Scientists develop herb passports for beer brewery

The traditional pint is increasingly losing ground to speciality beers. Using herbs is one of the ways to give these beers their specific flavour. Research shows that the taste of these herbs depends a great deal on where they are grown and on their harvest year. Brewers can use this knowledge to maintain the flavour and quality of their product.

The place where the herbs grow and the year in which they are harvested determine the aroma they release. This aroma, in turn, has a large impact on the taste sensation that the herbs create. Researchers at the Ghent Technology Campus of KU Leuven examined ten commonly used beer herbs, including coriander, orange zest, juniper berry and aniseed. Each herb was elaborately analysed, smelled and tasted.

"We noticed a lot of differences in the chemical composition of the herbs," says researcher and master brewer Gert De Rouck. "The number of chemical components responsible for aroma is always the same but the proportions in which they’re found is sometimes very different. This has major consequences for the flavour of the beer in which these herbs are used."

In addition to performing a chemical analysis, the researchers also examined the aromas. "All components of the aroma of a herb were separated in a machine. These components were then presented to our aroma experts, led by Filip Van Opstaele. They indicated whether the component had an aroma and, when possible, which one exactly."

This way, the researchers were able to build a database containing the aroma and taste characteristics of all tested herbs. This is very interesting for scientific research and beer brewers can also use it to maintain the taste and quality of their beer year after year. Of course, they should still pay attention to the inevitable variations that characterise natural resources.

New INSTALLATION TESTS BEER IN WOODEN BARRELS

Before the rise of brew kettles made of stainless steel, beer was brewed in wooden barrels - a practice that more and more breweries are reintroducing. The characteristics of the wood have a large impact on the flavour of the beer. To allow for the scientific follow-up of this shift towards more wooden barrels, the KU Leuven lab in Ghent invested in ten new tanks. The tanks are made of stainless steel, with one wooden side panel (see image). Gert De Rouck: "What matters is not just the type of wood you use, where it grew and how it was dried. The degree of toasting is important as well. Before a wooden beer barrel could be used, the inside was ’toasted’ over a fire. How this was done also determined the impact on the flavour of the beer. We’ll be able to test all these variable in the new installation."