Science Scene: How isotopes can help determine a beer’s origin

Paepin Goff

Austin is a city where smart is sexy, science is cool, and beer is trendy. Present at any South By Southwest event or concert at Stubb’s are hordes of young professionals consuming a considerable amount of craft beer. Deep in intellectual discussions flecked with brew-speak, beer connoisseurs guess the origin and romanticize over color and production method. Fortunately for bored dinner guests and wine afficianados, these guessing games could be made shorter with the help of science.   

Scientists are currently investigating the purity of different brewski brands through the study of beer chemistry. Beer snobs with “sophisticated palettes” may not know that their favorite lagers and ales are less pure than microbrewed counterparts, but if beer purity means anything to pretentious 20-somethings, then chemistry could be a game changer.

If, for instance, the neutron belonged to the element carbon, there would be six, seven or eight neutrons. These isotopic variations of the same element with different total numbers of neutrons are isotopes 12C, 13C and 14C.

These isotopes provide scientists with detailed information about the different plants used to make beer. Plant evolution led to two distinct pathways of photosynthesis, C3 and C4, and, consequently, there are two different ranges of isotope value ratios present in each pathway.

Beer is traditionally made from barley and hops that follow a C3 pathway. If a sample of beer has isotope values outside of a typical C3 range, it is a clue that something is affecting the beer’s purity. For instance, corn follows a C4 pathway and is chemically detectable.

If some beers are more pure than others, it makes sense that cheap beer would have more fillers with respect to their undiluted counterparts. In a 2002 analysis of 160 beers from around the world, a team of scientists found this to be the case.   

In the study, German-brewed beer was found to contain only C3 carbon, showing no signs of fillers. In the United States, fillers were most commonly added to lagers and ales originating from large breweries. On the other hand, microbrews from the United States contained little to no fillers.

The research was proposed as a guideline for detecting impurities in beer in order to hold breweries accountable. In 2014, a different research team investigated substitute products in beer from around the world. In all but one case, 162 beers were pinned down by country of origin using isotope analyses. Though none of the 162 samples violated any purity laws, the 2014 study provided a method for counterfeit beer detection.

These studies can benefit the scientific community by drawing attention to current research and offering consumers confidence in their purchases. At the end of a long day, chemistry is pretty cool, but the beer is ice-cold.