Herbs. While the botanically inclined will often use the word “herb” to describe plants with non-woody stems, the broader use of the word includes flowers and roots as well as leaves. Herbs have always been integral to beer, and they have played many different roles in brewing over the millennia. Today very few beer styles are significantly influenced by the use of any herbs other than the hop flower, but this was not always so.

Historically, herbs were used to stabilize beer, to retard spoilage, to increase palatability and cover brewing failures, to imbue the beer with medicinal qualities, and finally to make beer “stronger” or even hallucinogenic. In the early days of brewing, herbal components of beer might differ from batch to batch, with neither brewer nor consumers expecting much in the way of consistency. Consumers simply demanded that beer satisfy their needs and habits, while brewers did their best to produce reputable beer that people would buy. Those brewing and consuming beer at home used whatever materials were at hand.

In Europe, it has only been little more than 300 years since the hop almost totally displaced other herbs in the brewhouse. Herbs had previously been collected, dried, ground, and often blended and traded as a mixture called “gruit,” which was usually added to the kettle during wort boiling. See gruit. Before the Protestant Reformation in the mid-16th century, the Catholic Church monopolized gruit production in Europe. During the bubonic plague epidemic of the Middle Ages, specialty “plague beer” was offered as a purported remedy, probably without any significant effect. In this era a comprehensive use of spices coming from “overseas” also became popular, and brewers did not distinguish between local homegrown or collected herbs and imported exotic spices when mixing their gruit.

In the Nordic countries juniper branches and twigs, at least in part because of their antiseptic qualities, were used as a filter during the mashing process. Juniper might also be added when heating the sparge water and during the primary fermentation. See juniper and sparging. The resulting beer was strongly influenced by the acting bitter compounds and the aroma of the juniper itself. The Finnish traditional beer called sahti is still brewed using juniper in various ways. See sahti.

Examples of other bittering and antiseptic herbs historically used in northwestern Europe are sweet gale, also known as bog myrtle (Myrica gale L.), yarrow (Achillea millefolium), wormwood (Artemisia absinthium L.), heather (Calluna vulgaris), white horehound (Marrubium vulgare), stinging nettle (Urtica dioica), buckbean (Menyanthes trifoliata), the leaves of the ash tree (Fraxinus excelsior L.), and shoots of spruce and fir. Outside Europe the list of herbs and other plants used to bitter beer gets longer still, including species such as hopseed bush (Dodonae viscosa) from Australia, Indian ivy-rue (Zanthoxylum rhetsa) used in rice beers in Vietnam, whiteroot (Gouania lupuloides) used in ginger beer in Jamaica, common hoptree (Ptelea trifoliate) from the United States, shiny-leaf buckthorn (Rhamnus prinoides), used to brew the traditional tella in Ethiopia, and quassia (Quassia amara), exported from Brazil and used for centuries as a hop substitute. Almost all of these herbs and plant products add bitterness to balance the sweet flavors of malt, but they also add flavor and sometimes give the beer superior keeping qualities. Herbs have also been used to aromatize beer or for medical or even religious purposes.

The organic chemical composition of an herb depends on the cultivar itself, how it has been grown, and how it is treated after harvest. The valuable compounds are usually best expressed in brewing when the herbs are fresh. Other characters are best expressed if materials are dried and even stored before use (for instance, the hay-like aroma of birch).

The power of the hop flower to significantly extend the keeping qualities of beer eventually spelled the end of widespread use of other herbs. Once brewing became a genuine commercial concern, the hop plant solidified its place in European beers, and from there spread to England and beyond. During the last several years, however, the craft brewing revolution has seen the creation of many new beers inspired by old recipes involving herbs. Examples of herbs used are elder flowers (Sambucus nigra L.) to flavor spring or summer beers (Denmark), mint (Mentha spp.) to flavor stout (Italy), and heather to recreate a traditional ale style (Scotland).

Though herbs can help bring a range of fascinating flavors, they should be used in beer with caution. Some of the traditional medicinal plants have negative effects, and there may be concerns regarding allergic reactions, carcinogenic effects, and other unforeseen problems. Consultation of a pharmacopoeia is therefore recommended before adding herbs to beers brewed at home. Today’s commercial brewers are only allowed to include herbs upon approval by governmental authorities.