Wait this isn ' t Ganon ' s lair I ' m in Liberty City . <| sep |> the yeast needs to aerate inside the liquid in order to populate it well , stirring frequently will help kickstart the fermentation . I was doing some reading on this a couple of days ago and was surprised by what I found . If whoever ' s been editing Wiki is to be believed , strictly speaking , it ' s not actually necessary for oxygen to be present in the must since fermentation is an anaerobic process . It ' s less that yeast needs oxygen to ferment sugars , and more that certain kids of yeast can ferment despite the presence of oxygen . Certain kinds of yeast will only ferment in an anaerobic environment and will undergo cellular respiration create CO 2 and water in an aerobic one . The ones that we use for wine just seem to prefer fermentation over respiration when oxygen is present . Now I ' d like to find out why people prefer to aerate must , because when I learned to make wine , all the resources I found told me to aerate . Is it just a thing they learned from the person who taught them , who learned from the person who taught them , and so on ? And is that just a mead thing , or do winemakers do it too ?