If you’re anything like me, it begins as a sweet, shapeless sense of anticipation at the margins of the mind. By the time I am home, it has become more than a gratifying thought, enshrined in ritual and expectation. And yet, how often do we consider the marvel of alchemy that made it possible? The remarkable process that turned simple grape juice into this toothsome wonder? It’s easy to give recognition to the quality of the fruit or the skill of the winemaker, but without the love-hate relationship between yeast and oxygen, the party simply cannot start.
As both catalysts and custodians of fermentation, yeast takes its job seriously. These little powerhouses can start and finish juice fermentation on their own but oxygen helps them do a better job of converting sugars to alcohol and carbon dioxide. It also makes them more resilient, helping them to ferment all the sugars in the must to absolute dryness. There is always some oxygen present in the freshly pressed juice, and the yeast happily mops it up.
Oxygen is essential at all stages of the winemaking process, but how much depends on the stage and the variety and style of wine. Too much oxygen in the finished wine can reduce its shelf life and quality. Whereas lower levels of oxygen can furnish the wine with a much sought-after, earthy, flinty, and mineral expression, as it sits in the cellar. It is a true creator/destroyer.
The dynamic tension that arises from yeast and oxygen’s co-dependence during fermentation can be manipulated by the winemaker depending on what he or she is … Read more >