7 - Gram-positive spoilage bacteria in brewing

Abstract

It has been reported that the majority of spoilage incidents in the brewing industry are caused by Gram-positive bacteria. In most of these spoilage incidents, species belonging to the genera Lactobacillus and Pediococcus are the causative agents, leading to the acidification, hazes, sediments, ropiness, and off-flavor of beer products. These beer-spoilage lactic acid bacteria are also capable of growing at relatively low temperature and are often responsible for the abnormal fermentation and maturation processes. This chapter reviews the historical aspects and recent findings concerning beer-spoilage lactic acid bacteria, and discusses the key points regarding how to cope with these microorganisms. In addition, some other Gram-positive bacteria relevant to brewing are also described here, including nonspoilage lactic acid bacteria and endospore-forming bacteria.