Looking closely at beer with a method usually used in the biomedical field reveals far more ways to tinker with its taste.
A single type of beer contains at least 54 proteins from barley, yeast and corn, a new way of analyzing beer reveals.
The technique could help producers improve the head and other qualities of their products.
A common brand of German beer was found to contain 54 types of proteins, more than four times the amount found in any other beer, a finding brought to light with a technique normally used in the biomedical field.
Besides giving insight into what makes beer what it is, the technique could help beer drinkers learn more about what they're buying. The findings could also help manufacturers detect contamination or make a foamier, clearer or otherwise better product.
"This opens up a completely new horizon in beer analysis in general, and also in the analysis of any beverage," said lead author Pier Giorgio Righetti, of the The Polytechnic Institute of Milan. "We are now analyzing a lot of other beverages and finding a lot of surprising things that producers don't know are in their beverages."
"This could be great for consumers to track which grains a producer has been using that they are maybe not declaring," he added. "It could also help brewers refine their products. Now that we know how many trace proteins there are, producers could eliminate proteins that give a bad taste to beer or enhance the amount of proteins that give a better perfume."
Proteins are important in beer for two main reasons, said Charles Bamforth, a biochemist and professor of food science at the University of California, Davis. On the plus side, they provide a backbone of support for bubbles, which can then foam up without collapsing. On the other hand, proteins can fall out of the solution, producing a cloudiness or haze that people don't usually like.
Several studies have tried to characterize the beer proteome -- the full set of proteins in beer that survive the malting and brewing process. A French study a few years ago turned up a total of six. A Japanese study earlier this year turned up 12.
Righetti and colleagues used a different technique that allowed them to look at as much as a liter or more of beer at a time, instead of the 10 ml samples analyzed in previous studies. They collected a few samples from Italian-bottled Splügen beer.
Then, they used something called a combinatorial peptide ligand library to scan each sample for a large list of possible proteins. In this technique, small beads bind to different types of small proteins, called peptides. The beads pull the most abundant peptides out of the solution, and they magnify the scarcest ones, allowing the researchers to take a closer look at proteins that occur in just trace amounts. Previous studies have instead separated proteins from each other on a gel, requiring the use of less beer at once and often missing rare proteins that were masked by more common ones.
In total, the team reported in the Journal of Proteome Research, they found 17 barley proteins, 2 corn proteins, and 35 yeast proteins. Different types of beer would likely contain different proteins, Righetti said.
The technique is very simple, he added, and could lead to better quality control. In a separate study, he and his colleagues found traces of several fungal pests in samples of red wine, some of which make wine taste bad. In the same way, beer could become contaminated by unwelcome yeast, and protein analyses could catch the bad batches.
"My initial reaction was, 'Wow, this is interesting science,'" Bamforth said. "It's very interesting to know what proteins can be detected in beer. How easily this will be applied and how relevant it is, is a rather bigger question."
Brewers already have practical tools for adjusting the amount of foam on their beers, Bamforth said. And he finds it hard to imagine that a craft brewer would install a sophisticated lab for protein analysis. Still, he admitted, the new study was both interesting and kind of fun.
"It was only a matter of time before the word proteomics was put into beer," he said. "I prefer to talk about beeromics."