Bottling Kegging Spoilage Organisms Beer Styles Subject Index Send an e-mail Link to Us Fermentation is the process by which fermentable carbohydrates are converted by yeast into alcohol, carbon dioxide, and numerous byproducts. The byproducts have a considerable effect on the taste, aroma, and other characteristic properties of the beer.
Fermentation is dependent upon the composition of the wort, the yeast, and fermentation conditions.
Wort composition, as discussed in previous chapters, influences fermentation by the presence and concentration of various nutrients, pH, and degree of aeration and temperature. These factors can affect the rate of fermentation, the extent of fermentation, the amount of yeast produced, and the quality of beer produced. However, some modern ale strains are selected for use in cylindronconical fermenters because they are poor head formers, the yeast crop being harvested from the base of the fermenter. Furthermore, some ale strains work equally well in both traditional and cylindroconical fermenters, forming a yeast head in a traditional vessel and settling to the cone at the end of fermentation in the conical vessel. The factors that affect fermentation conditions are time, wort temperature, volume, fermenter design, pressure, agitation, and currents in the wort.