This study was conducted to capitalize on the waste produced by the vinification process which proved to be important sources of bioactive compounds with significant antifungal properties. ‘Cabernet ...Sauvignon’ grape pomace extracts were characterized in terms of total polyphenol content, antioxidant potential, but also evaluated in terms of antifungal effect against phytopathogenic fungi (Fusarium sp. and Alternaria sp.). The isolates used in this study were grown on three potato-dextrose-agar culture media, Czapek Dox and Malt-Agar. The highest amount of polyphenols was determined from the extract obtained by the microwave-assisted method (42.76 mg/g GAE), followed by the extract obtained by maceration (30.37 mg/g GAE). The lowest amount was obtained by the ultrasound-assisted method (15.06 mg/g GAE). However, the highest antioxidant activity was determined in the macerated extract, TEAC = 0.0523. The results of in vitro tests clearly indicated a high inhibitory percentage on the mycelium growth rate and, respectively, a significant decrease in spore germination power in Fusarium sp. (91.56%). However, for the pathogen Alternaria sp. further studies are needed to correctly validate the percentage of inhibition, as alcohol has been shown to have a negative effect on it.
Climate change has an important impact on the phenological phases of the grapevine. The consequences are directly reflected in quantitative and qualitative characteristics of the grapes. In fact, ...there is a decrease in the skin-to-pulp ratio (therefore a decrease in production with an excess of alcohol) and a consequent reduction in the aromatic potential of white grapes (lowering of the quality of musts). Volatile tioles are important aromatic compounds found in various foods and drinks; in particular they contribute to forming the aroma of some types of white wines as they are characterized by extremely low perception thresholds.
This work aimed to evaluate the effects of water stress on ecophysiology, technological maturity and on the thiol precursors of Vitis vinifera L. cv. Sauvignon Blanc vineyards in the Tuscan region (Italy) during two seasons. To this end, three treatments were established: WW (well watered), MW (medium watered), and WS (water stress with no irrigation). During the seasons, measurements were made of single-leaf gas exchange, pre-dawn and leaf midday water potential, leaf temperature, chlorophyll fluorescence, as well chlorophyll content. In addition, the parameters of plant yield, technological maturity (° Brix, acidity, pH and berries weight) and the precursors of 3-Mercaptohexanol (3MH) were analyzed: 3-S-cysteinylhexan-1-ol (Cys-3MH) and 3-S-glutathionylhexan-1-ol (GSH-3MH).
Well watered treatments (WW) showed less negative water potential, a higher rate of photosynthesis, of stomatal conductance, a lower leaf temperature (°C). Furthermore, WW showed higher levels of precursors accumulation (Cys-3MH and GSH-3MH) than the other treatments during two seasons. Technological analyses (° Brix and acidity) showed significant differences between WW and WS treatments. The lower berry weight was found in the WS treatment.
Finally as a result of climate change, precision irrigation has proved to be a good technique to rebalance the gap between technological and aromatic maturity in Sauvignon Blanc grapes.
•The role of water potential as a stress assessment tool.•Precision irrigation reduces water stress due to climate change.•Precision irrigation increase ecophysiological performance of vines.•Irrigation plays a key role in re-establishing optimal levels of tiol precursors.
Polysaccharides are important metabolites in red wine but are challenging to separate from yeast-derived mannoproteins, and costly to identify using sialylation and gas chromatography. Affinity and ...gel permeation chromatography was combined with immunodetection of various specific plant cell wall polysaccharide epitopes to understand this complex mixture of extracted cell wall polymers. A survey of Cabernet Sauvignon wines produced with and without pectolytic enzymes suggested that enzyme-treated wines have fewer polysaccharides in the 85–105 kDa and 1050–6000 kDa ranges. When yeast-derived mannoproteins are excluded (15.3% of total), pectolytic enzyme treatment was shown to alter the molecular weight wine polysaccharide composition between the 100–1000 kDa ranges. Furthermore, ELISA data suggested that many of the soluble polysaccharides in the 300–1000 kDa range are an arabinogalactan protein–rhamnogalacturonan I–xyloglucan co-polymer. This is the first report to use ELISA to identify changes in specific polysaccharide classes during enzyme preparation used in wine maceration.
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•Polysaccharide metabolites in red wine are hard to separate and identify.•Immunodetection of polysaccharide epitopes can help understand this complex mixture.•Cabernet Sauvignon treated with pectolytic enzymes have fewer polysaccharides.•Epitope mass profiling identified arabinogalactan protein-rich polysaccharides.
Elemental sulfur is a fungicide traditionally used to control Powdery Mildew in the production of grapes. The presence of sulfur residues in grape juice has been associated with increased production ...of hydrogen sulfide during fermentation, which could take part in the formation of the varietal thiol 3-mercaptohexanol. This work examines whether elemental sulfur additions to Sauvignon blanc juice can increase the levels of sought-after varietal thiols. Initial trials were performed in South Africa and indicated a positive impact of sulfur on the levels of thiols. Further experiments were then carried out with New Zealand Sauvignon blanc and confirmed a positive relationship between elemental sulfur additions and wine varietal thiols. The formation of hydrogen sulfide was observed when the addition of elemental sulfur was made to clarified juice, along with an increase in further reductive sulfur compounds. When the addition of sulfur was made to pressed juice, prior to clarification, the production of reductive sulfur compounds was drastically decreased. Some mechanistic considerations are also presented, involving the reduction of sulfur to hydrogen sulfide prior to fermentation.
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•Two sulfur addition trials undertaken in both South Africa and New Zealand•Sulfur addition to grape juice proportionally increased varietal thiols in the wine.•Reductive compounds were also formed when sulfur was applied after juice clarification.•A pathway for the production of 3MH with S0 as sulfur donor is proposed.
With Cabernet Sauvignon grape seeds as raw materials, grape seed polyphenols were extracted and purified, the stability of grape seed polyphenols under different pH, light, temperature, carbohydrate, ...stabilizer, oxidant reducing agent, preservative and metal ion were studied during processing and storage conditions, and the biological activity in vitro was also discussed. The results showed that grape seed polyphenol was the best stability under the condition of low temperature (4 ℃), weak acid (pH4~6), avoiding light and low temperature (4 ℃), and the retention rate of grape seed polyphenols was above 95%. High concentration (40%~50%) of sucrose and glucose had enhanced effect on the stability of polyphenols, lactose concentration had no significant effects on the stability of polyphenols (P˃0.05), and different concentrations of starch could significantly reduce the stability of polyphenols (P<0.05). Compared with Tween-80, sodium thiosulfate, a stabilizer, was more destructive to polyphenols. Both oxidants
Grape yield regulation is a method used to improve grape quality parameters. Experiments were carried out in 2021 on the grapevine (Vitis vinifera L.) wine varieties 'Feteasca regala' and 'Sauvignon ...blanc', focusing on the effect of two different methods of grape yield regulation on its selected parameters and must sugar content. The first method used was cluster thinning, leaving one bunch on the shoot. The next method used was cluster tipping when we removed the terminal part of each bunch. Yield reduction was carried out in the period between pea-sized berry phenophase (BBCH 75) and bunch closure phenophase (BBCH 77). The operations were carried out manually. Cluster thinning did not lead to a statistically significant difference in bunch weight compared to the control in any of the studied varieties. We observed a statistically significant (p <0.05) decrease in the average bunch weight in the variant cluster tipping. The 'Feteasca regala' hectare yield was 32.25% lower in the cluster thinning than the control. The hectare yield in the cluster thinning variant was reduced by 46.61% compared with the control. Cluster thinning variant of the Sauvignon blanc variety had a 19.13% lower yield than the control variant. The cluster tipping variant had a 29.03% lower yield than the control variant. In the case of the cluster thinning method, we observed a greater decrease in grape yield compared to the cluster tipping method. The obtained results indicate that cluster tipping method is preferable to the cluster thinning in terms of the profitability of grape production. The must sugar content was statistically significantly (p <0.05) increased in all the yield reduction variants. The variety 'Feteasca regala' had the highest sugar content of the must in the cluster thinning method, 19.42 kg/hL. The highest sugar content of 'Sauvignon blanc' was 21.33 kg/hL in the variant with cluster tipping. This shows that regulating the grape yield can improve the quality parameters of the grapes. On the other hand, it may lead to a decrease in yield per hectare below the break-even point. The justness and intensity of the method used must be carefully considered.
•Analyze the causes of shoot drying death of Cabernet Sauvignon in spring.•Compared with Early-ripening Kyoho, the xylem sap flow intensity of Cabernet Sauvignon was low and unstable during the ...dormancy release period.•Cabernet sauvignon's root water reached the peak later, and changes in the respiratory pathways and the accumulation of soluble sugar occurred slowly.•After grafted on SA15 Cabernet Sauvignon's recovery times of the total water content and free water content occurred earlier and have high expression of related genes.
Cabernet Sauvignon (Vitis vinifera) is one of the main wine-making varieties in the world. Its budding time is late, and cane dieback often occurs in northern China. In order to analyze the causes of shoot drying death of Cabernet Sauvignon in spring, the water supply capacity of the roots of Cabernet Sauvignon and Early-ripening Kyoho and the dynamic changes in the respiration metabolism of roots and buds during the ecodormancy were studied. Additionally, the effects of rootstock SA15 grafting on the sap flow and moisture content changes of Cabernet Sauvignon canes were investigated and the expression of root respiration related genes at different temperatures during the ecodormancy after rootstock SA15 grafting was analyzed. The results showed that compared with Early-ripening Kyoho, the xylem sap flow intensity of Cabernet Sauvignon was low and unstable during the ecodormancy, the roots water reached the peak later, and changes in the respiratory pathways and the accumulation of soluble sugar occurred slowly. The peak of the activity of the respiratory pathways in the Cabernet Sauvignon buds occurred significantly earlier than that of the roots. Compared with self-rooted vines, the peak in the sap flow of Cabernet Sauvignon canes grafted on rootstock SA15 occurred 24 days earlier, and the recovery times of the total water content and free water content occurred earlier. It also increased the roots respiration intensity and the expression of key enzymes of roost respiration under low temperature. In summary, Cabernet Sauvignon insufficient water supply capacity, resulting in difficulty replenishing the water lost from the canes in time and ultimately leading to spring dieback of Cabernet Sauvignon canes. The moisture recovery time of Cabernet Sauvignon canes can be increased by grafting them on rootstock SA15 to prevent the occurrence of spring dieback.
•Cabernet Sauvignon, Syrah and Monastrell grapes were winemaked.•We study the oligosaccharides in wines from three red grapes varieties.•Oligosaccharide composition and structure could be influenced ...by variety effect.•Molecular weights of oligosaccharides from red wines can be measured by SEC-MALLS.
Wine oligosaccharides were recently characterized and their concentrations, their composition and their roles on different wines remain to be determined. The concentration and composition of oligosaccharides in Cabernet Sauvignon, Syrah and Monastrell wines was studied. Oligosaccharide fractions were isolated by high resolution size-exclusion chromatography. The neutral and acidic sugar composition was determined by gas chromatography. The MS spectra of the oligosaccharides were performed on an AccuTOF mass spectrometer. Molar-mass distributions were determined by coupling size exclusion chromatography with a multi-angle light scattering device (MALLS) and a differential refractive index detector. Results showed significant differences in the oligosaccharidic fraction from Cabernet Sauvignon, Syrah and Monastrell wines. This study shows the influence that the grape variety seems have on the quantity, composition and structure of oligosaccharides in the finished wine. To our knowledge, this is the first report to research the oligosaccharides composition of Cabernet Sauvignon, Syrah and Monastrell wines.
Among wood diseases, esca complex has increased over the last decades around Europe, and there are no chemical solutions that can limit its spread in vineyards. During a 7-year trial in 3 vineyards, ...half of the surface was sprayed every season with a solution of Trichoderma asperellum and Trichoderma gamsii at the phenological stage of bleeding, and half of the vineyard remained untreated. During August and September every year, the fate of esca symptoms on the single vines was monitored, distinguishing light, medium-to-severe leaf tiger stripe symptoms, and acute symptoms, including apoplexy. During the 7-year period, the vines affected by esca (all symptoms) increased over time in both the control and the sprayed treatments. Among the symptoms, Trichoderma was demonstrated to reduce the impact of both light tiger-stripe symptoms and apoplexy, while no significant differences were shown in the medium-to-severe symptoms A 22% reduction in the incidence of infected vines was ascertained after seven years of Trichoderma application. Regarding meteorological conditions, a significant positive correlation was found between the amount of rain in May and the occurrence of Esca in the field at the end of the season.
•No chemical fungicides are effective in reducing the esca complex.•Trichoderma asperellum and T. gamsii compete for space and nutrients on pruning cuts.•Trichoderma asperellum and T. gamsii significantly reduced light symptoms and apoplexy.
