Exploring the roots of modern hopped beer is the second topic of Kirin Brewery's "Five Thousand Years of Beer" research project launched in 2001.

The study focused on gruit beer, once the standard throughout much of Europe. "Gruit" was a mixture of crushed herbs that gave flavor and aroma to the beer in the same way that hops does today. Kirin embarked on an in-depth study to recreate the beer and experience a taste that has been largely forgotten since the Middle Ages, with a world-renowned brewing expert from Germany and a cultural historian from Toyo University. Under their direction, with scant historical references and little prior research on the brewing practices of that age, period-authentic brewing equipment was devised and used to successfully brew a medieval gruit beerãrecreating the taste of a millennium ago.

Kirin prepared its gruit by pulverizing six herbs, these being sweet gale (Myrica gale), a favorite of medieval brewers for its bracing scent, ground ivy, betony, fennel, peppermint and mugwort. Used in place of hops in a brewing process that is fundamentally little changed today (except for the inclusion of oats), the gruit herbs gave the resulting beer a rich body, complex fragrance and refreshing bitterness that accompanied an alcohol content of around 8%.

from the Mitsubishi Monitor (february & march 2005)

Until hops became the main additive of beer, a beer using a blend of savory herbs was popular in medieval Europe. It was called "gruit beer", but no one today knows what it tasted like. We recently reproduced the beer ourselves to discover its flavor. We used oat, wheat, and barley malt in the reproduction process. We had great difficulty acquiring "sweet gale" (Myrica gale), an essential herb for gruit beer, because it has become rare in nature and there are restrictions on taking it. However, we finally managed to obtain it from Scotland. Eventually, we selected 36 different types of herbs, such as sweet gale, ground ivy, and anise. As for yeast, we used a top-fermenting yeast.

In laboratory tests and a pilot experiment on a 200-L scale, the procedure for saccharification, fermentation, and the final selection of herbs and their quantities were determined. In the actual brewing process, we used wooden casks for the brewing and fermentation, as well as a copper coolship, to reproduce medieval brewing techniques. We also stirred the brew by hand, which was the traditional method in those times. The reproduced gruit beer has an alcohol content of 8% and an original extract of 20°P. It has a bittersweet taste and is rather stout and strong. The "top note" of sweet gale is perceived when the drink is first smelled, and the savory herbs give the brew a distinctive taste. Although the contents of 4-VG and diacetyl are high, they are not noticeable as the taste is masked by the savory herbs. Gruit beer is very different from pilsner, the mainstream beer today, but it seems suitable for modern tastes.

We could gain a deeper insight into the influences of microbiological processes on a balanced flavor and a certain flavor stability of the beers. According to today's knowledge about spontaneously fermented beers, they must have something in common, such as by-products of Lactobacillus and Brettanomyces strains beside those of regular top-fermenting yeasts. Even in those times the content of air (oxygen) must have had a decisive influence on flavor and flavor stability, certainly without brewers having been aware of it at all.

from the Kirin Brewery Co., Ltd.