Background and Aims
Whole bunch fermentation is widely used in red wine production but research on whole bunch fermentation is limited, especially for cool climate Pinot Noir. Inclusion of whole ...bunches or grape stems was investigated in Pinot Noir wine production with respect to extraction of phenolic compounds and aroma production.
Methods and Results
Five Pinot Noir wines were microvinified by including grape stems or whole bunches at various levels: destemmed grapes (DS), 100% stems added back (DS100), 30% whole bunches (WB30), 60% whole bunches (WB60) and 100% whole bunches (WB100). The DS100, WB60 and WB100 treatments showed significantly increased tannin and monomeric phenolics but decreased anthocyanin in wines, which would consequently influence the mouthfeel and colour of wine. Volatile compounds responsible for green/vegetative, spicy, woody and medicinal aromas, including 3‐isobutyl‐2‐methoxypyrazine, 3‐isopropyl‐2‐methoxypyrazine, eugenol, ethyl cinnamate and phenol, were significantly increased in DS100, WB60 and WB100 treatments. The WB30 treatment did not show a significant increase of methoxypyrazines in the resultant wine.
Conclusions
By adding stems or a high proportion of whole bunches in fermentation, increased extraction of tannins may improve the mouthfeel and structure of Pinot Noir wine, but the significantly increased concentration of methoxypyrazines could negatively affect wine quality due to the enhanced green characteristics.
Significance of the Study
This study reveals the significant impact of stem inclusion during fermentation on phenolic and aroma compounds in Pinot Noir wine, which provides insights into better use of whole bunches and stems to improve Pinot Noir wine quality.
The role of microbial diversity in influencing the organoleptic properties of wine and other fermented products is well est ablished, and understanding microbial dynamics within fermentation ...processes can be critical for quality assurance and product innovation. This is especially true for winemakers using spontaneous fermentation techniques, where environmental factors may play an important role in consistency of product. Here, we use a metabarcoding approach to investigate the influence of two environmental systems used by an organic winemaker to produce wines; vineyard (outdoors) and winery (indoors) to the bacterial and fungal communities throughout the duration of a spontaneous fermentation of the same batch of Pinot Noir grapes. Bacterial (RANOSIM = 0.5814, p = 0.0001) and fungal (RANOSIM = 0.603, p = 0.0001) diversity differed significantly across the fermentation stages in both systems. Members of the Hyphomicrobium genus were found in winemaking for the first time, as a bacterial genus that can survive alcoholic fermentation. Our results also indicate that Torulaspora delbrueckii and Fructobacillus species might be sensitive to environmental systems. These results clearly reflect the substantial influence that environmental conditions exert on microbial populations at every point in the process of transforming grape juice to wine via fermentation, and offer new insights into the challenges and opportunities for wine production in an ever-changing global climate.
Direct injection Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), and ultra-high performance liquid chromatography coupled to mass spectrometry (UPLC/MS) were combined for the ...non-targeted analysis of wine metabolites. The unrivalled resolution on mass measurement allowed by the former and the separation ability of isomeric and isobaric substances by the latter, clearly increases the scope of detectable unknown metabolites in wines. Such methodology is illustrated through the comparison of chemical spaces of a young and an older Pinot noir wine. RP and HILIC chromatography could reveal up to five isomers for a given mass, throughout the explored mass range. CHO, CHOS and CHONS chemical spaces exhibited higher diversities in the older wine, illustrating a molecular oeno-diagenesis process during wine ageing, whereas nitrogen-containing compounds (CHON chemical space) appeared to be fewer in the older wine, likely due to precipitation. This methodological combination is a promising contribution to the wine metabolomics toolkit.
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The action of microorganisms on grape must during the fermentation process contributes significantly to the organoleptic properties of wine. The influence of the environment on microbial growth and ...metabolism is also well recognized. Organic winemakers rely on indigenous yeasts to drive their fermentation processes, however there are few studies that examine the possible influence of environmental factors on fermentation, and on sensory attributes of the finished product. We previously used a community metabarcoding approach to analyse the microbiome associated with organic wine produced in two differing environmental systems; outdoors (vineyard) and indoors (winery). The resultant wine from both systems were then assessed for aroma composition using GC-MS, and sensory attributes by a group of wine experts. Possible correlations between the identified microbial populations and sensory attributes were investigated to determine potential drivers. The results confirm the crucial role of the yeast, Saccharomyces in the modification of wine aroma and flavour. Moreover, analysis of the output of differential gene expression analysis (DESeq2) showed that the genus Gluconobacter might influence the ‘Mouth feel’ (astringency/tannin) and taste (bitterness) attributes of wines. Some volatile compounds were uniquely associated with a single wine. This suggests that measured differences in microbial community composition might play roles in their synthesis. Collectively, these results contribute to understanding the interplay of the complex microbial community matrix present in ‘wild’ ferments in terms of sensory and chemical characteristics of wine.
The effects of canopy treatment with chitosan and the effects of the vineyard location on the quality parameters, volatile and non-volatile profiles, and sensory profile of Pinot Noir wines from ...South Tyrol (Italy) were studied. Multivariate statistical analysis was applied to identify the most relevant compounds associated with the variability in phenolics and anthocyanins (analyzed by UHPLC-MS), volatile components (HS-SPME-GCxGC-ToF/MS), and basic enological parameters. A clear separation of low-altitude wines (350 m.a.s.l.), which had a high concentration of most of the identified volatile compounds, compared to high-altitude wines (800 and 1050-1150 m.a.s.l.) was pointed out. Low altitude minimized the concentration of the most significant anthocyanins in wines from a valley bottom, presumably due to reduced sun exposure. Wines obtained from chitosan-treated canopies, and, more particularly, those subjected to multiple treatments per year showed a higher amount of the main non-volatile phenolics and were sensorially described as having "unpleasant flavors" and "odors", which might suggest that grape metabolism is slightly altered compared to untreated grapevines. Thus, optimization of the treatment with chitosan should be further investigated.
In this study, Pinot noir wines were bottle aged for 12 and 18 months after micro-oxygenation (MOX) applied before or after malolactic fermentation (MLF) at two doses (10.8 and 52.4 mg/L/month). ...After ageing, a greater decrease in the total SO2 concentration was found in wines with the higher MOX dosage, demonstrating a long-term impact of higher oxygen exposure on wines' SO2 requirement. Meanwhile, a negative impact of MOX on wine colour development occurred over time, resulting in a large loss of colour measures (i.e., 420 nm for brown hues, 520 nm for red colour, SO2 resistant pigments, and colour intensity), which was greater with the early oxygen exposure. This was linked to a significantly lower content of large polymeric pigments in MOX treatments. Tannin concentration was, in the end, not affected by the MOX treatments. However, regarding tannin composition, considerably higher (-)-epicatechin extension units but much lower (-)-epicatechin terminal units were found with MOX treatments. In addition, a significant reduction of tannin trihydroxylation (%Tri-OH) but a higher galloylation (%Galloyl) and mean degree of tannin polymerisation (mDP) remained in wines with MOX, indicating a long-term negative influence on astringency intensity.
We identified two glycosyltransferases that contribute to the structural diversification of flavonol glycosides in grapevine (Vitis vinifera): glycosyltransferase 5 (Vv GT5) and Vv GT6. Biochemical ...analyses showed that Vv GT5 is a UDP-glucuronic acid:flavonol-3-O-glucuronosyltransferase (GAT), and Vv GT6 is a bifunctional UDP-glucose/UDP-galactose:flavonol-3-O-glucosyltransferase/galactosyltransferase. The Vv GT5 and Vv GT6 genes have very high sequence similarity (91%) and are located in tandem on chromosome 11, suggesting that one of these genes arose from the other by gene duplication. Both of these enzymes were expressed in accordance with flavonol synthase gene expression and flavonoid distribution patterns in this plant, corroborating their significance in flavonol glycoside biosynthesis. The determinant of the specificity of Vv GT5 for UDP-glucuronic acid was found to be Arg-140, which corresponded to none of the determinants previously identified for other plant GATs in primary structures, providing another example of convergent evolution of plant GAT. We also analyzed the determinants of the sugar donor specificity of Vv GT6. Gln-373 and Pro-19 were found to play important roles in the bifunctional specificity of the enzyme. The results presented here suggest that the sugar donor specificities of these Vv GTs could be determined by a limited number of amino acid substitutions in the primary structures of protein duplicates, illustrating the plasticity of plant glycosyltransferases in acquiring new sugar donor specificities.
•Fruit zone leaf removal resulted in greater concentrations of linalool, α-terpineol in wine.•Fruit zone leaf removal increased β-damascenone but not β-ionone in wine.•Fruit zone leaf removal ...resulted in higher concentrations of anthocyanins in wine.
The impacts of fruit zone leaf removal on volatile and anthocyanin compositions of Pinot noir wine were investigated over two growing seasons. Wine volatiles were analyzed by multiple techniques, including headspace solid phase microextraction-GC-MS (HS-SPME-GC-MS), headspace-GC-FID (HS-GC-FID) and stir bar sorptive extraction-GC-MS (SBSE-GC-MS). Fruit zone leaf removal affected the concentration of many grape-derived volatile compounds such as terpene alcohols and C13-norisoprenoids in wine, although the degree of impact depended on the vintage year and severity of leaf removal. Fruit zone leaf removal resulted in greater concentrations of linalool, α-terpineol and β-damascenone but had no impact on other terpene alcohols or β-ionone. Fruit zone leaf removal had no consistent impact on C6 alcohols, volatile phenols, lactones, fermentation-derived alcohols, acids, or most esters. Fruit zone leaf removal increased anthocyanins in final wine.
•The link between seasonal trend, grape ripening and wine aroma, was assessed.•Barbera and Pinot Noir wines from early harvested grapes were produced.•Norisoprenoids were quantified in wines during ...fermentation and after three months.•The highest β-damascenone content was detected in wines from less mature grapes.•β-Damascenone content increased during wine shelf life.
In view of climate change, the scheduling of an early harvest may be an agronomic option to limit wine alcohol, provided that a satisfactory content of secondary metabolites can be ensured in grapes. To better understand the link between grape ripening, seasonal trend and wine aroma, the aromatic expression of Barbera and Pinot Noir wines produced with early harvested grapes was assessed. Attention was focused on C13 norisoprenoids during both alcoholic fermentation and after three months of storage. At the end of fermentation, the highest β-damascenone content was detected in wines obtained from less ripe grapes, the content subsequently increased significantly after three months of storage; however, the levels of β-ionone decreased significantly during the same period. The reduction of wine alcohol as a result of harvesting earlier, especially for Barbera, was associated with optimal aromatic levels as well as good technological parameters.
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.
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