Grapevine-shoot stilbene extract as a preservative in red wine

UV-exposure decreases antimicrobial activities of a grapevine cane extract against Plasmopara viticola and Botrytis cinerea as a consequence of stilbene modifications-a kinetic study

BACKGROUND

Stilbenoid extracts, such as those originating from grapevine by-products (e.g. canes), are of interest for use as biopesticides in vineyard owing to their antimicrobial activities. However, stilbenoids are unstable in the environment, especially under light. This study aimed to chemically characterize the effect of UV light on stilbenoids present in a grapevine cane extract (CE), and to evaluate the antimicrobial activities against two major grapevine pathogens (Plasmopara viticola and Botrytis cinerea) of grapevine extracts exposed to UV.

RESULTS

Treatment with UV (365 nm) on a grapevine CE led to degradation of stilbenoids (up to 71% after 1 h). The stilbenoid stability depended on their chemical structure: only those possessing CC, as trans-resveratrol and trans-ε-viniferin, were affected with first their isomerization and secondly their oxidation/cyclization. As a consequence, UV-exposed extracts (UV-CEs) showed reduced antimicrobial activities against the two pathogens (mycelium and spores). For instance, regarding P. viticola, an UV-CE exposed during 4 h showed an almost total loss of its activity on oomycete development and a 2.4-fold inhibition of zoospore mobility in comparison to CE. For B. cinerea, the inhibition capacity of the same UV-CE was reduced by only 1.1-fold on mycelial development and by 3.2-fold on conidial germination compared to CE.

CONCLUSION

UV light triggered modifications on the structure of bioactive stilbenoids, resulting in losses of their antimicrobial activities. Photoprotection of stilbenoids has to be considered in the perspective of using them in vineyards as biopesticides. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Use of vine-shoots stilbene extract to the reduction of SO2 in red and rosé Italian wine: Effect on phenolic, volatile, and sensory profiles

Sulfur dioxide (SO2) is one of the most used additives in wine industry for its antioxidant and antimicrobial activity. However, due to health concerns, consumers' demand of wines with either reduced or totally replaced SO2 has increased. This study aimed to assess the effect of partial and total replacement of SO2 with a vine-shoots extract rich in stilbenes in rosé (cv. Sangiovese) and red (cv. Negramaro) wines respectively. Color as well as phenolic, volatile, and sensory profiles of wines were evaluated at bottling and during storage. The results showed that the vine-shoots extract increased the levels of trans-resveratrol, catechin, and gallic acid in wines. Moreover, the positive correlation of procyanidin dimers in red wine suggested an increase of the polymerization reactions. The amount of added extract probably provided lower antimicrobial protection compared to SO2, as indicated by the higher levels of ethyl phenol. The decrease of individual anthocyanins and oxidation aldehydes observed in wines with SO2 replacement and the higher levels of caftaric acid in the rosé wine with the extract suggested a shift of the oxidative protection, with a lower protection towards anthocyanin degradation and higher protection towards carbonyl formation and oxidation of readily oxidizable phenolic acids.

Development of a new paper-based voltage step electrocoagulation technique and application to wine classification

This study developed a novel voltage step electrocoagulation (VSEC) technique on paper for analysis and classification of red wine samples. The concept relies on the electrode system applying voltage steps along a strip of filter paper soaked with a wine sample. The system employed a cathode array system (CAS) for voltage step application and an aluminium anode undergoing corrosion to form the green sludges responsible for wine color bleaching along the paper. The VSEC technique led to the shade of colors along the paper which can be observed by the naked-eye or using image processing software. The system was applied to classify 15 wine samples into different groups and to perform dilution and adulteration tests. In addition, the approach could be applied to approximate antioxidant properties of the wine samples as observed via the correlation between the results from VSEC and IC₅₀ values obtained from the DPPH assay with an R² of 0.76.

Increasing the added value of vine-canes as a sustainable source of phenolic compounds: A review

Grapes represent one of the most produced fruit crops around the world leading to the generation of large amounts of vine-canes as a side product, with no current economically profitable application. However, vine-canes have been demonstrated to be natural sources of phenolic compounds with numerous health benefits associated, with several potential applications. Therefore, new ambitious applications focused on their re-use are needed, targeting a sustainable process that simultaneous produces functional products and mitigates the waste generation. This review gives to the readers a complete summary about the state of the art regarding the vine-canes extracts research. Vine-canes phenolic composition is addressed and related to the health benefits exhibited. This review comprises studies from the past two decades reporting the extraction processes to recover vine-cane phenolic compounds, including conventional and environmentally friendly technologies and discussing their advantages and disadvantages. The conditions that favour the extraction process for vine-cane polyphenols for each technique were also deeply explored for the first time, enabling to the reader apply only the best parameters to achieve the highest yields without huge investment in optimizations procedures. Furthermore, a correlation between the bioactive properties of the vine-cane extracts and their applications in multiple fields is also critically presented.

Grapevine Wastes: A Rich Source of Antioxidants and Other Biologically Active Compounds

Wine production is one of the most critical agro-industrial sectors worldwide, generating large amounts of waste with negative environmental impacts, but also with high economic value and several potential applications. From wine shoots to grape pomace or seeds, all of the wastes are rich sources of bioactive compounds with beneficial effects for human health, with these compounds being raw materials for other industries such as the pharmaceutical, cosmetic or food industries. Furthermore, these compounds present health benefits such as being antioxidants, supporting the immune system, anti-tumoral, or preventing cardiovascular and neural diseases. The present work aims to be a critical discussion of the extraction methods used for bioactive compounds from grapevine waste and their beneficial effects on human health.

In Vivo Genotoxicity Evaluation of a Stilbene Extract Prior to Its Use as a Natural Additive: A Combination of the Micronucleus Test and the Comet Assay

Genotoxic data of substances that could be used as food additives are required by the European Food Safety Authority. In this sense, the use of an extract from grapevine shoots containing a stilbene richness of 99% (ST-99), due to its antioxidant and antibacterial activities, has been proposed as an alternative to sulfur dioxide in wine. The aim of this work was to study, for the first time, the in vivo genotoxic effects produced in rats orally exposed to 90, 180, or 360 mg ST-99/kg body weight at 0, 24, and 45 h. The combination of micronucleus assay in bone marrow (OECD 474) and standard (OECD 489) and enzyme-modified comet assay was used to determine the genotoxicity on cells isolated from stomach, liver, and blood of exposed animals. The ST-99 revealed no in vivo genotoxicity. These results were corroborated by analytical studies that confirm the presence of stilbenes and their metabolites in plasma and tissues. Moreover, to complete these findings, a histopathological study was performed under light microscopy in liver and stomach showing only slight modifications in both organs at the highest concentration used. The present work confirms that this extract is not genotoxic presenting a good profile for its potential application as a preservative in the wine industry.

Bioactive Compounds from Vine Shoots, Grape Stalks, and Wine Lees: Their Potential Use in Agro-Food Chains

The winemaking sector is one of the most productive worldwide, and thus it also generates large amounts of by-products with high environmental impacts. Furthermore, global market trends and government regulations promote industrial alternatives based on sustainable production processes. As a result, several studies have focused their attention on the reuse of grape by-products in the agro-food chain. Vine shoots, grape stalks, and wine lees, although produced to a lesser extent than grape pomace, have increasingly been receiving attention for their applications in the food sector, since they are a good source of functional and bioactive compounds. In this framework, our review highlights the promising results obtained by exploiting the antioxidant and/or antimicrobial activity of vine shoots, grape stalks, and wine lees or their extracts to replace the most common oenological additives and to assay the activity against food pathogens. Further, innovative functional foods and sustainable food packaging have been formulated by taking advantage of polyphenols and fiber, as well as plant bio-stimulants, in order to obtain grapes and wines with high quality characteristics. Overall, these by-products showed the potential to be recycled into the food chain as functional additives for different products and applications, supporting the sustainability of the winemaking sector.

Cytotoxicity studies of a stilbene extract and its main components intended to be used as preservative in the wine industry

The use of stilbenes has been proposed as an alternative to sulfur dioxide in wine. Provided the feasibility from a technological approach, the cytotoxicity of an extract from grapevine shoots containing a stilbene richness of 99% (ST-99 extract) was assessed in the human cell lines HepG2 and Caco-2. In addition, the effects of the main stilbenes found in ST-99, trans-resveratrol and trans-ε-viniferin were studied, as well as its mixture. Similar cytotoxic effects were obtained in the exposures to trans-ε-viniferin, ST-99 and the mixture; however, trans-resveratrol alone exerted less toxicity. When HepG2 cells were exposed to trans-ε-viniferin, ST-99 and the mixture, the mean effective concentration (EC₅₀) were 28.28 ± 2.15, 31.91 ± 1.55 and 29.47 ± 3.54 µg/mL, respectively. However, in the exposure to trans-resveratrol, the EC₅₀ was higher 50 µg/mL. The morphological study evidenced damage at ultrastructural level in HepG2 cells, highlighting the inhibition of cell proliferation and the induction of apoptosis. The type of interaction produced by trans-ε-viniferin and trans-resveratrol mixtures was assessed by an isobologram analysis using the CalcuSyn software, evidencing an antagonist effect. These data comprise a starting point in the toxicological assessment; further studies are needed in this field to assure the safety of the extract ST-99.

Grapevine Cane Extracts: Raw Plant Material, Extraction Methods, Quantification, and Applications

Grapevine canes are viticulture waste that is usually discarded without any further use. However, recent studies have shown that they contain significant concentrations of health-promoting compounds, such as stilbenes, secondary metabolites of plants produced as a response to biotic and abiotic stress from fungal disease or dryness. Stilbenes have been associated with antioxidant, anti-inflammatory, and anti-microbial properties and they have been tested as potential treatments of cardiovascular and neurological diseases, and even cancer, with promising results. Stilbenes have been described in the different genus of the Vitaceae family, the Vitis genera being one of the most widely studied due to its important applications and economic impact around the world. This review presents an in-depth study of the composition and concentration of stilbenes in grapevine canes. The results show that the concentration of stilbenes in grapevine canes is highly influenced by the Vitis genus and cultivar aspects (growing conditions, ultraviolet radiation, fungal attack, etc.). Different methods for extracting stilbenes from grapevine canes have been reviewed, and the extraction conditions have also been studied, underlining the advantages and disadvantages of each technique. After the stilbenes were extracted, they were analyzed to determine the stilbene composition and concentration. Analytical techniques have been employed with this aim, in most cases using liquid chromatography, coupled with others such as mass spectrometry and/or nuclear magnetic resonance to achieve the individual quantification. Finally, stilbene extracts may be applied in multiple fields based on their properties. The five most relevant are preservative, antifungal, insecticide, and biostimulant applications. The current state-of-the-art of the above applications and their prospects are discussed.

Oenological potential and health benefits of Chinese non-Vitis vinifera species: An opportunity to the revalorization and to breed new varieties

The wine industry is focused on the producing wine mostly from European grapevine varieties (Vitis vinifera L.). China has experienced a significant growth of the vineyard surface, based on the cultivation of these grapevine varieties. Currently, China has become one of the countries with the largest surface of planted vineyards in the world. In the last years, there has been a trend to oenologically and viticulturally revalorize certain autochthonous grapevine species. China holds a great diversity of Vitis species, which are being the focus of study. This could be an important alternative for the diversification of wine production, providing new products with a strong identity. Additionally, the varietal homogenization has increased the vineyard genetic vulnerability in relation to the emergence of grapevine diseases and their resistance to chemical fungicides. In this way, non-Vitis vinifera species are characterized by having a high resistance to a wide range of biotic and abiotic factors, which can bring an opportunity to breed new varieties. However, there is little available information about the oenological potential of these species, which makes it a current interesting topic. Therefore, this review aims to summarize the oenological potential of non-Vitis vinifera species found in China, discussing their potential effects on human health and thus, to propose some Chinese wild grapes for their use in breeding programs.

Viticultural wood waste as a source of polyphenols of interest: Opportunities and perspectives through conventional and emerging extraction methods

Viticultural waste has been widely demonstrated to contain high-added value compounds named the stilbenes. Among them, trans-resveratrol (Rsv) and trans-ε-viniferin (Vf) are the most abundant in particular in grape canes. Various emerging methods such as ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) or pressurized solvent extraction (PSE) have been studied to recover Rsv and Vf from grape canes in order to enhance their extraction. This paper gives a critical overview of the techniques used to this end, integrating conventional and non-conventional methods investigated in the literature as well as those used in industrial processes. It finally highlights that the unconventional technics are usually less time-consuming than conventional extraction ones but further investigations for the discussed compounds and biomass are needed to optimize and understand the influence of the individual parameters of each extraction process.

In Vitro Toxicity Assessment of Stilbene Extract for Its Potential Use as Antioxidant in the Wine Industry

The reduction of sulfur dioxide in wine is a consumer's demand, considering the allergic effects that may occur in people who are sensitive to it. Stilbenes are candidates of great interest for this purpose because of their antioxidant/antimicrobial activities and health properties, and also because they are naturally found in the grapevine. In the present study, the in vitro toxicity of an extract from grapevine shoots (with a stilbene richness of 45.4%) was assessed in two human cell lines. Significant damage was observed from 30 μg/mL after 24 h, and 40 µg/mL after 48 h of exposure. Similarly, the ultrastructural study revealed a significant impairment of cell growing. The extract was able to protect cells against an induced oxidative stress at all concentrations studied. In view of the promising results, a more exhaustive toxicological assessment of the extract is needed to confirm the safety of its further use as additive in wine.

Effects of low sulfur dioxide concentrations on bioactive compounds and antioxidant properties of Aglianico red wine

This study analyzed the effect of low sulfur dioxide concentrations on the chromatic properties, phytochemical composition and antioxidant activity of Aglianico red wines with respect to wines produced from conventional winemaking. We determined the phytochemical composition by spectrophotometric methods and HPLC-DAD analysis and the in vitro antioxidant activity of different wine samples by the ORAC assay. The main important classes of fluorophore molecules in red wine were identified by Front-Face fluorescence spectroscopy, and the emission intensity trend was investigated at various sulfur dioxide concentrations. Lastly, we tested the effects of both conventional and low sulfite wines on ex vivo human erythrocytes under oxidative stimulus by the cellular antioxidant activity (CAA) assay and the hemolysis test. The addition of sulfur dioxide, which has well-known side effects, increased the content of certain bioactive components but did not raise the erythrocyte antioxidant capacity.

Sulfur free red wines through the use of grapevine shoots: Impact on the wine quality

Following a preliminary study to determine the possibility of using a grapevine shoot extract (VIN) as a sustainable alternative to sulfur dioxide (SO₂), in this study, the chromatic features, phenolic composition, and sensory analysis of wines treated with VIN at two concentrations were studied during storage in bottle for the first time. The highest differences were found in phenolic compounds after 12months of storage in bottle. The VIN wines had a low content of free anthocyanins and were high in vinyl-pyranoanthocyanins, and B-type vitisins. Consequently, they showed better chromatic characteristics. Moreover VIN, especially at high dose, preserved non-anthocyanin phenolic compounds better than SO₂. However, at this high dose some organoleptic properties were affected. VIN, when used at a low dose, is able to preserve wine composition without loss of quality.

Sensory, olfactometry and comprehensive two-dimensional gas chromatography analyses as appropriate tools to characterize the effects of vine management on wine aroma

For the first time, the influence of different vine management was evaluated in relation to volatile profile and sensory perception through GC×GC/TOFMS, QDA, GC-FID, GC/MS, and GC-O. GC×GC/TOFMS analyses and QDA have shown that a larger spacing between vine rows (2 rather than 1m), attachment of shoots upwards, and irrigation did not result in wine improvement. Conversely, wines elaborated with grapes from a vine with a lower bud load (20 per plant; sample M1) stood out among the other procedures, rendering the most promising wine aroma. GC×GC/TOFMS allowed identification of 220 compounds including 26 aroma active compounds also distinguished by GC-O. Among them, eight volatiles were important to differentiate M1 from other wines, and five out of those eight compounds could only be correctly identified and quantified after separation in second dimension. Higher levels of three volatiles may explain the relation of M1 wine with red and dry fruits.