Macrowine 2021
IVES 9 IVES Conference Series 9 Anthocyanins in tannat wines rapidly evolve toward unidentified red-coloured pigments

Anthocyanins in tannat wines rapidly evolve toward unidentified red-coloured pigments

Abstract

AIM: To assess the relationship between the reported low-stability of Tannat colour during wine storage and its pigment composition and evolution

METHODS: Twenty wines were elaborated under experimental conditions over two vintages, 2015 and 2016, eight corresponding to Tannat, and six to Syrah and Marselan. Wines were stored in darkness under cellar temperature conditions. Anthocyanins and tannins were quantified by spectrophotometric methods as well as by HPLC-DAD-ESI-MSn. Analysis were made three months after the end of winemaking, and twelve and twenty-four months later.

RESULTS: At three months, the pigment content determined by HPLC (spectrophotometer) ranged between 190-240 mg/L (370-665 mg/L) in Tannat, 200-320 mg/L (420-470) in Marselan and 100-305 (220-340) in Syrah. Colour intensity was between 17-28 AU in Tannat, 15-17 in Marselan and 10-16 in Syrah. From the second analytical date on, Tannat wines registered the lowest HPLC/spectrophotometer anthocyanin quotient, tendency increasing with wine age. Besides, Tannat wines presented much higher decreases of the HPLC anthocyanin content between analytical dates than the observed in Marselan and Syrah. This was independent from the type of pigment considered. Moreover, the unresolved HPLC broad peak was also of a higher relative magnitude in Tannat wines. This could not be explained by the tannin contents or pH measured in the wines. Spectrophotometric anthocyanin results did not show such differences among cultivars, neither in the proportion of SO2 bleachable pigments. Tannat wines showed as well the highest colour intensity decreases through time.

CONCLUSIONS

The result suggests that in Tannat wines, anthocyanins may evolve rapidly towards polymeric pigments that would still have red-bluish hues but would be less stable. These findings could be behind the low colour stability reported in literature for Tannat wines, and could be a starting point for future research.

DOI:

Publication date: September 14, 2021

Issue: Macrowine 2021

Type: Article

Authors

Guzmán Favre

Faculty of Agronomy, Universidad de la República, Av. Garzón 780. C.P., 12900 Montevideo, Uruguay ,Sergio, GÓMEZ-ALONSO, Regional Institute of Applied Scientific Research (IRICA), University of Castilla-La Mancha, Avda. Camilo José Cela S / N, 13071 Ciudad Real, Spain. José, PÉREZ-NAVARRO, Regional Institute of Applied Scientific Research (IRICA), University of Castilla-La Mancha, Avda. Camilo José Cela S / N, 13071 Ciudad Real, Spain. Diego, PICCARDO, Faculty of Agronomy, Universidad de la República, Av. Garzón 780. C.P., 12900 Montevideo, Uruguay  Gustavo, GONZÁLEZ-NEVES, Faculty of Agronomy, Universidad de la República, Av. Garzón 780. C.P., 12900 Montevideo, Uruguay

Contact the author

Keywords

colour stability and evolution, derived pigments, tannat, syrah, marselan

Citation

Related articles…

Mapping and tracking canopy size with VitiCanopy

Understanding vineyard variability to target management strategies, apply inputs efficiently and deliver consistent grape quality to the winery is essential. However, despite inherent vineyard variability, the majority are managed as if they are uniform. VitiCanopy is a simple, grower-friendly tool for precision/digital viticulture that allows users to collect and interpret objective spatial information about vineyard performance. After four years of field and market research, an upgraded VitiCanopy has been created to achieve a more streamlined, technology-assisted vine monitoring tool that provides users with a set of superior new features, which could significantly improve the way users monitor their grapevines. These new features include:
• New user interface
• User authentication
• Batch analysis of multiple images
• Ease the learning curve through enhanced help features
• Reporting via the creation of colour maps that will allow users to assess the spatial differences in canopies within a vineyard.
Use-case examples are presented to demonstrate the quantification and mapping of vineyard variability through objective canopy measurements, ground-truthing of remotely sensed measurements, monitoring of crop conditions, implementation of disease and water management decisions as well as creating a history of each site to forecast quality. This intelligent tool allows users to manage grapevines and make informed management choices to achieve the desired production targets and remain profitable.

Effects of organic mulches on the soil environment and yield of grapevine

Farming management practices aiming at conserving soil moisture have been developed in arid and semiarid-areas facing water scarcity problems. Organic mulching is an effective method to manipulate the crop-growing microclimate increasing crop yield by controlling soil temperature, and retaining soil moisture by reducing soil evaporation. In this sense, the effectiveness of different organic mulching materials (straw mulch and grapevine pruning debris) applied within the row of a vineyard was evaluated on the soil and on the vine in a Tempranillo vineyard located in La Rioja (Spain). Organic mulches were compared with a traditional bare soil management technique (based on the use of herbicides to avoid weed incidence). Mulching coverages favourably influenced the soil water retention throughout all the grapevine vegetative cycle. However, the soil-moisture variation was not the same under different mulching materials, being the straw mulch (SM) the one that retained more water in comparison with grapevine pruning debris (GPD) based-cover. The changes of soil moisture in the upper surface layer (0–10 cm) were highly dynamic, probably due to water vapour fluxes across the soil-atmospheric interface. However, both, SM and GPD reduced these fluctuations as compared with bare soils. A similar trend occurred with soil temperature. Both organic mulches altered soil temperature in comparison with bare soil by reducing soil temperature in summer and raising it in winter. Moreover, the same buffering effect for the temperature on the covered soil also remains in the deeper layers. To conclude, we could see that organic mulching had a positive impact on soil-moisture storage and soil temperature and the extent of this effect depends on the type of mulching materials. These changes led to higher rates of photosynthesis and stomatal conductivity compared to bare soils, also favouring crop growth and grape yields.

Inhibition of Oenococcus oeni during alcoholic fermentation by a selected Lactiplantibacillus plantarum strain

The use of selected cultures of the species Lactiplantibacillus plantarum in Oenology has grown in prominence in recent years. While initial applications of this species centred very much around malolactic fermentation (MLF), there is strong evidence to show that certain strains can be harnessed for their bio-protective effects. Unwanted spontaneous MLF during alcoholic fermentation (AF), driven by rogue Oenococcus oeni, is a winemaking deviation that is very difficult to manage when it occurs. This work set out to determine the efficacy of one particular strain of Lactiplantibacillus plantarum(Viniflora® NoVA™ Protect), against this problem in Cabernet Sauvignon must. The work was carried out at commercial scale and in a winery environment and compared the bio-protective culture with the more traditional approach of reducing must pH by the addition of tartaric acid. The combination of both was also investigated. The concentration of both Oenococcus oeni and Lactiplantibacillus plantarum was determined using qPCR. The adventitious Oenococcus oeni showed the most growth during AF in the control wine, whereas in the wines treated with Lactiplantibacillus plantarum a bacteriostatic effect against this species was observed. This effect was comparable to the wines treated with tartaric acid. This has particular commercial relevance for controlling the flora in musts with high pH, or when the addition of tartaric acid is either not permitted or is prohibitive for other reasons.

austrianvineyards.com: online viewer of all designations of Austrian wine

To digitally record and present all the origins of Austrian wines in the same perfect and clear way was the motivation for the Austrian Wine Marketing Board (Austrian Wine) to start with the project in 2018. In June 2021 the results were presented to the public in an online viewer showing all the designations of Austrian wine, available at https://austrianvineyards.com in a largely barrier-free manner. The online viewer provides tailored individual maps fitted to the respective zoom level. The smallest unit of wine-origins in Austria is called Ried and is displayed in a plot-specific manner highlighting areas under vine. Information on the Ried include administrative district, winegrowing municipality, cadastral municipality, large collective vineyard site, specific winegrowing region, generic winegrowing region, winegrowing area and, in many cases, an illustrative picture. Complementary data on the size, elevation (minimum-maximum), orientation (in 8 sectors plus flat) and gradient (minimum, maximum, average) are based on the area under vine according to the EU’s Integrated Administration and Control System. Additional information covers climate data. The diagrams are taken from the monthly breakdown of data in the annals of the Central Institute for Meteorology and Geodynamics, Austria provide a display of values for air temperature, precipitation, and sunshine hours for the reference year and the long-term average. Seasonal aggregated data on temperature, precipitation, and sunshine hours complete the display. Short descriptions with emphasis on geology and soil, field name in historical maps, etymology of the denomination, and main planted variety complements the available information for the main designations in the online viewer. These descriptions are compiled by winegrowers, geologists, historians, and journalists. All the information and data can be extracted to a pdf-file. Printed vineyard maps are also available. Missing content regarding wine origins in Styria will be completed in winter 2021/22.

Effect of fertigation strategies to adapt PGI Côtes de Gascogne production to hot vintage

The development of fertigation could be a possible solution to adapt PGI Côtes de Gascogne (south-western France) wine production to climate change. The goal would be to limit the negative effects of water stress on yield performance expectation (around 15 tons per hectare) and to make the use of fertilizers more efficient. This study aimed to compare the effects of three strategies of water and minerals supply on grapes and wines qualities. Two fertigation practices were compared to a rainfed control which is the current standard of the local grape growing production. The fertilizers (nitrogen and potassium) were (i) fully brought by irrigation pipe during the season, (ii) partially brought by irrigation pipe and partially on the soil or (iii) fully brought on the soil at the beginning of the season for the non-irrigated control (local standard). The trial was run on cv. Colombard trained on spur pruned with vertical shoot positioning system on a sandy-silty-clay soil over the 2020 vintage which was particularly hot for the region. Moderate to strong water deficit appeared during the growing period of the berries and held on after veraison. Irrigation strategies allowed for maintaining grapevine without water deficit and being significantly different from the control water status. Grapevine with fully or partial fertigation strategies produced 25% more yield mainly due to the increase of the bunch weight. Also, the fully fertigation showed the best ratio between yield and maturity and brought 30% less of fertilizers (both nitrogen and potassium) than the two other strategies. Finally, the analysis of aromatic compounds in Colombard wines, varietal thiols family, showed the same level of concentrations for the 3 treatments, confirming that the yield performance did not impact the aromatic potential in this trial.