the selling period, the nutritional quality of grape might be greatly affected. Phenolics content and composition are key indicators reflective of grape's nutritional quality. Herein, the paper investigated effects of short-term high temperature (40 °C; 2 h) on grape phenolics from five table grape varieties to evaluate grape quality. Twenty-three phenolics were identified and quantified through UHPLC-ESI-qTOF-MS2 and UHPLC-QQQ-MS2, respectively. The results observed that short-term high temperature significantly reduced flavonoids in European and American varieties. In Eurasian varieties, high temperature induced the accumulation of stilbenes and flavonols compounds while lowered other compounds. Myricetin 4′-methylether-3-O-rhamnoside, a differential metabolite responding to high temperature in all table grapes was screened. Combining with the analysis of molecular level, high temperature down-regulated the phenolics biosynthesis-related genes involved in phenolics metabolic pathways (flavonols, stilbenes, anthocyanins and flavan-3-ols metabolic pathways) in grapes except Muscat de Hambourg grapes, such as the expression of VvUFGT, VvANR, VvLAR, VvFLS, VvSTS, VvF3′5′H and VvAOMT. Our findings suggest that short-term high temperature during the selling period is not conducive to consumer expectations, due to the partial loss of grape nutrition quality.

Effects of the irrigation regimes on grapevine cv. Bobal in a Mediterranean climate: I. Water relations, vine performance and grape composition

Climate change scenarios are predicting an increase in temperature as well as more scarce and torrential rainfall episodes. Due to this, an imbalance between grape technological and phenolic maturity is being observed detrimentally affecting grapes composition. In semi-arid areas, irrigation management is a main field practice to influence grape ripening. The goal of the present study was to investigate in Vitis vinifera L. cv. Bobal grapevine responses to three watering regimes: (i) Rainfed, (ii) deficit irrigation (DI) replacing only 35% of the estimated crop evapotranspiration (ETc) and (iii) full irrigation (FI) replacing 100% ETc. In the mid-summer, rainfed grapevines showed different degrees of water stress determined by midday stem water potentials (Ψstem) ranging from −1.1 to −1.4 MPa depening on the season. Rainfed plants had in all seasons less vigor and production and, at harvest, higher concentrations of total soluble solids (TSS) and grape phenolics compounds, as well as lower pH, with respect to the other water regimes studied. DI grapevines, generally, had intermediate values between Rainfed and FI, which presented extreme values of the studied parameters respect to Rainfed. The effects observed on grape color parameters and phenolic compounds with the Rainfed regime were mainly due to a dehydration of the berry, which lowered the yield and the weight of the berry compared to the irrigated treatments. The lower TSS accumulation in the DI berries with respect to the Rainfed, will favor obtaining wines with lower alcohol content, currently more demanded by the consumers. Besides, despite the differences obtained between water regime treatments in the TSS accumulation, the extractability of the anthocyanins was similar, which is interesting since anthocyanin extraction from grapes is prerequisite to the formation of stable red wine pigments. Although the most convenient irrigation strategy might depend to the wine style to be obtained, DI is a strategy that can help to close the gap in the imbalance between the technological and phenolic maturity, positively affecting vine yield and performance with respect to the rainfed strategy.

Regulated deficit irrigation strategies affect the terpene accumulation in Gewürztraminer (Vitis vinifera L.) grapes grown in the Okanagan Valley

Regulated deficit irrigation (RDI) is a viticultural practice known to improve grape phenolics and color in red grapes; however, the impact of this practice on grape aromas remains largely unknown. The effects of RDI treatments applied at various berry developmental stages on canopy, yield, and free and glycoside-bound terpenes of the berry were investigated for three consecutive seasons. All RDI treatments reduced leaf photosynthesis and yield, but not when applied after veraison. Berry total soluble solids at harvest were reduced by RDI applied after veraison or throughout the season. Despite reducing berry sugars, RDI applied after veraison increased the concentration at harvest of key free terpenes for Gewürztraminer grapes such as geraniol and citronellol. RDI treatments down-regulated some terpene genes, which indicates that the observed changes in terpene concentration were not transcriptionally regulated. This study suggests that RDI applied after version can potentially improve wine aroma in Gewürztraminer.

α-Glucosidase Inhibitory Activity of Tannat Grape Phenolic Extracts in Relation to Their Ripening Stages

The present study aimed to screen grape extracts as novel α-glucosidase inhibitors to prevent type-2 diabetes and hyperglycemia. The total polyphenol content (TPC) was measured by Folin-Ciocalteu assay and the stilbene, anthocyanin and flavan-3-ol compounds were measured by Ultra High-Performance Liquid Chromatography coupled to Mass Spectrometry (UHPLC-MS). The α-glucosidase inhibitory of seed and skin Tannat grape extracts at four ripening stages were investigated. The highest TPC values were measured in seeds at the “veraison stage” (65.29 ± 5.33 g of Gallic Acid Equivalent (GAE) per kilogram of Fresh Weight (FW)). This was in accordance with the high flavan-3-ol contents measured for these two extracts (43.22 ± 2.59 and 45.45 ± 6.48 g/kg of seeds FW, respectively). The skin and seed extracts at the first stage of ripening exerted strong α-glucosidase inhibition, exceeding 95% (p < 0.05). A high linear correlation (R = 0.723, p ≤ 0.05) was observed between flavan-3-ol contents and the α-glucosidase inhibitory activity. The stilbene contents and this activity were moderately to strongly anti-correlated (R = –0.828, p ≤ 0.05 for trans-resveratrol). The enzyme kinetic studies revealed a mixed type of inhibition. This study brings promising results for the therapeutic potential of seed and skin Tannat grape extracts as a functional food product with anti-diabetic activity.

A Simple GC-MS/MS Method for Determination of Smoke Taint-Related Volatile Phenols in Grapes.

Volatile phenols (VPs) derived from smoke-exposed grapes are known to confer a smoky flavor to wine. Current methods for determination of VPs in grape berries either involve complex sample purification/derivatization steps or employ two analytical platforms for free and bound VP fractions. We report here a simple gas chromatography-tandem mass spectrometry (GC-MS/MS) method for quantification of both free and bound VPs in grapes, based on optimized (1) GC-MS/MS parameters, (2) an analyte extraction procedure, and (3) phenol glycoside hydrolysis conditions. Requiring neither sample cleanup nor a derivatization step, this method is sensitive (LOD ≤ 1 ng/g berries) and reproducible (RSD < 12% for repeated analyses) and is expected to significantly reduce the sample turnover time for smoke taint detection in vineyards.

Comparative Assessment of Phenolic Bioaccessibility from 100% Grape Juice and Whole Grapes

Abstract Objectives Grapes and their 100% juices are rich sources of health promoting phenolics. Juicing of grapes includes contact with phenolic rich seeds and skins that otherwise relies on mastication for phenolic release from fruit. To understand if 100% grape juice can provide a matrix with highly bioaccessible phenolics relative to whole fruit, differences in phenolic content and bioaccessibility from commonly consumed table, Concord (CG) and Niagara (NG) grapes and their 100% juices were compared. Methods Phenolic content in CG, NG, table grapes, 100% Concord grape juice (CGJ), and 100% Niagara grape juice (NGJ) were assayed by LC-MS prior to subjecting grapes and juices to in vitro digestion to determine phenolic bioaccessibility. Results are expressed as relative and absolute bioaccessible content of individual phenolic species and total phenolics as a sum of anthocyanins (AC), flavan-3-ols (FL3), flavonols (FV), stilbenoids, procyanidins, and phenolic acids (PA). Results Phenolic compounds were concentrated in CG and NG seeds as FL3 (304.1–390.7 mg/100 g dw). CG skins were rich in AC (1050.5 mg/100 g dw) and FV (80.8 mg/100 g dw). Grape product form had a significant impact on content (P &amp;lt; 0.01), relative bioaccessibility, and absolute bioaccessibility (P &amp;lt; 0.01). CG had a higher total phenolic content (21.9–50.7 mg/100 g fw) compared to CGJ (5.8 mg/100 g fw), though NG (4.9–10.8 mg/100 g fw) was similar in phenolic content as NGJ (9.4–10.8 mg/100 g fw). Absolute bioaccessibility of CGJ total phenolics (5.2 mg/100 g fw) was similar to CG (2.6–9.6 mg/100 g fw), while NGJ (5.1–5.7 mg/100 g fw) had higher bioaccessible phenolic content than NG (0.8–1.1 mg/100 g fw). Differences in initial content and bioaccessible fractions were driven by higher relative bioaccessibility of AC in CGJ (86–135%) compared to CG (14–39%) and FL3/PA in CGJ/NGJ (48–101; 39–85%) compared to CG/NG (0–3; 9–67%). Comparisons between juices and table grapes followed similar trends. Conclusions A greater fraction of grape skin and seed derived PA, AC, and FL3 are extracted through juicing and made bioaccessible relative to whole fruit. 100% juice may provide an improved matrix for delivery of grape phenolics and despite some processing losses, whole fruit and juice are similar in overall phenolic delivery to consumers. Funding Sources Welch Foods Inc.