Proanthocyanidin composition and antioxidant potential of the stem winemaking byproducts from 10 different grape varieties (Vitis vinifera L.)

Kombucha fermentation as a modern way of processing vineyard by-products into cosmetic raw materials

OBJECTIVE

The wine industry generates large quantities of by-products presenting a remarkably valuable composition in phytochemicals. The process that can significantly increase the content of bioactive compounds is fermentation by yeast and other microorganisms. The current study presents, for the first time, an evaluation of the potential of grape stems extract and its ferments using the Scoby consortium, as a cosmetic raw material for improving the skin care properties of facial cosmetics.

METHODS

Fermentation of grape stems using Scoby consortium was carried out for 10 and 20 days. Unfermented and fermented extracts were analysed for their antioxidant activity and chemical composition, with a particular emphasis on biologically active substances. Additionally, the influence of the addition of the obtained ferments to the model cosmetic creams on hydration, transepidermal water loss and skin pH were assessed.

RESULTS

The obtained results revealed that grape stems extract and its ferments are a rich source of phenolic compounds and show antioxidant activity, with the highest values observed for extracts on the 20th day of fermentation. Furthermore, the addition of the extract, as well as ferment, to the cream has a positive effect on skin hydration and reduces transepidermal water loss.

CONCLUSION

These results suggest that grape stem extracts are a prospective source of active compounds that may be valuable ingredients for the cosmetic industry. Unfermented and fermented extracts can be used in moisturizing cosmetic formulations and also to complement the treatment of dry and sensitive skin.

Bioprotection by non-Saccharomyces yeasts in oenology: Evaluation of O2 consumption and impact on acetic acid bacteria

Bioprotection by yeast addition is increasingly used in oenology as an alternative to sulfur dioxide (SO2). Recent studies have also shown that it is likely to consume dissolved O2. This ability could limit O2 for other microorganisms and the early oxidation of the grape must. However, the ability of yeasts to consume O2 in a context of bioprotection was poorly studied so far considering the high genetic diversity of non-Saccharomyces. The first aim of the present study was to perform an O2 consumption rate (OCR) screening of strains from a large multi species collection found in oenology. The results demonstrate significant inter and intra species diversity with regard to O2 consumption. In the must M. pulcherrima consumes O2 faster than Saccharomyces cerevisiae and then other studied non-Saccharomyces species. The O2 consumption was also evaluate in the context of a yeast mix used as industrial bioprotection (Metschnikowia pulcherrima and Torulaspora delbrueckii) in red must. These non-Saccharomyces yeasts were then showed to limit the growth of acetic acid bacteria, with a bioprotective effect comparable to that of the addition of sulfur dioxide. Laboratory experiment confirmed the negative impact of the non-Saccharomyces yeasts on Gluconobacter oxydans that may be related to O2 consumption. This study sheds new lights on the use of bioprotection as an alternative to SO2 and suggest the possibility to use O2 consumption measurements as a new criteria for non-Saccharomyces strain selection in a context of bioprotection application for the wine industry.

Development of Tannins and Methoxypyrazines in Grape Skins, Seeds, and Stems of Two Pinot Noir Clones during Ripening

Two Pinot noir clones (AM10/5 and UCD5) were analyzed for tannin and methoxypyrazines (MPs) in different grape tissues during berry development using liquid chromatography and two-dimensional gas chromatography-mass spectrometry. On a per berry basis, skin tannins reached the maximum level about 2-3 weeks after véraison, seed tannins at around véraison, and stem tannins 4 weeks before véraison. Clone AM10/5 showed significantly higher levels of seed and stem tannins on a per berry basis at harvest. Tannin concentration and composition varied among the different tissues. On a per berry basis, stem tannin levels were comparable to skin tannins but were 3 to 4 times lower than seed tannins, while stem tannins had an intermediate galloylation (5-7%) between seed tannins (12-18%) and skin tannins (2%) and lower prodelphinidin (4-7%) than skin tannins (31-36%). The mean degree of polymerization of stem tannins was similar to seed tannins but lower than skin tannins. MPs, including 3-isopropyl-2-methoxypyrazine (IPMP), 3-s-isobutyl-2-methoxypyrazine (SBMP), and 3-isobutyl-2-methoxypyrazine (IBMP), showed significantly higher concentrations than their sensory thresholds in grape stems but not in skins. The MPs development in stems showed an increasing trend toward véraison and then a decreasing trend toward harvest. Compared to AM 10/5, UCD5 stems showed a higher level of MPs, especially significantly higher concentrations of IPMP and IBMP at harvest. The extraction of MPs from grape stems could contribute negative green and vegetative characters to Pinot noir wines.

Antioxidant Activity of Sweet Whey Derived from Bovine, Ovine and Caprine Milk Obtained from Various Small-Scale Cheese Plants in Greece before and after In Vitro Simulated Gastrointestinal Digestion

Whey-derived peptides have been associated with different biological properties, but most peptides are usually further hydrolyzed during the digestive process. In the present study, the antioxidant capacity of 48 samples of sweet whey (SW) derived from cheeses obtained from small-scale cheese plants made with bovine, ovine, caprine or a mixture of ovine/caprine milk was assessed using both cell-free and cell-based assays. SW digestates (SW-Ds) and a fraction (<3 kDa; SW-D-P3) thereof were obtained after in vitro digestion and subsequent ultrafiltration. Antioxidant properties using four different assays were evaluated before and after digestion. Our data showed higher values (p < 0.05) for ORAC, ABTS, FRAP and P-FRAP after in vitro digestion (SW-Ds and SW-D-P3) when compared with the corresponding values before digestion. In the non-digested SW, ORAC values were higher (p < 0.05) for the bovine SW compared with all the other samples. In contrast, the ABTS assay indicated a higher antioxidant activity for the ovine SW both before digestion and for SW-D-P3 compared with the bovine SW. The fraction SW-D-P3 of the ovine SW, using HT29 cells and H2O2 as an oxidizing agent, increased (p < 0.05) the cellular antioxidant activity. Furthermore, the same fraction of the ovine/caprine mixed SW increased, through the NF-κB pathway, the expression of SOD1 and CAT, genes implicated in the oxidative response in macrophage-like THP-1 cells. These findings indicate that SW, and particularly bovine and ovine SW, could be a candidate source for physical antioxidants in human and animal nutrition.

Revealing the Beauty Potential of Grape Stems: Harnessing Phenolic Compounds for Cosmetics

Grape stems have emerged as a promising natural ingredient in the cosmetics industry due to their abundance of phenolic compounds, known for their antioxidant and anti-inflammatory properties. These compounds have shown great potential in promoting skin health, fighting signs of aging, and shielding against environmental stressors. With high concentrations of resveratrol, flavonoids, and tannins, grape stems have garnered attention from cosmetic scientists. Research has indicated that phenolic compounds extracted from grape stems possess potent antioxidant abilities, effectively combating free radicals that accelerate aging. Moreover, these compounds have demonstrated the capacity to shield the skin from UV damage, boost collagen production, and enhance skin elasticity. Cosmetic formulations incorporating grape stem extracts have displayed promising results in addressing various skin concerns, including reducing wrinkles, fine lines, and age spots, leading to a more youthful appearance. Additionally, grape stem extracts have exhibited anti-inflammatory properties, soothing irritated skin and diminishing redness. Exploring the potential of grape stem phenolic compounds for cosmetics paves the way for sustainable and natural beauty products. By harnessing the beauty benefits of grape stems, the cosmetics industry can provide effective and eco-friendly solutions for consumers seeking natural alternatives. Ongoing research holds the promise of innovative grape stem-based formulations that could revolutionize the cosmetics market, fully unlocking the potential of these extraordinary botanical treasures.

Background and Perspectives on the Utilization of Canes' and Bunch Stems' Residues from Wine Industry as Sources of Bioactive Phenolic Compounds

Viticulture activity produces a significant amount of grapevine woody byproducts, such as bunch stems and canes, which constitute potential sources of a wide range of phenolic compounds (PCs) with purported applications. Recently, the study of these byproducts has been increased as a source of health-promoting phytochemicals. Antioxidant, antimicrobial, antifungal, and antiaging properties have been reported, with most of these effects being linked to the high content of PCs with antioxidant properties. This Review summarizes the data related to the qualitative and quantitative composition of PCs recovered from canes and bunch stems side streams of the wine industry, the influence that the different environmental and storage conditions have on the final concentration of PCs, and the current reported applications in specific technological fields. The objective is to give a complete valuation of the key factors to consider, starting from the field to the final extracts, to attain the most suitable and stable characterized product.

A New Functional Food Ingredient Obtained from Aloe ferox by Spray Drying

Aloe mucilages of Aloe ferox (A. ferox) and Aloe vera (A. vera) were spray-dried (SD) at 150, 160 and 170 °C. Polysaccharide composition, total phenolic compounds (TPC), antioxidant capacity and functional properties (FP) were determined. A. ferox polysaccharides were comprised mainly of mannose, accounting for >70% of SD aloe mucilages; similar results were observed for A. vera. Further, an acetylated mannan with a degree of acetylation >90% was detected in A. ferox by ¹H NMR and FTIR. SD increased the TPC as well as the antioxidant capacity of A. ferox measured by both ABTS and DPPH methods, in particular by ~30%, ~28% and ~35%, respectively, whereas in A. vera, the antioxidant capacity measured by ABTS was reduced (>20%) as a consequence of SD. Further, FP, such as swelling, increased around 25% when A. ferox was spray-dried at 160 °C, while water retention and fat adsorption capacities exhibited lower values when the drying temperature increased. The occurrence of an acetylated mannan with a high degree of acetylation, together with the enhanced antioxidant capacity, suggests that SD A. ferox could be a valuable alternative raw material for the development of new functional food ingredients based on Aloe plants.

High-Power Ultrasound in Gas Phase: Effects on the Bioactive Compounds Release from Red Bell Pepper during In Vitro Gastrointestinal Digestion

High-power ultrasound in gas-phase (28.8 kW/m³ for 120 min at 17.5 ± 0.3 °C) has been evaluated as a pre-treatment to enhance the release of antioxidants and phenolic compounds from red bell pepper during digestion. The moisture content decreased (34 ± 4%) while both the antioxidant activity (between 4 ± 1% and 21 ± 1%) and the phenolic compounds content (37 ± 4%) increased after the treatment. Moreover, microstructural changes were observed in the treated sample, with the appearance of breaks in the plant tissue, cell shrinkage, and an increased number of cells per area unit (28 ± 2%). Bioaccessibility was determined by in vitro gastrointestinal digestion. The total release of antioxidants and phenolic compounds after gastrointestinal digestion was 22-55% higher and 45 ± 7% higher, respectively, in the sonicated sample, with cell swelling and a 9.2 ± 0.1% higher number of cells per area unit. Therefore, the ultrasound treatment caused microstructural changes in the red bell pepper tissue, which could help to explain the higher release of bioactive compounds.

Accelerated Solvent Extraction of Phenols from Lyophilised Ground Grape Skins and Seeds

The efficient extraction of phenols from grapes is an important step for their reliable quantification. The aim was to optimise the lyophilisation process and the extraction of phenols from grape skins and seeds. The phenol extraction yield from lyophilised tissues was investigated with different accelerated solvent extraction (ASE) operating conditions. Skins and seeds were separated from frozen berries and lyophilised without being ground. The weight loss during lyophilisation was followed daily. Phenols were extracted from lyophilised, cryo-ground seeds and skins with ASE at room temperature and 10.3 MPa using 80% aqueous acetone and 60% aqueous methanol. The effects of ASE operational parameters (the number of extraction cycles (ECs) and static time (ST) duration) were investigated. The yield of extracted phenols was evaluated spectrophotometrically by determining total phenolic index at 280 nm (TPI). The weight of skins and seeds significantly dropped after 24 h of lyophilisation and continued to decrease, although not significantly, up until the 9th day. The optimal lyophilisation time was estimated to be 3 days and 5 days for skins and seeds, respectively. The phenol extraction yield was significantly affected after changes of ASE conditions. Based on TPI, the optimal ASE conditions were as follows: (i) lyophilised seeds—eight ECs with 10 min ST using aqueous acetone and then four ECs with 20 min ST using aqueous methanol; (ii) lyophilised skins—eight ECs with 1 min ST using aqueous acetone and then one EC with 20 min ST using aqueous methanol.

Phenolic potential of new red hybrid grape varieties to produce quality wines and identification by the malvin

The hybrids are new varieties that are resistant to the cryptogamic diseases of vines, and they may be a good solution to the reduction of pesticide use. However, these new varieties have appeared recently and only few studies have been conducted to check the quality of the wine that they produce. In this study, wines originated from hybrids were chemically characterized (polyphenols, tannins, anthocyanins, and color analysis). Results show that their oenological parameters were close to those of the Vitis vinifera wines. The wines made from Vinifera (100%), with Vidoc, and all the resistant Bouquets studied are malvidin-3 glucoside dominant, and all the others hybrids varieties are cyanidin dominant. Furthermore, the hybrid wines had a higher concentration in condensed tannins and a lower one in molecular tannins compared with the Vitis vinifera wines, except for the Vidoc wines. As far as the anthocyanin content is concerned, the samples contained anthocyanin diglucosides, with the malvidin-3,5-diglucoside (malvin) the most abundant one. Also, their concentration in molecular anthocyanins were higher than the concentration in normal wines. The Vidoc wines do not contain any malvin. For the other wines, malvin co-eluted with cyanidin-3-O-glucoside and in this case, the cyanidin’s concentration was impressively higher than the Vidoc wines. The current OIV method gives different results for malvidol diglucoside compared to the use of an HPLC chromatography method (HPLC-DAD-QQQ). The current OIV method does not appear reliable in comparison with the HPLC method for detecting malvin. Finally, the hybrid wines had a darker blue/purplish color than the Vitis vinifera wines.

Nephroprotective Activity of Papaloquelite (Porophyllum ruderale) in Thioacetamide-Induced Injury Model

Acute kidney injury and impaired kidney function is associated with reduced survival and increased morbidity. Porophyllum ruderale is an edible plant endemic to Mexico used in Mexican traditional medicine. The aim of this study was to evaluate the nephroprotective effect of a hydroalcoholic extract (MeOH:water 70:30, v/v) from the aerial parts of P. ruderale (HEPr). Firstly, in vitro the antioxidant and anti-inflammatory activity of HEPr was determined; after the in vivo nephroprotective activity of HEPr was evaluated using a thioacetamide-induced injury model in rats. HEPr showed a slight effect on LPS-NO production in macrophages (15% INO at 40 µg/mL) and high antioxidant activity in the ferric reducing antioxidant power (FRAP) test, followed by the activity on DPPH and ABTS radicals test (69.04, 63.06 and 32.96% of inhibition, respectively). In addition, values of kidney injury biomarkers in urine (urobilinogen, hemoglobin, bilirubin, ketones, glucose, protein, pH, nitrites, leukocytes, specific gravity, and the microalbumin/creatinine) and serum (creatinine, urea, and urea nitrogen) of rats treated with HEPr were maintained in normal ranges. Finally, 5-O-caffeoylquinic, 4-O-caffeoylquinic and ferulic acids; as well as 3-O-quercetin glucoside and 3-O-kaempferol glucoside were identified by HPLC as major components of HEPr. In conclusion, Porophyllum ruderale constitutes a source of compounds for the treatment of acute kidney injury.

Phenolic Composition of Grape Stems from Different Spanish Varieties and Vintages

Grape stems are a by-product from the wine industry that has been underused to date despite having great potential for the agro-food and cosmetic industries. The aim of the present work was to characterize grape stem extracts obtained from different grape varieties from two vintages (2016 and 2018). Both spectrophotometric and chromatographic methods were used for sample characterization. The results showed that there exist significant differences in antioxidant activity, total phenolic content (TPC) and total flavonoid content (TF) among grape stems from different varieties in each vintage and from different vintage for the same variety. Catechin was the most abundant phenolic compound in all extracts from both vintages. In general, Mazuelo presented higher concentration values of the different phenolic compounds than Garnacha and Tempranillo. It was observed than extreme temperatures and accumulated precipitations, which were higher in the 2016 vintage, had an impact on the polyphenol synthesis. Therefore, grape stems from the 2018 vintage presented higher TPC and TF values than their counterparts from the 2016 vintage. In addition, the statistical analysis revealed that the influence of environmental factor such as light, temperature and precipitations have different impact on the synthesis of polyphenols depending on the family of the specific compound.

Correlations between Total Antioxidant Capacity, Polyphenol and Fatty Acid Content of Native Grape Seed and Pomace of Four Different Grape Varieties in Hungary

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.

Current trends and possibilities for exploitation of Grape pomace as a potential source for value addition

Grape pomace (GP) is a low-value by-product that contains a significant amount of high value-added products. The huge amount of non-edible residues of GP wastes (seeds, skins, leaves and, stems) produced by wine industries causes' environmental pollution, management issues as well as economic loss. Studies over the past 15-20 years revealed that GP could serve as a potential source for valuable bioactive compounds like antioxidants, bioactive, nutraceuticals, single-cell protein, and volatile organic compounds with an increasing scientific interest in their beneficial effects on human and animal health. However, the selection of appropriate techniques for the extraction of these compounds without compromising the stability of the extracted products is still a challenging task for the researcher. Based on the current scenario, the review mainly summarizes the novel applications of winery wastes in many sectors such as agriculture, pharmaceuticals, cosmetics, livestock fields, and also the bio-energy recovery system. We also summarize the existing information/knowledge on several green technologies for the recovery of value-added by-products. For the promotion of many emerging technologies, the entrepreneur should be aware of the opportunities/techniques for the development of high-quality value-added products. Thus, this review presents systematic information on value-added by-products that are used for societal benefits concerning the potential for human health and a sustainable environment.

A Review on Stems Composition and Their Impact on Wine Quality

Often blamed for bringing green aromas and astringency to wines, the use of stems is also empirically known to improve the aromatic complexity and freshness of some wines. Although applied in different wine-growing regions, stems use remains mainly experimental at a cellar level. Few studies have specifically focused on the compounds extracted from stems during fermentation and maceration and their potential impact on the must and wine matrices. We identified current knowledge on stem chemical composition and inventoried the compounds likely to be released during maceration to consider their theoretical impact. In addition, we investigated existing studies that examined the impact of either single stems or whole clusters on the wine quality. Many parameters influence stems' effect on the wine, especially grape variety, stem state, how stems are incorporated, when they are added, and contact duration. Other rarely considered factors may also have an impact, including vintage and ripening conditions, which could affect the lignification of the stem.

Grape Stem Extracts with Potential Anticancer and Antioxidant Properties

The application of plant extracts for therapeutic purposes has been used in traditional medicine because plants contain bioactive compounds with beneficial properties for health. Currently, the use of these compounds that are rich in polyphenols for the treatment and prevention of diseases such as cancer, diabetes, and cardiovascular diseases, many of them related to oxidative stress, is gaining certain relevance. Polyphenols have been shown to have antimutagenic, antioxidant, and anti-inflammatory properties. Therefore, the objective of the present work was to study the potential effect of grape stem extracts (GSE), rich in phenolic compounds, in the treatment of cancer, as well as their role in the prevention of this disease associated with its antioxidant power. For that purpose, three cancer lines (Caco-2, MCF-7, and MDA-MB-231) were used, and the results showed that grape stem extracts were capable of showing an antiproliferative effect in these cells through apoptosis cell death associated with a modification of the mitochondrial potential and reactive oxygen species (ROS) levels. Additionally, grape stem extracts showed an antioxidant effect on differentiated intestinal cells that could protect the intestine from diseases related to oxidative stress. Therefore, grape extracts contain bioactive principles with important biological properties and could be used as bio-functional food ingredients to prevent diseases or even to improve certain aspects of human health.

Tuning of Proanthocyanidin Extract's Composition through Quaternary Eutectic Solvents Extraction

Currently available proanthocyanidins extraction methods rely on dedicated crops and have low specificity and yield which limits their industrial application. Consequently, the development of novel methodologies and the use of sustainable sources is of great importance. Eutectic solvents have been proposed has good alternatives for conventional solvents due to their low price, easiness of preparation, biocompatibility and ability of being custom made to a specific application. Herein the effective extraction of proanthocyanidins from grape pomace and the possibility of tuning the extract's characteristics such as mean degree of polymerization and galloylation percentage is explored by means of varying the composition of a quaternary eutectic solvent composed by choline chloride, glycerol, ethanol and water. It was found that mean degree of polymerization values can vary from 6.0 to 7.37 and galloylation percentage can vary from 32.5% to 47.1% while maintaining extraction yield above 72.2 mg of proanthocyanidins per g of biomass. Furthermore, the increase of temperature up to 100 °C has showed a significant effect on the extraction yield being possible to increase it by 238% when compared to the conventional extraction method.

Use of alimentary film for selective sorption of haloanisoles from contaminated red wine

Haloanisoles (HAs) are known to compromise wine quality because of their mouldy off-flavours. Up to now no treatment exists to eliminate the presence of these unpleasant volatiles in wine. This research aimed i) to assess the alimentary plastic film efficacy to remove or lessen HAs content in polluted wines; and ii) to evaluate its impact on wine quality. The film-treatment reduced significantly (p < 0,05) the 2,4,6-trichloroanisole (TCA) content of initial wine. This decrease became more noticeable as the contact time film-wine increased. Chromatic characteristics, phenolic and proanthocyanidin contents, and woody aroma profile did not change because of the film-treatment. A significant sorption of certain esters was observed, but as HAs were removed under detection thresholds, fruity perception of wines was improved. Globally, the alimentary plastic film was able to improve the organoleptic quality of wines contaminated with HAs, by reducing the cork taint and enhancing their overall fruity aroma.

Fate of Residual Pesticides in Fruit and Vegetable Waste (FVW) Processing

Plants need to be protected against pests and diseases, so as to assure an adequate production, and therefore to contribute to food security. However, some of the used pesticides are harmful compounds, and thus the right balance between the need to increase food production with the need to ensure the safety of people, food and the environment must be struck. In particular, when dealing with fruit and vegetable wastes, their content in agrochemicals should be monitored, especially in peel and skins, and eventually minimized before or during further processing to separate or concentrate bioactive compounds from it. The general objective of this review is to investigate initial levels of pesticide residues and their potential reduction through further processing for some of the most contaminated fruit and vegetable wastes. Focus will be placed on extraction and drying processes being amid the main processing steps used in the recuperation of bioactive compounds from fruit and vegetable wastes.

A New Extract from Pomegranate (Punica granatum L.) By-Products as a Potential Oenological Tannin: Preliminary Characterization and Comparison with Existing Commercial Products

Oenotannins are nowadays widely used as co-adjuvant in the winemaking process. The increasing cultivation and consumption of pomegranate (Punica granatum L.) leads to high amounts of by-products, mainly peels. Aim of this study was to propose a dried tannin-rich extract from pomegranate by-products as a new oenotannin. A decoction was prepared from mesocarp of the Wonderful pomegranate variety only using hot water as extracting solvent. The dried decoction was physical-chemically characterized and compared to 7 existing commercial oenotannins from different botanical origin (grape seed, oak, gallnut), according to UV-Vis Spectroscopy, Colorimetric analysis (CIELab), gelatin index, reactivity to proteins, HPLC-DAD, DPPH, and Total Polyphenols content by both Folin-Ciocalteu and the International Organization of Vine and Wine (OIV) methods. Data showed the lowest antiradical (AR) and total polyphenolic content (TPC) for the pomegranate tannin but also the highest AR/TPC ratio suggesting a good radical scavenging potential of this new tannin. Pomegranate tannin showed high reactivity with proteins, a unique chromatographic profile, and a low color impact. The new pomegranate tannin showed an interesting potential for oenological applications in particular for reducing the use of sulfites during vinification and for the white wine stabilization.

Antifungal Activity of Phenolic and Polyphenolic Compounds from Different Matrices of Vitis vinifera L. against Human Pathogens

Phenolic compounds, the most widely distributed class of natural products in the plants, show several biological properties including antifungal activity. Phenolics contained in grapes can be classified in two main groups, flavonoids and non-flavonoids compounds. Variability and yield extraction of phenolic and polyphenolic compounds from different matrices of Vitis vinifera depends of cultivar, climate, soil condition and process technology. Unripe grapes, berry skins and seeds, leaves, canes and stems and not-fermented and fermented pomaces represent large reusable and valuable wastes from agricultural and agro-industrial processes. This review summarizes studies that examine the extraction method, chemical characterization, and antifungal activity of phenolic and polyphenolic compounds from edible and non-edible V. vinifera matrices against human fungal pathogens. In the world, around one billion people have fungal diseases related to skin, nail or hair and around 150 million have systemic diseases caused by fungi. Few studies on antifungal activity of plant extracts have been performed. This review provides useful information for the application of V. vinifera phenolics in the field of antifungals for human use.

Stability of Phenolic Compounds in Grape Stem Extracts

Grape stem is rich in phenolic compounds, especially stilbenes. These antioxidants can be degraded during the storage of grape stem extracts for long periods of time. The aim of this work was to analyze the stability of Mazuelo stem extracts during storage at 25 and 40 °C, in two different light conditions (amber and transparent vials). The stability of the antioxidants was studied after 2, 4 and 6 months of conservation. Gallic acid and the quercetin derivative concentration were stable throughout the storage period. In contrast, catechin disappeared from all the extracts in just two months of storage. Anthocyanins were significantly affected by temperature, and light enhanced their degradation when the extracts were kept at 40 °C. Resveratrol and viniferin showed a similar behavior. Their concentration decreased from the beginning of storage, and in both cases, they were significantly affected by both temperature and light.

Characterization of antioxidant, α-glucosidase and tyrosinase inhibitors from the rhizomes of Potentilla anserina L. and their structure-activity relationship

Five new flavonoids (1-5), along with 25 known compounds, were isolated from the rhizomes of Potentilla anserina L. and their structures were identified using spectroscopic and chemical evidence. The extract, all fractions, and all isolated compounds were evaluated for their antioxidant, α-glucosidase, and tyrosinase inhibitory activities, and their structure-activity relationship was interpreted. The biflavanols and quercetin-3-O-α-l-rhamnopyranoside-2″-gallate (14) exhibited significant antioxidant and α-glucosidase inhibition activities. In this study, anti-tyrosinase activity and its mechanism of active compounds (potenserin C (4), potenserin D (5), and quercetin-3-O-α-l-rhamnopyranoside-2″-gallate (14)) were explored by a combination of computational simulations and kinetic studies. Kinetic studies indicated that potenserin C (4) and quercetin-3-O-α-l-rhamnopyranoside-2″-gallate (14) inhibited tyrosinase in a competitive manner, whereas potenserin D (5) acted in a reversible noncompetitive manner. The molecular docking result indicated that the substitution of the glucose moiety with galloyl and the presence of 3', 4', 5'-OH in flavonoid aglycones played a crucial role for the tyrosinase inhibiting effect. Moreover, the presence of biflavanols increased the activity against tyrosinase because of strong hydrogen binding, π-alkyl binding, and electrostatic interaction. Thus, the presented experiments developed several new lead compounds that could act as antioxidants and α-glucosidase inhibitors. Furthermore, biflavanols and quercetin-3-O-α-l-rhamnopyranoside-2″-gallate played important roles in the anti-browning activity during food processing.

Oenological tannins to prevent Botrytis cinerea damage in grapes and musts: Kinetics and electrophoresis characterization of laccase

Enzymatic parameters (K_M and V_max), residual activity, effect of bentonite and electrophoresis characterization of laccase in the presence of different oenological tannins (OT) were investigated in relation to B. cinerea negative effects in grapes and musts. Five OT were tested (gallotannin, ellagitannin, quebracho, grape-skin and grape-seed) in comparison with ascorbic acid (AA), sulfur dioxide (SO₂) and bentonite. We added OT, AA, SO₂ and bentonite to botrytized must obtained by inoculation of grapes with B. cinerea strain 213. Laccase activity was measured by the syringaldazine method at different concentrations of substrate. Enzymatic parameters were determined using Michaelis-Menten and Lineweaver-Burk plots. The B. cinerea strain was also grown in a liquid medium for laccase production. Molecular weight of laccases and effect of OT upon these laccases were studied by SDS-PAGE. Results confirm that bentonite, contrary to OT, did not permit to reduce laccase activity. Regardless the tannin considered, V_max, K_M and laccase activity were reduced and gallotannin, grape-skin and grape-seed tannin presented the greatest ability. Efficiency of grape-seed tannin addition in order to reduce the laccase activity, was comparable to that of AA or SO₂ at the typical doses employed in oenology for each one. Oenological tannins appear to be excellent processing aids to prevent laccase effects and contribute to reduce the use of SO₂ in grapes and musts.

New perspectives on the biosynthesis, transportation, astringency perception and detection methods of grape proanthocyanidins

Proanthocyanidins (PAs) are important secondary metabolites crucial for the quality of grape berry and wine. Despite important advances in our understanding of the structural and regulatory genes involved in the PAs biosynthesis pathway, our knowledge about the details of biosynthetic and regulatory networks, especially the mechanism of polymerization and transportation remains limited. We provided an overview of the latest discoveries related to the mechanisms of grape PAs structure, astringency properties, detection methods, biosynthesis and transportation. We also summarized the environmental influencing factors of PAs synthesis in grape. Future trends were discussed.

Valorisation of Grape Stems as a Source of Phenolic Antioxidants by Using a Sustainable Extraction Methodology

Pressurized liquid extraction with ethanol:water mixtures was proposed for obtaining phenolic antioxidants from grape stems. The optimal extraction conditions were elucidated by using a central composite rotatable design (solvent (X₁, 0–100% ethanol:water v/v), temperature (X₂, 40–120 °C) and time (X₃, 1–11 min)). Response surface methodology determined 30% ethanol:water, 120 °C and 10 min as the optimal extraction conditions regarding total phenolic content (TPC) (185.3 ± 2.9 mg gallic acid/g of extract) and antioxidant activity (3.55 ± 0.21 mmol Trolox/g, 1.22 ± 0.06 mmol Trolox/g and 1.48 ± 0.17 mmol Trolox/g of extract in ABTS, DPPH and ORAC methodologies, respectively). The antioxidant activity was attributed to total polymer procyanidins and flavan-3-ol monomers and oligomers, although other phenolic compound contributions should not be ruled out. Forty-two phenolic compounds were identified in the optimal extract, mainly polymer procyanidins and, to a lesser extent, monomers and oligomers of flavan-3-ols, quercetin-3-O-glucuronide, ε-viniferin, gallic and caftaric acid. Ethyl gallate, ellagic acid, protocatechuic aldehyde, delphinidin-7-O-glucoside and cyanidin-3-O-glucoside were reported for the first time in grape stem extracts. In conclusion, this study highlights the use of this winery side stream as a source of antioxidants within a sustainable food system.

Ultrasound-Assisted Aqueous Extraction of Biocompounds from Orange Byproduct: Experimental Kinetics and Modeling

Orange byproduct (flavedo and albedo) from juice extraction, was used as raw material for this study. Kinetics of total phenolic and total flavonoid contents and antioxidant activity was experimentally determined during both conventional (agitation at 80 rpm) and ultrasound assisted (at 520 and 790 W/L) aqueous extraction from orange byproduct at 5, 15, and 25 °C. An extraction mathematical model was also developed. Significant increase of biocompounds extraction yields was observed as temperature and acoustic power density increased. Ultrasound assistance allowed higher yields at lower temperatures and shorter times. Yields of total phenolic and total flavonoid contents and antioxidant activity obtained with ultrasound extraction (790 W/L, 25 °C, 3 min) were 29%, 39%, and 197% higher, respectively, than those obtained by conventional extraction. The extraction kinetics curves were properly represented by the Weibull model for both conventional and acoustic extraction (mean relative error lower than 5%). Naringin, neohesperidin, and hesperidin were the main phenolic compounds found in the extracts, followed by ferulic, sinapic, and cuomaric acids. Neohesperidin, hesperidin, coumaric acid, and sinapic acid presented the highest yields, especially when extraction was assisted by ultrasound. Meanwhile, naringin and ferulic acid were extracted in a lesser extent, most likely due to their lipophilic character.

Interactions between whey proteins and cranberry juice after thermal or non-thermal processing during in vitro gastrointestinal digestion

This study entails the possible interactions between whey protein and cranberry juice after processing, impacting either the protein digestibility or the bioaccessibility of cranberry antioxidants using an in vitro gastrointestinal digestion model.

Impact of Extraction Conditions on the Phenolic Composition and Antioxidant Capacity of Grape Stem Extracts

The use of grape stems for the extraction of bioactive compounds to be used in the pharmaceutical, food, and cosmetic industries is a promising objective. The aim of this work is to determine the influence of the different extraction conditions (temperature, ethanol concentration, and ratio of sample/solvent) on phenolic composition and antioxidant capacity of Mazuelo stem extracts. In general, the ethanol concentration of the extraction solvent was the factor that had the greatest influence on the extraction of different bioactive compounds. The greatest content of total phenolic compounds and the highest antioxidant activity of the extracts were obtained with 50% ethanol and at 40 °C. The most abundant compound found in the different extracts obtained from Mazuelo grape stem was (+)-catechin, but appreciable concentrations of gallic acid, a quercetin derivative, and stilbenes (trans-resveratrol and trans-ε-viniferin) were also extracted. Quercetin and malvidin-3-glucoside showed the highest correlation with the antioxidant capacity of the extracts, while stilbenes did not present such relation. The maximum concentration of gallic acid was extracted with water but the extraction of most of the compounds was maximum on using 50% ethanol. Consequently, the selection of the extraction method to be used will depend on the particular compound to be extracted in greatest quantity.

Disease Resistant Bouquet Vine Varieties: Assessment of the Phenolic, Aromatic, and Sensory Potential of Their Wines

The search for grape varieties resistant to diseases and to climatic changes notably concerns the wine industry. Nine monovarietal wines from new red grape varieties resistant to cryptogamic diseases (downy and powdery mildews) were evaluated in terms of their total phenolic, anthocyanin and proanthocyanidin contents, anthocyanin profile, volatile composition, and sensory attributes. Thus, the question remains, will these hybrid grapes (≥97.5% of Vitis vinifera genome) lead to wines with organoleptic properties similar to those of Vitis vinifera wines that consumers are used to? Total phenolic (1547–3418 mg GA/L), anthocyanin (186–561 mg malvidin/L), and proanthocyanidin (1.4–4.5 g tannins/L) contents were in broad agreement with those previously described in the literature for monovarietal wines produced with well-known red grape varieties (Cabernet Sauvignon, Merlot, Syrah). With regard to fruity aroma, ethyl esters of straight-chain fatty acids (530–929 μg/L) stood out clearly as the major volatile components for all hybrid wines considered. Sensory analysis revealed significant differences (p < 0.05) for visual aspect, aroma, flavor, global balance, astringency, and body. Overall, these new hybrid grape varieties are not only resistant to cryptogamic diseases, but also present enough potential to become quality wines, since their phenolic and volatile attributes are close to those of common red monovarietal wines.

Low-Cost Ru/C-Catalyzed Depolymerization of the Polymeric Proanthocyanidin-Rich Fraction from Bark To Produce Oligomeric Proanthocyanidins with Antioxidant Activity

A new method has been developed for the high-value utilization of larch bark, which is regarded as a low-value byproduct of the logging industry. Polymeric proanthocyanidins (PPCs) were extracted from the Larix gmelinii bark and depolymerized by catalytic hydrogenolysis, using ruthenium/carbon (Ru/C) as the catalyst. The method has been found that although the molecular weight of the depolymerized product was significantly lower, the basic structural units were not destroyed, and the product retained a condensed flavanol polyphenol structure; the depolymerized product contains very little Ru metal and thus complies with food safety standards; the antioxidant properties of both the depolymerized products and PPCs were better than those of the commonly used antioxidant 2,6-di-tert-butyl-4-methylphenol. The relative molecular weight and steric hindrance of the depolymerized products were lower than those of the PPCs, leading to better antioxidant performance. A new technical route for the depolymerization of PPCs from the L. gmelinii bark is provided. The route offers practical and commercial advantages, and the product could have many applications as an antioxidant.

Phenolic compounds of grape stems and their capacity to precipitate proteins from model wine

Reintegration of grape stem, a by-product from wine production, into the food chain is of high interest from an economic and environmental perspective. Therefore, an investigation of stems was undertaken and is described here. It is known that quality of stems is of high variability. In this study the stems from four grapevine varieties (Syrah, Cabernet Sauvignon, Merlot and Chasselas) cultivated in Switzerland were treated in following ways: drying, cutting and separation into fractions based on particle size. All fractions were then characterised for their phenolic compounds content. It was found that Chasselas fractions contained most phenolic compounds. The addition of grape stems of the four different varieties allowed reduction of the protein content of a model wine. The extent of protein precipitation was highly correlated with the amount of phenolic compounds in stems added. Among the examined varieties, Chasselas brought most promising results, with the high reduction of the protein at low level of stem addition.

Phytochemical composition and immunobiological activity of Hawthorn Crataegus mexicana nanoencapsulated in Longfin yellowtail Seriola rivoliana leukocytes

The aims of this study were to determine the presence of phenolic compounds in Hawthorn Crataegus mexicana, species native to Mexico, nanoencapsulated (CmNano) with maltodextrin at 100 and 170 °C (CmNano100 and CmNano170) and its antioxidant and immunological effects in Longfin yellowtail Seriola rivoliana leukocytes. The phytochemical study revealed an important level of total phenolic (TPC), flavonoid (TFC) and tannin (CTC) contents in CmNano100, which correlated with a strong antioxidant capacity. CmNano100 or 170 were safe or not cytotoxic for head-kidney (HKL) and peripheral blood (PBL) leukocytes. The in vitro study demonstrated that CmNano increased the percentage of phagocytic cells, stimulated the production of reactive oxygen species, and modulated antioxidant ability by increasing superoxide dismutase activity in leukocytes with respect to the control group. In addition, CmNano100 also increased the transcription of proinflammatory cytokine IL-1β and down-regulated MyD88 and TNF-α mRNA transcription. These results suggest that maltodextrin nanoencapsulates protected and maintained the antioxidant properties of C. mexicana. In addition, they enhanced antioxidant and immunological parameters in Longfin yellowtail S. rivoliana leukocytes. Therefore, this study provides novel insights of CmNano for its potential application as functional food in aquaculture.

Natural extracts from grape seed and stem by-products in combination with colloidal silver as alternative preservatives to SO2 for white wines: Effects on chemical composition and sensorial properties

The search for alternative additives to sulfur dioxide, with antioxidant and antimicrobial activity, in the production of wines is one of the current objectives of the enological industry. In the present study, aqueous extracts obtained from winery byproducts (grape seeds and stems), alone or in combination with colloidal silver complex, have been used in white vinification. The antimicrobial effect of the extracts was similar to that of sulfur dioxide, being more effective on lactic and acetic bacteria in those wines to which colloidal silver was added. The effect on the color, the phenolic compounds and the volatile fraction of the wines was evaluated, as well as their sensory profile. The use of both extracts modified the color of the wines, increasing the chromatic parameters a* and b*, indicating a browning tendency, although no other signs of oxidation were found. Wines with seed extracts contained higher amounts of flavan-3-ols, and a significant increase in some volatile compounds such as fatty acid ethyl esters and benzene compounds, which were identified in the extracts. From a sensorial point of view, the wines with stem extracts were the most similar to those elaborated with SO₂, detecting a certain bitterness in wines with seed extracts.

Optimizing Nucleophilic Depolymerization of Proanthocyanidins in Grape Seeds to Dimeric Proanthocyanidin B1 or B2

Depolymerization of polymeric proanthocyanidins (PPCs) in grape seeds into oligomeric proanthocyanidins (OPCs), especially the dimers, has important academic significance and practical value. Reaction conditions including nucleophilic reagent/PPC mass ratio, HCl concentration, reaction time, and temperature were systematically optimized by central composite design to maximize the yield of the dimeric product B2 or B1. The yield of B2 reached 3.35 mg mL^-1 under the conditions of (-)-epicatechin/PPC mass ratio 2.8, HCl concentration 0.06 mol, reaction time 16 min and temperature 36 °C, and that of B1 reached 3.64 mg mL^-1 under the conditions of (+)-catechin/PPC mass ratio 2.8, HCl concentration 0.07 mol, reaction time 17 min, and temperature 34 °C. Overall, this study has provided theoretical guidance and a practical approach to improvethe reaction process and economic value of proanthocyanidins in grape seed proanthocyanidin extract.

Ultrasound assisted low-temperature drying of kiwifruit: Effects on drying kinetics, bioactive compounds and antioxidant activity

BACKGROUND

Low-temperature drying is considered to be a promising technique for food processing. It preserves thermolabile compounds and might be intensified by acoustic assistance. The effect of acoustic assistance (20.5 kW m^-3 ) during low-temperature drying of kiwifruit (at 5, 10 and 15 °C, and 1 m s^-1 ) on drying kinetics, bioactive compounds (such as ascorbic acid, vitamin E, and total polyphenols), and antioxidant activity was studied.

RESULTS

Drying time was shortened by 55-65% when using power ultrasound. A diffusion model was used to evaluate the drying kinetics. The effective diffusion coefficient increased by 154 ± 30% and the external mass transfer coefficient increased by 158 ± 66% when ultrasound was applied during drying, compared with drying without ultrasound application. With regard to bioactive compounds and antioxidant activity, although samples dried at 15 °C presented significantly higher (P < 0.05) losses (39-54% and 57-69%, respectively) than samples dried at 5 °C (14-43% and 23-50%, respectively) when ultrasound was not applied, the application of ultrasound during drying at 15 °C significantly reduced (P < 0.05) those losses in all quality parameters (15-47% and 47-58%, respectively).

CONCLUSION

Overall, low-temperature drying of kiwifruit was enhanced by acoustic assistance preserving bioactive compounds and antioxidant activity, especially at 15 °C. © 2018 Society of Chemical Industry.

Influence of freezing on the bioaccessibility of beetroot (Beta vulgaris) bioactive compounds during in vitro gastric digestion

BACKGROUND

The effect of freezing (in liquid nitrogen at -196 °C , at -80 °C and at -20 °C) on the food matrix structure and the consequent effect on the bioaccessibility of total polyphenol content (TPC) and antioxidant activity (AA) of beetroot was investigated by an in vitro digestion method. The in vitro digestion involved incubation in simulated saliva followed by incubation in simulated gastric juice. Bioaccessibility of bioactive compounds was evaluated by measuring the TPC and the AA during in vitro digestion in both the beetroot matrix and the gastric juice.

RESULTS

Release of TPC and AA of beetroot was higher in frozen samples (55 ± 5% for TPC and 68 ± 5% for AA) than in the fresh beetroot sample (∼46% for TPC and ∼53% for AA). The mass transfer kinetics were described by using a Weibull model with mean relative errors lower than 8.5% contributing to a better understanding of the influence of freezing on the bioaccessibility of bioactive compounds.

CONCLUSIONS

From the treatments tested in this study, freezing with liquid nitrogen resulted in the greatest increase in bioaccessibility of the antioxidant and phenolic compounds of beetroots. © 2018 Society of Chemical Industry.

Effects of convective drying and freeze-drying on the release of bioactive compounds from beetroot during in vitro gastric digestion

Drying may alter the microstructure of vegetables and influence the release of bioactive compounds during digestion.