METALS AND POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) IN BEER: A REVIEW

Abstract

The major cations in beer are potassium, sodium, magnesium, and calcium with the anions, chloride, sulphate, nitrate and phosphate. The minor ones include iron, copper, zinc, manganese, lead, arsenic and phosphorous. These metals are important in beer fermentation because they supply the appropriate environment for yeast growth and influence yeast metabolism. Copper and iron are involved in beer conditioning and ageing through reactions resulting in the formation of reactive oxygen species which readily oxidize organic compounds present in beer, changing the quality of foaming and flavour stability of beer. Small amounts of nitrogen-containing constituents are present and phosphorous is associated with some of these. Only trace amounts of sulphur-containing compounds are present but some of these are very potent flavouring agents. Beer is also subject to PAHs contamination due to the drying and roasting of barley. PAHs have been detected in different types of beverages such as tea, coffee, distilled drinks, wine, and fruit juice. Although PAHs are usually found in low concentrations in foods and beverages, they are one of the main factors that contribute to the onset of cancer in humans. This review covers the determination of levels of metals and polycyclic aromatic hydrocarbons in beer. The review was designed to cover the sources of metals and PAHs in beer as well as functions of metals and methods for the determination of metals and PAHs in beer. It was also designed to give insight to the health concerns of beer consumers.