In spite of the bad reputation of CO2 and its effect on personnel safety, CO2 is also a friend in the winemaking process. Managed properly, a layer or blanket of CO2 on top of wine will prevent contact of wine with air. Wine exposed to air will cause many issues, including oxidation, increased activity of certain non-beneficial microorganisms and production of other undesirables (such as high volatile acidity—aka vinegar smell and taste, and chemical smells and tastes).

To the end of protecting the top of the wine when CO2 production slows down, we have a strict policy of topping up in carboys as far as possible with floating lids in tanks over 100 L. This lid prevents air from contacting wine after the production of the CO2 blanket is reduced -which occurs after a Brix of about 8, or a specific gravity of about 1.030. In addition to floating lids, we also use Nitrogen to assist with our oxygen management practices. In these videos, Peter explains the processes.