Brewing with Bittering Herbs
The addition of hops to beer is a relatively “new” development, culminating with the Reinheitsgebot of 1516, or German Purity Law, that decreed beer could only be brewed with water, barley, and hops. But for, like, a thousand years before the Reinheitsgebot, hops were only part of the spicing included in beer recipes. And, like, five thousand years before that, hops were not even a typical beer ingredient, as beer was brewed with a spice mixture called gruit. With such a long history, gruit beers are puzzling. One of the glaring voids in brewing a gruit beer is the lack of how to measure bitterness in obscure herbs.
Nowadays, brewers use a measure called International Bitterness Units, or IBUs, to quantify bitterness from hops compounds. IBUs are defined as parts per million iso-alpha-acids. This measure is how brewers plan bitterness in the final beers. But trying to estimate bitterness in beers using herbs without alpha-acids is somewhat of a guessing game. However, The European Pharmacopoeia has defined another a measurement of bitterness called bitterness value, defined as “the reciprocal of the dilution of a compound, a liquid or an extract that still has a bitter taste.” This is compared with quinine hydrochloride, which has a bitterness value of 200,000.* In simpler terms a solution of 1 part quinine to 200,000 water still has a bitter taste.
Bitterness value can have a practical application for gruit brewing if it is converted to an estimate of International Bitterness Units (IBUs). Iso-alpha acids, the main bittering compound in hops, is fairly close to quinine hydrochloride with a bitterness value of 175,000.** By knowing this and the bitterness value of various herbs, we can convert bitter herbal compounds to achieve desired IBUs in gruit beers. All it takes is a simple calculation (see chart).
Three of my favorite bitter herbs are quassia bark, horehound, and gentian root. Each has a historical context and offers a different bitterness profile.
Quassia Bark
Quassia is a genus of South American trees that can grow over 100 feet in height. The genus was named after a Surinam slave Graman Quasi in the eighteenth century, who discovered the bittering and medicinal properties of the bark. Quassia gained relevance in the production of porter in London in the early 1800s. Some less than honest porter brewers used quassia and other “adulterants” to avoid paying the hop tax. It was reputed that one pound of quassia bark was equivalent to sixteen pounds of hops.*** Quassia bark is the main bittering component in Known Gnome Old Timey Porter, a beer we named when we were very, very drunk, and pays tribute to the roll quassia bark played in early 19th century brewer tax evasion.
Quassia bark’s principle bittering compound is quassin, which herbalist use to aid digestion and strengthen the stomach. It is no wonder that quassia is used as a digestive bitter as quassin has a bitterness value of 17,000,000 (almost 100 times more bitter than iso-alpha acids in hops). However quassin is only found in concentration of around 0.1% in quassia bark. The bitterness quality of quassia is tame and smooth, but has a little more depth than some of the other herbs the article will examine.
Horehound
White horehound is a member of the mint family and is found all over Europe and is indigenous to Britain. Horehound was used to brew horehound ale “an appetizing and healthful beverage, much drunk in Norfolk and other country districts.” ****Horehound is still used today in cough drops and lozenges because of claims of its very strong expectorant properties.
The main bittering compound in horehound is Marrubiin, which has a bitterness value of 21,000,000 and is found in a concentration of 0.3%. The bitterness from horehound is quite sharp with a menthol-like finish.
Bitterness from marrubiin is showcased in Prisoners Dilemma Colonial Style Mild Ale, a tribute to James Squire. James Squire was an Australian convict who was caught stealing this herb to craft home brewed beer in a hop-less Australia in the late 18th century. Upon arrest, he was sentenced to 150 lashes of the whip, but averted capital punishment only because he was selling his home brew to a local Lieutenant for personal consumption. James Squire went on to be the grand patriarch of the Australian hop farming when we successfully cultivated hops for the first time in 1806.***** To my knowledge, he did not grow any Galaxy hops.
Gentian Root
Great yellow gentian is an herbaceous plant native to mountains in southern and central Europe. The plant was named after King Gentius of Illyria, who ruled in about 180 BC. Gentius was credited for discovering the tonic properties of Gentian. Gentian is still used today as an aperitif in products such as Underberg and used in the soft drink, Moxie.
The main bittering component in Gentian is amarogentin, which clocks in at a whopping 58,000,000 bitterness value and is found in 0.15% concentration in the root. The bitterness of gentian is fairly clean, and besides being potent, lacks some complexity.
Brewing with Bitter Herbs
Converting bitterness value into an estimate of IBUs can be done with a little algebra. By factoring the bitterness valve of these herbs against 175,000, the bitterness value of iso-alpha-acids, and accounting for typical bittering compound concentration levels in the herbs, this formula will provide an estimate of how many IBU-equivalents dried bittering herbs will contribute to the final beer. To estimate amount of herb (in grams) to use for desired IBU level use the formula:
Some considerations when brewing with these herbs is they are very potent so a little goes a long way. Additionally, the concentration of the bitter components varies slightly as alpha acids do in hops. The listed concentrations are average levels. But without knowing exactly what the concentration there will be some variance, especially since the bittering potential of the compounds are so high.
Bitterness is a key component of beer and helps balance sweetness of malt. Despite general perception, bitterness does not just vary weak to strong and can provide a complex flavor, especially when the source of the bitterness is from something other than iso-alpha-acids. By exploring and brewing with these historical bittering herbs we hope to expand the world of craft beer at least a little further.
*EUROPEAN PHARMACOPOEIA 5.0, pg 221
**Fundamentals of beer and hop chemistry, Denis De Keukeleire, http://www.scielo.br/scielo.php?pid=S0100-40422000000100019&script=sci_arttext
***Cornell, Martyn, Beer: The Story of the Pint, Headling Book Publishing, 2003, pg 125
****Grieves, M, A Modern Herbal http://botanical.com/botanical/mgmh/h/horwhi33.html
*****Sydney Gazette and New South Wales Advertiser, dated 16 March 1806
