Fermentation effect produced during beer fermentation? Fermentation is the conversion of the glucose in the wort by yeast into ethanol and carbon dioxide gas. Before fermentation begins, the cooled wort needs to be transferred to the vessel where the yeast is added. The final fermentation is completed through three processes of primary fermentation, secondary fermentation and conditioning stages. The fermentation process generates a lot of heat, and the tanks are constantly cooled to maintain the proper temperature.