Dark Beer Contains Higher Amounts of Iron

VALLADOLID, SpainDark beer contains higher amounts of free iron than pale and non-alcoholic beers, which helps oxidize the organic compounds during the brewing process and gives beer stability and flavor, according to a study published in the Journal of the Science of Food and Agriculture.

Researchers at the University of Valladolid analyzed 40 types of beers from all five continents and found dark beers have an average free iron content of 121 ppb compared to 92 ppb in pale beers and 63 ppb in non-alcoholic beers. The beers with the highest iron content were a dark Spanish beer (165 ppb) and a dark Mexican beer (130 ppb). Those that had the lowest levels of iron were from The Netherlands and Ireland (41 ppb and 47 ppb, respectively).

"Although these quantities are very small, the differences are apparent and could be due to the production processes or raw materials used in manufacturing," they said.

The findings indicate higher iron content in dark beer could be explained by the malt and hop extracts used to produce it. However, pale beer production includes a filtering stage in which diatomaceous earth is used. This sedimentary rock is a porous material with micro-algae used to lighten the beer; it traps the iron, causing its concentrations to decrease. Non-alcoholic beer undergoes vacuum evaporation processes to remove the alcohol. The process also removes iron ions given that they are dragged by the volatile molecules.