The benefits of dark beer

The darker the beer, the more iron it contains according to Spanish researchers.

A team from the University of Valladoid in Spain analysed 40 types of beer from five continents – 17 Spanish beer brands and 23 from other countries – including 28 pale, six dark and six non-alcoholic beers.

They discovered that dark beers have an average free iron content of 121ppb, compared to 92ppb in pale beers and 63ppb in their non-alcoholic counterparts.

“Although these quantities are very small, the differences are apparent and could be due to the production processes or raw materials used in manufacturing,” said Carol Blanco, professor of food technology at the university.

The beer with the highest iron content was a dark Spanish beer – with 165ppb – and a dark Mexican beer, which had 130ppb. Those with the lowest level of iron content originated in The Netherlands – 41ppb – and Ireland, which had 47ppb.

The study – published in Journal of the Science of Food and Agriculture – indicated that the higher iron content in dark beer could be explained by the malt and hop extracts used to produce it.

The filtering stage in pale beer production uses diatomaceous earth – a sedimentary rock with micro-algae which traps the iron, causing the concentrations to decrease. Non-alcoholic beer is subjected to vacuum evaporation to remove the alcohol, which also removed the iron.

The research also allowed the team to validate a technique they developed to analyse iron – differential pulse adsorptive stripping voltammetry. The technique is an ultra-sensitive, selective, rapid, reliable and cost-effective method.

Measuring the level of iron – and other metals – in beer is important because they are essential for human health, but they are also relevant in the brewing process as levels of metals can determine its organoleptic characteristics, stability and quality.

Free iron in pale, dark and alcohol-free commercial lager beers http://www.ncbi.nlm.nih.gov/pubmed/21328359