Shiraz ferments were injected with different levels of oxygen (20% and 40% O2 as gas mixtures) to assess the impact of early oxygen exposure on wine tannins and colour measures after fermentation, ...and after 2 and 12 months bottle-ageing under either Saranex™ or Saran Tin™ screw caps. The O2-treated ferments contained lower concentrations of anthocyanins and tannins, and tannin composition showed lower molecular masses, conversion yields, and proportions of prodelphinidin subunits than those from the control ferments. The colour measures and tannin characteristics of the control wines after 12 months resembled those of the O2-treated wines at 2 months bottle-ageing, and oxygen exposure during fermentation had a greater impact on tannin structure than closure type. Early oxygen exposure during winemaking may result in wines with phenolic compositions that are characteristic of more aged wines, which may reduce the need for extended wine ageing.
Display omitted
Anthocyanins are polyphenolic compounds present in grapes that are responsible for the initial colour of red wine and their incorporation into derived pigments leads to long term colour stability. ...The ability to predict the effect of process variables, either controlled by winemakers or that naturally change throughout fermentation, on the extraction of anthocyanins is vital to producing red wine of high quality. A 23 factorial experiment with additional points located at central factor conditions was used to determine the impact of temperature, sugar and ethanol concentrations on the mass transfer properties of anthocyanins from fresh Pinot noir grape solids. Factor conditions were chosen to replicate ethanol and sugar concentrations that would be found in a 14% red wine and its respective unfermented juice. A previously described mathematical model was applied to anthocyanin extraction curves to determine mass transfer coefficients and distribution constants for the generation of response surface models able to predict these mass transfer variables for dynamic fermentation scenarios. The coefficient of determination for the model solution exceeded 0.94 in all cases, demonstrating a good agreement between experimental and mathematically-derived anthocyanin concentrations. Following this, simulations of anthocyanin extraction under fermentation conditions were conducted using a previously developed wine fermentation model allowing for the prediction of extraction rates and anthocyanin concentrations under various winemaking scenarios. The extraction simulations predicted a previously observed but so far undescribed anthocyanin extraction pattern during fermentation.
Display omitted
Abstract This work studies the influence of the thickness of oak alternatives on the composition and quality of red wines. A red wine was aged in control conditions and also in contact with oak ...chips, and with thin and thick oak staves for 12 months. As expected, all the wines aged in contact with all the oak alternatives were enriched in total polyphenols and had a higher colour intensity. In addition, the contact with all the oak alternatives enriched the wine in furfural and total furans, vanilla and total aldehydes and ketones, eugenol and total volatile phenols, and in β-methyl-γ-octalactones. However, the thickness of the oak alternative seems to play an important role in the composition and quality of the wine. Specifically, the wines aged in contact with the two types of staves had a more intense colour than the wine aged with oak chips, as well as a higher total phenolic index and higher eugenol concentration. Moreover, the β-methyl-γ-octalactones concentration was higher in the wine supplemented with thick staves. Finally, the wines supplemented with the two types of staves had a higher intensity of the spicy attribute than the wine aged with oak chips. The wine supplemented with thick staves had a higher intensity of candy/pastry, toasted, smoked, complexity, aromatic intensity, sweetness, structure, and persistence. Finally, the panel preferred the wine aged with thick staves followed by, in descending order, the wines aged with thin staves, oak chips, and the control.
Today, many non-Saccharomyces strains have been verified can be positive for the development of wine anthocyanin and aroma in different fermentation scenarios. Moreover, oenological tannins are ...widely used in wine industry to improve the colour profile and aroma complexity. The aim of this work is to analyze the fermentation characters of non-Saccharomyces strains and investigate the effects of pre-fermentative addition of oenological tannins on the wine components as well as sensory properties. For this purpose, five selected non-Saccharomyces strains and grape seed tannin were used to carry out the different fermentation trials. As a result, the grape seed tannin were less likely to influence growth kinetics of non-Saccharomyces strains. Schizosaccharomyces pombe has been proved can be effective to reduce the malic acid content while increase the level of vinylphenolic pyranoanthocyanin, which is positive for wine colour stability. Pre-fermentative use of oenological tannin was verified could be beneficial for the wines fermented with non-Saccharomyces regarding the improvement of wine colour, anthocyanin composition and the complexity of volatile compounds. Nevertheless, sensory analysis showed that oenological tannin could be less effective to modify the aroma impression of non-Saccharomyces wines.
•S. cerevisiae is a dominant factor in sequential fermentations.•Oenological tannin increases higher alcohols in sequential fermentations.•Oenological tannin improves pyranoanthocyanins in S. pombe wine.•Oenological tannin slightly influences the aroma of non-Saccharomyces wines.•Oenological tannin can significantly enhance wine astringency.
Summary
Pinot noir wines were made with inclusion of different amount of whole bunches or grape stems: destemmed grapes only (DS), 30% whole bunch (WB30), 60% whole bunch (WB60), 100% whole bunch ...(WB100), and destemmed grapes with 100% stems added back (DS100). Wines were analysed using modified Somers assay and CIELab method at the end of fermentation and after a 2 years bottle ageing. CIELab analysis showed that DS100 was significantly different from all other treatments at both sampling points, and whole bunch addition treatments (except of WB30) only showed significant colour difference compared to DS treatment after bottle ageing. Total anthocyanins were significantly reduced in stem inclusion treatments at the end of alcoholic fermentation, but after the 2 years bottle ageing, only DS100 treatment showed significantly lower anthocyanins than DS treatment. Stem inclusion treatments significantly increased tannin concentration. Total anthocyanins and tannins in wines reduced by 69%–71% and 24%–31% respectively after bottle ageing.
Grape stems impact on Pinot noir wine colour.
Yeasts and wine colour Korte, Dorota; Mozetič Vodopivec, Branka; Butinar, Lorena ...
Croatian journal of food science and technology,
11/2019, Volume:
11, Issue:
2
Journal Article
Peer reviewed
Open access
Historically, yeasts from the genus Saccharomyces have been conventionally used in the production of wine and other fermented beverages. Traditionally, their main role has been the transformation of ...sugars into ethanol, however, research has shown that yeasts also influence wine aroma, texture, flavour and colour. In lieu of this, non-Saccharomyces yeasts, which have been considered as spoilage yeasts in the past, have been exploited as potential wine starters because they can improve the sensorial characteristics of wines. Because they are considered to be poor fermenters, mixed fermentations with Saccharomyces yeasts are applied either in a form of co-inoculation or sequential fermentation. Among wine characteristics, colour of red wines has special importance because it is the first wine characteristic perceived by the consumers. Red wine colour stems from anthocyanins, located in the grape skins that are extracted to grape must during maceration/fermentation. Various technological strategies in the winemaking process have already been employed to improve wine colour. One of them is yeast-mediated colour improvement employing a careful selection of yeast starters that can promote the synthesis of stable colour pigments pyranoanthocyanins from anthocyanins. The two most known groups of pyranoanthocyanins are vinylphenolic pyranoanthocyanins and vitisins. In comparison to anthocyanins they are less susceptible to pH, SO2 bleaching and oxygen presence. Their concentration in the wines differs according to the yeast strain used and the type of fermentation applied. Furthermore, wine colour can also be influenced by the cell wall adsorption capability of yeasts. Numerous studies have shown the positive influence of a careful selection of non-Saccharomyces yeast in promoting stable pigments synthesis in the production of wine. In this review, we discuss how application of different yeast species – Saccharomyces and non-Saccharomyces can enhance wine colour through different fermentation strategies applied
•Pre-fermentative juice substitution was performed for Cabernet Sauvignon and Shiraz.•Volatile and non-volatile compounds were analysed and sensory attributes were rated.•Shiraz colour and phenolic ...profiles were negatively impacted by juice substitution.•Sensory profiles of the wines differed depending on the substitution treatment.•An earlier harvest date could still be preferable for managing wine alcohol levels.
Pre-fermentative juice substitution with water or early harvest wine has the potential to produce lower alcohol wines without critically modifying colour or tannin properties and only marginally changing volatile and sensory profiles. Whether this approach is suited to producing lower alcohol wines in the absence of excessive grape ripeness remained to be determined. The current study extends on pre-fermentative approaches to alcohol management under milder grape ripening conditions and builds on an existing study with McLaren Vale Cabernet Sauvignon fruit, allowing for a direct comparison under two distinct vintage conditions. Given its importance to Australia, Shiraz was also included and underwent the same consecutive harvest and juice substitution treatments. Cultivar-dependent implications on wine chemical properties were apparent and declines in wine colour and tannin were particularly evident in Shiraz wines, although impacts on overall wine quality and sensory parameters were minor when adjusting musts within the limit of 13.5 °Baumé.
Garnacha variety is one of the most important red Mediterranean grape cultivars grown in the world. However, it may not reach optimum chromatic characteristics in warm climates such as Andalusia ...(Southern Spain). This study analyses the impact of the application of microwaves over the crushed grapes (MW) at laboratory scale over two vintages on the characteristics of Garnacha wines elaborated from grapes cultivated in a warm climate as an additional procedure to traditional red winemaking (CT) to obtain highly coloured wines. Oenological and colour parameters were measured to determine the effects of this treatment on wines throughout the winemaking process. Overall, wines made by MW had a higher phenolic content and colour intensity. The analysis of the detailed composition of the wine showed that the treatment with microwaves before the alcoholic fermentation leads to important differences in its colour properties. Thus, the treatment with microwaves induced easily perceptible changes in CIELab coordinates (lower L* and higher a* and C*
ab
values than CT). Additionally, it also showed to be significantly effective to increase the extraction of phenolic compounds from grape solids into grape juice, both globally (total polyphenol index and Folin–Ciocalteu index), and particularly regarding flavanols and flavonols content. Most of the above-mentioned significant differences remained with ageing. The reported results are promising and the treatment with microwaves in the optimized conditions seems a feasible auxiliary alternative in warm climates, where wines produced from some red grape cultivars often show suboptimal colour characteristics.
Nowadays, consumers demand red wines with deep colour, soft tannins and fruit scents, but these wines can only be obtained from grapes with complete phenolic maturity. Diverse methods have been ...proposed for measuring phenolic maturity. However, all these methods only provide the average value and do not consider any possible heterogeneity. Throughout ripening, grapes were separated according to their density, which revealed the existence of a large heterogeneity. Grapes at harvest were also separated by density in three groups. The higher the density of the grapes the higher ethanol content, pH, colour intensity, total phenolic index and anthocyanin and proanthocyanidin concentrations, and the lower the titratable acidity and bitterness of the wines. When the grapes were denser the wines were also better balanced in flavour and mouthfeel sensation. These results suggest that grape heterogeneity may influence the final wine composition and quality and therefore it should be considered at harvest.
PDF
