Occasionally we will come across customers that like to ferment their wine in a pail with an airlock on it. This in days past, was the suggested way to begin your wine. Today , we realize it is a no-no.
Yeast requires high levels of oxygen in order to do their wonderful job of taking sugar in the must (grape juice and concentrate) and making alcohol. To do this breeding yeast devours dissolved oxygen in your fermenting wine. This is especially important during the early hours and days of fermentation. Alcohol conversion doesn’t start to occur until the yeast reaches a certain population. By providing adequate oxygen this critical population is achieved earlier. For that matter warmer temperatures also encourage the yeast to breed.
Excluding the oxygen from the primary pail through the use of an airlock can slow down fermentation. You should choose a primary pail that allows air, but not fruit flies into the fermenting wine. The kit instructions also tell you to whip your wine or stir it very well before pitching the yeast. This is partially due to mixing the added water but more importantly it is to introduce oxygen into the must.
By racking (transferring) your wine to the carboy, you are also introducing oxygen to your wine. The oxygen “kick” we help aerate your wine and provide the yeast with a hit of oxygen to properly finish fermentation. After your wine has finished active fermentation oxygen is not required, and can actually be detrimental. That’s why we place the water-filled airlock on the carboy.