Determination and fractionation of metals in beer: a review.

Major, minor and trace metals are important in beer fermentation since they supply the appropriate environment for yeast growth and influence yeast metabolism. A real concern is the content of copper (Cu) and iron (Fe), which are involved in beer conditioning and ageing through reactions resulting in formation of reactive oxygen species. The reactive oxygen species readily oxidize organic compounds present in beer, changing the quality of foaming and the flavour stability of beer. In view of brewing technology and beer processing, knowledge regarding functions of metals and their speciation in brewing liquors and beer is of special significance. Metals in beer also have a certain nutritional importance, but their actual effect related to beer consumption depends on the type of species they form with low and high molecular mass organic ligands which naturally occur in beer. This review covers the determination and fractionation of metals in beer using atomic spectrometry methods. Special attention is drawn to the role of metals in beer and brewing, possible metal associations, methods of beer preparation before analysis on the total metal content, and approaches to metal partitioning in beer.