Chapstick-Flavored Beer or Beer-Flavored Chapstick?

Hydroxybenzenes, carbolic acids, phenyl alcohols…phenols. They go by many names, but you may know this class of compounds as “smokey, medicinal, spicy, clove-y.” I know this group of aromatic alcohols as the bane of my brew-existence.

If you take a ring of carbon, alternating double bonds, tag on an hydroxyl group, then combine it with various side chains, you get embalming fluid…or a saison. Ok, it’s not THE embalming fluid, but phenol is commonly used to preserve stiffs and also commonly found in chapstick and used as a antiseptic. So when someone says a beer has a medicinal flavor, what they mean is it IS MEDICINAL. Would you like a lemon on your hefe-weizen, or perhaps a bandaid?

Why do I hate them so much? Perhaps I failed the organic chemistry test on the aromatic compound chapter? Maybe 4-vinyl guaiacol killed my father. Maybe not. Really, it just comes down to the fact that they taste gross and are usually a sign that something went wrong during fermentation. Sure some beers have these flavors as part of their flavor profile…a little clove to balance the banana (isoamyl acetate, I <3 you). But even then, the smokey, medicinal flavor should be kept in check. When producing a beer that’s not supposed to taste like burnt rubber, these compounds show up if the beer got infected with wild yeast or bacteria.

To avoid these compounds, you have to understand where they come from and where they go. Precursors to phenolic compounds can be found in the aleurone layer of grains–barley and wheat. Ferulic Acid and p-courmaric acid are the two main culprits, and they’re found in higher concentrations in wheat. These compounds have the aromatic ring and hydroxyl group just like a phenolic compound, but have other side chains and a carboxyl group too. Why is the carboxyl group important? Just so I can say that “ferulic acid can be thermally decarboxylated during the boil to form elevated levels of phenolics”…and I sound pretty smexy (smart + sexy). Some phenolics precursors are formed during enzymatic de-esterfication during the mash (esters are an organic acid and an alcohol combined)…avoid the temperatures that favor the enzymes (140F to 148F-ish), and avoid the smoke-flavors. Most phenols, however, are produced during fermentation when these precursors ferulic acid and p-courmaric acid are converted to phenols if the yeast or bacteria have a particular phenotype. As you would imagine, yeast of the “wheat styles” have this phenotype (like torulaspora delbruekii) and English strains of yeast (like saccharomyces cerevisiae–”ale yeast”) do not. Smexy.

Black Star has a couple recipes that use yeast that are prone to producing phenolic compound flavors. Cul Sec, which used to be a sort of “double wit beer” was a phenol-bomb. I just couldn’t make a high alcohol beer with witbier yeast (think, double Hoegaarden) without producing TONS of phenols…it tasted like a car tire dipped in sugar. I lowered the wheat content and avoided mash temps 140F-148F, and it lowered the phenol level, but it was still outtawhack. So I most recently switched the yeast to a saison style yeast. This unicellular workhorse can tolerate higher alcohol production without higher phenol production. Saisons have that clovey, smokey flavor without being too medicinal. Success…or should I say, Cul Seccess? No, I shouldn’t.