Monitoring of some selected heavy metals throughout the brewing process of craft beers by inductively coupled plasma mass spectrometry

Herbicides, fungicides and bactericides containing heavy metals used in agriculture make it possible to find these toxic metals in beer (Čejka et al. in Ecol Chem Eng S 18:67–74, 2011). The aim of this work was to monitor the distribution of some toxic heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) zinc (Zn), iron (Fe) and arsenic (As) during craft beers production (three types of beer produced in four different breweries). The instrumental method adopted in this investigation was inductively coupled plasma mass spectrometry. The collected results demonstrated how a very low (μg/L) heavy metal contamination (mainly Cr, Zn and Cu) was provided by raw materials (water, malt, hops and yeasts) and that these toxic metals mostly pass into the residuals (spent grains, hot trub and yeasts), so only a negligible fraction of them can be detected in beer. For example, treating hops with a high dose of pesticides containing Cu did not cause an increase in its content in final beer because a large part of copper remains in hot trub. Furthermore, the filtration phase caused the increase in the concentration of Cd, Zn, Fe and As, probably due to the use of filtration aids. These increases were insignificant healthwise [http://www. edqm.eu/en/Metals-and-alloys-used-in-food-contact-materials- and-articles-1st-Edition-(CouncilofEurope,2002)]. The craft beers produced without the final filtration did not present this increase. Pb and Ni were always found below the detection limits.