Rosés: a very precise colour objective
In rosé wines, the trend is towards pale colours. This has been the case for more than 10 years at Gérard Bertrand’s winery, well before the trend became widespread. “For every rosé wine we have a very precise colour objective: it should be constant throughout the year, i.e. from one bottling period to the next, and any changes should always be minimal. We are very demanding. For a single reference, the colour should be visually identical all year round”, says Johan Censier, Cellar and Laboratory Manager. Achieving this involves certain difficulties, because the slightest variation can be seen straight away in pale colours. Then there are constraints on wine supplies, which can vary over the year, so the task becomes even more complex. To make the management of the colour of its rosés easier, the company has acquired a NomaSense Colour P100 to obtain an extra degree of precision in the fining and blending of its wines.
Fine-tuning the colour by adapting finings
When we receive the wines, our role is to fine-tune the colour through fining and blending to get closer to the target colour.
Thanks to the measurements made by the Color, the work has been optimised by characterising the target colours of the products, comparing the colours of the wines at different stages and evaluating the impact of a particular treatment on the colour of the wine. “The Color provides a lot of data, although we basically work with the a* parameter, which indicates the level of red in the colour, b* for yellow and delta E, which indicates the difference between two colours. The equipment allows us to record a target colour, so when a raw wine is received we analyse its colour and obtain an early indication of the level of difference in relation to the target colour for the vintage to be produced.”
Grading the effect of finers on the colour
This enables us to grade the effect of the finer on the a* and b* values depending on the dose applied. For example, if the target colour has an a* of 2.3 and the raw wine has an a* of 3, fining should reduce the value of a* by 0.7. The table that emerged from the tests helps us identify the dose of the fining agent used to obtain this reduction, which enables us to quickly establish instructions for fining. Instead of performing clarification tests in the laboratory, which require handling and a certain time frame, we basically gain a week! This is excellent, because we work on a just-in-time basis.
When measuring it is also important to consider certain parameters that can influence the results. “We always need to compare what can be compared. To obtain the best possible repeatability and ensure that there is no bias, the colour analysis of the colour should be done on one’s own filtered wine. Likewise, the colour can change depending on the level of free SO2 in the wine. It is important to take this into account when measuring, as the effect of fining tends to be sharply accentuated when the level of free SO2 is high.” Working on the colour therefore requires an accurate assessment of the colour, but also the ability to analyse all the elements that could make that colour change, in order to anticipate the end result. “The investment is totally justified. With this equipment, we can anticipate the different treatments and their effect on the colour of the wine more precisely. We have been able to grade oenological products and then fine-tune the doses depending on their impact on the colour. This complements the work done upstream on the vintage wines,“ Johan Censier points out.
About Société Gérard Bertrand
- Owner and Trader in Languedoc-Roussillon
- 12 Domaines and Châteaux owned – 3 million bottles
- Own vineyard – 600 hectares
- Trading volume – 20 million bottles
- Partnerships with independent wine producers and cooperatives
- Leader in the French organic wine market
- Conversion of all facilities to biodynamic methods
- 50% of turnover comes from exports