Understanding the Sensitivity of Grape Terpenes to Jasmonates Using In Vitro Culture and In Vivo Vineyard Experiments.

Terpene volatiles define the flavor of terpenic grape cultivars. However, grape terpene concentrations can vary 2- to 3-fold across seasons and vineyards, impacting vintage quality. The plant hormone methyl jasmonate (MeJA) stimulates grape terpene production but is expensive and can decrease berry weight and maturity. The synthetic jasmonate prohydrojasmon (PDJ) is cost-effective yet has not been evaluated on grape maturity and terpene production. Here, we performed in vitro (berry culture) and in vivo (vineyard) experiments using Gewürztraminer (Vitis vinifera L.) to evaluate the time- and concentration-dependent sensitivity of maturity parameters and terpene content to MeJA and PDJ. In vitro berry weight was reduced by high MeJA and PDJ concentration across timings. Terpenes were most sensitive to low MeJA concentration at veraison (increased 24-fold) in vitro. Moderate PDJ concentration applied at veraison doubled (increased twofold) terpene concentration in vivo without impacting berry weight or maturity. In conclusion, PDJ may provide a solution to mitigate seasonal variability in terpene production in terpenic grape cultivars.

Effects of different iron treatments on wine grape berry quality and peel flavonoid contents.

In this study, eight-year-old wine grape plants (Cabernet Sauvignon) were subjected to five different iron treatments: ferrous sulfate, ferric ethylenediaminetetraacetic acid (EDTA-Fe), ferric citrate, ferric gluconate, and ferric sugar alcohol, and conventional fertilization. Foliar spraying with clear water was used as the control treatment. The effects of different iron treatments on berry quality and flavonoid accumulation in grape peels were explored. All five iron treatments affected the sugar, acid, and peel flavonoid contents of grape berries, but the contents varied greatly among the different iron treatments. Foliar spraying with iron increased berry sugar content and reduced acid content. In addition, foliar spraying with ferrous sulfate, EDTA-Fe, ferric gluconate, and ferric sugar alcohol reduced the total anthocyanin, flavanol, and flavonol contents in the peel. The unique flavonoid monomer content of the peel was significantly higher under ferric citrate treatment than under the control and other iron treatments. Moreover, the results showed that foliar spraying with ferric citrate balanced the berry sugar-acid ratio and also increased the anthocyanin, flavanol, and flavonol contents of the grape peel, thereby improving the overall nutritional status of the berries and the final wine quality. The results obtained in this study demonstrate that different iron treatments could improve grape berry quality and clarify the effects of different exogenous iron treatments.

Zinc Biofortification in Vitis vinifera: Implications for Quality and Wine Production.

Nowadays, there is a growing concern about micronutrient deficits in food products, with agronomic biofortification being considered a mitigation strategy. In this context, as Zn is essential for growth and maintenance of human health, a workflow for the biofortification of grapes from the Vitis vinifera variety Fernão Pires, which contains this nutrient, was carried out considering the soil properties of the vineyard. Additionally, Zn accumulation in the tissues of the grapes and the implications for some quality parameters and on winemaking were assessed. Vines were sprayed three times with ZnO and ZnSO4 at concentrations of 150, 450, and 900 g ha-1 during the production cycle. Physiological data were obtained through chlorophyll a fluorescence data, to access the potential symptoms of toxicity. At harvest, treated grapes revealed significant increases of Zn concentration relative to the control, being more pronounced for ZnO and ZnSO4 in the skin and seeds, respectively. After winemaking, an increase was also found regarding the control (i.e., 1.59-fold with ZnSO4-450 g ha-1). The contents of the sugars and fatty acids, as well as the colorimetric analyses, were also assessed, but significant variations were not found among treatments. In general, Zn biofortification increased with ZnO and ZnSO4, without significantly affecting the physicochemical characteristics of grapes.

Leaf Eco-Physiological Profile and Berries Technological Traits on Potted Vitis vinifera L. cv Pinot Noir Subordinated to Zeolite Treatments under Drought Stress.

In Mediterranean areas, extreme weather conditions such as high diurnal temperatures during the growing season could tweak vine physiology and metabolism, affecting grapes' quality. Moreover, uncertainty in spatial and temporal distribution precipitation is an issue for the water resources of the vineyards, forcing the winemakers to continuously face an increasing water demand in recent decades, which has led them to non-sustainable choices for ambient (i.e., irrigation solutions). The aspiration of this experiment was to explore the effects of zeolite treatments (clinoptilolite type) on Vitis vinifera L. (potted vines) ecophysiology and berry metabolism under two water regimes. The plants were subordinated to two different predawn water potential regimes (0 ≤ ΨPD ≤ -0.4, WWCtrl and -0.4 ≤ ΨPD ≤ -0.9, WSCtrl), both associated with zeolite treatments (WWt and WSt). Gas exchanges, predawn and midday stem water potential, chlorophyll fluorescence, temperature, and relative water content were overseen on leaves at veraison, maturation, and harvest. Technological analyses were performed on the berries. Moreover, data were analyzed with principal component analysis and Pearson's correlations. This experiment supplies new evidence that zeolite applications could impact both physiological profiles (higher photosynthesis and stomatal conductance) as well as berry skin metabolism (sugar and size) of vines, giving a better skill to counteract low water availability during the season and maintaining a better hydraulic conductivity.

Productiveness and Berry Quality of New Wine Grape Genotypes Grown under Drought Conditions in a Semi-Arid Wine-Producing Mediterranean Region.

One alternative for adapting viticulture to high temperatures and the scarcity of water is the development of new varieties adapted to such conditions. This work describes six new genotypes, derived from "Monastrell" × "Cabernet Sauvignon" (MC16, MC19, MC72, MC80) and "Monastrell" × "Syrah" (MS104, MS49) crosses, grown under deficit irrigation and rainfed conditions in a semi-arid wine-producing area (Murcia, southeastern Spain). The effect of genotype, year, and irrigation treatment on the phenological, productiveness, morphological, and grape quality data was evaluated. The study material was obtained and selected as part of a breeding program run by the Instituto Murciano de Investigación y Desarollo Agrario y Medioambiental (IMIDA). The results obtained show that under rainfed conditions, the values for productive variables decreased, while those referring to the phenolic content increased. Notable variation in the parameters evaluated was also seen for the different genotypes studied. The behavior of the genotypes MC80 and MS104 under rainfed conditions was noteworthy. In addition to maintaining very adequate yields, phenolic contents, must pH, and total acidity values, MC80 fell into the best 'phenolic quality group' and MS104 returned a low º°Baumé value, ideal for the production of low-alcohol-content wines. These genotypes could favor the development of sustainable quality viticulture in dry and hot areas.

Influence of Interaction Effects of the Different Pollenizers on the Blatina Variety (Vitis vinifera L.) Grape Cluster and Seed Characteristics.

Indigenous grape varieties represent a significant potential for viticultural diversification. Due to fertilization problems, certain varieties from this group require suitable pollenizers for successful fertilization and in order to achieve high-quality grapes. The study was conducted during the years 2016 and 2017 in the vineyard in Herzegovina (southern part of Bosnia and Herzegovina). The aim of this research is to define a suitable pollenizer for the 'Blatina' variety, which has a functionally female flower. Manual pollination was performed with five different pollenizers during the flowering period by applying pollen to the 'Blatina' variety inflorescence during the full bloom stage in the early morning hours. Pollinated inflorescences were isolated, marked, and monitored until the end of the vegetation, while open-pollinated clusters were the control group. The most important characteristics of grape clusters and seeds were analyzed. The best results during the research were obtained by open pollination. The significant effect of the pollenizers was registered in parameters: cluster mass, mass of grape berries in the cluster, number of grape berries per cluster, and average seed mass. Varieties 'Zilavka' and 'Vranac' had better characteristics compared to other pollenizer varieties. The results show that the Blatina variety production with a greater number of pollenizers ensures stable yields.

Insight into how fertilization strategies increase quality of grape (Kyoho) and shift microbial community.

Organic and bioorganic fertilizers were increasingly used for agricultural soil. However, little is known on what kind of organic fertilizer application strategies can promote grape production well and how appropriate fertilization strategies improve soil properties and shift microbial community. This study investigated the improvement in soil physicochemical properties as well as their relations with microbial community structure and grape quality under different fertilization strategies. Our results found that (bio)organic fertilizer (CF1, CF2, and BF) especially combined application of organic and bioorganic fertilization (CBF) had smaller effects on electrical conductivity (EC) and pH, while it improved soil nutrients including N, P, K, and organic matter (OM) well, thereby promoting the grape quality comparing to the group without any fertilizer (CK) and with chemical fertilizer (NPK). Especially, the concentrations of Cr, Hg, Zn, and Cu were reduced by 13.63%, 12.50%, 12.52%, and 11.75% in CBF, respectively. Additionally, CF1, CF2, and BF, especially CBF, optimized the communities' composition and increased the abundance of some plant probiotics such as Solirubrobacter and Lysobacter. Nevertheless, excessive application of organic fertilizer derived from livestock manure could cause the accumulation of heavy metals such as Zn and Cu in soil and leaves, which could further influence the grape quality. Additionally, the structure of microbial communities was also changed possibly because some bacterial genera showed distinct adaptability to the stress of heavy metals or the utilization capacity of N, P, K, and OM. Our results demonstrated that combined application of organic and bioorganic fertilization showed a great influence on soil physicochemical properties, whose positive changes could further optimize microbial communities and facilitate the promotion of grape quality.

Application of Near-Infrared Spectroscopy and Hyperspectral Imaging Combined with Machine Learning Algorithms for Quality Inspection of Grape: A Review.

Grape is a fruit rich in various vitamins, and grape quality is increasingly highly concerned with by consumers. Traditional quality inspection methods are time-consuming, laborious and destructive. Near-infrared spectroscopy (NIRS) and hyperspectral imaging (HSI) are rapid, non-destructive and accurate techniques for quality inspection and safety assessment of agricultural products, which have great potential in recent years. The review summarized the applications and achievements of NIRS and HSI for the quality inspection of grapes for the last ten years. The review introduces basic principles, signal mode, data acquisition, analysis and processing of NIRS and HSI data. Qualitative and quantitative analysis were involved and compared, respectively, based on spectral features, image features and fusion data. The advantages, disadvantages and development trends of NIRS and HSI techniques in grape quality and safety inspection are summarized and discussed. The successful application of NIRS and HSI in grape quality inspection shows that many fruit inspection tasks could be assisted with NIRS and HSI.

Effect of nitrogen regulation on berry quality and flavonoids during veraison stage.

Nitrogen regulation can effectively promote the improvement of berry components and the formation of flavor compounds in wine grapes. In order to understand the effects of foliar nitrogen spraying on grape quality and flavonoid substance, took Cabernet Sauvignon as the test subject, grape leaves were sprayed by ammonium sulfate, calcium ammonium nitrate, urea, phenylalanine, and glutamate during veraison, and clear water was used as the control. The results showed that spraying ammonium sulfate could improve the contents of soluble solids, anthocyanins, and total phenols of grape berries; spraying phenylalanine significantly increased the content of titratable acid and tannin and decreased the ratio of sugar to acid in grape berries; compared with the control group, spraying glutamate could significantly upregulate some flavonol monomers; spraying calcium ammonium nitrate can adjust the monomer content of some flavanols; urea spraying significantly increased the contents of most anthocyanins, flavanols, and flavonol and increased the contents of total anthocyanins, total flavanols, and total flavonol in grape skins, laying a foundation for the improvement of the nutritional value of grapes and wine in the future.

Effects of leaf removal on hexose accumulation and the expression of sugar unloading-related genes in syrah grapes.

Leaf removal (LR) around the cluster zone is a common practice for regulating grape quality. The purpose of this study was to assess the effects of cluster-zone leaf removal, applied at the pea-size stage of berry development, on berry soluble sugar, organic acid and phenolic compound, sugar unloading-related gene expression of Vitis. vinifera L. Syrah. Four different severities of leaf removal were applied: no leaf removal (Control), removing 2 leaves above the cluster (LR1), removing 4 leaves above the cluster (LR2), and removing 6 leaves above the cluster (LR3). The three leaf removal treatments (LR), especially removing 4 leaves (LR2), resulted in significantly higher reducing sugar, soluble sugar (glucose, fructose and sucrose), total anthocyanin and citric acid contents as compared to the control group during ripening for both vintages. At harvest, the LR treatments increased the transcript abundance of most sugar unloading-related genes. In addition, VvHT3, VvHT5, VvSUC11, VvSUC12, VvSS and VvcwINV were positively correlated with both reducing sugar contents and soluble sugar contents. Our results suggest that removing 4 leaves above the cluster is useful for improving the quality of Syrah (Vitis vinifera L.) grapes in cool climate regions with excessive leaves. These findings provide insights into the molecular basis of the relationship between leaf removing and hexose (glucose and fructose) accumulation in the grape berries.

Biodiversity effects on grape quality depend on variety and management intensity.

Interactions between plants can be beneficial, detrimental or neutral. In agricultural systems, competition between crop and spontaneous vegetation is a major concern. We evaluated the relative support for three non-exclusive ecological hypotheses about interactions between crop and spontaneous plants based on competition, complementarity or facilitation.The study was conducted in Swiss vineyards with different vegetation management intensities. In all, 33 vineyards planted with two different grape varieties were studied over 3 years to determine whether low-intensity vegetation management might provide benefits for grape quality parameters. Management intensity varied with the degree of control of spontaneous inter-row vegetation. Features of spontaneous vegetation measured included total cover, total species richness and abundance of nitrogen-fixing plants. Grape quality parameters of known importance to wine making (yeast assimilable nitrogen, sugars, tartaric acid and malic acid) were determined by Fourier-transform infrared spectroscopy (FTIR). Using structural equation modelling, we evaluated hypotheses about the multivariate responses of grape quality parameters as well as the direct and indirect (plant-mediated) effects of management.Observed effects of management differed between grape varieties. Management intensity and abundance of N-fixing plants significantly influenced grape quality parameters while total richness of spontaneous plants did not have detectable effects. Abundance of N-fixing plants was enhanced by low-intensity management resulting in increased N content in the red grape variety Pinot noir, potentially enhancing grape quality, while measured soil N content did not explain the increase.Synthesis and applications. Our study shows that crop quality can be enhanced by spontaneous plants, in this case by the abundance of a key functional group (N-fixers), most likely through plant-plant or plant-microbe facilitation. However, beneficial interactions may have a high specificity in terms of facilitation partners and may have contrasting effects at low taxonomic resolutions such as crop varieties. Generally, increasing plant biodiversity in agricultural systems may increase competition with crops. Thus, the identification of suitable interaction partners and a careful balance between crop variety and spontaneous plant species may be necessary to utilize beneficial interactions and to reduce the trade-off between agricultural production and biodiversity to achieve a sustainable ecological benefit in agricultural systems.

A Review of Ladybug Taint in Wine: Origins, Prevention, and Remediation.

Ladybug taint (also known as ladybird taint) is a relatively recently recognized fault that has been identified in wines from a wide range of terroirs. Alkyl-methoxypyrazines-particularly 2-isopropyl-3-methoxypyrazine-have been determined as the causal compounds, and these are introduced into grape must during processing, when specific species of vineyard-dwelling Coccinellidae are incorporated into the harvested fruit. Coccinella septempunctata, and especially the invasive Harmonia axyridis, are the beetles implicated, and climate change is facilitating wider dispersal and survivability of H. axyridis in viticultural regions worldwide. Affected wines are typically characterized as possessing excessively green, bell pepper-, and peanut-like aroma and flavor. In this paper, we review a range of vineyard practices that seek to reduce Coccinellidae densities, as well as both "standard" and novel wine treatments aimed at reducing alkyl-methoxypyrazine load. We conclude that while prevention of ladybug taint is preferable, there are several winery interventions that can remediate the quality of wine affected by this taint, although they vary in their relative efficacy and specificity.

Investigating a Selection of Methods for the Prediction of Total Soluble Solids Among Wine Grape Quality Characteristics Using Normalized Difference Vegetation Index Data From Proximal and Remote Sensing.

The most common method for determining wine grape quality characteristics is to perform sample-based laboratory analysis, which can be time-consuming and expensive. In this article, we investigate an alternative approach to predict wine grape quality characteristics by combining machine learning techniques and normalized difference vegetation index (NDVI) data collected at different growth stages with non-destructive methods, such as proximal and remote sensing, that are currently used in precision viticulture (PV). The study involved several sets of high-resolution multispectral data derived from four sources, including two vehicle-mounted crop reflectance sensors, unmanned aerial vehicle (UAV)-acquired data, and Sentinel-2 (S2) archived imagery to estimate grapevine canopy properties at different growth stages. Several data pre-processing techniques were employed, including data quality assessment, data interpolation onto a 100-cell grid (10 × 20 m), and data normalization. By calculating Pearson's correlation matrix between all variables, initial descriptive statistical analysis was carried out to investigate the relationships between NDVI data from all proximal and remote sensors and the grape quality characteristics in all growth stages. The transformed dataset was then ready and applied to statistical and machine learning algorithms, firstly trained on the data distribution available and then validated and tested, using linear and nonlinear regression models, including ordinary least square (OLS), Theil-Sen, and the Huber regression models and Ensemble Methods based on Decision Trees. Proximal sensors performed better in wine grapes quality parameters prediction in the early season, while remote sensors during later growth stages. The strongest correlations with the sugar content were observed for NDVI data collected with the UAV, Spectrosense+GPS (SS), and the CropCircle (CC), during Berries pea-sized and the Veraison stage, mid-late season with full canopy growth, for both years. UAV and SS data proved to be more accurate in predicting the sugars out of all wine grape quality characteristics, especially during a mid-late season with full canopy growth, in Berries pea-sized and the Veraison growth stages. The best-fitted regressions presented a maximum coefficient of determination (R 2) of 0.61.

Soil and Regulated Deficit Irrigation Affect Growth, Yield and Quality of 'Nero d'Avola' Grapes in a Semi-Arid Environment.

The present work studied the effect of two consecutive years of regulated deficit irrigation (RDI) compared to rain fed management on the vegetative growth, yield, and quality of 'Nero d'Avola' grapes. The trial was conducted separately in two soils (vertisol and entisol) located at the top and bottom hillside of the same vineyard. Vertisol was characterized by greater depth, organic matter, exchangeable K2O, and total N than entisol. RDI was based on an irrigation volume at 25% of estimated crop evapotranspiration (ETc) up to end of veraison and 10% of estimated ETc up to 15 days before harvest. Predawn water potential (PDWP) was used as indicator of plant water status and irrigation timing. No difference in irrigation management was evident between vertisol and entisol. Under Mediterranean climate conditions, RDI was able to enhance grape yield and vegetative growth, especially in vertisol, but it reduced berry titratable acidity and total anthocyanins. 'Nero d'Avola' showed to adapt to drought conditions in the open field. Both soil type and irrigation regimes may provide opportunities to obtain different 'Nero d'Avola' wine quality and boost typicality.

Reduction of the Number of Samples for Cost-Effective Hyperspectral Grape Quality Predictive Models.

Developing chemometric models from near-infrared (NIR) spectra requires the use of a representative calibration set of the entire population. Therefore, generally, the calibration procedure requires a large number of resources. For that reason, there is a great interest in identifying the most spectrally representative samples within a large population set. In this study, principal component and hierarchical clustering analyses have been compared for their ability to provide different representative calibration sets. The calibration sets generated have been used to control the technological maturity of grapes and total phenolic compounds of grape skins in red and white cultivars. Finally, the accuracy and precision of the models obtained with these calibration sets resulted from the application of the selection algorithms studied have been compared with each other and with the whole set of samples using an external validation set. Most of the standard errors of prediction (SEP) in external validation obtained from the reduced data sets were not significantly different from those obtained using the whole data set. Moreover, sample subsets resulting from hierarchical clustering analysis appear to produce slightly better results.

Prohexadione-calcium on downy mildew and botrytis bunch rot epidemiology, and yield and technological and phenolic parameters of the Merlot vine cultivar in the highland region of southern Brazil / Efeitos da prohexadiona de cálcio na epidemiologia do mildio e podridão de botrytis e no desempenho vitícola da cultivar de videira Merlot em região de altitude do sul do Brasil

ABSTRACT: Prohexadione-calcium (ProCa) is a gibberellin biosynthesis inhibitor and the objective of this study was to evaluate the effect of ProCa on the downy mildew (DM) and Botrytis bunch rot (BBR) epidemiology, and the yield and technological and phenolic parameters of grape Merlot cultivar. Experiments were carried out in a commercial vineyard in São Joaquim Municipality/SC, Southern Brazil, during the 2017-2018 and 2018-2019 growing seasons. ProCa was applied at four doses and three phenological stages: A) 0 g ha−1 (control); B) 1000 g ha−1 (inflorescence fully developed); C) 500 + 500 g ha−1 (inflorescence fully developeted and full flowering); D) 500 + 500 + 500 g ha−1 (inflorescence fully developed, full flowering, and berries pea-sized). DM and BBR incidence and severity were quantified weekly from the first symptom appearance until harvest, and their epidemiology was compared according to: a) the beginning of symptom appearance; b) the time to reach the maximum disease incidence and severity; c) the maximum value of disease incidence and severity; d) the area under the disease progress curve. In general, there were significant differences in the ProCa doses for all epidemiologic parameters of DM and BBR compared with the control plot; however, there was no significant difference among the ProCa doses. The principal epidemiological variables that differentiated the effect of ProCa on the DM and BBR control were the Smax and AUSDPC. Some yield and technological and phenolic parameters were negatively affected by different doses of ProCa, but it was still a good option for DM and BBR control in highland region of southern Brazil during the 2017-2018 and 2018-2019 growing seasons.

RESUMO: A prohexadiona-cálcio (ProCa) é um inibidor da biossíntese de giberelina e o objetivo desse estudo foi avaliar o efeito do ProCa na epidemiologia do míldio da videira (MV) e da podridão de Botrytis (PB) e no desempenho vitícola da cultivar de videira Merlot. Experimentos foram realizados em um vinhedo comercial no município de São Joaquim/SC, Sul do Brasil, durante as safras 2017-2018 e 2018-2019. A ProCa foi aplicada em quatro doses e três estágios fenológicos: A) 0 g ha-1 (controle); B) 1000 g ha-1 (inflorescência totalmente desenvolvida); C) 500 + 500 g ha-1 (inflorescência totalmente desenvolvida e floração completa); D) 500 + 500 + 500 g ha-1 (inflorescência totalmente desenvolvida, floração completa e baga tipo ervilha). A incidência e severidade de MV e PB foram quantificadas semanalmente a partir do aparecimento dos primeiros sintomas até a colheita e a epidemiologia das doenças foram comparadas de acordo com: a) o início do aparecimento dos sintomas; b) tempo para atingir a máxima incidência e severidade da doença; c) valor máximo da incidência e severidade da doença; d) área abaixo da curva de progresso da doença. Em geral, houve diferenças significativas na dose de ProCa para todos os parâmetros epidemiológicos de MV e PB em comparação com o controle; no entanto, não houve diferença significativa entre as doses de ProCa. As principais variáveis ​​epidemiológicas que diferenciaram o efeito da ProCa no controle do MV e PB foram o Smax e o AUSDPC. Algumas variáveis vitícolas da cultivar Merlot foram afetados negativamente por diferentes doses de ProCa, mas ainda foi uma boa opção o uso da ProCa para o controle do MV e PB em região de altitude do sul do Brasil durante as safras 2017-2018 e 2018-2019.

Effects of Arthrospira platensis Extract on Physiology and Berry Traits in Vitis vinifera.

Several advantages on physiology, productivity, and grape quality have been reported for grapevine treated with seaweed extracts, but little is known about the importance of cyanobacterial-based biostimulants in viticulture. The purpose of this pioneering work was to analyze the broad-spectrum effects of the Arthrospiraplatensis F&M-C256 extract on Vitis vinifera L. cv. Pinot Nero grown in pots in optimal conditions and under water stress. To evaluate the effects, major physiological parameters of the plants and the quali-quantitative parameters of grape were analyzed. According to the results obtained in this study, ameliorating effects in leaf gas exchanges induced by A. platensis F&M-C256 treatments were detected in both irrigation regimes. Above all, A. platensis F&M-C256 allowed keeping stomata open without negative consequences in water potential in treated vines under water-stress conditions. In terms of berry traits, A. platensis F&M-C256-treated vines presented higher berry weight in comparison with untreated vines in both water regimes and improved berry composition in treated vines subjected to drought. The results of the present study demonstrated an A. platensis-dependent physiological response in case of abiotic stress, which prominently affects grape traits at harvest.

Development of a new strategy for studying the aroma potential of winemaking grapes through the accelerated hydrolysis of phenolic and aromatic fractions (PAFs).

Current methods for assessing grape aroma potential are based on the fast hydrolysis of precursor fractions but provide hydrolyzates of poor aromatic quality. A new strategy based on the accelerated hydrolysis of reconstituted phenolic and aromatic fractions (PAFs) extracted from grapes is herein developed. PAFs are obtained by solid phase extraction on 10 g-C18 sorbents of partially dealcoholized "mistelle", obtained from grapes treated with ethanol. Under optimal conditions, PAFs contain all aroma precursors but the most polar ones, such as those of DMS, more than 85% of the total phenolics and just traces of metal cations and of amino acids. PAFs reconstituted in model wine, aged in strict anoxia 7 weeks at 45 °C or 24 h at 75 °C, develop strong aromas. At least 30 different odorants including lipid derivatives, volatile phenols, vanillins, norisoprenoids, terpenes, bencenoids and 3-mercaptohexanol were identified by GC-Olfactometry and GC-MS. Methodological aspects of the extraction, hydrolysis and analysis are optimized and discussed.

Spraying ozonated water on Bobal grapevines: Effect on grape quality.

Ozone is a powerful oxidant that is increasingly used as sanitizing agent in the wine industry and even in the vineyard to control grapevine diseases. In this study, we evaluated the effect on grape enological quality of ozonated water spraying treatments carried out in Bobal grapevines during two consecutive harvest seasons. In the first season, ozonated water was applied once during the ripening period on grapevines trained on the traditional gobelet system (S1). In the second season, ozonated water was applied three times between the fruit set and harvest on grapevines grown on a vertical trellis system (S2). Grape quality on harvest day was evaluated through several enological and chromatic parameters, the phenolic maturity, the Varietal Aroma Potential Index (IPAv) and the phenolic and volatile composition. The S1 treatment had a positive effect on the technological maturity, the chromatic parameters, the seed maturity and the content of glycosylated aroma precursors, phenolic compounds and free terpenoids of grapes. The S2 treatment also improved the technological maturity and the content of total anthocyanins (pH 1.0) and free terpenoids, but had a negative impact on the chromatic parameters, the anthocyanin extractability and the content of glycosylated aroma precursors and phenolic compounds. Therefore, ozonated water sprayed on Bobal grapevines affected the quality of grapes, but the effect seemed to depend on the number of applications.