The aim of this research was to determine the effect of development and UV‐B on flavonols and the regulation of gene activity in Vitis vinifera L. var. Sauvignon blanc grapes. Particular emphasis was ...placed on gene activity associated with the low and high fluence UV‐B responses. Flavonols, particularly quercetin and kaempferol glycosides, increased substantially upon fruit exposure due to UV‐B, with spatial analysis locating the changes to the berry skin. Of five VvFLS genes in grapes, two (VvFLS4 and 5) were found to be transcriptionally active, with VvFLS4 also being responsive to UV‐B but VvFLS5 was not. Of the transcription factors known to regulate FLS (VvMYB12, VvMYCA1 and VvWDRs), only VvMYB12 was found to be responsive to UV‐B. A number of candidate genes associated with the low and high UV‐B fluence responses were also studied (VvUVR8, VvHY5, VvCOP1 and VvCHS; PR genes and VvMAPK3; respectively). The genes associated with the low fluence response exhibited transcriptional regulation in line with reports from other species, while the PR genes and VvMAPK3 only appeared to be responsive in a high UV‐B fluence environment. Together, these data supports the view flavonol biosynthesis in grape is stimulated predominantly through the low fluence UV‐B response pathway.
This research investigates the effect of development and UV‐B on flavonols and the regulation of gene activity in Vitis vinifera L. var. Sauvignon blanc grapes. Results suggest flavonol biosynthesis and gene activity are stimulated by UV‐B and the low fluence UV‐B pathway is a major determinant of this response. There is also a strong influence of development on gene expression. This is the first research to analyse signal transduction associated with the recently discovered UV‐B photoreceptor UVR8 and makes a substantial contribution to understanding UV‐B responses in an important commercial species.
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.
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.
The pinking phenomenon has been known in the wine world for the past 50 years. The phenomenonoccurs when a white wine turns pink under certain conditions. Since then, a Portuguese study ...foundmalvidin-3-O-glucoside in Siria grapes making a connection to anthocyanin as the causing agent. Control(K), naturally pinked (NP) and pink induced (PI) Sauvignon blanc wine samples were analysed by LCMSand WineScanTM (Fourier Transform Infrared – FTIR) after Solid Phase Extraction. The monomericanthocyanins were analysed by a pH differential method, and CieLab was used to differentiate colourdifferences between the control and pinked samples. It was found that malvidin-3-O-glucoside was belowthe threshold values to facilitate pinking in Sauvignon blanc wines. Petunidin-3-O-glucoside showed aslight peak in the LC-MS analysis, and together with the malvidin-3-O-glucoside, the potential to pinkthe white wines increased. FTIR results showed that phenols and anthocyanins absorption could not bedistinguished and that there were possibly other compounds involved in the pinking of white wines. Analysisby CieLab expressed the PI wines as a darker pink colour than the control wine and the absorbency valueat 500 nm was at least three times higher for PI than the control, showing the aggressive oxidative natureof H2O2 on wine.
•The level of phenolic substances per berry increased in grape skin during ripening.•Tannins per gram of berry decreased due to dilution effect caused by berry growth.•PR proteins increased in both ...grape skin and pulp during ripening.•Grape pulp showed much higher level of PR proteins than grape skin.
Grape proteins, particularly pathogenesis-related (PR) proteins, are responsible for white wine haze formation which is of great concern to winemakers. Phenolic substances in grapes have also been reported with involvement in protein haze formation by interaction with proteins. The protein and phenolic substances in grapes are important in determining their concentrations in juice and resultant wine, and thus consequent wine protein stability. This study investigated the changes in these haze formation related components in ‘Sauvignon Blanc’ grape skin and pulp during ripening. The phenolic content on per berry basis generally increased in grape skin and pulp, but the phenolic concentration on per gram of berry basis showed a decreasing trend in grape skin, suggesting the accumulation effect of phenolics in skin is less than the dilution effect caused by berry growth. Tannin was only detected in grape skin but not in the pulp and the changes in tannin were similar to total phenolics. PR proteins were synthesized and accumulated along with the increase of total soluble solids (TSS) in both skin and pulp from véraison until harvest during ripening. The increase of PR proteins in grapes during ripening was also reflected in corresponding juice. The results suggested most of PR proteins in juice is likely extracted from grape pulp, and the riper the grapes the more PR proteins may be extracted into juice. The higher level of phenolics in riper grapes could increase the extraction of phenolics into juice and thus decrease the final concentration of PR proteins.
We developed a sensory-based methodology to aromatically enrich wines using different aromatic fractions recovered during fermentations of Sauvignon Blanc must. By means of threshold determination ...and generic descriptive analysis using a trained sensory panel, the aromatic fractions were characterized, selected, and clustered. The selected fractions were grouped, re-assessed, and validated by the trained panel. A consumer panel assessed overall liking and answered a CATA question on some enriched wines and their ideal sample. Differences in elicitation rates between non-enriched and enriched wines with respect to the ideal product highlighted product optimization and the role of aromatic enrichment. Enrichment with aromatic fractions increased the aromatic quality of wines and enhanced consumer appreciation.
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•Sauvignon Blanc wines were enriched with natural aromas condensed from fermentation.•By means of a sensory-based methodology, positive aromatic condensates were selected.•The selected aromatic groups improved the perception of wine quality.•CATA showed the positive effect of aromatic enrichment on consumer perception.
The analytical scope of static headspace–gas chromatography–ion mobility spectrometry (SHS–GC–IMS) was applied to wine aroma analysis for the first time. The method parameters were first fine-tuned ...to achieve optimal analytical results, before the method stability was demonstrated, in terms of repeatability and reproducibility. Succinct qualitative identification of compounds was also realized, with the identification of several volatiles that have seldom been described previously in Sauvignon Blanc wine, such as methyl acetate, ethyl formate, and amyl acetate. Using the SHS–GC–IMS data in an untargeted approach, computer modeling of large datasets was applied to link aroma chemistry via prediction models to wine sensory quality gradings. Six machine learning models were compared, and artificial neural network (ANN) returned the most promising performance with a prediction accuracy of 95.4%. Despite its inherent complexity, the ANN model offered intriguing insights on the influential volatiles that correlated well with higher and lower sensory gradings. These findings could, in the future, guide winemakers in establishing wine quality, particularly during blending operations prior to bottling.
► Combination of infrared and chemometrics opens the possibility to discriminate between Australian and New Zealand Sauvignon Blanc. ► This type of method used by the wine industry will guarantee the ...provenance of the wines to the consumers. ► This method will also help to study and understand the effect of climate change on grape and wine production.
The combination of UV, visible (Vis), near-infrared (NIR) and mid-infrared (MIR) spectroscopy with multivariate data analysis was explored as a tool to classify commercial Sauvignon Blanc (Vitis vinifera L., var. Sauvignon Blanc) wines from Australia and New Zealand. Wines (n=64) were analysed in transmission using UV, Vis, NIR and MIR regions of the electromagnetic spectrum. Principal component analysis (PCA), soft independent modelling of class analogy (SIMCA) and partial least squares discriminant analysis (PLS-DA) were used to classify Sauvignon Blanc wines according to their geographical origin using full cross validation (leave-one-out) as a validation method. Overall PLS-DA models correctly classified 86% of the wines from New Zealand and 73%, 86% and 93% of the Australian wines using NIR, MIR and the concatenation of NIR and MIR, respectively. Misclassified Australian wines were those sourced from the Adelaide Hills of South Australia. These results demonstrate the potential of combining spectroscopy with chemometrics data analysis techniques as a rapid method to classify Sauvignon Blanc wines according to their geographical origin.
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