The growing popularity of hoppy beers may be due to their fruity aroma. That aroma comes from several compounds including thiols, terpenes and esters. Thiols are present in beer in only very small amounts, but that is all that is needed to create that desired flavor and aroma. Unfortunately, in such small quantities, they are also hard to detect.

Brewers in search of a way to accurately track thiols in beer have been limited to methods that are either not sensitive enough or that require potentially harmful substances. However, researchers have found a new automated process to assess thiols at very low concentrations, without solvents.

Prior studies were able to analyze some, but not all, of the thiols brewers want to know about, and resulted in complicated, multi-step procedures. Another process used coated polymers in the air above wine to convert aerosolized wine thiols to compounds that are measured more easily. This method is not sensitive enough to measure the small amounts in beer.

The goal to create a safer, faster, more sensitive approach led scientists from the Research Institute for Beer and Beverage Analysis in Berlin, Germany, to modify the sample preparation method used in wine analyses Source: American Chemical SocietySource: American Chemical Societyto convert the aerosolized thiols to compounds that have higher analytical density. They adapted and applied an approach using tandem mass spectrometry to detect and measure the highest possible amount of the resulting compounds.

The researchers tested their method on 13 commercially available beers from several countries. All were made with hop varieties likely to have high thiol content. The distribution of thiol content found in the selected beers was consistent with earlier studies. This method, therefore, meets the requirements to detect thiols in beer in a safer, simpler and quicker manner, the researchers said.

One surprise came when the team was able to detect only one of the three thiols expected in a beer containing real grapefruit juice. This, they said, suggested that the grapefruit most likely contributed scent compounds other than thiols.

The research is published in the Journal of Agricultural and Food Chemistry.

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