The Forced Fermentation Test (FFT)

The purpose of a Forced Fermentation Test (FFT) is to determine the limit of attenuation of a specific wort.

This test may be performed by any Meadmaker with or without a lab and is a very simple and effective test which you should do periodically, whether you are having problems hitting your final gravities or not.

Once the wort is aerated, pitched, and ready for fermentation, pull a large enough sample to allow for at least one specific gravity test and any other tests you might want to run. You are going to force the fermentation to go to its maximum attenuation through high temperature and constant stirring.

Procedure

  1. Aseptically collect a sample of wort from the tank;
  2. Place on stir plate or shaker table at 27ºC (80ºF) or the optimal temperature of your yeast stain;
  3. Once the activity stops, take a specific gravity reading;

This test of fermentation should reach final gravity faster than your main fermentation and you can use this information to help make decisions about your main fermentation.

An Forced Fermentation Test is not to diagnose problems with the fermentation, because so many fermentation parameters are different between a FFT and a main fermentation, among them time, temperature, oxygenation, and yeast health, it would be impossible to diagnose exactly what went wrong, if anything, in the main fermentation. The only real data that a FFT gives you is the FG and thus the limit of attenuation for that wort.

Please do not try to drink the FFT result, because it taste terrible.

Good fermentation’s.