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The study was conducted to study the sustainability and enhanced nutrition gains obtained from incorporating grape skin powder (GSP) extracted from both Fetească Neagră and Rară Neagră grape varieties into yogurt. Grape skins are major leftovers from wineries, having high amounts of phenolic compounds and dietary fiber responsible for their ability to improve the characteristics of food. The research aimed to evaluate the effect of GSP addition at varying concentrations (0.5%, 1.0%, and 1.5%) on the yogurt's physicochemical properties, antioxidant activity, color parameters, and sensory attributes. Analysis revealed that both Fetească Neagră and Rară Neagră GSP increased the total phenolic content and antioxidant activity; however, Fetească Neagră showed greater improvements, with TPC reaching 1.52 mg GAE/100 g and DPPH inhibition up to 26.63%. Although slightly lower, TPC rose to 1.43 mg GAE/100 g and DPPH inhibition increased to 18.93% with Rară Neagră enhancing these parameters conversely. Color changes were observed in fortified yogurts where lightness decreased (L*) and redness increased (a*) due to the pH-dependent anthocyanin stability. Syneresis, indicative of yogurt's water-holding capacity, was reduced at higher concentrations of GSP from both varieties, suggesting improved textural integrity. Sensory evaluation indicated that consumers generally favored yogurts with lower concentrations of GSP. Yogurts fortified with Fetească Neagră GSP received higher overall preference, while those with Rară Neagră GSP were also well-received for their distinct flavor profiles when used at suitable levels. These results show that GSP from both types of grapes improves the nutritional value of yogurt and complies with the principles of sustainable food production through reutilizing agro-industrial waste. [ABSTRACT FROM AUTHOR]

The insoluble dietary fiber (IDF) of grape skins was modified by high-temperature steaming combined with the snail enzyme method using grape skins as raw material, the aim of this study was to increase the yield of soluble dietary fiber (SDF) and improve the physicochemical properties of SDF and IDF. The effects of different factors on the yield of SDF were studied, and the physicochemical indexes of dietary fiber before and after modification were determined. The experimental results were as follows: Steaming time of 60 minutes, steaming temperature of 120 ℃, the material to liquid ratio was 1:25 g/mL, enzyme addition of 3.50%, enzymatic hydrolyswas temperature of 34.0 ℃, and enzymatic hydrolysis time of 55 minutes. Under these conditions, the yield of SDF was 10.25%. The water holding capacity, oil holding capacity, and swelling capacity of modified SDF were increased by 1.74, 1.53, and 1.13 times, respectively. The water holding capacity, oil holding capacity, and swelling capacity of the modified IDF were increased by 1.01, 1.26, and 1.27 times, respectively. Compared with the unmodified SDF and IDF, the structure of the modified SDF and IDF became more loose, and the glucose adsorption capacity, glucose dialysis retardation index, and α-amylase inhibition were significantly improved. Among them, the modified SDF had the strongest glucose adsorption capacity, and the glucose dialysis delay index was also higher than other dietary fiber samples. When the addition amount was 8 mg/mL, the inhibition rate of the modified SDF on α-amylase reaches its maximum value (54.71%). In summary, the modified SDF and modified IDF had better characteristics, which would provide a theoretical basis for modified grape skin dietary fiber.

The insoluble dietary fiber (IDF) of grape skins was modified by high-temperature steaming combined with the snail enzyme method using grape skins as raw material, the aim of this study was to increase the yield of soluble dietary fiber (SDF) and improve the physicochemical properties of SDF and IDF. The effects of different factors on the yield of SDF were studied, and the physicochemical indexes of dietary fiber before and after modification were determined. The experimental results were as follows: Steaming time of 60 minutes, steaming temperature of 120 °C, the material to liquid ratio was 1:25 g/mL, enzyme addition of 3.50%, enzymatic hydrolys was temperature of 34.0 °, and enzymatic hydrolysis time of 55 minutes. Under these conditions, the yield of SDF was 10.25%. The water holding capacity, oil holding capacity, and swelling capacity of modified SDF were increased by 1.74, 1.53, and 1.13 times, respectively. The water holding capacity, oil holding capacity, and swelling capacity of the modified IDF were increased by 1.01, 1.26, and 1.27 times, respectively. Compared with the unmodified SDF and IDF, the structure of the modified SDF and IDF became more loose, and the glucose adsorption capacity, glucose dialysis retardation index, and α-amylase inhibition were significantly improved. Among them, the modified SDF had the strongest glucose adsorption capacity, and the glucose dialysis delay index was also higher than other dietary fiber samples. When the addition amount was 8 mg/mL, the inhibition rate of the modified SDF on α-amylase reaches its maximum value (54.71%). In summary, the modified SDF and modified IDF had better characteristics, which would provide a theoretical basis for modified grape skin dietary fiber. [ABSTRACT FROM AUTHOR]

Grapes present recognized beneficial effects on human health due to their polyphenolic composition. The grape overproduction together with the wine sales down and the world socioeconomic situation makes the wine grape valorization a promising strategy to give an added-value to this natural product. The objective of the present work was to study the influence of in vitro gastrointestinal digestion on antioxidant capacity and polyphenolic profile of skin and seed extracts of different grape varieties (Tempranillo, Graciano, Maturana tinta and Hondarrabi zuri). After in vitro gastrointestinal digestion, total phenolic content (TPC) of seed polyphenolic extracts decreased significantly for all the varieties. The highest decrease was for Tempranillo going from 108 ± 9 to 50 ± 3 mg / g dry matter (dm). This variety also showed the highest decrease of 90% in antioxidant capacity. However, for all the skin polyphenolic extracts there was an increase in TPC. The highest variation was also for Tempranillo. It varied from 10.1 ± 0.8 to 55.1 ± 0.9 mg / g dm. Among red varieties Tempranillo skin polyphenolic extract showed the lowest undigested anthocyanin content but the highest bioaccessibility index (BI) of 77%. For flavanols, flavonols and procyanidins the seed polyphenolic extracts showed a BI at the intestinal phase between 11% for (+)-epicatechin gallate to 130% procyanidin A2. The results of this study suggest that grape skin extracts and grape seed extracts are a reliable source of bioaccessible antioxidant polyphenols, to be used for the development of antioxidant supplements with specific functionalities depending on the grape variety. [ABSTRACT FROM AUTHOR]

Maximizing the yield of bioactive molecules extracted from plant materials requires the investigation of extraction process variables; therefore, in this research, a traditional aqueous solid–liquid extraction method was employed on two distinct grape pomace skin samples. The grape skin pomace represents a potentially valuable source of biologically active compounds, particularly polyphenols. Experiment 1 utilized ground grape pomace skin, whereas experiment 2 utilized grape pomace skin that had been both dried and ground beforehand. Employing a Box–Benkhen experimental design and response surface modeling in the Statistica 14.0 software package, this study evaluated the impact of temperature, extraction time, solid-to-liquid ratio (S/L), and mixing speed on extraction efficiency. The extracted compounds were assessed for both physical properties (conductivity, total dissolved solids, and pH) and chemical properties (total polyphenol content and antioxidant activity using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays). The optimization matrix design identified the specific conditions required to achieve the optimal physical and chemical properties of grape skin extract as follows: (i) for experiment 1, extraction time (t) = 15 min, temperature (T) = 80 °C, solid-to-liquid ratio (S/L) = 10 g/L, and mixing speed (rpm) = 500 1/min and (ii) for experiment 2, extraction time (t) = 15 min, temperature (T) = 80 °C, solid-to-liquid ratio (S/L) = 10 g/L, and mixing speed (rpm) = 375 1/min. Under optimal process conditions, 26.1284 mgGAE/gd.m. and 25.1024 mgGAE/gd.m., respectively, were obtained. These findings demonstrate the effectiveness of the optimization process in identifying precise extraction conditions that yield the optimal chemical properties of grape skin extracts. [ABSTRACT FROM AUTHOR]

This research explores a novel approach in beer production by incorporating waste materials such as grape seeds and skins, derived from wine processing, into the brewing process. This initiative holds promise for effective waste utilization, advancing craft beer, and utilizing cost-effective raw materials. Experiments explore the integration of grape by-products into beer production, evaluating their impact on polyphenol levels and sensory characteristics. The laboratory and pilot brewhouse trial results revealed a significant increase in the total polyphenol content when 0.6 % grape seeds were added during the boiling process. Specifically, the total polyphenol value doubled, reaching up to 500 mg/l compared to the 250 mg/l found in classical pilsner-type beer. The study indicates that grape seed addition is significantly more effective than grape skin addition under the same conditions, yielding around 1.5 times or more polyphenols. Sensory evaluations revealed a preference for beers supplemented with white grape seeds compared to red grape seeds, providing a unique taste experience with a pleasant grape aroma. Moreover, beers with grape seed additions exhibited elevated levels of specific polyphenolic compounds, particularly catechin and epicatechin. Additionally, the antioxidant capacity of the beer slightly increased with grape seed incorporation and colloidal stability was not negatively affected. [ABSTRACT FROM AUTHOR]

The study was conducted to study the sustainability and enhanced nutrition gains obtained from incorporating grape skin powder (GSP) extracted from both Fetească Neagră and Rară Neagră grape varieties into yogurt. Grape skins are major leftovers from wineries, having high amounts of phenolic compounds and dietary fiber responsible for their ability to improve the characteristics of food. The research aimed to evaluate the effect of GSP addition at varying concentrations (0.5%, 1.0%, and 1.5%) on the yogurt’s physicochemical properties, antioxidant activity, color parameters, and sensory attributes. Analysis revealed that both Fetească Neagră and Rară Neagră GSP increased the total phenolic content and antioxidant activity; however, Fetească Neagră showed greater improvements, with TPC reaching 1.52 mg GAE/100 g and DPPH inhibition up to 26.63%. Although slightly lower, TPC rose to 1.43 mg GAE/100 g and DPPH inhibition increased to 18.93% with Rară Neagră enhancing these parameters conversely. Color changes were observed in fortified yogurts where lightness decreased (L*) and redness increased (a*) due to the pH-dependent anthocyanin stability. Syneresis, indicative of yogurt’s water-holding capacity, was reduced at higher concentrations of GSP from both varieties, suggesting improved textural integrity. Sensory evaluation indicated that consumers generally favored yogurts with lower concentrations of GSP. Yogurts fortified with Fetească Neagră GSP received higher overall preference, while those with Rară Neagră GSP were also well-received for their distinct flavor profiles when used at suitable levels. These results show that GSP from both types of grapes improves the nutritional value of yogurt and complies with the principles of sustainable food production through reutilizing agro-industrial waste.

The reusability of by-products in the food industry is consistent with sustainable and greener production; therefore, the aim of this paper was to evaluate the applicability of multiple linear regression (MLR), piecewise linear regression (PLR) and artificial neural network models (ANN) to the prediction of grape-skin compost's physicochemical properties (moisture, dry matter, organic matter, ash content, carbon content, nitrogen content, C/N ratio, total colour change of compost samples, pH, conductivity, total dissolved solids and total colour change of compost extract samples) during in-vessel composting based on the initial composting conditions (air-flow rate, moisture content and day of sampling). Based on the coefficient of determination for prediction, the adjusted coefficient of determination for calibration, the root-mean-square error of prediction (RMSEP), the standard error of prediction (SEP), the ratio of prediction to deviation (RPD) and the ratio of the error range (RER), it can be concluded that all developed MLR and PLR models are acceptable for process screening. Furthermore, the ANN model developed for predicting moisture and dry-matter content can be used for quality control (RER >11). The obtained results show the great potential of multivariate modelling for analysis of the physicochemical properties of compost during composting, confirming the high applicability of modelling in greener production processes. [ABSTRACT FROM AUTHOR]

This study examines the potential of adding grape skins to red ceramics to evaluate its effect on the physical and mechanical properties of the clayey body. Five compositions were prepared with different percentages of biomass incorporation: 0%, 2.5%, 5%, 7.5%, and 10%. The specimens were conformed using vacuum extrusion in a laboratory extruder, with dimensions of 120 mm in length and a straight section of 30 × 15 mm. After drying, the pieces were sintered in a laboratory muffle furnace at 700 °C, 800 °C, 900 °C and 1000 °C. Chemical, mineralogical, thermal, physical, morphological, and microscopy tests were conducted on the clayey raw materials. An acceptable formulation was achieved by incorporating up to 5% biomass, fired at 900 °C. For water absorption, the incorporation of up to 5% of biomass fired at 700 °C satisfies the normative limits to produce structural blocks and sealing blocks. From 900 °C onwards, it meets the parameter intended for making roof tiles. The linear shrinkage of the pieces fired up to 900 °C is slightly altered by the incorporation of up to 5% of biomass fired under 800 °C are below 2%. The bending strength, at 700 °C there was an increase in mechanical strength directly proportional to the increase in biomass. However, at 800 and 900 °C, there was a gradual decrease in the bending strength. In turn, at 1000 °C, there was a sudden reduction in bending strenght for all formulations with biomass incorporation.

Due to global warming and the effects associated with it, the wine industry is facing important challenges during the winemaking process and the production of high-quality wines. In this study, mistelas and naturally sweet wines were produced with the 'Pedro Ximénez' grapevine cultivar, overripened by sun drying and fermented with and without the presence of grape skins. Some oenological parameters related to alcoholic fermentation and low-molecular-weight polyphenols and furans were considered. Naturally sweet wines with skins presence showed a higher value of viable biomass than those with grape skins absence. However, in terms of density and ethanol production, sweet wines with grape skins absence presented lower and higher values, respectively, than the other elaborations. No significant differences in the organic acids and low-molecular-weight polyphenols and furans contents, with respect to the presence or absence of grape skins, were observed. In this sense, this research proves that the production of sweet wines from sun-dried grapes with the presence/absence of grape skins during alcoholic fermentation could be a possible choice in areas where agro-climatic conditions make it possible. [ABSTRACT FROM AUTHOR]

Wine pomace, also mentioned as grape pomace (GP), is a byproduct of the wine industry, containing about 50% grape skins, 25% grape seeds and 25% stems. These wastes are of great value and great potential as a source of biologically active compounds. This opens up new prospects for the rational use of GP in the food industry. It is no coincidence that numerous new technologies for processing these byproducts have recently emerged to create a wide range of diverse new food products by enriching traditional foods with antioxidants, dietary fiber and mineral compounds. The most popular GP processing products are extracts and powders. Powders do not require special storage conditions, and they are highly adaptable, mixing well with other types of food raw materials, especially loose ones. Therefore, they are widely used in such products as bread, cookies, pasta, muffins, etc. Grape powders improve the structure of the dough, slow down the oxidation of fats, for example, in cookies, and increase the nutritional value of flour products. Finally, we will discuss these perspectives on the use of grape pomace as an ingredient in the formulation of flour-containing food products. [ABSTRACT FROM AUTHOR]

Panettones enriched with bioactive compound powder produced from Shiraz grape by-product (Vitis vinifera L.) and arrowroot starch (Maranta arundinaceae L.) were developed and characterized. Three were made with the partial replacement of wheat flour by bioactive compound powder in concentrations of 10%, 15%, and 20%, and one was traditionally made. These products were characterized for physicochemical parameters, technological properties, and bioactive properties. The panettones produced had a violet/bluish coloration, probably because of the phenolic compounds present in the grape skin. In the analysis of the physicochemical characteristics, the formulations EP10%, EP15%, and EP20% did not differ statistically from the traditional formulation in terms of moisture content, lipids, proteins and water activity. The last one is an important point observed, because this factor can contribute to the control of water migration of multicomponent products and microbiological activity, contributing to the longer shelf life of the product. The formulations with 15% and 20% bioactive compound powder presented higher levels of ash (%), with 1.64 and 1.81, respectively. The pH presented results that can confer a positive effect on the softening of the kernel, as well as a protective effect from the microbiological point of view. Besides, color intensity, and flavonoid (>1.5 mg QE.g−1) and anthocyanins (>1.2 mg.g−1) content increased with increases in the concentrations of the powdered compound, especially in the EP20% formulation, indicating that panettones may present a potential antioxidant capacity due to the increase in bioactive compounds.Therefore, panettones presented adequate appearances, heights, and texture profiles and can be considered as a product with good nutritional, technological, and functional qualities, and the bioactive compound powder represents a green alternative to synthetic colorants in foodstuffs.

Lipids are a diverse group of organic compounds that serve essential roles due to their biological functions for all prokaryotic and eukaryotic organisms. Despite the fundamental role of lipid class in plants, there is still a relatively low level of knowledge regarding the composition of grape lipids. This research represents the first investigation into the lipids of the Croatian grape variety 'Maraština' (Vitis vinifera L.), employing a targeted approach and the UHPLC-MS/MS method to conduct a comprehensive analysis of the lipid profile of grape skins. The study investigated the profile of free fatty acids, glycerolipids, glycerophospholipids, triterpenoids, sphingolipids, and free fatty acid esters in eleven vineyards located along the cultivation area of 'Maraština' variety (Dalmatia, Croatia). Grape skins from vineyards that were exposed to more sunlight and higher daily temperature during the vegetation period mainly resulted in a richer profile of free fatty acids. Among lipids, 'Maraština' grape skins were characterized mainly by a triterpenoid compound; oleanolic acid (249.49 µg/g of FW), and free fatty acids, especially palmitic acid C16:0 (26.09 µg/g of FW), and lignoceric acid C24:0 (12.40 µg/g of FW). Hierarchical clustering analysis represented valuable insights into the diversity of lipids in 'Maraština' grape skin. [ABSTRACT FROM AUTHOR]

[Display omitted] • A one-step leaching process for spent LiCoO 2 based on the mechanochemical method. • The new application of grape skins promotes the leaching of spent LiCoO 2. • Effect of mechanical activation on the interfacial reaction of spent LiCoO 2. • The mechanism of mechanochemical leaching was analyzed by BET, PSD, XRD, and XPS. A one-step system based on mechanochemical activation and the use of grape skins (GS) was proposed to recover metals from lithium-ion batteries (LIBs) cathode waste. The effects of the ball-milling (BM) speed, BM time, and quantity of added GS on the metal leaching rate were explored. The spent lithium cobalt oxide (LCO) and its leaching residue before and after mechanochemistry were characterized by SEM, BET, PSD, XRD, FT-IR, and XPS analysis. Our study shows that mechanochemistry promotes the leaching efficiency of metals from LIBs battery cathode waste by changing the cathode material properties (that is, reducing the LCO particle size (12.126 μm ∼ 0.0928 μm), increasing the specific surface area (0.123 m2/g ∼ 15.957 m2/g), enhancing the hydrophilicity and surface free energy (57.44 mN/m2 ∼ 66.18 mN/m2), promoting the generation of mesoporous structures, refining grains, disrupting the crystal structure, and increasing the microscopic strain, while deflecting the binding energy of the metal ions). A green, efficient and environmentally friendly process for the harmless and resource-friendly treatment of spent LIBs has been developed in this study. [ABSTRACT FROM AUTHOR]

The reusability of by-products in the food industry is consistent with sustainable and greener production; therefore, the aim of this paper was to evaluate the applicability of multiple linear regression (MLR), piecewise linear regression (PLR) and artificial neural network models (ANN) to the prediction of grape-skin compost’s physicochemical properties (moisture, dry matter, organic matter, ash content, carbon content, nitrogen content, C/N ratio, total colour change of compost samples, pH, conductivity, total dissolved solids and total colour change of compost extract samples) during in-vessel composting based on the initial composting conditions (air-flow rate, moisture content and day of sampling). Based on the coefficient of determination for prediction, the adjusted coefficient of determination for calibration, the root-mean-square error of prediction (RMSEP), the standard error of prediction (SEP), the ratio of prediction to deviation (RPD) and the ratio of the error range (RER), it can be concluded that all developed MLR and PLR models are acceptable for process screening. Furthermore, the ANN model developed for predicting moisture and dry-matter content can be used for quality control (RER >11). The obtained results show the great potential of multivariate modelling for analysis of the physicochemical properties of compost during composting, confirming the high applicability of modelling in greener production processes.

To explore the in vivo hypolipidemic effect of the compound composition of crataegus, ume, grape skin, wolfberry and mulberry. There were 50 SPF-grade healthy male SD rats, 10 rats were given maintenance feed as a blank control group, and 40 rats were given model feed as a model group. After the model group was given the model feed for 2 weeks, the 40 animals in the model group were randomly divided into 4 groups according to the TC level, namely high, medium and low dose groups (1.5, 0.5, 0.25g/kg·BW) and the model control group. After grouping, the three dose groups were given the test sample orally at 10mL/kg·BW every day, and the blank control group and the model control group were given the same volume of distilled water at the same time. After continuous intragastric administration for 30 days, serum total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) were measured. The liver coefficient, hepatic lipase (HL), and lipoprotein lipase (LPL) activity levels were measured, and the degree of hepatic steatosis was observed by HE staining. The results showed that compared with the model control group, the levels of serum TC, TG and LDL-C in the high-dose and middle-dose groups significantly decreased (P

Wine pomace, also mentioned as grape pomace (GP), is a byproduct of the wine industry, containing about 50% grape skins, 25% grape seeds and 25% stems. These wastes are of great value and great potential as a source of biologically active compounds. This opens up new prospects for the rational use of GP in the food industry. It is no coincidence that numerous new technologies for processing these byproducts have recently emerged to create a wide range of diverse new food products by enriching traditional foods with antioxidants, dietary fiber and mineral compounds. The most popular GP processing products are extracts and powders. Powders do not require special storage conditions, and they are highly adaptable, mixing well with other types of food raw materials, especially loose ones. Therefore, they are widely used in such products as bread, cookies, pasta, muffins, etc. Grape powders improve the structure of the dough, slow down the oxidation of fats, for example, in cookies, and increase the nutritional value of flour products. Finally, we will discuss these perspectives on the use of grape pomace as an ingredient in the formulation of flour-containing food products.

Due to global warming and the effects associated with it, the wine industry is facing important challenges during the winemaking process and the production of high-quality wines. In this study, mistelas and naturally sweet wines were produced with the ‘Pedro Ximénez’ grapevine cultivar, overripened by sun drying and fermented with and without the presence of grape skins. Some oenological parameters related to alcoholic fermentation and low-molecular-weight polyphenols and furans were considered. Naturally sweet wines with skins presence showed a higher value of viable biomass than those with grape skins absence. However, in terms of density and ethanol production, sweet wines with grape skins absence presented lower and higher values, respectively, than the other elaborations. No significant differences in the organic acids and low-molecular-weight polyphenols and furans contents, with respect to the presence or absence of grape skins, were observed. In this sense, this research proves that the production of sweet wines from sun-dried grapes with the presence/absence of grape skins during alcoholic fermentation could be a possible choice in areas where agro-climatic conditions make it possible.

Consumer interest in health-promoting foods has prompted researchers to use wine by-products to increase food's functional characteristics. This research aims to examine the skin bioactivities of Samos white (small-berry Muscat) and red (Augustiatis) grape skin extracts (M-GSkE, A-GSkE). Total phenolic content, antiradical activity, the inhibition of plasma oxidation and platelet aggregation, and the phenolic profile were examined. A-GSkE and M-GSkE showed high total phenolics (1.19 ± 0.13 vs. 2.12 ± 0.23 mM GAE), antiradical activity (7.7 ± 0.4 vs. 6.6 ± 0.3 μM GAE for ABTS; 31.12 ± 0.8 vs. 26.4 ± 1.0 μM GAE for DPPH), resistance to plasma oxidation (5.7 ± 0.4 vs. 1.1 ± 0.2 μM GAE), and antithrombotic activity (19.7 ± 0.1 vs. 26.6 ± 0.2 μM GAE). Ferulic (41.3 ± 0.1 > 13.2 ± 0.1 μg/g DM), vanillic (26.3 ± 1.7 > 12.2 ± 1.2 μg/g DM), and gallic (16.6 ± 0.1 > 8.4 ± 2.9 μg/g DM) acids along with ε-viniferin (3.6 ± 0.4 > 2.8 ± 0.3 μg/g DM) were identified in higher content in A-GSkE. Catechin (59.8 ± 1.5 μg/g DM), chlorogenic acid (43.8 ± 0.9 μg/g DM), and resveratrol (0.83 ± 0.13 μg/g DM) were identified only in M-GSkE, while caffeic acid 19.8 ± 0.4 μg/g DM) and daidzein (16.8 ± 0.1 μg/g DM) were identified only in A-GSkE. The specialized bioactivities researched in two previously unexplored Samos' wine grape skin extracts give them added value. The valorization of such by-products promises a sustainable future in the food sector of local communities and an improvement in local public health. [ABSTRACT FROM AUTHOR]

Polyphenols are organic compounds that can be found in food, especially in fruits, vegetables, and their products. It was shown that their presence significantly affects the properties of food products and that the consumption of food rich in phenolic compounds has a beneficial effect on human health. The subjects of this research were polyphenols: anthocyanins, flavonols, and flavan-3-ols in the skin of grapevine variety Regent. Polyphenols from grape skins were extracted via microwave-assisted extraction (MAE) and matrix solid-phase dispersion (MSPD) as unconventional and green techniques. Therefore, the main aim of this work was to optimize the conditions for the extraction of polyphenolic compounds from grape skin using MAE and MSPD. The extracts were analyzed using high-performance liquid chromatography with a diode array detector and fluorescence detector. Analyses showed that MAE was a very effective method for extracting polyphenolic compounds from grape skin with 10 mL of 60% ethanol for 5 min at 40 °C. The best results for the MSPD extraction of polyphenolic compounds from grape skin were obtained with phenyl as an MSPD sorbent with 10 mL of acetonitrile:water 50:50 v/v as an elution solvent. This scientific research can be used for the better use of grapes as a basis for obtaining flavonoids for commercial purposes. [ABSTRACT FROM AUTHOR]

Lipids are a diverse group of organic compounds that serve essential roles due to their biological functions for all prokaryotic and eukaryotic organisms. Despite the fundamental role of lipid class in plants, there is still a relatively low level of knowledge regarding the composition of grape lipids. This research represents the first investigation into the lipids of the Croatian grape variety ‘Maraština’ (Vitis vinifera L.), employing a targeted approach and the UHPLC-MS/MS method to conduct a comprehensive analysis of the lipid profile of grape skins. The study investigated the profile of free fatty acids, glycerolipids, glycerophospholipids, triterpenoids, sphingolipids, and free fatty acid esters in eleven vineyards located along the cultivation area of ‘Maraština’ variety (Dalmatia, Croatia). Grape skins from vineyards that were exposed to more sunlight and higher daily temperature during the vegetation period mainly resulted in a richer profile of free fatty acids. Among lipids, ‘Maraština’ grape skins were characterized mainly by a triterpenoid compound; oleanolic acid (249.49 µg/g of FW), and free fatty acids, especially palmitic acid C16:0 (26.09 µg/g of FW), and lignoceric acid C24:0 (12.40 µg/g of FW). Hierarchical clustering analysis represented valuable insights into the diversity of lipids in ‘Maraština’ grape skin.

Grape pomace powder added to food is a trend in current literature, although there is still little data on consumers’ attitudes towards this ingredient. Thus, this study aimed to evaluate consumers’ behavior regarding the consumption of grape pomace-based products. To achieve this objective, 315 volunteers were recruited online in order to investigate whether grape residue powder added to a cake affects the initial acceptance of the product using a 7-point hedonic scale. By employing the theory of planned behavior (TPB), the main drivers of intention to purchase products with this by-product were evaluated with 5 hypotheses (attitude, health and environmental concerns, personal beliefs, and previous knowledge) with a 7-ponit Likert scale. Our findings showed that informing consumers of the presence of grape pomace powder in food formulation positively impacted the acceptance of the product. The TPB approach indicated that attitude, environmental concern, knowledge, and personal beliefs are key drivers of grape pomace powder consumption. The hypothesis that health concerns play a significant role in consumer intention of purchasing was statistically rejected. The results support the food industry marketing sector to explore the sustainable aspect of products added with food by-products with possible good acceptance.

The resveratrol (3,5,4'-trihydroxystilbene) is a phytoalexin belonging to the class of polyphenolic compounds called stilbene, produced in response to stress factors by a wide variety of plants, including Vitis vinifera. This study presents the high performance liquid chromatography (HPLC) system detection of the forms of resveratrol (cis- and trans-) isomers in the skin of the Cabernet Sauvignon and Merlot black grapes from the Șimnicu de Sus wine grape-growing area during the 2019 and 2020 period. The resveratrol isomers were determined throughout the period of maturation of the studied varieties (15 July to 5 September) of the grape berries skin samples. The resveratrol content of grapes skin decreased constantly from the green phase until the full maturity for both varieties, reaching zero for cis-resveratrol (0.043mg/L for Cabernet Sauvignon variety in 2020) in the matured fruits. [ABSTRACT FROM AUTHOR]

Summary: Grape is a popular fruit crop that generates about one‐fourth of total weight as pomace during winemaking and commercial juice production. However, a significant amount of resveratrol and related stilbenes is present in grape skin, and their effective isolation enables the production of functional foods. Herein, an improved analytical method for the determination of trans‐resveratrol and related stilbenes in grape skin waste by QuEChERS method coupled with a high‐performance liquid chromatograph‐photodiode array detector‐mass spectrometer was developed. By employing a Gemini C18 column and a mobile phase of acetic acid in water (pH 3.6) and acetonitrile, a total of five resveratrol and related stilbenes could be separated within 15 min with a flow rate of 0.8 mL min−1 and detection wavelength at 306 nm. The optimised QuEChERS conditions were 10 mL of acetonitrile, 1 mL of grape skin extract and 900 mg of magnesium sulphate plus 25 mg of primary secondary amine. Principal component analysis by two principal components (74.18%, 25.82%) could well describe the trans‐resveratrol recovery at different QuEChERS conditions. A mean recovery, as well as coefficient of variation (CV, %) of repeatability and intermediate precision, ranged from 96.6% to 104.4%, 1.96% to 3.10% and 1.68% to 4.27%, respectively, conforming to the regulation set by Taiwan Food and Drug Administration. Quantitation revealed cis‐piceid to be present in largest amount (2.616 μg mL−1), followed by trans‐piceid (1.027 μg mL−1), trans‐resveratrol (0.967 μg mL−1), ε‐viniferin (0.660 μg mL−1) and cis‐resveratrol (0.183 μg mL−1) in grape skin extract, with their corresponding contents in dried grape skin being 4.185, 1.643, 1.539, 1.056 and 0.293 μg g−1, respectively. [ABSTRACT FROM AUTHOR]

This work investigated the structural, biochemical, and molecular characteristics of grape skin cell wall during ripening, related to susceptibility to Botrytis cinerea. The comparative study between the two main grape cultivars in Champagne region, Pinot noir and Chardonnay, quantified: (1) the maturity and physical profile of grape skin; (2) the morphological characteristics; (3) soluble pectic polysaccharides located in grape skin cell walls; and (4) the gene expression of the two main degrading enzymes (VvPME1 and VvPG1) and PME activity. During the maturation period, the grape skins of the two cultivars appear different in their structure and composition. Chardonnay is characterized by higher relative humidity (RH) and level of VvPG1 expression, lower disease incidence and penetrometry values, and thicker cell walls than Pinot noir skins. Thus, the cell wall composition is sufficiently different between grape varieties from the same area to allow their discrimination and could be used to better manage the harvest date. [ABSTRACT FROM AUTHOR]

In winemaking, large amounts of grape skin (GS) are generated as by-products, which contain not only abundant degradable cellulose, hemicellulose, and pectin but various functional polyphenols. In contrast to most studies focusing on the utilization of extractives, the current study investigates the use of ultrasonicated grape skin (UGS) containing all components to develop a multifunctional composite film. Owing to dissociation during ultrasonication, all GS components were well dispersed in water to obtain the UGS suspension. Transmission electron microscopy (TEM) indicated that the celluloses were successfully transformed into cellulose nanofibers, which can improve the uniformity of the composite film. Subsequently, biodegradable and multifunctional composite films were fabricated by combining the UGS and polyvinyl alcohol (PVA). The UGS and PVA formed a good interface, which was attributable to strong hydrogen bonds, and the resulting films exhibited excellent thermal stability and moisture-sensitive mechanical properties. The polyphenols in the UGS suspension endowed the composite film with multiple functions, including pH-responsive color change, excellent antioxidant activity, ultraviolet shielding, and antimicrobial properties. The use of PVA enhanced the flexibility, strength, and elongation of the UGS film. Therefore, the easily prepared, tailored, multifunctional, and biodegradable UGS/PVA composite film exhibits superior potential for application in agriculture, cosmetics, and healthcare. [ABSTRACT FROM AUTHOR]

Polyphenols are organic compounds that can be found in food, especially in fruits, vegetables, and their products. It was shown that their presence significantly affects the properties of food products and that the consumption of food rich in phenolic compounds has a beneficial effect on human health. The subjects of this research were polyphenols: anthocyanins, flavonols, and flavan-3-ols in the skin of grapevine variety Regent. Polyphenols from grape skins were extracted via microwave-assisted extraction (MAE) and matrix solid-phase dispersion (MSPD) as unconventional and green techniques. Therefore, the main aim of this work was to optimize the conditions for the extraction of polyphenolic compounds from grape skin using MAE and MSPD. The extracts were analyzed using high-performance liquid chromatography with a diode array detector and fluorescence detector. Analyses showed that MAE was a very effective method for extracting polyphenolic compounds from grape skin with 10 mL of 60% ethanol for 5 min at 40 °C. The best results for the MSPD extraction of polyphenolic compounds from grape skin were obtained with phenyl as an MSPD sorbent with 10 mL of acetonitrile:water 50:50 v/v as an elution solvent. This scientific research can be used for the better use of grapes as a basis for obtaining flavonoids for commercial purposes.

Grapes are known to synthesize resveratrol, a stilbene phytoalexin, associated with cancer chemopreventive activity and cardioprotection. The effect of ultrasound (US) abiotic elicitor treatments on trans-resveratrol content in Kalecik Karası fresh and frozen grape skin was determined. D-optimal point change design was used under RSM for the experimental design of US treatment. The optimization was solved with the help of the Pareto areas and the optimal input variable values were determined by the desirability function with fuzzy similar perceivable ratio method. The optimum conditions of US treatment for fresh grape skin were determined as follows: incubation time—24 h, US application method-(P01), US frequency—20 kHz, US treatment time—60 min and ultrasonic intensity (UI)—1.15 W cm−2. The trans-resveratrol content (0.18 ± 0.01 mg/g) in the untreated grape skin significantly increased with optimum US treatment (3.58 ± 0.08 mg/g), increasing production to 19.9 times. [ABSTRACT FROM AUTHOR]

In this study, seeds, skins and stems of the red wine grape varieties Boğazkere, Cabernet Sauvignon, Merlot, Nero d’Avola, Sangiovese and Syrah grown in Turkey were analysed for their phenolic compounds. The highest total phenolic compound and DPPH were found in the stem of Boğazkere respectively as 62550 mg GAE/kg dw and 614 µmol/g dw; the highest ABTS•+, (+)-catechin, (–)-epicatechin were detected in the seed of Nero d’Avola respectively as 617 µmol trolox/g dw, 8650 mg/kg and 1902 mg/kg dw; the highest total anthocyanin and rutin were measured in the skin of Boğazkere respectively as 143.52 mg/kg dw and 9692 mg/kg dw; the highest quercetin was found in the seed of Boğazkere as 49.21 mg/kg dw and the highest trans-resveratrol was measured in the stem of Syrah as 61.56 mg/kg dw.

In this study, seeds, skins and stems of the red wine grape varieties Boğazkere, Cabernet Sauvignon, Merlot, Nero d'Avola, Sangiovese and Syrah grown in Turkey were analysed for their phenolic compounds. The highest total phenolic compound and DPPH were found in the stem of Boğazkere respectively as 62550 mg GAE/kg dw and 614 µmol/g dw; the highest ABTS•+, (+)-catechin, (-)-epicatechin were detected in the seed of Nero d'Avola respectively as 617 µmol trolox/g dw, 8650 mg/kg and 1902 mg/kg dw; the highest total anthocyanin and rutin were measured in the skin of Boğazkere respectively as 143.52 mg/kg dw and 9692 mg/kg dw; the highest quercetin was found in the seed of Boğazkere as 49.21 mg/kg dw and the highest trans-resveratrol was measured in the stem of Syrah as 61.56 mg/kg dw. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cells (DSSCs), a powerful system to convert solar energy into electrical energy, suffer from the high cost of the Pt counter electrode and photosensitizer. In this study, the dual application of waste grape skin is realized by employing the grape skin and its extract as the carbon source of the carbon-based counter electrode and photosensitizer, respectively. The ultraviolet–visible absorption and Fourier transform infrared spectroscopy verify the strong binding between the dye molecules (anthocyanins) in the extract and the TiO2 nanostructure on the photoanode, contributing to a high open-circuit voltage (VOC) value of 0.48 V for the assembled DSSC device. Moreover, the waste grape skin was subjected to pyrolysis and KOH activation and the resultant KOH-activated grape skin-derived carbon (KA-GSDC) possesses a large surface area (620.79 m2 g−1) and hierarchical porous structure, leading to a high short circuit current density (JSC) value of 1.52 mA cm−2. Additionally, the electrochemical impedance spectroscopy reveals the efficient electron transfer between the electrocatalyst and the redox couples and the slow recombination of electrolytic cations and the photo-induced electrons in the conduction band of TiO2. These merits endow the DSSC with a high photovoltaic efficiency of 0.48%, which is 33% higher than that of a common Pt-based DSSC (0.36%). The efficiency is also competitive, compared with some congeneric DSSCs based on other natural dyes and Pt counter electrode. The result confirms the feasibility of achieving the high-value application of waste grape skin in DSSCs.

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This work is designed to reveal the varietal characteristics of terpene glycosides (TGs) in ripe Meili grapes. TGs in grape skins were extracted using three ethanol/water solvents, purified and enriched using XAD-2 resin, and collected using ethyl acetate/methanol (9:1, v/v). The aglycones released from TGs were analyzed by headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS). TGs were detected by ultra-high-performance liquid chromatography–quadrupole time-of-flight mass spectrometry (UPLC–Q-TOF-MS), the identification was conducted by both mass fragmentation and TGs database, and the quantitation was realized by octyl-β-d-glucopyranoside. Results showed that 19 aglycones for TGs were found in grape skins by GC–MS, which was mainly monoterpenol with molecular formula C10H18O (linalool, l-α-terpineol, geraniol, nerol, etc.), C10H20O (citronellol), and C10H18O2 (pyranoid/furanoid linalool oxide, etc.). C10H18O aglycones may be the most stable ones, and linalool was the most abundant, occupying 44.88–47.99% of the total content. Forty-nine TGs were detected by UPLC–Q-TOF-MS. Monoterpenol pentosyl-glucosides were the main TGs, especially C10H18O2 pentosyl-glucoside, which constituted 51.94–52.72% of the total concentration. [ABSTRACT FROM AUTHOR]

BACKGROUND: There is concern that DNA damage may occur in skin cells due to UV irradiation. In this study, we investigated whether extracts from grape skin, which should be discarded, can suppress DNA damage caused by UV radiation. OBJECTIVE: This study aims to investigate the effectivity of GSE in diminishing UV-induced cytotoxicity in normal human epidermal keratinocytes (NHEK) cells. METHODS: The polyphenol content in GSE was carried out using the HPLC instrument. UV dose was selected by measurement of cell viability, and ELISA results of DNA photoproduct. Optimum extracts condition of grape skin selected by DNA photoproduct content as well as at this condition; Bax/Bcl-2 ratio and cytochrome c gene expressions were evaluated by Western blotting. RESULTS: In this study, we confirmed that GSE protect against DNA damage-induced cell death. Condition for 80% EtOH for 24 h at 60 °C was suitable to extract for grape skin. Red grape skin (Zweigelt) was more effective than white grape skin (Niagara) in preventing (before irradiation) and repairing (after irradiation). UV-induced upregulation of Bax/Bcl-2 ratio and cytochrome c expression were reduced by GSE treatment. CONCLUSIONS: The study demonstrated a promising potential of GSEs in skin therapeutics application. [ABSTRACT FROM AUTHOR]

Featured Application: The interest for green and sustainable utilization of industry by-products, such as grape pomace, is increasing rapidly, and is in line with the recognition of the necessity to protect the environment. Our investigation, mainly focused on natural deep eutectic solvents (NADES), could contribute to further exploitation of these solvents for extraction of biologically active compounds from different plants. Finally, the present study provides profound understanding of antioxidant activity and polyphenol composition of grape seeds and skin, highlighting the quality of some insufficiently investigated Serbian autochthonous varieties and suggesting their broaden use. In the past few years, research efforts have focused on plant exploitation for deriving some valuable compounds. Extraction has been usually performed using petrochemical and volatile organic solvents, but nowadays, increased recognition of environmental pollution has prompted the utilization of green solvents as alternatives. Therefore, the aim of the present study was to exploit deep eutectic solvents (DES) (choline chloride: citric acid and choline chloride: glucose) as solvents for extracting valuable phenolic antioxidants from grapes. Investigation was conducted on ten grape varieties, observing seeds and skin as different matrix. Total polyphenol content (TPC) was determined by Folin-Ciocalteu spectrophotometric microassay. Antioxidant activity was investigated using four different tests and results were combined in a unique Antioxidant Composite Index (ACI) to reveal comprehensive information about this biological activity. Polyphenol compounds were identified and quantified with the aim of HPLC-diode array detector (DAD). Overall results support that DES (particularly choline chloride: citric acid) were comparable to conventional solvent, and in most cases even outperformed acidified aqueous ethanol (concerning extraction efficiency and antioxidant activity). Regardless of varietal distinctions, grape seeds have higher antioxidant capacity compared to grape skin, and such findings are according to their phenol compound concentrations. [ABSTRACT FROM AUTHOR]

The effects of including extruded linseed in pig diets supplemented with either polyphenol-rich red grape skin extract (3 g kg-1) or synthetic antioxidants (200 mg kg-1 α- tocopheryl acetate plus 0.21 mg kg-1 of selenium) on shelf-life of pork stored in modified atmosphere packaging (MAP) at different oxygen concentrations (0 and 70%) were evaluated. Linseed reduced n-6/n-3 fatty acid ratio in lipids of backfat and loin. Color parameters, pH, weight losse, oxidative stability (TBARS), did not differ between antioxidants neither in raw, nor in cooked, nor in stored muscle. High oxygen concentration in MAP increased TBARS and ΔE, yielding redder meat. [ABSTRACT FROM AUTHOR]

Resveratrol, a phenolic compound possessing vital biological activities such as anti-cancer, is present abundantly in grape skin, a waste produced during the processing of grape juice. The objectives of this study were to prepare resveratrol-gold nanoparticles and a resveratrol nanoemulsion from grape skin and study their inhibition effects on pancreatic cancer cells BxPC-3. The spherical-shaped citrate gold nanoparticles (GNPs) and resveratrol-gold nanoparticles (R-GNPs) were, respectively, prepared with a surface plasmon resonance peak at 528 and 538 nm, mean particle size of 20.8 and 11.9 nm, and zeta-potential at −32.7 and −66.7 mV, by controlling an appropriate concentration of citrate/resveratrol and gold chloride as well as stirring time and temperature. The resveratrol nanoemulsion, composed of soybean oil, Tween 80, and sucrose fatty acid ester in glycerol and water, possessed a high storage stability with a mean particle size of 14.1 nm, zeta-potential of −49.7 mV, and encapsulation efficiency of 95.5%. An antiproliferation study revealed that both R-GNPs and resveratrol nanoemulsion could effectively inhibit the growth of pancreatic cancer cells BxPC-3, with the latter showing a higher inhibition effect. Western blot analysis implied that both can down-regulate expressions of cyclin A, cyclin B, CDK1, and CDK2 and up-regulate expressions of p53 and p21, accompanied by enhancing cytochrome C expression, decreasing BcL-2 expression, increasing Bax expression, and leading to the elevation of caspase-8, caspase-9, and caspase-3 activities for cell apoptosis execution. Future research is needed to study the inhibition of pancreatic tumors in vivo by R-GNPs and resveratrol nanoemulsions.

This work investigated the structural, biochemical, and molecular characteristics of grape skin cell wall during ripening, related to susceptibility to Botrytis cinerea. The comparative study between the two main grape cultivars in Champagne region, Pinot noir and Chardonnay, quantified: (1) the maturity and physical profile of grape skin; (2) the morphological characteristics; (3) soluble pectic polysaccharides located in grape skin cell walls; and (4) the gene expression of the two main degrading enzymes (VvPME1 and VvPG1) and PME activity. During the maturation period, the grape skins of the two cultivars appear different in their structure and composition. Chardonnay is characterized by higher relative humidity (RH) and level of VvPG1 expression, lower disease incidence and penetrometry values, and thicker cell walls than Pinot noir skins. Thus, the cell wall composition is sufficiently different between grape varieties from the same area to allow their discrimination and could be used to better manage the harvest date.

In this study, eight different types of imidazolium-based ionic liquids (ILs) were applied as new solvents in the extraction of flavonoids from grape skin, and compared to the conventional organic solvent extraction that was not reported earlier. The structure of anions, cations and concentration of ILs significantly affected extraction yields. The highest mass fractions of proanthocyanidins and anthocyanins were obtained with 2.5 mol/L of 1-butyl-3-methylimidazolium bromide [C4mim][Br] and 2.5 mol/L of 1-ethyl-3-methylimidazolium bromide [C2mim][Br], respectively. The studied ILs provided an excellent preliminary result in the extraction of anthocyanins. Significantly higher mass fractions of total and all free anthocyanins were extracted with 2.5 mol/L of [C2mim][Br] and 2.5 mol/L of 1-methylimidazolium hydrogen sulfate [mim][HSO4] than with conventional solvent with the exception of anthocyanin-3-O-acetylmonoglucosides in the latter. On the other hand, 2.5 mol/L of [C4mim][Br] and 2.5 mol/L of 1-(4-sulfobutyl)-3-methylimidazolium hydrogen sulfate [sC4mim][HSO4] showed significantly higher selectivity towards anthocyanin-3-O-acetylmonoglucosides and anthocyanin-3-(6-O-p-coumaroyl)monoglucosides.

Grape pomace is one of the most abundant solid by-products generated during winemaking. A lot of products, such as ethanol, tartrates, citric acid, grape seed oil, hydrocolloids, bioactive compounds and dietary fiber are recovered from grape pomace. Grape pomace represents a major interest in the field of fiber extraction, especially pectin, as an alternative source to conventional ones, such as apple pomace and citrus peels, from which pectin is obtained by acid extraction and precipitation using alcohols. Understanding the structural and functional components of grape pomace will significantly aid in developing efficient extraction of pectin from unconventional sources. In recent years, natural biodegradable polymers, like pectin has invoked a big interest due to versatile properties and diverse applications in food industry and other fields. Thus, pectin extraction from grape pomace could afford a new reason for the decrease of environmental pollution and waste generation. This paper briefly describes the structure and composition of grape pomace of different varieties for the utilization of grape pomace as a source of pectin in food industry.

Grape seeds (GS) and grape skins (GK) are natural sources of polyphenols with featured antioxidant capacity. An experiment was conducted to investigate the effect of these polyphenol sources in diets formulated to contain the same total extractable grape polyphenol content on growth performance, protein and extractable polyphenol digestibility, plasma and meat α- and γ-tocopherol and thigh meat oxidation in broiler chickens. Five experimental diets were formulated: control, control + vitamin E (200 mg/kg), 30 g/kg GS diet, 110 g/kg GK diet, GS + GK diet (a mixture of 24.4 g/kg GS and 13.1 g/kg GK designed to simulate a reconstituted grape pomace). Feeding chickens with 110 g/kg GK reduced (p < 0.001) daily weight gain, worsened (p < 0.001) feed conversion ratio, increased (p < 0.001) non-extractable polyphenol content in the ileum and in the excreta and decreased (p < 0.05) ileal protein digestibility. Regardless of the grape polyphenol source used, the inclusion of grape byproducts in the diets led to an increase of total extractable polyphenol contents in the ileum (p < 0.01) and the excreta (p < 0.001), which resulted (p < 0.001) in a decrease of extractable polyphenol digestibilities. Alpha- and gamma-tocopherol concentrations increased (p < 0.001) in plasma and in seven-day stored meat in birds fed the diet combining GS and GK with respect to the control group. As it happened with the vitamin E supplementation, feeding the combination of GS and GK also reduced (p < 0.001) the concentration of the lipid peroxidation marker (malondialdehyde) in the stored meat of chickens.

The antioxidant activity and the tocopherol and polyphenol contents of organic grapevines residue were analyzed after Soxhlet extraction of grape seeds and skin with ethanol and petroleum ether. The highest antioxidant activity was determined for the ethanol extract of the seeds and was 58.65 µM Trolox/mg, which was four times higher than for the ethanol extract of the skin at 14.24 µM Trolox/mg. It was comparable to that of the alpha-tocopherol (62.28 µM Trolox/mg) and butylated hydroxyanizol (69.55 µM Trolox/mg). A concentration of 29.5 µg/mL ethanol seed extract was needed to decrease the initial DPPH radical concentration by 50%. The high antioxidant activity was because of the high tocopherol (402.28 mg/kg) and total phenols contents (113.7 gallic acid equivalent (g/kg)) in the seeds. The dominant polyphenol in the ethanol seed extract was coumaric acid (10.97 g/kg). The dominant polyphenols in the ethanol skin extracts were rutin (6.79 g/kg), quercetin (3.75 g/kg), and catechin (3.99 g/kg), which can be used in functional foods to reduce risk factors for several human diseases. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effects of process conditions on the solid-liquid extraction of bioactive compounds from the Alicante Bouschet grape skin from the semi-arid region of Brazil. The influence of temperature (23-57 °C), ethanol concentration (16-84%) and citric acid concentration (0-4%) on the total phenolic content, monomeric anthocyanin content and on the antioxidant capacity of the extracts measured by oxygen radical absorbance capacity and cation radical scavenging activity (ABTS·+) methods was investigated. Ethanol concentration and temperature had a significant influence on total phenolic compounds extraction and antioxidant capacity while monomeric anthocyanins extraction was only affected by ethanol concentration. The conditions selected as the most adequate for the extraction were: temperature of 40 °C, 50% v/v ethanol and 2% m/v citric acid. [ABSTRACT FROM AUTHOR]

Considering the potential of applying grape skin extract (GSE) as functional ingredients in products that must be thermally processed, the aim of this study was to evaluate the stability of individual polyphenols in grape skin extracts submitted to heating at different temperatures. Polyphenolic compounds were extracted by applying 20% aqueous ethanol containing 1% acetic acid for 1 h at 50 °C on a magnetic stirrer. The obtained extract was divided into aliquots and submitted to heating at different temperatures for a various time. The content of individual phenolic compounds in all incubated extract was determined by the HPLC method. All studied compounds were very stable during heating at 40 °C. Among analyzed anthocyanins, diglucosides were more stable than corresponding monoglucosides. Gallocatechin and procyanidins B1 and B2 contents were decreased, while catechin and epicatechin contents were increased during thermal treatments. At both incubation temperature contents of caftaric and coutaric acid were decreased, while in the same time contents of caffeic and coumaric acids were raised which could be due to hydrolysis. A significant increase of gallic, protocatechuic, vanillic, and syringic acid contents was due to thermal degradation of delphinidin-3-O-glucoside, cyanidin-3-O-glucoside, peonidin-3-O-glucoside, and malvidin-3-O-glucoside, respectively. trans-Piceid showed high stability toward thermal treatments. [ABSTRACT FROM AUTHOR]

With the increasing needs of clean water supplies, the use of biomass wastes and residues for environmental remediation is essential for environmental sustainability. In this study, the residues from winery and citrus juice industries, namely grape skin and orange peel, respectively, were first converted to hydrochars by hydrothermal carbonization (HTC) and then a cationic dye (methylene blue) adsorption was studied on hydrochars. Hydrochars from both feedstocks were produced at three different temperatures (180, 220, and 250 °C) and a fixed residence time (1 h) to evaluate the hydrochar’s performance on the dye adsorption. The hydrochars were characterized in terms of their pH, pH at point of zero charge (pHPZC), surface functionalities, and surface area. A batch adsorption study of the dye was carried out with variable adsorbate concentration, pH, and temperature. Two adsorption isotherms namely Langmuir and Freundlich models were fitted at 4, 20, and 36 °C. The thermodynamic properties of adsorption (Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS)) were evaluated from the isotherms fittings. Results showed that the dye adsorption on both hydrochars was significant and followed Langmuir isotherm. The maximum adsorption capacity on citrus waste hydrochar was higher than the winery waste hydrochar at any corresponding HTC temperature. Although hydrochars showed the lowest surface area (46.16 ± 0.11 and 34.08 ± 1.23 m2/g for citrus and winery wastes, respectively) at 180 °C, their adsorption was the highest, owing to their maximum density of total oxygen functional groups (23.24 ± 0.22 and 32.69 ± 1.39 µmol/m2 for citrus and winery wastes, respectively), which decreased with the increase in HTC temperature. This research shows a sustainable route for the production of highly effective adsorbent materials at lower HTC temperatures from citrus and winery wastes.

In the past few years, research efforts have focused on plant exploitation for deriving some valuable compounds. Extraction has been usually performed using petrochemical and volatile organic solvents, but nowadays, increased recognition of environmental pollution has prompted the utilization of green solvents as alternatives. Therefore, the aim of the present study was to exploit deep eutectic solvents (DES) (choline chloride: citric acid and choline chloride: glucose) as solvents for extracting valuable phenolic antioxidants from grapes. Investigation was conducted on ten grape varieties, observing seeds and skin as different matrix. Total polyphenol content (TPC) was determined by Folin-Ciocalteu spectrophotometric microassay. Antioxidant activity was investigated using four different tests and results were combined in a unique Antioxidant Composite Index (ACI) to reveal comprehensive information about this biological activity. Polyphenol compounds were identified and quantified with the aim of HPLC-diode array detector (DAD). Overall results support that DES (particularly choline chloride: citric acid) were comparable to conventional solvent, and in most cases even outperformed acidified aqueous ethanol (concerning extraction efficiency and antioxidant activity). Regardless of varietal distinctions, grape seeds have higher antioxidant capacity compared to grape skin, and such findings are according to their phenol compound concentrations.

A bio-electronic tongue has been developed to evaluate the phenolic content of grape residues (seeds and skins) in a fast and easy way with industrial use in mind. A voltammetric electronic tongue has been designed based on carbon resin electrodes modified with tyrosinase combined with electron mediators. The presence of the phenoloxydase promotes the selectivity and specificity towards phenols. The results of multivariate analysis allowed discriminating seeds and skins according to their polyphenolic content. Partial least squares (PLS) has been used to establish regression models with parameters related to phenolic content measured by spectroscopic methods i.e., total poliphenol content (TPC) and Folin–Ciocalteu (FC) indexes. It has been shown that electronic tongue can be successfully used to predict parameters of interest with high correlation coefficients (higher than 0.99 in both calibration and prediction) and low residual errors. These values can even be improved using genetic algorithms for multivalent analysis. In this way, a fast and simple tool is available for the evaluation of these values. This advantage may be due to the fact that the electrochemical signals are directly related to the phenolic content.

Grape pomace is an agro-industrial by-product from the production of must (grape juice) by pressing whole grapes. In order to evaluate the seeds and skins of the grape pomace, it must first be dried and then separated in a screen machine. The drying of pomace is an important and necessary process for the optimum separation of seeds. The main purpose of this study was to determine the optimum drying process for obtaining high-quality grape seed oil. In this research, open air and solar energy drying methods were compared in terms of water activity, total bacterial and mold-yeast count, along with the chemical and fatty acid compositions of pressed grape residues. Oleic acid and linoleic acid contents ranged from 16.56-16.96% and 71.45-71.96%, respectively. Antioxidant activities ranged from 2.33-2.80 μmol trolox/g. The results showed that the drying methods did not decrease the nutritional quality of grape residues and prevented microbial growth by decreasing water activity to below 0.60. [ABSTRACT FROM AUTHOR]