Open-top Fermentors

Open-top fermentors are containers that by definition are open to the outside air, whether they are tanks that have no lids, open concrete tanks, harvest bins, or even buckets. The must is placed into the fermentor and left open to the environment during the fermentation period. Although the tank itself does not have a lid, open-top fermentors are usually used in a facility that has some cover overhead to prevent debris or other undesirable materials from falling into the fermentor. The must will be covered by a blanket of carbon dioxide produced from the fermentation once it commences, which prevents the oxidation of the wine. The wine is transferred to a closed vessel for storage once fermentation is completed and the must is pressed. Open-top fermentors are commonly used in the production of Pinot Noir, and are the container of choice if punchdowns are the form of cap management used. Open-tops are not recommended for white wine production as they can increase the chance for oxidation to occur which white wines are more sensitive to.