Raka-Ray agar is a medium for the selective isolation of lactic acid bacteria from beer and brewing processes, for in-process quality control of beer. Contamination of beer and the beer brewing process by members of the lactobacillus family leads to spoilage, mainly through their production of metabolic products that affect the flavour of the final product. The detection of these organisms is complicated by the diversity of their nutritional and environmental needs. A number of different formulations have been described for the isolation of lactic acid bacteria from brewing products and processes. The Raka-Ray agar was developed by adding various growth-promoting compounds to Universal Beer Agar. This work led to the recognition that the addition of sorbitan monooleate, liver extract and N-acetylglucosamine produced superior growth compared to the standard formulation of Universal Beer Agar.