I love me some skunk beer, and I love me some skunk weed beer! One specific beer that comes to mind when I think skunk is Heineken. There are some pretty skunk IPA’s out there also, but Heineken has my vote for one of the spunkiest beers on the shelf. So what makes a beer skunk? Well, many variables contribute to the outcome of a beer in both taste and scent. However, during the fermentation process, there are sulfur compounds that exist in your favorite brews. These sulfur compounds can create quite a stink, but they can also act as a natural antioxidant like garlic. Take my hand, (not the one with a beer in it) and follow me on this brew-ha journey about hydrogen sulfide in beers!
Sulfur compounds are an essential part of the brewing process, and it’s been noted as early as 1898 that hydrogen sulfide exists in fermentation gases. This odor can rock the nostrils and make for an unpleasant experience for any un-expecting brew connoisseur. The presence of hydrogen sulfide is usually low, with a subtle smell and light taste. These aromas and flavors can be picked up by the savvy brew connoisseur, but are often unnoticed by the average beer drinker. These chemical compounds often evolve into other compounds when PH balances change, temperatures change, or if the beer begins to stale.
Hydrogen sulfide has a unique odor in it, some of it’s most potent forms. When I think of Hydrogen, I think of a lit match. You know the smell that wafts right after you strike the match, that is the odor that emits from this gas. Now sulfide flavors in beer can range from rotten eggs (my gas after a night of drinking), skunky (Heineken), and other pungent aromas that can be compared to these. Yeast flavors also play a role in the makeup of these tastes and odors in your beer.
The ingredients and process of fermentation are what creates these sulfur-like flavors in some of your favorite beers. How much of those flavors and aromas are present in your beer will depend on the brewing process and if your favorite brewer uses an H2s Scavenger for filtering and purification. Sometimes these flavors are left in the brew to compliment other aspects of the flavor profile, while other times, it’s considered bad batch, and the beer is disposed of. Most U.S. craft breweries are aware that yeast plays a vital role in the brewing process and that there are certain strains that are more likely to produce higher volumes of sulfur compounds during the brewing process. These flavor profiles often differentiate one beer from another.
While some aim to add these flavor profiles, most try everything they can to avoid them. Hydrogen sulfide removal can be accomplished by adding a sulfur trap to remove the compound from the batch. It’s not always yeast that causes this either, and some H2s can be introduced into a batch from mishandling the batch, extreme temperature fluctuation, and the introduction of harmful bacteria. The introduction of these elements can transform the batch into a funky-flavored disaster consisting of H2s and mercaptans. Mercaptan removal is another process that can be introduced into the brewing process and should be considered for the removal of unwanted off-flavoring.
Sulfuric Flavoring In Beer
Sulfur flavor profiles in U.S. beers aren’t prevalent, hence the reason I referenced Heineken in the introduction. Those flavor profiles, however, can be found in American wine and cider batches. Where in Britain, there are sulfites used in beers as additives. There are also sulfites found in other ingredients like hops, which are a significant component to successful brewing batches of alcohol. The sulfur is typically introduced into the hops from the farmers growing it. These compounds are introduced for various reasons in limited amounts and are used to control mildew. Most of this is removed while the hops are prepared for fermentation, however, there are going to be traces of the compound left after the hops have been boiled. Any remnants of sulfur can usually be removed through the fermentation and filtering process.
These sulfur flavor profiles are created when H2s, mercaptans, and similar compounds are found together in beer. This is something to avoid, and it can become more outrageous as these compounds begin to concentrate. The majority of this flavoring is produced from barley and adjuncts. Typically hydrogen sulfide is present in finished batches of beer but is not an active flavor profile. If present, it can disrupt the completion of the batch if not appropriately managed. Some studies show H2s levels in filtered beer doubles after the beer has been pasteurized. This leads to the statement that the sulfur compounds are present in most beers, but not necessarily active. These compounds can then be activated during the bottling process.
There are other sulfuric compounds that can add notes of cabbage or garlic into a batch. These flavors have been associated with diethyl sulfide, diethyl disulfide, and polysulfides. Again, these are undesirable flavoring profiles that will keep Dracula away, oh, and the ladies!
While this might have been a boring read to some of you, but these are some important points for the home brewer to be conscious of. Unintentionally introducing Hydrogen sulfides into your homebrews can spoil your drinking plans. I can’t imagine a worse experience than setting up a home brewing kit, taking the time to ferment your batch, bottling, and opening your first beer with a buddy only to find that it smells like rotten eggs. Trust me, it’s happened, and having a little bit of this knowledge hand before you begin brewing will help you avoid this mistake.