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Controlling dissolved CO2

The blending winery of Groupe Vigneron Ardéchois is located in Roums on a site entirely dedicated to the production and bottling of wines. Here, several routine analyses are carried out on batches on a daily basis before bottling. “We acquired a NomaSense CO2 to gradually replace the laboratory equipment we were using, as it is no longer produced and the maintenance service for the equipment may cease any day soon”, explains Sylvain Da Silva, Laboratory Technician of Groupe Vignerons Ardéchois. For each tank, dissolved CO2 is monitored at each stage after reception in the winery until bottling, so that the wine reaches the dissolved CO2 level required. “We carry out these analyses because some of our clients have specific requirements, plus an initial quality check at the start, middle and end of the bottling process to ensure that the batches show conformity. Moreover, we needed highly accurate equipment to follow our oenologists’ instructions, because the correct dose is essential to obtain the required organoleptic impact,” adds Sylvain Da Silva.

Obtaining the right level of CO2 for each vintage

The need for accuracy is even more important because the range of wines produced by the group is enormous. “Across the range of our wines, dissolved CO2 levels can vary from 700 to 1,400 mg/L. Getting the right level is very important for the characteristics of each vintage because this has an impact on the sensory profile of the wines”, explains Yohan Paulet, Head of Quality of Groupe Vignerons Ardéchois.
Below a certain level of dissolved CO2, white and rosé wines can lack aromatic expression, freshness and length in the mouth. CO2 concentrations in red wines can harden them, Yohan adds.  An accurate adjustment is therefore essential to obtain the right concentration of CO2 in each tank or bottle.

Multifunction use in the laboratory and cellars

The NomaSense CO2  analyser provides this precision in more than one area of use. “In contrast to bench-mounted analysers, it is now possible to carry out measurements during handling. This means we can work on the adjustment phase more accurately,” Sylvain Da Silva explains. “Moreover, the analyser takes into account the temperature at the time of measurement, which is really important in everyday working conditions, well adapted to the cellar. Wines sometimes come out of a cold stabilisation phase or undergo a simple temperature change related to the seasons, and this can have a fairly considerable impact on the result,” he says.

Very good repeatability

The results shown by the NomaSense CO2 have been very close to those obtained by the other method, with very small differences of just 50 mg/L. The repeatability is excellent and a single measurement is sufficient for a reliable result. Moreover, sampling is much easier and more representative, as the volume of the sample is 50 mL, which ensures better representativity of the real value in the vat. In the search for a new CO2 analyser, after several years the NomaSense CO2 is seen to be the ideal equipment for the management of dissolved CO2 in wines.

Sylvain Da Silva
Laboratory Technician, Groupe UVICA, Vignerons Ardéchois

About Groupe Vignerons Ardéchois

  • Almost 1,500 winegrowers on 6.500 hectares, i.e. 85% of the wine production of Sud-Ardèche
  • A leader in the production of varietal and Protected Geographical Indication wines
  • 12 vinfification wineries in each of the terroirs in the Ardèche
  • 1 inox vat room with a capacity of 50,000 hectolitres and bottling of products
  • 1 Wine Tourism area: Néovinum