Turning Wastes into Resources: Red Grape Pomace-Enriched Biscuits with Potential Health-Promoting Properties.

The life-long adherence to a dietary pattern able to provide a high amount of polyphenols demonstrating beneficial cardiometabolic effects is demanding for the general population. In this study, red grape pomace (GP) was used as an ingredient to increase the daily polyphenols' intake. The incorporation of crude crushed GP at 20 and 30% (w/w) in a control (CTR) biscuit formula improved the nutritional profile by increasing the fiber and reducing lipid and energy content while providing up to 540 mgGAE of polyphenols per 100 g. Besides anthocyanins, GP contains flavonoids and grape-seed procyanidins, contributing to the remarkable antioxidant capacity of 20- and 30-GP biscuits. Upon in vitro gastro-duodenal enzymatic digestion, the concentration of reducing sugars for 20-GP and 30-GP compared to the CTR biscuits dropped significantly, meaning that the combined action of GP fibers and polyphenols could delay the intestinal absorption of glucose. Overall, 60 volatiles were detected in biscuits. All in all, the content of Maillard reaction products was lower in GP than in CTR biscuits, possibly due to the free radical scavenging ability of polyphenols. Despite the high rates of GP utilized, the sensorial attributes and the overall liking of the GP biscuits-especially the 20-GP ones-were not substantially affected. These findings will support nutritional studies to assess the potential role as functional foods of GP biscuits, and, afterwards, the large-scale production of a food mainly based on a waste ingredient turned into a resource.

Effect of using biodegradable film constituting red grape anthocyanins as a novel packaging on the qualitative attributes of emergency food bars during storage.

This study presents a novel packaging film based on whey protein isolate/κ-carrageenan (WC) with red grape pomace anthocyanins (RGA) to investigate its impact on some qualitative attributes of emergency food bars (EFBs) for 6 months at 38°C. Increasing the RGA dose in WC films from 5% (WCA5) to 10% (WCA10) reduced hydrogen bonding between polymers and polymer homogeneity in the matrix according to FTIR and SEM. Tensile strength slightly declined in WCA5 from 7.47 ± 0.26 to 6.97 ± 0.12, while elongation increased from 27.74 ± 1.36 to 32.36 ± 1.25% compared to WC film. The maximum weight loss temperature (TM) increased by incorporating 5 wt% RGA from 182.95°C to 244.36°C, whereas TM declined to 187.19°C in WCA10 film. WVP and OTR slightly changed in WCA5 (from 7.83 ± 0.07 and 2.57 ± 0.18 to 8.41 ± 0.03 g H2O.m/m2.Pa.s × 10-9 and 1.79 ± 0.32 cm3 O2/m2.d.bar, respectively), but significantly impaired in WCA10 compared to WC film. WCA5 and WCA10 films had high AA%, 68.77%, and 79.21%, respectively. WCA10 film presented great antimetrical properties against Staphylococcus aureus with an inhibition zone of 6.00 mm. The light transmission of RGA-contained films in the UV spectrum was below 10%. The WCA5 film effectively restrained moisture loss and hardness increment until the end of the storage period, which were 14.33% and 28.76%, respectively, compared to day 0. Antioxidant films provided acceptable resistance against oxidation to EBF treatment. Sensory panels scored WCA5 and WCA10 higher in overall acceptance with 5.64 and 5.40 values, respectively, while complaining about the hardness of OPP treatment. The results of this investigation demonstrated that incorporating RGA, preferably 5 wt%, into WC-based film effectively improved the qualitative properties of EFB during the 6-month shelf life. This film might be a promising alternative for packaging light and oxygen-sensitive food products.

Organosolv Treatment of Red Grape Pomace for Effective Recovery of Antioxidant Polyphenols and Pigments Using a Ternary Glycerol/Ethanol/Water System under Mild Acidic Conditions.

The purpose of this investigation was (i) the development of a novel, green tertiary solvent system, composed of water, ethanol and glycerol, and (ii) the implementation of an organosolv treatment of red grape pomace (RGP) for the efficient production of polyphenol-containing extracts with enhanced antioxidant properties. The treatment developed was performed under mild acidic conditions, imparted by the addition of citric acid, and it was first evaluated on the basis of severity, establishing linear models that described the correlation between treatment performance and combined severity factors. To solicit treatment optimization, response surface methodology was implemented, considering solvent acidity and residence time as the treatment variables. The optimized treatment afforded maximum total polyphenol (166 ± 6 mg GAE g-1 DM), total pigment (4.4 ± 0.2 mg MvE g-1 DM) and total flavanol (31.5 mg CtE g-1 DM) yields and extracts with particularly enhanced antioxidant activity. This might be attributed to specific constituents with high antioxidant potency, such as catechin, determined in the extract using high-performance liquid chromatography. Thus, the treatment developed is proposed as a highly efficient process to generate RGP extracts enriched in polyphenolic compounds, with enhanced antioxidant activity. Such extracts might then be valorized as food additives, to provide antioxidant protection and/or pigmentation.

Integral Use of Red Wine Pomace after Hydrostatic High Pressure: Application of Two Consecutive Cycles of Treatment.

The influence of applying hydrostatic high pressure (HHP) to red grape pomace cv. Tempranillo was studied to obtain an ingredient rich in bioactive compounds for the manufacture of food products. Four treatments were investigated: (i) 600 MPa/1 s; (ii) 600 MPa/300 s, and other two treatments with 2 cycles of HHP: (iii) 2 cycles of 600 MPa/1 s; and (iv) 1 first cycle of 400 MPa/1 s and a second cycle 600 MPa/1 s. Treated pomace was stored at different temperatures (4 and 20 °C). The application of two consecutive cycles had no effect on the microorganisms' inactivation compared to only one cycle. Immediately after HHP, the phenolic compounds content was maintained. However, HHP had no influence on the polyphenol oxidase enzyme (PPO), and so the phenolic compounds were significantly reduced during storage. Hence, the shelf-life of red grape pomace was significantly reduced at both temperatures, although phenolic compounds were better preserved under refrigeration than at room temperature.

Dried grape pomace with lactic acid bacteria as a potential source for probiotic and antidiabetic value-added powders.

Two drying methods (convective (CD) and infrared (IR)) on grape pomace with probiotics were analysed, based on kinetic models and survival rate. The moisture ratio decreases linearly with drying time. The IR drying time reduced up to 14.3% at 50 °C. The Page model allowed to calculate the drying constant (0.188-0.404 s-1), whereas the effective moisture diffusivity ranged from 6.64 × 10-9 to 9.38 × 10-9 m2/s for CD and from 8.83 × 10-9 to 11.16 × 10-9 m2/s for IR, respectively. Chromatographic analysis highlighted the presence of 28 anthocyanins, with cyanidin-3-O-monoglucoside as a main bioactive in both powder. The probiotic survivale rate reached 7.0 log CFU/g dry weight after 14 days of storage at 4 °C. The extracts affected conformation of α-amylase, with binding constants lower for IR extract (15.94 ± 1.61 × 10-2 Mol/L) when compared with CD (25.09 ± 2.14 × 10-2 Mol/L). The IC50 values were significant higher for the IR (6.92 ± 0.09 µMol C3G/mL) when compared with CD extract (10.70 ± 0.12 µMol C3G/mL).

Evaluation of Chemical-Nutritional Characteristics of Whey and Ricotta Obtained by Ewes Fed Red Grape Pomace Dietary Supplementation.

This study aimed to investigate the effect on the chemical quality of whey and Ricotta obtained from ewes fed a red grape pomace (GP) dietary supplementation. The analyses were performed on whey, before and post Ricotta cheese-making, and in Ricotta after 1 (T1) and 5 (T5) d of ripening at 4°C. Moreover, fatty acid profile of whey before ricotta (WBR) cheese-making and Ricotta T1 of ripening and volatile profile of Ricotta T1 and T5 were investigated. The diet did not affect whey and Ricotta lipid content, conversely, significant variations were instead observed with regard to color. A lower amount of total phenolic compounds was found in WBR cheese-making, on the contrary, an opposite trend was highlighted in Ricotta T1 although no variations in antioxidant properties were detected. Moreover, GP modified fatty acid profile of whey and Ricotta but did not have any effect on protein profile of the main whey protein. The reduction of hexanal in Ricotta during the ripening suggest a better oxidative stability. The obtained results therefore suggested that the GP inclusion in the ewes diet, while modifying some chemical parameters, did not induce negative effects on the characteristics and quality of dairy by-products.

Grape Pomace for Topical Application: Green NaDES Sustainable Extraction, Skin Permeation Studies, Antioxidant and Anti-Inflammatory Activities Characterization in 3D Human Keratinocytes.

Food waste is a global problem due to its environmental and economic impact, so there is great demand for the exploitation of new functional applications. The winemaking process leads to an incomplete extraction of high-value compounds, leaving the pomace still rich in polyphenols. This study was aimed at optimising and validating sustainable routes toward the extraction and further valorisation of these polyphenols, particularly for cosmeceutical applications. New formulations based on red grape pomace polyphenols and natural deep eutectic solvents (NaDESs) were here investigated, namely betaine combined with citric acid (BET-CA), urea (BET-U) and ethylene glycol (BET-EG), in which DESs were used both as extracting and carrying agents for polyphenols. The flavonoid profile determined by HPLC-MS/MS analysis showed similar malvidin content (51-56 µg mL-1) in the DES combinations, while BET-CA gave the best permeation performance in Franz cells, so it was further investigated in 3D human keratinocytes (HaCat spheroids) injured with the pro-oxidant agent menadione. BET-CA treatment showed good intracellular antioxidant activity (IC50 0.15 ± 0.02 µg mL-1 in malvidin content) and significantly decreased (p < 0.001) the release of the pro-inflammatory cytokine IL-8, improving cell viability. Thus, BET-CA formulation is worthy of investigation for potential use as a cosmetic ingredient to reduce oxidative stress and inflammation, which are causes of skin aging.

Polyethylene glycol inactivates red grape pomace condensed tannins for broiler chickens.

1. This study was conducted to investigate the effect of inactivating GP condensed tannins using graded levels of polyethylene glycol (PEG) on feed intake, physiological, carcase, and meat quality traits of male Cobb 500 broilers. 2. Three hundred, two-week old, male Cobb 500 broilers (334.6 ± 21.43 g live weight) were allocated to 30 pens carrying 10 birds each. Five isonitrogenous and isoenergetic diets were formulated for grower (14-35 d) and finisher (36-42 d) phases by diluting a commercial broiler diet with untreated GP (PEG0) at 6.5% (w/w) or with the same amount of GP but pre-treated with PEG at 2.5% (PEG1), 5% (PEG2), 10% (PEG3) or 15% (w/w) (PEG4) and randomly allocated to pens in a four-week feeding period. 3. Feed intake, weight gain, feed conversion efficiency (FCE), and blood, carcase and meat quality parameters were determined. Weekly weight gain and FCE linearly (P < 0.05) increased in week 4 and linearly (P < 0.05) decreased in week 6 in response to PEG treatment levels. 4. Mean corpuscular volume linearly (P < 0.05) decreased in response to PEG levels, whereas blood urea nitrogen/creatinine ratio, urea, total protein, globulin and cholesterol showed quadratic trends in response to PEG levels. Spleen and ileum weights tended (P < 0.1) to linearly decrease with PEG levels. Heart weight and meat redness tended (P < 0.1) to quadratically respond to increasing levels of PEG. 5. It was concluded that PEG treatment partially inactivated GP condensed tannins without compromising the health status of broiler chickens. An optimum PEG inclusion level could not be determined for feed intake, weight gain and FCE. However, the presence of other antinutrients such as fibre and low molecular weight phenolics in GP may be responsible for the linear decreases observed in this study.

Development of antioxidant and antimicrobial xanthan-based cryogels with tuned porous morphology and controlled swelling features.

Novel porous films based on xanthan gum (XG), poly(vinyl alcohol) (PVA), and red grape pomace (RGP), as entrapped natural antioxidant agent, were prepared by freeze/thawing, a versatile and non-destructive method. The stability of XG/PVA films was dependent on the crystalline zones created by PVA under freeze/thawing treatment. After three cryogenic cycles, the introduction of RGP into the 3D polymer matrix plays a major role by hindering the access of water into the cavities already formed during the first and second cryogenic cycles. By contrast, XG/PVA-based cryogels with enhanced mechanical strength were obtained when the number of freeze/thawing cycles increased from three to seven, while pores stability was improved by entrapment of RGP. The remarkable antioxidant and antimicrobial activity of XG/PVA/RGP cryogel films compared to the XG/PVA films, indicates the potential application of these systems in food packaging.

Valorization of Red Grape Pomace Waste Using Polyethylene Glycol and Fibrolytic Enzymes: Physiological and Meat Quality Responses in Broilers.

The amount of grape pomace (GP) waste that can be included as a functional feed in broiler diets is limited by anti-nutritional compounds such as fiber and condensed tannins. This study evaluated the effect of pre-treating GP with polyethylene glycol (PEG) and a cellulolytic enzyme mixture on physiological and meat quality parameters of broilers. Cobb 500 broilers (249.2 ± 20.31 g live-weight) were reared on five isoenergetic and isonitrogenous diets: 1. Commercial chicken diet (CON); 2. CON containing untreated GP at 100 g/kg (dGP); 3. CON containing 100 g/kg GP pre-treated with PEG (50 g/kg) (dPEG); 4. CON containing 100 g/kg GP pre-treated with enzyme (1 g/kg) (ENZ); and 5. CON containing 100 g/kg GP pre-treated with PEG (50 g/kg) and enzyme (1 g/kg) (PENZ). Overall body weight gains were similar in broilers reared on the CON, dPEG, ENZ and PENZ diets but lower in dGP chickens. The meat of birds reared on dPEG, ENZ, dGP and CON had a similar water-holding capacity, which was lower than in PENZ chickens. Diets influenced the size of duodenum, ileum, jejunum and caeca. Polyethylene glycol treatment promoted similar body weight gains and hot carcass weights as the commercial control diet, suggesting that the anti-nutritional effects of condensed tannins were successfully ameliorated.

Obtaining Multiple Coproducts from Red Grape Pomace via Anthocyanin Extraction and Biogas Production.

Red grape pomace (RGP), a byproduct of red wine production, is an abundant food processing waste stream in California, rich in both anthocyanins, a class of red-blue pigments, and lignocellulose. Extraction of anthocyanins and biofuel production from RGP have been investigated independently, but no research has examined employing both strategies together for maximal valorization. In this study, anthocyanins were most effectively extracted from RGP at 80 °C. Convection- and vacuum-oven drying of the pomace were found to decrease anthocyanin yield, whereas lyophilization did not significantly affect yield. Fermentable sugars were successfully separated from the crude extract via solid-phase extraction. Ionic liquid pretreatment of RGP was determined to be a nonviable option for application to anaerobic digestion. Extraction reduced biomethane output, but supplementation with the aqueous fraction of the extract mitigated much of this difference, indicating sequential extraction and fractionation of anthocyanins from RGP can minimize the impact on biofuel yields.

Effect of Drying on the Phenolic Content and Antioxidant Activity of Red Grape Pomace.

Winemaking by-products are considered to be a rich source of bioactive compounds. Grape pomace is susceptible to microbial degradation due to the degree of residual moisture, so the drying of this pomace for conservation is considered to be an essential first step. Previous studies concerning the way in which drying affects winery by-products have produced contradictory results. In this study, a new methodology for drying grape pomace in a climatic chamber has been evaluated. Five red grape pomace varieties were dried in a climatic chamber at 40 °C and 10% relative humidity and the phenolic content and antioxidant activity of the dried and wet pomace samples were compared. The results indicate that this drying process is both feasible and beneficial because significant increases in the extractability of phenolic compounds and antioxidant activity were achieved.

Oxidation phenomena and color properties of grape pomace on nitrite-reduced meat emulsion systems.

The present study focuses on the effect of different levels of red grape pomace (1 and 2%, w/w) on the color changes, lipid oxidation (TBARS), antioxidant activity, microbial counts, total phenol content and sensory attributes of the sausages formulated with various levels of sodium nitrite (30, 60 and 120mg/kg). It was found that the addition of grape pomace (1%, w/w) in combination of reduced nitrite levels to the beef sausage samples reduced TBARS content and the degree of lipid oxidation. Antioxidant activity and total phenol contents were further evaluated based on DPPH scavenging activity method. A significant reduction in lightness (L*) and yellowness (b*) of systems containing grape pomace was observed, following by an increase in the oxidative stability and the radical scavenging activity. Acceptability of beef sausages was not significantly (P>0.05) affected by the addition of grape pomace and had relatively greater scores from a sensory point of view.

Optimization of polyphenol extraction from red grape pomace using aqueous glycerol/tartaric acid mixtures and response surface methodology.

Grape pomace is a food industry waste containing a high burden of antioxidant polyphenols and several methodologies have been developed for their efficient extraction. However, a sustainable and environmentally friendly process should involve recovery means composed of benign, non-toxic solvents, such as tartaric acid and glycerol, which are natural food constituents. In this line, this study examined the extraction of polyphenols using aqueous tartaric acid/glycerol solutions. The aim was to assess the role of acid and glycerol concentration in the extraction yield, employing a Box-Behnken experimental design and response surface methodology. The results showed that solutions containing only glycerol (20%, w/v) are more suitable for retrieving polyphenols, flavonoids, and pigments from grape pomace, while tartaric acid exerted a negative effect in this regard, when tested at concentrations up to 2% (w/v).

Screening of Anthocyanins and Anthocyanin-Derived Pigments in Red Wine Grape Pomace Using LC-DAD/MS and MALDI-TOF Techniques.

Two phenolic extracts were made from a red wine grape pomace (GP) and fractionated first by sequential liquid-liquid extraction with organic solvents. The aqueous fraction was fractionated by low-pressure chromatography on Toyopearl HW-40 gel and on C18. Different fractions were obtained by sequential elution with aqueous/organic solvents, and then analyzed by liquid chromatography and mass spectrometry (LC-DAD/MS and MALDI-TOF). Over 50 anthocyanin-based pigments were detected by LC-DAD/MS in GP, mainly pyranoanthocyanins including A- and B-type vitisins and methylpyranoanthocyanins. The presence of oligomeric malvidin-3-O-coumaroylglucoside-based anthocyanins was also detected in GP using both LC-DAD/MS and MALDI-TOF.