3.2.5.b Sulphite management

What is the advantage of sulphiting at the beginning of harvest?

Sulphur dioxide has multiple properties: it is an antiseptic, antifungal, antioxidant, and solvent. In wine, we speak of Free SO2, Combined SO2, Total SO2 and Active SO2.

Sulphur use is no longer systematic and the quantities added have been drastically reduced. However, it continues to be used in certain cases at the beginning of the harvest and/or during vatting for several reasons:

• It prevents harmful micro-organisms from developing and allows the selection of Saccharomyces type yeasts that are more tolerant of sulphur. This therefore enables safer natural fermentation.

• In the case of botrytized grapes, sulphiting inhibits laccase (an oxidation enzyme).

In what instances is it possible not to add sulphur?

The key to sulphur-free winemaking is a healthy, ripe harvest. Several parameters make it possible to manage a sulphur-free vinification:

• A good inerting system from vatting to early fermentation to avoid potential deviations
• An efficient temperature control system to quickly begin the fermentation at the right time (whether or not there has been a cold maceration period)
• The use of a fermenting starter vat or yeast inoculation to ensure the prompt onset of fermentation. The latter is optional, but is effective in ensuring smooth fermentation.

How much should be used and in what form?

The typical dose ranges from 0 to 8 g/hl but, in general, a maximum of 4 g/hl is used when necessary. The majority of the Artémis Group's estates, such as Domaine d'Eugénie and Château Latour, are moving towards a decrease or even total elimination of SO2 at vatting.

The most practical form to use at this stage is the liquid form (sulphur dioxide, potassium bisulphite, potassium metabisulphite, etc.). The choice of the solution will depend mainly on the concentration of SO2 (from 6 to 18% depending on the product) and the product formulation.