Stage changes in the beer fermentation process Beer fermentation is a central part of the beer brewing process. The fermentation process usually manifests itself in four stages: lagging stage, active stage, resting stage and conditioning stage. As a professional brewer, he should effectively control all aspects of fermentation, so that beer can be produced according to plan. Our professional brewers will introduce the changes in the beer fermentation process during the brewing process, and provide reasonable suggestions for you to brew delicious beer.