The Fermentation Trap

The worst thing that could possibly happen to a winemaker is to have his wine turned into vinegar (sour wine), which happens when the wine comes in contact with vinegar bacteria. These bacteria are often allowed access to the wine by their carrier, the vinegar fly. Though the wine can be attacked at any stage of the winemaking process, it is more likely that the vinegar fly is drawn to it during the secondary fermentation. This is when a winemaker needs to use a fermentation trap.

The fermentation trap, or fermentation lock, is a device used in winemaking that allows carbon dioxide to escape the fermentation vessel, while inhibiting the entry of air, thereby avoiding possible bacterial contamination. Unequivocally the most popular and commonly used design of a fermentation trap is a glass U-tube with three bulbs. This structure is fit (airtight fit) atop the fermenting vessel, ensuring that there is no leakage or else the fermentation trap will not work. The bottom of the glass stem of the fermentation lock must be above the level of the fermenting liquid.

Then the U-bend of the trap is filled with water to the bottom of the two bulbs. It is advisable to dissolve a small portion of a Campden tablet in the water for sterilization or purification purposes. Campden is a sulphite that kills vinegar bacteria introduced by that obnoxious vinegar fly.

The first stage of the fermentation process, aerobic fermentation, requires oxygen. However, when we cut off air supply by means of a fermentation trap, we force the yeast to turn to a secondary method of self-reproduction in absence of oxygen. The fermentation lock is also a telltale sign of the progress of fermentation. The fermenting wine gives off carbon dioxide, which builds up pressure inside the fermentation jar or vessel, and then pushes its way through the solution in the U-bend trap, thereby creating bubbles.

As fermentation goes on, the formation of bubbles will slowly cease and the solution will become more balanced. It is then that you should move the fermentation vessel to a warm environment to see if there is any further activity in the solution. If not, it would be accurate to say that the fermentation process has finished. And the fermentation trap has served its purpose by protecting the wine from that obnoxious vinegar fly and the vinegar bacteria.

Author: Luke Wright