Grape Composition Research Articles

Enhancing Royal grape quality through a three-year investigation of soil management practices and organic amendments on berry biochemistry

BackgroundGrape composition, characterized by mineral content, hormone levels, and antioxidant enzyme activities, fundamentally influences berry quality, nutritional value, and vine health. Various viticultural practices, particularly tillage methods and organic fertilization techniques, significantly impact these compositional parameters. This study investigates the effects of these agricultural practices on grape composition to establish optimal protocols for enhanced berry production and quality.MethodsA three year study (2020–2022) evaluated the effects of soil management on grape quality in ‘Royal’ grapes (VIVC: 349). Using a Randomized Complete Block Design with four replicates of 12 vines, the study tested three tillage methods (chisel, disc harrow, and no-tillage) and four organic fertilizers (Antep radish, broccoli, olive blackwater, and a control). Treatments were analyzed for berry mineral content (macro and micronutrients), hormone levels (auxin, ABA, zeatin, SA, JA, cytokinin and GA), and antioxidant enzyme activities (SOD, POD, CAT, APX, GR, GST, G6PD and 6PGD).ResultsBased on our results, the disc harrow tillage method in conjunction with olive blackwater fertilizer demonstrated superior mineral accumulation, yielding peak concentrations of nitrogen (3.72%), phosphorus (0.40%), and magnesium (0.41 mg/kg) during the 2021 growing season. Endogenous hormone levels exhibited treatment-specific responses, with maximum indole-3-acetic acid (17.33 ng/g) accumulation observed under no tillage control conditions in 2022, while abscisic acid concentrations peaked (49,172.53 ng/g) under no tillage with broccoli fertilization. Antioxidant enzyme activities were significantly enhanced under chisel tillage combined with broccoli fertilizer treatment, leading to optimal superoxide dismutase (1426.54 EU) and peroxidase (14,936.81 EU) activities. Principal component analysis revealed that the first two components explained 51.35% of total variance, with distinct temporal clustering of treatment effects.ConclusionThe optimal cultivation practice for ‘Royal’ grape variety was determined to be chisel tillage method combined with broccoli fertilization, which maximized both mineral nutrient content and hormone levels. These findings provide practical insights for viticulturists to optimize cultivation techniques for improved grape quality and nutritional value.Graphical

Winter pruning timing, development and quality of Cabernet Sauvignon in Southern Brazil

The objective of this study was to evaluate the influence of winter pruning timing on phenology, productivity, and quality of Cabernet Sauvignon grapes and wines in 2022/2023 production cycle. The experimental design was randomized blocks, with 3 replications, each experimental unit consisted of 5 plants. The treatments involved four pruning timings (end of May, June, July and August). Phenology assessments were beginning and end of bud break, flowering, maturation and percentage of bud break. Production was evaluated by the number of clusters per plant, weight and size of clusters, productivity per plant and per hectare. The analyzes of must were pH, total acidity and soluble solids (°Brix). In wine, pH, total acidity, sugars, alcohol, volatile acidity and color were analyzed. In the end a wine sensory analysis was carried out. The results showed that the bud break of plants pruned early, in May, occurred at the same time as plants pruned in June and July. Early pruning resulted in lower productivity. The grape must from plants pruned late, in August, showed higher total acidity and lower values ​​of soluble solids and sugars. Early pruning did not change the duration of the cultivar's phenological subperiods, nor did it bring forward the harvest in relation to the control. The different pruning times influenced productivity more than the composition of grapes and wines, indicating that it is possible to extend the pruning period.

Late-season source limitation practices to cope with climate change: delaying ripening and improving colour of Cabernet-Sauvignon grapes and wine in a hot and arid climate

The current rise in temperatures is hastening grape ripening, resulting in unbalanced wines with high alcohol content but poor colour, aroma and phenolic composition. Late-season canopy manipulation practices aimed at reducing the size of the photosynthetic apparatus after veraison have been shown to delay ripening in cooler climates. However, these methods have not directly been compared in regions with high irradiance and temperature, where berry composition is negatively affected by late fruit exposure. In this two-year Cabernet-Sauvignon trial, we compared the application of pinolene (P) to late shoot topping (T) and late above-bunch zone leaf removal (LR), all performed during the late stages of ripening, with an untreated control (C). Vine water status was monitored weekly from the time of treatment application until harvest. Gas exchange was monitored only in 2021, from treatment application through to harvest. Berry samples were collected to measure berry weight, total soluble solids, pH, titratable acidity, and the anthocyanin profile. At harvest, we assessed yield components, rated sun damage on clusters, and produced experimental wines. Wine colour and chemical characteristics were evaluated. The application of P scarcely improved gas exchange and stem water potential. Conversely, LR and T increased water potential but did not affect leaf gas exchange. T was the only treatment that significantly decreased sugar accumulation, followed by P, which showed some effect although not significant. Grape yield was not altered, despite the use of P resulted in a lower berry weight in 2022. Canopy manipulation increased lighting conditions in the canopy and caused a significant presence of damaged fruits, especially in LR. Berry anthocyanins were not affected, but LR resulted in a lower concentration of total anthocyanins in the wine and altered the anthocyanin profile. P increased wine acidity, while LR and T improved wine colour. This study suggests that late-season canopy management can effectively control ripening speeds and improve the composition of grapes and wines. However, it is essential to avoid grape overexposure by employing the appropriate techniques to ensure grape quality is not compromised.

Evaluation of the impact of vine pruning periods on grape production and composition: an integrated approach considering different years and cultivars

Several studies have already highlighted how late pruning, conducted after bud break, can result in a delay in phenology and, consequently, in ripening. However, the effects of pruning periods on vegetative and productive parameters are less well known. The aim of this study was to evaluate the effect of pruning periods on ripening kinetics, grape composition at harvest and yield parameters, considering the grapevine cultivar and year. The experimentation was conducted from 2011 to 2013 in two of the main Italian wine-growing areas: Franciacorta, in Northern Italy, and Montefalco, in Central Italy. In Franciacorta: Chardonnay and Pinot Noir were considered while in Montefalco, the varieties included were Sauvignon Blanc, Grechetto di Orvieto, Sagrantino, and Sangiovese. Six different pruning periods were compared: at leaf fall (NOV), during dormancy (DEC, JAN, FEB), in the pre-bud break period (MAR) and late, post-bud break (APR). Results obtained showed that the effects of the pruning period are clear and sufficiently replicable only considering pre-bud brake pruning (APR). The observation of the ripening kinetics highlighted in fact a delay in grape ripening for APR in both contexts as well as a lower values for the sugar-acidity ratio at harvest. In terms of grape yield, a moderately negative effect of APR was observed in Montefalco, while a more severe effect was observed in Franciacorta. This analysis gives a comprehensive understanding of the effects of pruning timing on grape yield and composition, providing viticulturists with transversally applicable information, useful for an aware management of the vineyard.

Polyphenolic compounds in Sauvignon Blanc - from grapes to wine

At harvest, the metabolic composition of wine grapes reflects the accumulated effect of the environmental conditions, the stresses endured, and viticultural manipulations applied during the growing season. The role of the winemaker is to extract and nurture this “metabolite potential” throughout the winemaking process. However, it is typically difficult to relate this grape potential to that of the eventual wines. In this study, a holistic view of Sauvignon Blanc grape and wine polyphenolic compounds was attempted by measuring these compounds from different matrices, from ripe grape tissues up to the final wine, including the submatrices, such as juice, pomace and sediment. Sauvignon Blanc vines from one vineyard block were manipulated to yield berries with distinctly different phenolic potentials by creating a high light (HL) or a low light (LL) microclimate in the fruiting zone of the canopy during the growing season. The analyses of the HL and LL berries and wines, as well as concomitant analyses of the phenolic compounds in the submatrices, allowed their tracing as they were (i) transferred from one matrix to another, (ii) lost as waste products, or (iii) affected by different winemaking practices (skin contact and/or fermentation in contact with the juice sediment) implemented in the experimental design. In berries, flavonols showed the largest increase due to sun exposure (HL treatment) but were absent from the juice samples at all juice processing stages. They were however detected in the juice sediment, together with high concentrations of organic acids and sugars. Juice processing was noted for dramatic fluctuations in metabolite concentrations suggesting intense metabolic activity in this pre-fermentation matrix. Both skin contact and sediment contact treatments delivered wines with higher concentrations of coutaric acid (the ester formed from coumaric and tartaric acid) and the flavanol catechin while epicatechin concentrations was unaffected. The higher catechin concentrations did not lead to increased perceived bitterness in the wines, except in the sediment contact treatments. The total phenolic compound concentration of wine from LL (low phenolic potential) grapes was comparable to wine from HL (high phenolic potential) grapes, when skin contact, or sediment contact treatments were employed. From a sensory perspective, the sediment contact decreased the fruity aromas of Sauvignon Blanc, while the skin contact treatment enhanced the sensorial properties of the wines made from the LL grapes, allowing increased extraction from the skin-accumulated impact compounds.

Geological Influences on Wine Quality: Analyzing Nebbiolo Grapes from Northern Italy

This study investigates the critical relationship between soil characteristics, trace element concentrations in Nebbiolo grapes, and the resulting wine quality, emphasizing the importance of terroir in winemaking. Italy, particularly the regions of Piedmont, Lombardy, and the Aosta Valley, is home to Nebbiolo, a prestigious grape variety known for its depth and aging potential in wines like Barolo and Barbaresco. The research focuses on seventeen grape and wine samples, highlighting how soil mineral composition could affect grape composition and wine characteristics. The analysis employed ICP-AES (inductively coupled plasma atomic emission spectrometry) to measure trace elements such as Al, Ba, and Mn, linking their concentrations to the soil’s geological properties. Elements were categorized into three groups based on their origins—natural soil contributions (Al, Ba, Li, Mn, Mo, Sr, Ti), those influenced by production cycles (Ca, Mg, K, Cu, Zn, Fe), and artificial sources (Co, Cr, Ni, V)—asserting that the first group serves as the most reliable indicators for tracing wines back to their vineyard origins. By establishing a chemical fingerprint for Nebbiolo wines, this research aims to enhance their authenticity and market value while providing insights into the intricate interplay between soil, grape varietals, and winemaking practices and contemporary challenges like climate change and evolving market demands.

Exogenous phenylalanine application effects on phytochemicals, antioxidant activity, HPLC profiling, and PAL and CHS genes expression in table grapes (Vitis vinifera cv. ‘Qzl Ouzum’)

BackgroundGrape (Vitis vinifera L.) is one of the most important fruit products globally and has a high nutritional value with potent antioxidant and anti-cancer activities. In current years, phenylalanine application has been particularly noticed for enhancing the nutritional quality of horticultural crops. With the aim of quality improvement, the effects of foliar application of phenylalanine at 5 concentrations (0, 100, 500, 1000, and 2000 μM) on Vitis vinifera cv. ‘Qzl Ouzum’ berry compositions were studied. The studied parameters included antioxidant activity, phenolics, flavonoids, anthocyanin, catalase and phenylalanine ammonia-lyase enzyme activity, and phenolic compounds content based on HPLC analyses (myricetin, quercetin, kaempferol, syringetin, catechin, gallic acid, caffeic acid, p-coumaric acid, resveratrol).ResultsPhenylalanine at 1000 μM increased total phenols, flavonoids, anthocyanins, and PAL enzyme activity. In addition, HPLC analysis revealed a significant accumulation of individual phenolic compounds by phenylalanine treatment. The highest values were recorded in the treatments with 100 and 500 μM phenylalanine for most of the phenolic components. Real-time quantitative RT-PCR results showed that the expression of PAL and CHS genes was induced by phenylalanine. The highest PAL and CHS gene expression was observed at 500 μM and then at 1000 μM phenylalanine treatment.ConclusionsWith the use of phenylalanine, the activity of the PAL and CHS enzyme and PAL and CHS gene expression were significantly increased and led to a greater accumulation of phenolic compounds and antioxidant activiety. This study suggests that the use of phenylalanine as a main precursor for the synthesis of phenolic compounds, can improve the phenolic composition of grapes and could be a practical approach to advance fruit quality in the production of grape cv. ‘Qzl Ouzum’.

The influence of climatic factors on the quality of grapes in the vineyards Murfatlar and Iasi

The objective of the present study was to evaluate the influence of key climatic factors (temperature and precipitation) during the growing season on the ripening and chemical composition of grapes for white and red wines in two vineyards renowned for the quality of their wines: Murfatlar and Iași, over two consecutive years (2023 and 2024). The climatic variability, characterized by high air temperatures and prolonged periods without precipitations contributed to a forced ripening of the grapes, with harvesting taking place in 2024 one week earlier than in 2023 in both vineyards. The high temperatures during ripening accelerated the accumulation rate of sugars, resulting in concentrations exceeding 200 g/L for white wine grape cultivar and over 220 g/L for red wine grape cultivars in the Murfatlar wine center, and concentrations ranging between 192.6-206.0 g/L for white grape varieties and 200.7-221.0 g/L for red grape cultivar in the Copou Iasi wine center. The results obtained, analyzed statistically, highlighted significant differences in the primary metabolites of grape berries (sugars and organic acids), influenced by vineyard and climatic conditions over the two studied years. Maintaining traditional viticultural regions remains a challenge for producers, requiring various strategies to compensate for these imbalances and to produce high-quality, balanced wines.

Impact of organic mulches on grapevine health, growth and grape composition in nutrient-poor vineyard soils

Effective vineyard management is essential for maintaining grapevine cultivation in semi-arid regions impacted by climate change. Utilising organic mulches is a viable soil management practice that improves soil properties, such as moisture retention, erosion control and soil structure. However, the effect of organic mulches on plant development and grape composition remains unclear. The present study analysed the effects of three organic mulches and two conventional soil management practices on vine physiology, agronomy and grape composition over three years under semi-arid conditions in northern Spain. Three organic mulches (spent mushroom compost-SMC, straw-STR and grapevine pruning debris-GPD) were compared with two conventional soil management practices (herbicide-HERB and tillage-TILL) in nutrient-poor soil. Physical and chemical soil properties, grapevine physiological response, leaf nutrition, growth development, yield and grape composition were evaluated in the Tempranillo cultivar. The SMC mulch improved soil water content, leaf nitrogen concentrations and vegetative growth, resulting in higher yields without compromising grape composition. Conversely, STR mulch increased soil water content, reduced soil temperature, and improved plant water status and leaf gas exchange variables without affecting vine growth and yield. However, no significant differences in grape carbon isotopic discrimination (δ13C) were observed between soil management treatments. SMC’s nutrient-rich composition, fine granularity and low C/N ratio could thus promote short-term plant development in poor-nutrient soils, and STR and GPD organic mulches may offer long-term benefits for vine development. A strong correlation was obtained between reflectance values and vegetative growth, yield and leaf nutritional content, offering a non-destructive and rapid assessment method. Overall, organic mulches represent a viable soil management alternative that enhances plant development and yield without reducing grape composition. This research provides valuable insights for winegrowers interested in suitable viticultural practices and highlights the importance of analysing soil and mulch properties to select the most appropriate organic mulch.

Climate, soil, and viticultural factors differentially affect the sub-regional variations in biochemical compositions of grape berries

Climate, soil, and viticultural factors differentially affect the sub-regional variations in biochemical compositions of grape berries

Modelling the climate changing concentrations of key red wine grape quality molecules using a flexible modelling approach

Grape (Vitis vinifera) composition is a weather-dependent determiner of wine quality. With changing climates, we can expect variation in wine-quality. To understand the extent of this we built path models to create a generalised Cabernet-Sauvignon grape quality model focusing on the total concentrations of six important molecular groups (sugar, pH, phenols, tannins, flavanols, anthocyanins). Path models statistically connect factors from input to output using a series of dependent models. As such, this modelling approach takes the output from one model and puts it into the next model as a chain. By varying climate inputs, we can simulate how changes in climate impact the final composition of the grapes throughout their ripening. We explore the impact of changes in composition under several climate change scenarios namely: changes in light, temperature, and rainfall by changing the climatic inputs to the path model. We find that, under moderate-projected climatic changes (a combination of RCP4.5 and SRES A2 and B2), we expect higher concentrations of sugars, lower acidity (a more neutral pH), and higher total concentrations of aromatic compounds (tannins, phenols, flavanols, and anthocyanins). We also find that an earlier start of ripening leads to the same result. These two results combined suggest the potential for stronger red wines in future, with more flavour-related compounds and in particular tannins which often give greater ageing potential.

Using sensory and instrumental analysis to assess the impact of grape smoke exposure on different red wine varietals in California

This study is an investigation of the impact of volatile phenols (VPs) released from burning wood during wildfires on grape composition and the resulting wines. Baseline levels of VPs in grapes and sensory differences between smoke-impacted wines and non-smoke-impacted wines were determined. The differences were related to different levels of smoke taint marker compounds in different wine matrices, using modified descriptive analysis (DA), multivariate statistics, gas chromatography mass spectrometry (GC-MS) and liquid chromatography-triple quadrupole tandem mass spectrometry (LC-QqQ-MS) of the free and total VPs, and individual bound glycosides, respectively. Across two DA panels, Cabernet Sauvignon, Cabernet Franc, Petite Verdot, Merlot, Syrah, Malbec, and Zinfandel wines made from grape originating from different areas in California were evaluated. The results show sensory differences between highly smoke-impacted and non-impacted wines with wines made from highly smoke-impacted grapes characterized as smoky, barbeque, medicinal, and having a retro-nasal ashtray character. Low smoke-impact wines based on free and total VP concentrations were not significantly different from the non-impacted wines when rated through descriptive analysis. The amount of smoke exposure was the largest contributor to smoke impact determined by sensory evaluation, but the different wine matrices from different locations and varietals also played an important role in determining the level of perceived smoke impact. The results of this study will contribute to our understanding of smoke impact and how it influences wine characteristics by relating smoke marker indicator compounds to wine sensory attributes.

Evaluation of three doses of urea applied to leaves, sprayed at pre-veraison and veraison, on Tempranillo must volatile composition over two seasons

Evaluation of three doses of urea applied to leaves, sprayed at pre-veraison and veraison, on Tempranillo must volatile composition over two seasons

Portuguese Grapevine Leaves: A Neglected By-Product with High Potential

In Portugal, grapevine leaves are generally treated as agro-industrial waste, despite being rich in bioactive compounds that offer benefits to human health. This study compiles the most relevant and current data on the phytochemical composition and bioactive properties of grape leaves from both red and white varieties cultivated in the country. These by-products are abundant in flavonoid and non-flavonoid phenolic compounds, such as flavonols, derivatives of hydroxycinnamic acids, carotenoid pigments, and chlorophylls, as well as fatty acids, which have scientifically proven antioxidant, antimicrobial, anti-inflammatory, antidiabetic, cardio-, neuro- and hepatoprotective properties, among others. The combination of these beneficial properties, along with the low toxicity of their compounds, makes grapevine leaves a by-product with great potential for use in the food, pharmaceutical, and cosmetic industries. The key challenge is to develop sustainable methods to reintegrate this by-product into the supply chain, in alignment with the sustainability goals of the 2030 Agenda.

Exploring grapevine canopy management: effects of removing main leaves or lateral shoots before flowering

Over the course of a six-year trial, we investigated the physiological response of the Swiss white cultivar Vitis vinifera Petite Arvine, rich in varietal thiols, to the following canopy removal treatments from the cluster area, i.e. from the shoot base to the sixth leaf of each shoot: A) lateral shoots only, B) lateral shoots + 50 % main leaves, C) lateral shoots + 100 % main leaves or D) main leaves only. All leaf removal (LR) treatments were performed at the pre-flowering stage.Intensive pre-flowering removal of both lateral shoots + 100 % main leaves from the cluster area (C) strongly reduced yield potential (‒47 % on average) and tended to reduce the concentration of 3-mercaptohexanol precursors (Cys-3MH) in the must (‒21 %; p-value < 0.10). The effect of LR on berry set and must composition was modulated by removing fewer main leaves (‒24 % in yield potential and ‒6 % in Cys-3MH concentration). Climate conditions primarily influenced yield and grape composition.Main leaves and lateral shoots played different physiological roles: removal of main leaves only (D) resulted in a larger leaf area (+15 %) due to the development of lateral shoots in the cluster area and a lower yield potential (‒12 %) due to fewer berries per cluster when compared one-to-one with removal of lateral shoots only (A). In the must at harvest, treatment D had higher concentrations of malic acid (+12 %), yeast-assimilable nitrogen (+10 %) and glutathione (+8 %), but there were no significant trends for TSS, pH, Cys-3MH or Folin index. The overall effects of pre-flowering LR on wine composition were negligible in the context of this trial.The study highlighted the different physiological roles of the main leaves and lateral shoots, suggesting that pre-flowering leaf removal should be used cautiously, taking into account the plant’s resilience to environmental conditions. This research is part of a broader project on grapevine canopy management in temperate climates in Switzerland.

A diel multi-tissue genome-scale metabolic model of Vitis vinifera.

Vitis vinifera, also known as grapevine, is widely cultivated and commercialized, particularly to produce wine. As wine quality is directly linked to fruit quality, studying grapevine metabolism is important to understand the processes underlying grape composition. Genome-scale metabolic models (GSMMs) have been used for the study of plant metabolism and advances have been made, allowing the integration of omics datasets with GSMMs. On the other hand, Machine learning (ML) has been used to analyze and integrate omics data, and while the combination of ML with GSMMs has shown promising results, it is still scarcely used to study plants. Here, the first GSSM of V. vinifera was reconstructed and validated, comprising 7199 genes, 5399 reactions, and 5141 metabolites across 8 compartments. Tissue-specific models for the stem, leaf, and berry of the Cabernet Sauvignon cultivar were generated from the original model, through the integration of RNA-Seq data. These models have been merged into diel multi-tissue models to study the interactions between tissues at light and dark phases. The potential of combining ML with GSMMs was explored by using ML to analyze the fluxomics data generated by green and mature grape GSMMs and provide insights regarding the metabolism of grapes at different developmental stages. Therefore, the models developed in this work are useful tools to explore different aspects of grapevine metabolism and understand the factors influencing grape quality.

The study of biochemical composition of grape and wine from Armenian selectionvariety Nrneni

Background: In Armenia, autochthonous, modern cultivars, and wild grape populations are highly diverse. Different types of wine can be produced due to the climatic zones. Grapes are a popular fruit all over the world, consisting of bioactive compounds and antioxidants, such as proanthocyanidins, anthocyanins, flavonols, organic and phenolic acids, and stilbenes. It is well known that grape varieties have different yields as well as quantitative and qualitative characteristics of the berry, which impact the quality of wine. Objective: Conduct an in-depth study of Indigenous grape varieties and clones is essential in the development of the best wine. Our focus is to specifically study Nrneni, an artificially selected Armenian grape variety. P.K. Ayvazyan, G.P.Ayvazyan created this variety by crossing a combination of Alikante Bouchet and Cabernet Sauvignion with Saperavi. The resulting product has pulp and juice that are an intense red color. Methods: In the Ararat Valley region, the grapes were hand-harvested at the end of September once they reached full technical maturity. The wine was made by the classic red winemaking method. Physicochemical analyses of grape and wine were carried out by OIV methods. Organic acids were separated and identified using liquid chromatography. A photocalorimetric method was used to determine the total phenolic compounds. Results: The chemical composition of red wine made from Nrneni grapes was assessed. In the process of wine production, storage, and maturation, grapes produce a variety of other substances, including organic acids, polysaccharides, and polyphenols, some of which contribute to the wine's sensory properties (such as flavor, color, and taste) and health benefits. Grapes are excellent sources of bioactive compounds, especially polyphenols. The total and extractable anthocyanin and flavonoid content of the Nrneni grape variety was determined. The conducted studies showed that Anthocyanins were present in high amounts of 2366.4 mg/kg. Flavonoids were present in 10183.0 mg/kg in the 2022 vintage, and 3159.9 mg/kg and 12563.7 mg/kg in the 2023 vintage. Extractable anthocyanin and flavonoid amounts were 1135.87 and 4684.18 mg/kg in 2022, 1540.32 and 5836.67 mg/kg in 2023 respectively. These indicators are also high in the wine: 502.18mg/l and 2971.15mg/l in 2022 vintage, while 975.7and 4208 mg/l in 2023 vintage. Theoretical varieties are present in 8.9 g/l and 2.02 g/l in 2022, and 6.5 g/l and 1.6 g/l in 2023. Licosaccharides, acetic acids, citric acids, and succinic acids are produced by alcoholic and malolactic fermentation. Conclusion: There is a wide range of bioactive compounds in red grapes and red wine that have been shown to have potential health benefits. According to studies, the Nrneni grape variety and the wine produced with these grapes have functional and oenological potential due to their high levels of biologically active substances, such as phenolic compounds and organic acids. Keywords: bioactive compounds, grape, organic acids, phenolic compounds, red wine.

Influence of thermal processing on physicochemical properties and fatty acid composition of grape seed oils

In this study, the oils from four different grape seed varieties were heat-treated at 40 and 80 °C for 30 minutes to determine the changes in physicochemical properties and fatty acid composition. Overall, the heat treatments increased the peroxide value and free fatty acids in the oils. The highest total phenolic content values (from 259.67 to 524.77 mg GAE/kg) for all varieties were detected at the control temperature and decreased after both heat treatment applications. Likewise, to total phenolic content and antioxidant activity of the grape seed oils decreased significantly as the temperature applied increased. The dominant fatty acid in all varieties was detected as linoleic acid (from 71.10 to 72.09%), followed by oleic (from 14.55 to 16.64%) and palmitic (from 7.45 to 8.64%) acids. Considering the effect of heat treatment on the major fatty acids, the increase in temperature caused a small decrease in linoleic acid values and a more significant increase in oleic acid values.

Effects of grapevine canopy leaning on grape composition and wine quality of ‘Bobal’

Exploring new field strategies for adapting winegrowing regions to the adverse effects of climate change becomes imperative. This study focuses on the effects of canopy architecture through the trellis systems leaning of North–South oriented vineyard’s rows vertical shoot positioned (VSP) system by 30° towards either the East (ESP) or the West (WSP) as a possible adaptation technique. The trial was conducted over two seasons in a Vitis vinifera L. cv. Bobal vineyard located in Requena (Valencia), eastern Spain, under a temperate-warm climate. The canopy leaning was considered to affect the radiation load and its timing with potential effects on vine physiology and grape metabolism and, consequently, on grape and wine quality. Leaning treatments affected vegetative growth, likely due to slight differences in vine water status. In comparison to VSP and ESP, WSP intercepts more light in the morning, when the photosynthetic capacity of the vines is at its highest. However, this results in a more negative vine water potential, which in turn leads to a reduction in vigour with no impact on yield. Musts from the WSP showed a tendency to increase total acidity compared to VSP, while ESP tended to decrease it. This was likely due to the reduction in temperature within the cluster microclimate in WSP in comparison to the ESP and VSP treatments. In addition, musts from the WSP treatment showed higher colour intensity, anthocyanins and polyphenols, potentially attributable to its more negative potentials, likely due to its more negative potentials, which may have prompted the synthesis of phenolic compounds. Consequently, wines from the WSP treatment displayed higher total acidity and lower pH, as well as higher colour intensity, anthocyanins, and polyphenolic content. In addition, WSP wines had higher concentrations of esters and higher alcohols. The improvements in grape and wine composition are likely due to an increased cluster radiation interception in the morning and reduced heating in the afternoon when VPD is higher. Our findings demonstrate that canopy management by leaning VSP vines towards the West can be a useful technique for adapting grape and wine composition to climate change and provide insights into its physiological basis.

Evaluation of passive samplers as a cost-effective method to predict the impact of wildfire smoke in grapes and wines

Wildfire smoke exposure alters grape composition, potentially resulting in "smoke tainted" wines. This has been correlated with elevated levels of smoke-derived volatile phenols (VPs) in grapes and wines. This work sought to create a predictive tool that could correlate levels of VPs in smoke with concentrations in grapes and wines. Therefore, passive samplers and Cabernet Sauvignon grapes were intentionally exposed to various smoke intensities, and wines were made thereafter. As expected, concentrations of VPs in grapes and wines were positively associated with the intensity of smoke exposure. Interestingly, levels of guaiacol in the passive samplers had a strong positive correlation with concentrations in grapes (R2=0.9999) and wines (R2=0.9998). The passive samplers were able to accurately predict guaiacol levels in smoke exposed grapes and wines with percent errors ranging from 0.08 to 11.3%. These results suggest the capability of passive samplers to act as a monitoring system in vineyards during smoke events.