Abstract
There is evidence that vineyard yeast communities are regionally differentiated, but the extent to which this contributes to wine regional distinctiveness is not yet clear. This study ...represents the first experimental test of the hypothesis that mixed yeast communities—comprising multiple, region-specific, isolates, and species—contribute to regional wine attributes. Yeast isolates were sourced from uninoculated Pinot Noir fermentations from 17 vineyards across Martinborough, Marlborough, and Central Otago in New Zealand. New methodologies for preparing representative, mixed species inoculum from these significantly differentiated regional yeast communities in a controlled, replicable manner were developed and used to inoculate Pinot Noir ferments. A total of 28 yeast-derived aroma compounds were measured in the resulting wines via headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. Yeast community region of origin had a significant impact on wine aroma, explaining ∼10% of the observed variation, which is in line with previous reports of the effects of region-specific Saccharomyces cerevisiae isolates on Sauvignon Blanc ferments. This study shows that regionally distinct, mixed yeast communities can modulate wine aroma compounds in a regionally distinct manner and are in line with the hypothesis that there is a microbial component to regional distinctiveness, or terroir, for New Zealand Pinot Noir.
This study shows that mixed yeast communities of vineyards impact wine aroma in a regionally distinct manner in New Zealand Pinot Noir.
•Nanoparticle tracking analysis (NTA) was used to analyze particle size in wine.•Tannin, monomeric phenolics and an ethanol-insoluble fraction were prepared from wine.•The insoluble fraction ...contained complexed polysaccharide, protein and large tannins.•Tannin analyzed by NTA gave particles of 75–89nm and larger particles of ≅200nm were formed on addition of the ethanol-insoluble fraction.•This is the first instance of NTA in wine and its use for the analysis of colloids.
Precipitates were prepared from two compositionally different Pinot noir wines with addition of excess ethanol, and contained primarily polysaccharide, tannin and protein. The ethanol-soluble material was further fractionated into polymeric (tannin) and monomeric phenolics. Tannin associated with precipitates was of a higher molecular mass than that remaining in ethanolic solution. Wine fractions were reconstituted at the ratios of the original wine and analyzed using nanoparticle tracking analysis. The average particle size of the tannin fraction was 75–89nm, and increased when combined with the precipitate (≅200nm). Addition of the monomeric fraction to the tannin–precipitate complex increased both the incidence and concentration of smaller particles, reducing the average particle size. The formation of aggregates occurred in all fractions and only minor differences in particle size distribution were found between wines. Differences in particle concentration between wines appear to be due to differences in the total concentration of macromolecules rather than compositional differences.
γ-Nonalactone is a linear aliphatic lactone ubiquitous in wine, associated with coconut, sweet, and stone fruit aroma descriptors. Little research has been conducted looking at the importance of this ...compound to New Zealand (NZ) wine aroma.
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H
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-γ-Nonalactone, a novel isotopologue of γ-nonalactone, was synthesised in this work for use in a stable isotope dilution assay (SIDA) for quantification of γ-nonalactone in NZ Pinot noir wines for the first time. Synthesis was carried out using heptaldehyde as the starting material, and
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C atoms and
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H atoms were introduced via Wittig olefination and deuterogenation steps, respectively. The suitability of this compound as an internal standard was demonstrated by spiking model wine at normal and elevated conditions during sample preparation, with subsequent analysis via mass spectrometry showing stability of
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-γ-nonalactone. A model wine calibration, with concentrations of γ-nonalactone from 0 to 100 µg L
−1
, was shown to have excellent linearity (
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> 0.99), reproducibility (0.72%), and repeatability (0.38%). Twelve NZ Pinot noir wines, representative of a range of NZ Pinot noir–producing regions, prices, and vintages, were analysed by solid-phase extraction–gas chromatography–mass spectrometry (SPE-GC–MS). The concentrations of γ-nonalactone ranged from 8.3 to 22.5 µg L
−1
, the latter of which was close to the odour detection threshold of this compound. These findings provide a basis for further research into γ-nonalactone and its impact on NZ Pinot noir aroma and provide a robust method for the quantification of this compound in Pinot noir.
Graphical abstract
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•Topoclimate variations are classified with the Solar Radiation Identity (SRI).•SRI identifies geographical conditions with noticeable impact on wine quality.•The new classification ...has been tested Pinot Noir and Sauvignon Blanc grape varieties.•The SRI directly marks differences in the varietal phenolic content.•Geographical identity classification supports decision-making in viticulture.
A new approach for applied research and decision-making in the sector of viticulture related to the mountain territory and the global warming phenomenon is purposed. A high-resolution topoclimate model 5 m × 5 m was applied to classify the different vineyard characters in South Tyrol, an Italian wine region where a considerable dense concentration of different top quality wines is present. Determining the connections between the territory and microclimate can lead to more accurate assessments of the vineyards natural identities and the characteristics of their wines. The results of our geospatial statistical analysis on all the about 26,000 vineyards are used to generate a geographical classification index termed the Solar Radiation Identity (SRI). This quantitative index can characterize the topoclimatic potential of each local vineyard but also be extended to other wine regions with a global perspective. The SRIv index rate can be related to the biosynthetic activity of the vines as well as to the quality of the vineyard's grapes and wine. A qualitative analysis of zones with different SRIv distinguished manifest differences in the concentration of natural polyphenols anthocyanins and tannins in Pinot Noir wines. In the Sauvignon Blanc wines from some specific vineyards with low SRIv, the varietal characteristics that enhance the thiol molecules are quite evident and singular. The proposed analysis method can support the correct matching between vineyard and grape varietals, as well the process of identifying ideal sites for new vineyards, by recognizing original areas that may increase ecological diversity or can favor the quality production. This topoclimate classification can also provide insights into how to reduce the wine product vulnerability, in terms of its protect designation of authentic geographical origin or to better adapt the vine varieties to climate change.
The frequency and intensity of wildfires have been increasing over the last 50 years and negatively impacted the wine industry. Previous methods of smoke mitigation during grape processing have shown ...little impact in reducing smoke taint in wines. Therefore, a novel method of using edible spray coatings for vineyard application was developed to help prevent volatile smoke phenol uptake in wine grapes. Four cellulose nanofiber‐based coating suspensions incorporated with chitosan and/or β‐cyclodextrin were evaluated. Films derived from the coating suspensions were exposed to volatile phenols found in wildfire smoke (guaiacol, 4‐methyl guaiacol, m‐cresol, o‐cresol, p‐cresol, syringol, and 4‐methyl syringol) and evaluated with ultraviolet‐visible spectroscopy where the results indicated that the coatings could uptake smoke phenols in varying degrees. The coatings were also applied in a vineyard at three different application times during grape growth: pea‐sized, pre‐bunch closure, and both at pea‐sized and pre‐bunch closure. The results showed that the application time did not have a significant (p < 0.05) effect on berry size, weight, °Brix, pH, or titratable acidity. The type of coating, time of application and washing were found to impact the number of volatile phenols in the grapes after a smoke event. Results from this study indicated that edible coatings could help mitigate smoke uptake in wine grapes without sacrificing the growth and key composition parameters of wine grapes.
Practical Application
This research provides a novel spray coating that can be applied to wine grapes in the vineyard to potentially mitigate volatile smoke compounds in wine grapes without impacting fruit growth and key compositional parameters of wine grapes, thus maintaining high quality of wines for consumers. Results from this study can also be potentially applied to other agricultural commodities to solve the issues caused by the wildfire smoke.
Summary
Bunch rot caused by Botrytis cinerea infections is a notorious problem in grapevine cultivation. To produce high quality fruits, grapevine plants are treated with fungicides, which is cost ...intensive and harmful to the environment. Conversely, loose cluster bunches show a considerably enhanced physical resilience to bunch diseases. With the aim to identify genetic determinants that modulate the development of bunch architecture, we have compared loose and compact 'Pinot noir' clones. Loose cluster architecture was found to be correlated with increased berry size, elongated rachis and elongated pedicels. Using transcriptome analysis in combination with whole genome sequencing, we have identified a growth‐regulating factor gene, VvGRF4, upregulated and harbours heterozygous mutations in the loose cluster clones. At late stages of inflorescence development, the mRNA pools of loose cluster clones contain predominantly mRNAs derived from the mutated alleles, which are resistant to miR396 degradation. Expression of the VvGRF4 gene and its mutated variants in Arabidopsis demonstrates that it promotes pedicel elongation. Taken together, VvGRF4 modulates bunch architecture in grapevine 'Pinot noir' clones. This trait can be introduced into other cultivars using marker‐assisted breeding or CRISPR‐Cas9 technology. Related growth‐regulating factors or other genes of the same pathway may have similar functions.
Significance Statement
In grapevine, clones with loose cluster architecture show an enhanced physical resilience to Botrytis cinerea infections, however the genetic basis of this phenotype was not known. A combination of RNA‐seq and DNA‐seq analysis of 'Pinot noir' clones revealed that heterozygous mutations in the growth‐regulating factor gene VvGRF4 are associated with the loose cluster phenotype, which can be introduced into other cultivars using marker‐assisted breeding or CRISPR‐Cas9 technology.
Mature berries of Pinot Noir grapevines were sampled across a latitudinal gradient in Europe, from southern Spain to central Germany. Our aim was to study the influence of latitude-dependent ...environmental factors on the metabolite composition (mainly phenolic compounds) of berry skins. Solar radiation variables were positively correlated with flavonols and flavanonols and, to a lesser extent, with stilbenes and cinnamic acids. The daily means of global and erythematic UV solar radiation over long periods (bud break-veraison, bud break-harvest, and veraison-harvest), and the doses and daily means in shorter development periods (5–10 days before veraison and harvest) were the variables best correlated with the phenolic profile. The ratio between trihydroxylated and monohydroxylated flavonols, which was positively correlated with antioxidant capacity, was the berry skin variable best correlated with those radiation variables. Total flavanols and total anthocyanins did not show any correlation with radiation variables. Air temperature, degree days, rainfall, and aridity indices showed fewer correlations with metabolite contents than radiation. Moreover, the latter correlations were restricted to the period veraison-harvest, where radiation, temperature, and water availability variables were correlated, making it difficult to separate the possible individual effects of each type of variable. The data show that managing environmental factors, in particular global and UV radiation, through cultural practices during specific development periods, can be useful to promote the synthesis of valuable nutraceuticals and metabolites that influence wine quality.
Real-time process metrics are standard for the majority of fermentation-based industries but have not been widely adopted by the wine industry. In this study, replicate fermentations were conducted ...with temperature as the main process parameter and assessed via in-line Oxidation Reduction Potential (ORP) probes and at-line profiling of phenolics compounds by UV-Vis spectroscopy. The California and Oregon vineyards used in this study displayed consistent vinification outcomes over five vintages and are representative of sites producing faster- and slower-fermenting musts. The selected sites have been previously characterized by fermentation kinetics, elemental profile, phenolics, and sensory analysis. ORP probes were integrated into individual fermentors to record how ORP changed throughout the fermentation process. The ORP profiles generally followed expected trends with deviations revealing previously undetectable process differences between sites and replicates. Site-specific differences were also observed in phenolic and anthocyanin extraction. Elemental composition was also analyzed for each vineyard, revealing distinctive profiles that correlated with the fermentation kinetics and may influence the redox status of these wines. The rapid ORP responses observed related to winemaking decisions and yeast activity suggest ORP is a useful process parameter that should be tracked in addition to Brix, temperature, and phenolics extraction for monitoring fermentations.
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