Ultimately, the brewer aims to produce a beer that will satisfy the consumer time and again. To achieve this promise
to the consumer, the product needs to comply with its specification (content, taste and appearance). Control of the
microbiological status of raw materials (water, cereals and priming sugars), yeast, wort and plant sterility (fermentation
vessels, process gases, postfermentation plant and containers) (Campbell, 2003) is essential to achieve this
quest. The challenges the brewer face are numerous. Different microbial contaminants can be present in different parts
of the process due to changing environments (pH changes, aerobic vs. anaerobic nature, nutrient concentrations, ethanol
and CO2 concentrations). For a review of beer spoilage organisms and the stage of the brewing process at which
they occur, refer to Vaughan et al. (2005). For a comprehensive discussion on beer spoilage organisms, in general, refer
to Rainbow (1981) and Back (2005).