Muscadine Grape Juice Research Articles

<p>Chronic and acute effects of red wine versus red muscadine grape juice on body composition, blood lipids, vascular performance, inflammation, and antioxidant capacity in overweight adults</p>

Purpose: Red wine may benefit health due to the presence of polyphenolic compounds. This research investigated effects of wine (W) versus grape juice (J) on body composition, blood lipids (cholesterol, HDL, LDL, and triglycerides [TG]), vascular responses (augmentation index [AIx] and central pulse wave velocity [cPWV]), inflammation (C-reactive protein [CRP]), and plasma antioxidant capacity (ferric-reducing ability of plasma [FRAP]) in sedentary individuals. Methods: In a randomized crossover design, 19 participants consumed 300 mL of W or J for two weeks and then acutely in the lab. Blood was drawn at baseline, post two weeks, and within 1 hr after consuming treatment. Repeated measures ANOVA with 2 (treatment) × 3 (time) was used for FRAP, AIx, and cPWV and 2 (treatment) × 2 (time) for blood lipids and CRP. A paired t-test was used to compare differences in diet and weight change. Results: Acute, but not chronic, consumption of wine significantly increased FRAP (treatment P = 0.028) and significantly decreased AIx (treatment P = 0.038) while juice exhibited no effects. An overall treatment effect existed for TG (P = 0.028) in wine only. Cholesterol, LDL, HDL, and CRP were not affected in either group. Conclusion: Acute, but not chronic, consumption of wine significantly increased antioxidant capacity and resulted in beneficial changes to the vasculature as determined by AIx.

Bioactive polyphenols from muscadine grape and blackcurrant stably concentrated onto protein‐rich matrices for topical applications

Natural botanical agents that are antimicrobial, or that modulate skin hyperpigmentation via tyrosinase inhibition, are increasingly sought in the cosmetic industry. In this study, an efficient tactic is demonstrated for concentrating and stabilizing skin-beneficial bioactive compounds from muscadine grape and blackcurrant juice or muscadine pomace, into hemp flour (HF), hemp protein isolate (HPI) and soy protein isolate (SPI) matrices suitable for cosmetic applications. Anthocyanins were most efficiently captured from blackcurrant juice into HF (8.39mgg(-1) ). HPI most effectively captured total phenolics from muscadine pomace (72.32 and 77.32 mgg(-1) from Noble and Carlos, respectively), while the three matrices incorporated highest levels of ellagic acid, gallic acid, and PAC B1 from Noble muscadine grape juice. The enriched matrices demonstrated effective in vitro inhibition of tyrosinase (up to 57.29% for blackcurrant juice-HPI matrix), and in general, juice sources provided greater inhibition on L-dopamine oxidation by tyrosinase than pomace sources. The polyphenol-enriched matrices effectively inhibited microbial proliferation in a screening assay against Staphylococcus aureus bacteria, whereas untreated HF, HPI or SPI did not inhibit bacterial growth. The technology of combining and stably concentrating phytoactive polyphenols with proteins has potential use for cosmetic topical applications.

Effect of time–temperature conditions and clarification on the total phenolics and antioxidant constituents of muscadine grape juice

Juices have lower quantities of total phenolics content (TPC), anthocyanins, and antioxidant compared to the whole fruit. Furthermore, only low levels of these compounds are extracted from fruit skins during the initial juice processing steps with the majority staying in the skins and seeds. Once the initial juicing starts, degradative reactions begin to convert endogenous polyphenols into new compounds. Even though temperature is the key factor which determines this degradation rate, there is limited information about the temperature at which it begins, and the effects of centrifuging particles before or after thermal processing. The objectives were, first to determine the effects of different time–temperature conditions on the TPC, and antioxidant activity; second, to assess both parameters when the juice was clarified before or after thermal processing. Processing conditions were: 50–80 °C, and 1–30 min as residence time. At temperatures greater than 60 °C, both parameters began to decrease. The optimum processing condition for greatest retention of both parameters was 60 °C and 30 min. TPC and antioxidant activity retention were significantly higher on the juice clarified after thermal processing, compared to the one clarified before. This information can help juice processors and equipment manufacturers to optimize their process and design.

An ideal point density plot method for determining an optimal sensory profile for Muscadine grape juice

The objective of this study was to compare the use of the Euclidian distance ideal point mapping (EDIPM), a newly developed method, to the external response surface approach to optimize the formulation of muscadine grape juices. EDIPM is a method which allows the identification of individual consumer’s ideal point in product maps and yields group maps identifying product placement opportunities. It is based on identifying for individuals the point in the map (i.e., the ideal point) minimizing the correlation between distances to the test products and hedonic scores given by the individual. This method was compared to the external preference mapping extension proposed by Danzart [Danzart, M. (1998). Quadratic model in preference mapping. In Proceedings of the fourth sensometrics meeting.].

Stability of Copigmented Anthocyanins and Ascorbic Acid in Muscadine Grape Juice Processed by High Hydrostatic Pressure

Intermolecular copigmentation is one of the mechanisms of stabilization of anthocyanins in nature and is also responsible for the characteristic color and stability of aged red wines. In the present study, the effect of polyphenol oxidase (PPO) activity on phytochemical stability of an ascorbic acid-fortified muscadine grape juice following high hydrostatic pressure (HHP) processing (400 and 550 MPa for 15 min) and after 21 d of storage at 25 degrees C was investigated. Addition of rosemary and thyme polyphenolic extracts (copigmentation) was evaluated as a means to stabilize anthocyanins and ascorbic acid during pressurization and subsequent storage. Polyphenolic extracts were partially purified in order to reduce their content of PPO substrates, and improve their stabilization properties within juice matrix. Overall PPO activity increased (3- and 2.5-fold) following HHP at 400 and 550 MPa, respectively, although it was significantly lower in copigmented treatments. Higher anthocyanin losses occurred at 400 (approximately 70%) than at 550 MPa (approximately 46%), which were correlated to antioxidant losses (r = 0.89). Similarly, greater ascorbic acid losses were observed at 400 (84%) than at 550 MPa (18%). Copigmentation increased anthocyanin retention in reference to pressurized controls (3- and 3.2-fold for rosemary and thyme treatments, respectively) and decreased ascorbic degradation (20 to 32%). In stored samples, higher anthocyanin content (>2-fold) and antioxidant capacity (>1.5-fold) was observed for copigmented treatments when compared to control juices. Addition of partially purified copigments increased muscadine grape juice color, antioxidant activity and also reduced phytochemical losses during HHP processing and storage.

Inactivation of polyphenol oxidase in muscadine grape juice by dense phase-CO2 processing

Abstract The effect of dense phase-CO2 processing (DP-CO2) on polyphenol oxidase (PPO) activity, polyphenolic and antioxidant changes in muscadine grape juice under different processing pressures (27.6, 38.3, and 48.3 MPa) and CO2 concentrations (0, 7.5, and 15%) were measured. Subsequently two DP-CO2 conditions (48.3 MPa at 0 or 15% CO2) were evaluated for polyphenolic and antioxidant changes during storage (4 °C, four weeks). Pressure alone was responsible for a 40% decrease in PPO activity that resulted in 16–40% polyphenolic and antioxidant losses. Increasing CO2 from 0 to 7.5% was responsible for an additional 35% decrease in enzyme activity and a two-fold greater polyphenolic retention. However, insignificant changes in PPO activity or polyphenolic retention were observed when CO2 was increased to 15%. During storage, juices with residual PPO activity following processing resulted in greater polyphenolic (8- to 10-fold) and antioxidant capacity (four-fold) degradation compared to control juices with no PPO activity. This study demonstrated that partial PPO inactivation can be obtained by DP-CO2 and that CO2 level was the primary variable influencing PPO activity and polyphenolics and antioxidant capacity retention in muscadine grape juice.

Muscadine grape products intake, diet and blood constituents of non-diabetic and type 2 diabetic subjects

Objective Red wines and grape juices contain polyphenolics with antioxidant and antiplatelet properties that may be protective against oxidative stress leading to hypertension, insulin resistance, and type 2 diabetes (T2D). This study evaluated the effects of supplementing meals of subjects with 150 mL of muscadine grape juice (MJ), muscadine grape wine (MW), and dealcoholized muscadine grape wine (Dz-W) on glycemic indices, blood constituents, lipid profile, anthropometric, and nutrient intakes of healthy and T2D subjects over a 28-d period. Methods Subjects with T2D were assigned to take MJ, MW, or Dz-W. Non-diabetics consumed MJ and controls were given no test drinks. Several metabolic indicators associated with diabetic conditions were measured at baseline and repeated after 28 d. Results Diabetics given MW and Dz-W showed lower levels of blood glucose, insulin, and glycated hemoglobin, indicating better glycemic control. Elevated dietary vitamin C and E levels were observed in diabetics given Dz-W, indicating improved antioxidant status. Decreased red blood cell membrane saturated fatty acids and increased mono- and polyunsaturated fatty acids for subjects with T2D given MW suggested improved membrane fluidity. Lower sodium and chloride values for subjects T2D given MW suggested lower risk for developing hypertension. Improved hepatic conditions were noted by decreases in alanine aminotransferase and aspartate aminotransferase among subjects with T2D given MW, indicating better insulin sensitivity and decreased tendency toward impaired liver function. Conclusion Daily intake of 150 mL of MW or Dz-W with meals improved several metabolic responses among diabetics compared with diabetics given MJ.

Enhancing the Retention of Phytochemicals and Organoleptic Attributes in Muscadine Grape Juice through a Combined Approach between Dense Phase CO2Processing and Copigmentation

This study evaluated the phytochemical stability and organoleptic attributes of an ascorbic acid-fortified muscadine grape juice as affected by dense phase CO2 processing (DP-CO2) and addition of thyme polyphenolic cofactors (Thymus vulgaris; 1:100 anthocyanin-to-cofactor molar ratio) in efforts to prevent phytochemical losses that occur during storage of anthocyanin-containing beverages, especially in the presence of carbonyl compounds commonly produced during thermal processing and storage. DP-CO2 processing insignificantly altered initial juice phytochemical and antioxidant content, whereas thermal pasteurization reduced anthocyanins (263 mg/L), ascorbic acid (42 mg/L), soluble phenolics (266 mg/L), and antioxidant capacity (6 microM Trolox equivalents/mL). Similar trends were observed during storage, and data showed that increasing the CO2 level from 8 to 16% during DP-CO2 was instrumental in reducing juice phytochemical and antioxidant degradation. Copigmentation was instrumental in retaining higher anthocyanin, soluble phenolics, and antioxidant capacity during storage without affecting initial juice aroma and flavor characteristics. Moreover, on the basis of overall likeability scores, panelists preferred copigmented juices, which had increased juice color intensity and masked the detrimental color fading that occurred during storage, especially when compared to thermally pasteurized juices. DP-CO2 and copigmentation were effective strategies to reduce phytochemical and color deterioration that occurred in muscadine juice during storage without affecting their organoleptic attributes.

Microbial Stability, Phytochemical Retention, and Organoleptic Attributes of Dense Phase CO2 Processed Muscadine Grape Juice

Dense phase CO2 processing (DP-CO2) is a promising alternative to thermal pasteurization potentially inactivating microorganisms without affecting food phytochemicals or organoleptic characteristics. To demonstrate these effects, studies were conducted by changing processing pressure and CO2 concentration in relation to microbial destruction. Subsequent storage stability (10 weeks at 4 degrees C) of muscadine grape juice processed by DP-CO2 (34.5 MPa at 8% or 16% CO2) was evaluated and compared to a heat-pasteurized juice (75 degrees C, 15 s). Thermal pasteurization decreased anthocyanins (16%), soluble phenolics (26%), and antioxidant capacity (10%) whereas no changes were observed for both DP-CO2 juices. DP-CO2 juices also retained higher anthocyanins (335 mg/L), polyphenolics (473 mg/L), and antioxidant capacity (10.9 micromol of Trolox equivalents/mL) than thermally pasteurized juices at the end of storage. Insignificant differences in sensory attributes (color, flavor, aroma, and overall likeability) were observed between unprocessed and DP-CO2 juices, while significant differences were observed between unprocessed and heat-pasteurized juices. Panelists preferred DP-CO2 over heat-pasteurized juices throughout the first 6 weeks of storage, whereby the growth of yeast and mold adversely affected the juice aroma. Comparable microbial counts were observed between DP-CO2 and thermally pasteurized juices during the first 5 weeks of storage. DP-CO2 protected phytochemicals in muscadine juice during processing and storage without compromising microbial stability or sensory attributes over 5 weeks of storage.

Red clover isoflavonoids as anthocyanin color enhancing agents in muscadine wine and juice

Isoflavonoid extracts from red clover ( Trifolium pratense) leaves were found to enhance overall color and stability of anthocyanin 3,5-diglucosides present in muscadine grape ( Vitis rotundifolia) juice and wine through intermolecular copigmentation reactions. Predominant isoflavonoids present in red clover included formononetin, biochanin A, and prunetin and were the major polyphenolics identified to influence anthocyanin color and stability. Since red clover isoflavonoids have poor water solubility characteristics, this allowed for removal of extraneous non-isoflavonoid compounds using hot water and subsequent extraction with ethanol. Isoflavonoid solubility was evaluated as a function of ethanol concentration with recoveries up to 57% found in 20% solutions. Changes in maximum absorbance, total soluble phenolics, isoflavonoids, and anthocyanins were evaluated in muscadine juice and wine following the addition of isoflavonoid extracts with maximum color enhancement found at an anthocyanin to cofactor ratio of 1:8, after which their solubility was prohibitive. Additionally, dried leaves and ethanolic extracts of red clover were added prior to and following fermentation of muscadine wine (11% ethanol) stimulating the natural copigmentation that takes place during red wine fermentation and aging processes. Once fermentation was complete, finished wines were evaluated over a 9-week storage period at 20 and 37 °C. Despite low levels of isoflavonoids present, color improvement and anthocyanin stability was observed in the wines during storage. Little information is available on copigmentation reactions occurring in actual food systems, yet red clover isoflavonoids proved to be novel and effective color enhancing compounds when used in low concentrations in young muscadine wines.

(377) Consumer Acceptance of Mayhaw (Crataegus opca Hook. and Arn.) Fruit Juice Blended with Muscadine (Vitisrotundifolia Michx.) Grape Juice

Growth in juice-based products is supported by an increasing consumer base, which perceives fruit and fruit-based beverages as an integral component of nutritious food types that can benefit health. New flavor combinations, as well as added ingredients (i.e., vitamins) continue to help boost juice appeal as a nutraceutical. New juice-based food products such as blends, jellies, marinades, and pastry fillings could benefit from the unique flavor attributes specific to mayhaw fruit juice. Juice from one cultivar of muscadine grape (Vitisrotundifolia Michx.) `Carlos' (bronze skinned) was mixed with varying levels of juice from one cultivar of mayhaw (Crataegusopaca) `Texas Star' (reddish-orange skinned) fruit. Five different blend combinations were tested for both individual juice quality and for juice-blend compatibility. A consumer preference test was conducted (n = 75) on a 9-point hedonic scale for color, taste, and overall liking. Next to the taste/flavor preference scores for control (6.8), mayhaw juice used as the primary flavor ingredient in blends was the second most preferred of all juices by the panelists. A 50/50 juice blend and 70/30 mayhaw/muscadine blend were the least desirable of the five combinations tested. Juices from 60/40, 30/70, and 40/60 mayhaw/muscadine were considered by the panelists as best in flavor and overall acceptability. “Taste” had the strongest effect on overall acceptability of juice from varying levels of mayhaw juice in combination with muscadine grape juice. Panelists' mean score averages collectively were favorable of 60:40 and 50:50 juice blends and were significant (P < 0.05) toward acceptance of a “mayhaw-muscadine” fruit juice blended drink.

Phytochemical Stability and Color Retention of Copigmented and Processed Muscadine Grape Juice

Muscadine (Vitis rotundifolia) grape juice was assessed for color and phytochemical stability as influenced by anthocyanin copigmentation with a water-soluble rosemary extract, fortification with ascorbic acid, and processing by heat or high hydrostatic pressure (HHP). The roles of polyphenolic cofactors in the presence and in the absence of ascorbic acid were assessed as a means to improve the overall processing stability of the juice. Addition of rosemary extract from 0 to 0.4% (v/v) readily formed copigment complexes with anthocyanins and resulted in concentration-dependent hyperchromic shifts from 10 to 27% that corresponded to increased antioxidant activity. The presence of ascorbic acid was generally detrimental to juice quality, especially in the presence of rosemary extract, and resulted in overall anthocyanin, ascorbic acid, and antioxidant activity losses. Although thermal and high-pressure processing methods were detrimental to juice quality, HHP resulted in greater losses after processing, likely due to action from residual oxidase enzymes. Although physicochemical attributes were enhanced by copigmentation with rosemary extract, methods to inactivate residual enzymes should be addressed prior to copigmentation to prevent degradation of anthocyanins in the presence of ascorbic acid.

Contribution of Free and Glycosidically Bound Volatile Compounds to the Aroma of Muscadine Grape Juice

ABSTRACTFree and glycosidically bound volatile compounds were isolated and identified from muscadine grape juice. Most abundant in free and bound form was the muscadine character‐impact aroma compound 2,5‐dimethyl‐4‐hydroxy‐3(2H)‐furanone (Furaneol). Other aroma compounds, such as o‐aminoacetophenone and 2‐phenylethanol were found in free and bound forms. A high level of 2‐phenylethanol was intheglycosideformand many bound monoterpenes were identified. p‐Vinylguaiacol, a potential off‐flavor in muscadine juice was found at a low level in bound form. Enzymatic hydrolysis of glycoside precursors could lead to release of volatile compounds with both potentially positive and deleterious effects on the overall aroma.

Identification of Predominant Aroma Compounds in Muscadine Grape Juice

ABSTRACTThe aroma components of muscadine (Vitis rotundifoliaMichx) grape juice were analyzed by gas chromatography (GC)/mass spectrometry and GC/olfactometry (aroma extract dilution analysis). 2,5‐Dimethyl‐4‐hydroxy‐3(2H)‐furanone (furaneol), with a burnt sugar‐like aroma, was the most intense aroma in the juice. Other predominant compounds included 2,3‐butanedione, ethyl butanoate, ethyl 2‐methylbutanoate, 2‐phenylethanol, and o‐aminoacetophenone. These compounds were described as buttery/cream cheese, bubble gum/fruity, green apple/fruity, rosy, and foxy, respectively. Furaneol and o‐aminoacetophenone were thought to be responsible for characteristic candy and foxy‐like aroma notes of muscadine grape juice. Flavor dilution chromatograms were similar for juices prepared from grapes harvested on different dates and from different locations.

Stability of Non‐Pasteurized, Refrigerated Muscadine Grape Juice

ABSTRACTThe stability of nonpasteurized muscadine grape juice processed with and without 100 mg/L potassium metabisulfite was monitored during storage at 3°C. The muscadine flavor intensity, sweetness, off‐flavor levels, and color of white juices remained stable, and ethanol levels remained low for 7 wk. However, the flavor intensity and sweetness of nonsulfited white juice decreased, and off‐flavor and ethanol levels increased after 7 wk. Sulfite lowered microbial levels in white juice throughout 9 wk. Red juices did not develop significant levels of off‐flavors or ethanol during 9 wk, although the flavor intensity declined, especially in nonsulfited red juice. Sulfite lightened the color of red juice, but the color was stable in both sulfited and nonsulfited red juices.

Factors Influencing Ellagic Acid Precipitation in Muscadine Grape Juice During Storage

ABSTRACTEllagic acid sedimentation in white muscadine grape juice was monitored following different processing treatments and storage temperatures. High storage temperatures (40°C) greatly accelerated sediment formation, and pasteurization (100°C, 10 min) resulted in a faster sediment formation than sterile filtration. Sediment also increased substantially after juice was hydrolyzed (121°C and pH 2 for 10 min). Ultrafiltration of juice through a 10,000 or 30,000 dalton membrane resulted in significantly less sediment formation in the juice. Treatment of juice with polyvinylpolypyrrolidone (0.1– 0.2 g/L juice), egg albumen (6–10 mg/L juice) or gelatin (0.05 – 0.4 g/L juice) resulted in a significant reduction of juice phenolics and sediment formation. A commercial pectinase added to the grapes increased sediment formation and total phenolics in the juice. Levels of ellagic acid in juice were very low and did not correlate well with amount of sediment formed.

Identification and Reduction of Ellagic Acid in Muscadine Grape Juice

ABSTRACTThe precipitate which forms during storage of clarified and pasteurized Magnolia and Carlos muscadine juices was examined using paper chromatography, HPLC, and ultraviolet, infrared, and mass spectrometries. The methanol washed juice precipitate was identified as ellagic acid. The concentrations of ellagic acid in Magnolia juice treated with polyvinylpolypyrrolidone (PVPP) at 0.12, 0.36, 0.60, 0.84, and 1.08 g/L and gelatin at 0.06, 0.12 and 0.24 g/L were determined. The treatment using 1.08g PVPP/L was most effective in reducing ellagic acid, total phenolics, and juice browning.

Identification and Quantitation of Ellagic Acid in Muscadine Grape Juice

Muscadine grape juice will occasionally produce a sediment upon standing for long time periods. In order to seek approaches to elimination of this sediment, it was necessary first to identify it and then to quantitate the material responsible. The sediment was identified through various chemical and spectrophotometric means as ellagic acid. This material could be separated, identified, and quantitated in juice by using HPLC. A simple spectrophotometric assay also sufficed for quantitation. Different juice sources contained highly variable amounts of ellagic acid.

Effects of Maturity, Skin Contact and Carbonation on the Quality of Sterile‐Filtered White Muscadine Grape Juice

ABSTRACTThe effects of grape maturity, skin contact and carbonation on the quality of sterile‐filtered muscadine grape juice were investigated. A sensory panel preferred the late maturity juices that had a higher degree of muscadine character and lower total phenolics. Tartaric and malic acid levels decreased with increasing maturity, with malic decreasing to a greater extent. A 24 hr skin contact. at 2°C had no significant effect on sensory results, but increased color intensity, phenolic and organic acid levels as compared to immediate pressing. Carbonated juices were lighter in color and were preferred equally to non‐carbonated juices. Juice obtained from a hard pressing regime had slightly higher levels of organic acids than free run juice at the early harvest only.

Changes in Muscadine Grape Juice Quality During Cold Stabilization and Storage of Bottled Juice

Muscadine grapes (Vitis rotundifolia, Michx.) of two cultivars (Noble and Carlos) were washed and extracted. The resulting juice was cold stabilized for 0, 7 and 60 days at 2°C, then treated, bottled, pasteurized and stored at 2°C and 24°C for 0, 4, 8, and 12 months. Carlos juice was lower in phenols and pH and higher in acidity than Noble. The high total anthocyanins and phenols in the Noble juice caused a significant loss in pigment during cold stabilization. Dilution of juice with 40% water and adjustment of the sugars was beneficial to flavor and color of Carlos, yet 40% dilution was too high for Noble juice. Treatment of either juice with CaCO3 increased pH and decreased acidity. During 12 months storage, the Carlos juice became darker due to browning, while the Noble juice became lighter by losing pigment, especially at 24°C.