FROM WASTE TO HEALTH: AN INTEGRATIVE BIOINFORMATICS APPROACH TO THE THERAPEUTIC POTENTIAL OF BURGUND GRAPE POMACE EXTRACTS OBTAINED BY MICROWAVE-ASSISTED EXTRACTION

The sustainable management of winery residues could represent a cornerstone for promoting environmental and economic sustainability from a circular economy perspective. In this context, our study aimed to evaluate Vitis vinifera L. ‘Nero di Troia’ cultivar grape pomace as a valuable waste product for the cultivation of Pleurotus mushroom, in comparison with traditional wheat straw-based cultivation. Mushroom extracts were prepared through the eco-friendly microwave-assisted extraction technique, using green solvents with different polarity degrees. Total protein content, total polyphenol content, and antioxidant activity (FRAP and DPPH assays) were assessed for the water and EtOH hydrophilic extracts. Grape pomace often gave higher values than wheat straw, especially for the P. eryngii var. eryngii water extract protein content, which was 3.5-fold higher (0.68 ± 0.14 mg BSA/mL and 0.192 ± 0.025 mg BSA/mL, respectively). The ethyl acetate extracts of both mushroom species gave biologically relevant results in terms of inhibiting activity against acetylcholinesterase, an enzyme involved in the pathogenesis of Alzheimer’s disease (50% inhibitory activity at concentrations ≤ 1.5 mg/mL), thus paving the way for more in-depth investigation. The extract’s metabolic profile was investigated through GC-MS analysis. The results show that incorporating grape pomace into mushroom production represents a concrete step toward more sustainable biotechnological processes.

Acid, enzyme, ultrasonic, and microwave were used to assist extraction of polyphenols in grape pomace, skins, and seeds. The relationship among extraction technologies, polyphenolic content and antioxidant capacities was analyzed by principal component analysis (PCA), and the effective extraction condition for specific target was optimized by response surface methodology. Polyphenolic content could be mostly enhanced by microwave‐assisted processing, while PCA showed that ultrasound‐assisted processing had a more positive effect on the antioxidant activity of extracts. Microwave and ultrasonic assisted consecutive extraction on Merlot seed showed the superiority and the numerical optimization for the highest global desirability value of antioxidants extraction was obtained at the condition of 1:24.50 (liquid–solid ratio), 68.00% EtOH, 3.24 min (microwave time) and 60.00 min (sonication time) with desirability of 0.973. The predicted extraction condition of total phenolics, total flavonoids, and proanthocyanidins were 19.51 mg GAE/g DW, 29.06 mg RE/g DW, and 24.47 mg CE/g DW, respectively; while the values for antioxidant activity were 87.25% hydroxyl radicals‐scavenging activity, 83.39% superoxide radical‐scavenging activity, and 1.86 (at 700 nm) reducing power.Practical applicationsPolyphenols present an important antioxidant activity and health‐beneficial properties. Sustainable and relatively cheap raw material should be utilized in the production, such as winery byproducts. However, microwave‐assisted processing may affect the antioxidant activity of extracts despite that the polyphenolic content could be enhanced. This research provides information about optimization of novel extraction technique (microwave and ultrasonic assisted consecutive extraction), which could be successfully used for polyphenols extraction due to increased yield of target compounds and improved quality of the liquid extracts in terms of antioxidant activity. These findings are a useful tool for producers of winery byproducts to achieve an effective and economically viable extraction process as well as optimal composition and bioactivity in terms of antioxidant capacity.

This work aims at producing high dynamic shock waves by Pulsed Arc Electro-hydraulic Discharges (PAED) in a water based mixture in order to increase polyphenols extraction from grape pomace. Grape pomace is the main winemaking by-product composed of skins, seeds and stems. They contained valuable compounds like polyphenols. These molecules have attracted interest for their antioxidant activity. A triggered air-gap switch was used to discharge capacitors into the mixture containing grape pomace and water. The gap switch breakdown (40 kV maximum pulse voltage) produced a high dynamic shock wave in the liquid. The pulse energies were set to 160 J and 4 kJ with a pulse repetition frequency of 0.5 Hz. The contents of total solutes and total polyphenols of extracts were obtained by the values of degree Brix and absorbance at 280 nm respectively. Results point out the intensification of the extraction of total solutes and total polyphenols from grape pomace after PAED treatment. However, maintaining constant the ratio of energy to product mass (in our case, it was equal to 0.53 J/g) was not enough to obtain similar results for laboratory and semi-pilot experiments. Other parameters should be taken into account (treatment chamber design, pressure wave distribution ...). For example, a treatment of 53 kJ/kg at the laboratory scale gives similar results as a treatment of 160 kJ/kg at the pilot scale. In these conditions, the content of polyphenols in extracts is approximately 300 mg/L and the degree Brix is 1.2%.

Grape pomace (GP), a major byproduct obtained from the winemaking process, is characterized by a high amount of phenolic compounds and secondary plant metabolites, with potential beneficial effects on human health. Therefore, GP is a source of bioactive compounds with antioxidant, antimicrobial, and anti-inflammatory activity. As people are paying more attention to sustainability, in this work, we evaluate two different extractions (aqueous and hydroalcoholic) of GP bioactive compounds. In vitro simulated gastrointestinal digestion of the GP extracts was performed to improve the bioavailability and bioaccessibility of polyphenols. The antioxidant activity (ABTS and DPPH assays) and the phenolic characterization of the extracts by UHPLC-DAD were evaluated. The antimicrobial effects of GP antioxidants in combination with a probiotic (Lactiplantibacillus plantarum) on the growth of pathogenic microorganisms (Escherichia coli, Bacillus megaterium, and Listeria monocytogenes) were evaluated. As a result, an increase of antioxidant activity of aqueous GP extracts during the gastrointestinal digestion, and a contextual decrease of hydroalcoholic extracts, were detected. The main compounds assessed by UHPLC-DAD were anthocyanins, phenolic acids, flavonoids, and stilbenes. Despite lower antioxidant activity, due to the presence of antimicrobial active compounds, the aqueous extracts inhibited the growth of pathogens.

The aim of this study was to determine the polyphenol content and antioxidant activities in commercialized date and pomegranate concentrates that are available in local market. A total of seven samples comprised of two brands of date concentrates (D1 and D2) and five brands of pomegranate concentrates (P1, P2, P3, P4, and P5) have been analyzed for their polyphenol content and antioxidant activity. The Folin-Ciocalteu assay was used to determine the polyphenol content (TPC) of the samples while 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and Ferric Reducing Antioxidant Power (FRAP) assays were used to determine the antioxidant activity. The results showed the commercialized date concentrate D2 contained the highest TPC ( 1243.00 ± 67.00 mg GAE/100 ml) and antioxidant activity using FRAP assay (2.67 ± 0.01 mmol TE/100 ml). Date concentrate D1 showed the highest antioxidant activity using DPPH assay ( 0.39 ± 0.02 mmol TE/100 ml). The pomegranate concentrate P5 showed the highest reading for TPC ( 3260.10 ± 428.70 mg GAE/100 ml), DPPH (1.61 ± 0.05 mmol TE/100 ml) and FRAP assays (20.98 ± 0.42 mmol TE/100 ml) . As a conclusion, the studied commercial date and pomegranate concentrates available in the local market contained high polyphenol and antioxidant contents although the content levels were different from one brand to another. Further study is needed to identify the causes of this distinction. The results of this study could help the consumers to make a better selection of commercialized date and pomegranate concentrates that are available in local market in term of polyphenol content and antioxidant activity. DOI : http://dx.doi.org./10.17576/JSKM-2019-1702-15

Received: 2021-10-04 | Accepted: 2021-11-29 | Available online: 2021-12-31 https://doi.org/10.15414/afz.2021.24.04.340-344 Grape pomace is a bioactive compound rich winery by-product having antioxidant properties. However, its use in equine nutrition in this regard have been unexploited to date. Thus, this study aimed to investigate whether dried grape pomace (DGP) could enhance the antioxidant mechanisms of horses. Redox status was assessed through glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity in blood serum, and ferric reducing ability of plasma (FRAP). Twelve horses were assigned to three groups recieving a basal diet (control group) or the basal diet supplemented with 200 g of DGP (experimental group 1), or 400 g of DGP (experimental group 2) for 30 days. Dietary DGP supplementation of horses at a level of 200 g positively affected their redox status through increased FRAP (P<0.05). 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This study was undertaken to investigate the effect of heat treatment on polyphenolic content and antioxidant activity in grape pomace (GP) and grape seed extract (GSE). GP and GSE were heat treated in a furnace or autoclaved at 100 °C for 15, 30 and 60 min. Structural modifications of the polyphenols during thermal processes were determined by HPLC–MS, and the antioxidant activity was determined by ABTS, DPPH and photochemiluminescence methods. In general, furnace thermal treatment of GSE and GP did not affect the total extractable polyphenols content, tannin content, procyanidin components and the antioxidant activity. Autoclave treatment caused an extensive hydrolysis of gallocatechin (70%), catechin (61%), epicatechin (65%), procyanidin B1 (75%) and procyanidin B2 (73%) in GSE, and an increase in gallic acid (71%), gallocatechin (100%) and epicatechin gallate (129%) in GP. Autoclave treatment did not affect the antioxidant activity of GSE or GP. It can be concluded that the effect of autoclave was more severe than furnace heat treatment modifying the phenolic profile in a different manner depending on the grape seed product used. These modifications were not related with changes in antioxidant activity.

Optimization of the green extraction process of antioxidants derived from grape pomace

Grape pomace (GP), a by-residue from the wine industry, contains bioactive molecules such as phenolic compounds, and anthocyanins, among others, with potential health benefits. In the current study, these bioactive molecules were extracted from GP of different Vitis vinifera L. varieties (Tinta Negra, Complexa, Malvasia Roxa, Malvasia, Sercial, Verdelho, Boal, Terrantez) using the micro quick, easy, cheap, effective, rugged, and safe (µQuEChERS) procedure. The GP extracts were investigated using ultra-high performance liquid chromatography (UHPLC-PDA) to establish the phenolic fingerprint, and by in vitro assays to assess the antibacterial, anti-inflammatory, and antioxidant activities. Nine phenolic compounds were identified and quantified in GP extracts, with gallic acid (ranging from 10.4 to 12.9 g/100 g), catechin (2.97 to 5.08 g/100 g), quercetin (2.17 to 2.85 g/100 g), and trans -resveratrol (0.28 to 1.82 g/100 g) being the most prominent. GP from the Complexa variety exhibited the highest levels of total anthocyanin content (TAC, 6.67 mgCGE/100 g), total phenolic compounds (TPC, 4727 mgGAE/100 g), and antioxidant activity (DPPH, 9472 mgTE/100 g), while the Tinta Negra variety had the highest total catechin content (TCC, 947 mgCATE/100 g). A strong correlation ( p < 0.001) was observed between the TPC-TAC, TPC-DPPH, DPPH-TAC, and TAC-TCC. Moreover, o-coumaric acid and quercetin are significantly ( p < 0.001) correlated with TPC, TAC, TCC, and DPPH assays. The investigated GP extracts, at a concentration of 100 µg/mL, showed promising inhibition of albumin protein denaturation compared to aspirin (reference standard). The findings showed that the GP extracts were more useful at inhibiting Staphylococcus aureus compared to Escherichia coli . It is important to emphasise that the GP extracts demonstrated antioxidant, anti-inflammatory, and antibacterial properties, positioning it as an agro-waste with promising potential for use in the development of innovative functional foods, dietary supplements, and cosmetics, aligning with the circular bioeconomy model for its valorisation.

The grape pomace is a by-product from the industrial processing of grape juice, which can be used as a source of bioactive compounds. The aim of this study was to separate the phenolic compounds from grape pomace using an acidic aqueous solution with 2 % citric acid as a solvent, using both ultrasound-assisted extraction, with powers of 250, 350 and 450 W and times of 5, 10 and 15 min, and microwave-assisted extraction using powers of 600, 800 and 1,000 W and times of 5, 7 and 10 min. The results showed that for both methods of extraction, the contents of total phenolic compounds and antioxidant activity by ABTS and DPPH increased with time, and microwave at 1,000 W for 10 min corresponded to the best extraction condition. However, the contents of phenolic compounds and antioxidant activity were lower than exhaustive extraction using acidified methanol solution.

Grape pomace is a valuable source of various bioactive compounds such as plant-derived polyphenols and polyunsaturated fatty acids (PUFAs). The commercial demand of grape skin and seed powders as nutraceuticals is still growing. However, no distinction is currently made between unfermented native grape seed and grape seed pomace powders regarding their antioxidant activities. Our aim was to find the relationship between the polyphenol and fatty acid content as well as the antioxidant capacity of native and fermented grape seeds of four different grape varieties harvested in the Villány wine region. According to our results, none of the three investigated polyphenols (resveratrol, rutin, quercetin) could be detected in native grape seed samples in correlation with their significantly lower total antioxidant capacities compared to fermented seed samples. Pinot Noir (PN) grape seed pomace samples with the highest resveratrol and oil content showed significantly higher total antioxidant capacity than Cabernet Sauvignon (CS), Syrah (S) and Blue Portugal (BP) samples. Based on the statistical analysis, positive correlation was found between the fatty acid content and the resveratrol concentration in the pomace samples of different grape varieties. In contrast, rutin concentrations were negatively proportional to the fatty acid content of the fermented samples. No significant correlation was found considering the quercetin content of the samples. According to our findings, grape pomace seems a more promising source in the production of nutraceuticals, since it contains polyphenols in higher concentration and exerts significantly higher antioxidant activity than native grape seeds.

<p>This study was designed to investigate the impact of different extraction methods (ultrasound-assisted extraction, maceration, and microwave-assisted extraction) on the content of polyphenols and biological activities of leaf extract of <italic>Paeonia daurica</italic> subsp. <italic>daurica</italic> collected in Južni Kučaj (Serbia). The total polyphenol and flavonoid content were achieved by the UV-Vis spectroscopy. FTIR analysis was conducted to investigate structural properties of the extracts. <italic>In vitro</italic> methods (2,2<sup><italic>′</italic></sup>-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) - ABTS and 2,2-diphenyl-1-picrylhydrazyl – DPPH assays) were carried out to measure the antioxidant activity of the extracts, while their antibacterial activity was tested against three Gram-positive and three Gram-negative bacterial strains. Analyzing the results of antioxidant activity, the highest anti-DPPH potential was achieved in the extracts of LPD obtained by maceration. The extraction method proven to produce the most effective antibacterial agents is maceration. Moreover, inhibitory activity of extracts against acetyl–and butyrylcholinesterase, <italic>α</italic>-amylase, <italic>α</italic>-glucosidase, and tyrosinase was evaluated in the enzyme inhibition assays. Overall, the results of this research indicated the possible use utilization of leaf extracts of <italic>Paeonia daurica</italic> subsp. <italic>daurica</italic> Andrews in food technology and pharmacy.</p>

The use of antioxidants and antibacterials in food industry has become increasingly necessary to ensure the high quality of food. Grape pomace is the main by-product of winemaking industry that concentrates bioactive metabolites with more studied antioxidant activity and possible antibacterial activity. The grape pomace contains fragmented skin, broken cells, pulp remains, stalks and seeds with high amount of phenolic compounds due to their poor extraction during the winemaking process. Anthocyanins, catechins, flavonol glycosides, phenolic acids, alcohols and stilbenes have been identified among the compounds present in grape pomace. In this study, antibacterial activity against different pathogens (Escherichia coli ATCC 25922, Candida albicansATCC 90028, Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 25923) was evaluated and the relation with polyphenols content and antioxidant activity of grape pomace from selected grapes from Iaşi vineyard was studied. The grape pomace samples were obtained after the fermentation process from the 2017 harvest of Sauvignon Blanc, Traminer, Busuioacă de Bohotin, Cabernet Sauvignon, Merlot, Fetească Neagră and Fetească Regală grape varieties. The antioxidant properties were evaluated using the DPPH method, FRAP assay and Folin Ciocalteu method. The content of resveratrol was quantified using an HPLC method. Samples with antioxidant activity showed the highest phenolics content. This study reveals that grape pomace is a potential source of natural antioxidant agents. The pomace extracts were tested to establish the effects on Gram-positive and Gram-negative bacteria. The analysed samples exhibited insignificant antibacterial activity and the method requires optimization. Grape marc represents an important source of resveratrol and other bioactive compounds that could be a valuable source of antioxidants for further utilization in food and pharmaceutical industry.

Grape pomace (GP) is a major byproduct of wine and juice industry, rich in polyphenolics with demonstrated health benefits. Extrusion processing for development of healthy and quality GP supplemented corn starch snack foods was evaluated using response surface methodology. The retainability of polyphenolic content and antioxidant activity after extrusion processing were further assessed. The processing variables were feed moisture (16, 20, and 24 ± 0.2% w.b.), screw speed (150, 200, and 250 rpm), and the level of GP supplementation (0, 5, and 10% w/w). Extrudates with 5% GP and 16 ± 0.2% feed moisture had a high overall expansion ratio (ER) of 3.83 ± 0.14, and overall low density (0.11 ± 0.00 g/cm3). Total polyphenolic content (TPC) of the extrudates (5% GP, and 16% feed moisture) extruded at 150 and 250 rpm retained up to 74.1% and 78.57% respectively, while TPC was retained at 95% when extruded under 200 rpm with 10% GP and 16% feed moisture. Additionally, the total antioxidant activity and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of the 5% GP extrudates retained 98% after extrusion processing. Moreover, polyphenolic extract of 5% GP extrudates suppressed reactive oxygen species (ROS) in CaCO2 cells induced by hydrogen peroxide. In conclusion, GP incorporation in cornstarch extrudates improved both the physicochemical quality as well as nutritional value of products. Our study indicates that GP can be effectively incorporated into extruded foods by providing enhanced nutritional value without losing the expansion characteristics.

Background: Dittrichia graveolens (L.) is a strongly aromatic plant distributed in Mediterranean regions. This research concerns the optimization of the Total Phenolic Content (TPC) and the Total Tannin Content (TTC) of Dittrichia graveolens (L.) extracts using Response Surface Methodology for Ultrasound Assisted Extraction (UAE) and Microwave Assisted Extraction (MAE). Central Composite Design (CCD) was used to evaluate the effect of the solvent concentration and the extraction time, in different methods on TTC and TPC. The antioxidant activities and antibacterial activities were evaluated. Methods: The plant extracts were prepared using maceration, microwave and ultrasound assisted extraction. TPC and TTC were measured using Folin-Ciocalteu method. The antioxidant activities were studied using DPPH reagent and disc diffusion method was used to study the antibacterial activities. Results: This study showed the optimum condition for UAE was 49.96% methanol concentration and 11.2 min sonication, while for MAE was 55.44% methanol concentration and 2.26 min microwave extraction. It also indicated that MAE was the most effective method in comparison to UAE and maceration. The antioxidant activities of MAE extract (IC50=7.7mg/mL) were more than UAE extract (IC50=21.5mg/mL) and maceration (IC50=32.3mg/mL). Conclusion: As a conclusion, it was indicated that MAE was the most effective method. The higher total phenolic content caused higher antioxidant activities as MAE extract had the highest antioxidant activities. The antibacterial test showed the great potential of this plant as an antibacterial compound resource against different bacteria.