Enthusiasm and innovation in brewing often outpace science and explanation. One of the most recent unexplained phenomena in homebrewing and the professional world of beer is “hop burn.” Part off flavor, part unpleasant sensation, hop burn (also referred to as “hop bite”) began to show up in sensory panels and online forums over the last five years, alongside hazy IPAs accelerating to the forefront of the industry.

While there haven’t been official studies or scientific papers published on hop burn — yet — it makes sense that this sensation emerged only when the new hopping techniques for making hazies came into practice.

To help guide homebrewers through hopping techniques, two experts weigh in on the phenomenon’s probable origins, and methods to avoid or soften the bite in beer brewed at home.

Feeling the Burn

Hop burn is most often perceived after swallowing beer — likely while sipping or sampling a very fresh NEIPA — when the drinker is assessing aftertaste. It’s an extreme astringency, akin to sucking on a dry bag of black tea.

If you want to experience this sensation for yourself, simply drop a hop pellet or two in a beer — make it a hazy or NEIPA for the most intense experience — and let it soak until it falls apart. Then, take a sip. Chunks of hop aren’t part of the off flavor; but the drying scratchiness at the back of the throat is. Warning: Some find it so harsh, it may feel like gagging or choking.

When sampling from fermenters at his brewery in Columbia, Md., Sapwood Cellars co-founder Scott Janish says, “the burn can be so bad from the tank that you cough when trying to get it down.”

Janish is also the author of  “The New IPA: A Scientific Guide to Hop Aroma and Flavor,” a book that takes an extensive look into the newest scientific findings in the world of hops. When his book was published in 2019, hop burn was a still-emerging concern.

Hop Oils and Compounds

Now that we know what hop burn feels like, where do the offending compounds come from?

“It’s generally believed this [hop burn] is a result of overloading on polyphenols found in the vegetative matter of hops,” says Chad Kennedy, hop specialist at Brewers Supply Group (BSG), a national supplier based in Shakopee, Minn.

While there have yet to be studies published in relation to hop burn specifically, previous research has tied hop polyphenols to astringency. Because this vegetative matter does not contain alpha acids or essential oils, there’s a rule of thumb brewers can reference when assessing the risk of hop burn from a specific hop varietal: The higher the alpha-acid content of the hop variety, the lower the polyphenol levels of that variety. “Likewise, the lower the alpha-acid content, the higher the polyphenol content,” says Janish.

Contact and Extraction

Beer contact with the vegetal matter of hops has always been known to cause unpleasant flavors to some extent. Before massive dry-hop additions of four or more pounds per barrel came into practice, excessive grassiness or garlic-like notes were the main concern, and astringency was one of the lesser worries for brewers making dry-hopped beers.

Hop burn, then, “was an unexpected consequence of ‘going big’ with dry-hopping,” Kennedy says.

Beyond the sheer volume of hops being added to the fermenter (which are double or even triple pre-hazy-era IPAs), there’s another aspect that affects the onset of hop burn: The longer the vegetative hop matter stays in contact with the beer, the more polyphenols can be extracted, which results in a more astringent and rough mouthfeel.

It is this aspect of polyphenol extraction that allowed brewers taking part in the IBU “arms race” of the early 2010s to push bitterness to extremes without the same burning sensation. To brew those severely bitter beers, wort was only in contact with hops long enough to isomerize IBUs in the kettle (for homebrewers, no longer than 60 minutes of contact). So, even the hoppiest of “West Coast IPAs” extracted far fewer polyphenols from the hops boosting their IBU numbers.

“Certain polyphenols (like xanthohumol) have been tested in much higher concentrations in NEIPAs than West Coast IPAs,” Janish of Sapwood Cellars says. Many NEIPA brewers add hops to active fermentation when the pH is lower and protein levels may be higher; both are conditions that encourage polyphenol extraction from hop matter.

Beyond drawing out these potentially hop-bite-inducing compounds, the chemistry of hazy IPAs may hold those compounds in place, instead of allowing them to fall out of suspension. To get technical, Janish says, “It’s likely the more viscous grist of NEIPAs is keeping more of these otherwise non-polar and astringent compounds in solution.”

Choose the Right Hops

Based on this evidence, there are a few ways to minimize hop burn at the recipe-writing stage of homebrewing. The first is by dry-hopping with hops containing high levels of alpha acids and, therefore, lower levels of polyphenols. Hops like the ultra-fruity El Dorado variety that can pack up to 17 percent alpha acid are popular in hazy IPAs for this reason (Sierra Nevada’s Hazy Little Thing, Scaled from Trillium Brewing Company, and Bell’s Brewery Official to name a few). The second is to use at least some hops on the hot side, to provide additional flavor to balance potential burn.

Janish suggests adding at least some bittering hops: “To my palate, if a NEIPA is too heavily dry-hopped without enough supporting flavor from the kettle, this can increase the hop-bite astringency,” he says.

Find the Right Method

Once the recipe is set, it’s time to move on to hopping methods. “The oils we are looking for from hops when dry-hopping go into solution a lot quicker than many brewers think about. So, longer time on the hops is not necessarily better,” says Kennedy. In other words, minimal time on hops gives beer less time to absorb astringent polyphenols, which lead to the undesired bite.

For this reason, Kennedy suggests racking beer off the hops quickly and thoroughly. Commercial brewers have found that extreme measures of hop separation, such as centrifugation, help lessen hop burn. However, Kennedy notes, such methods are not possible, nor required, at the homebrewing level. His advice for homebrewers is to “cold crash a beer if you can before racking, as this will help create a bit more solid pile at the bottom of your fermenter and help you in a good racking.”

Janish takes this suggestion a step further, encouraging the use of a clarifier such as gelatin after dry-hopping. (Sapwood Cellars uses Biofine Clear because it is a vegan brewery.) This helps pull out more hop particulate, and therefore helps decrease hop burn while still leaving well-made NEIPAs plenty hazy.

Let It Mellow

Homebrewers can take a cue from the pros by allowing beers to condition off of the hops before serving. While conducting research for his book, Janish found, “in conversations with other professional brewers where hop burn was something they were trying to figure out, I was amazed then that many brewers would prefer their hazy IPAs to sit a week to condition for the burn to mellow out a little before packaging.”

Of course, not all commercial brewers have the luxury of sitting on a full tank for that long. For homebrewers, though, waiting an extra week before drinking is a more viable option. This conditioning can take place in a fermenter, keg, or even in bottles — anywhere that can hold the beer while not in contact with hop matter.

“Burn does seem to mellow with some time, though again, I don’t think there is any scientific literature on what this curve looks like,” says Kennedy. It may take some experimentation to find the magic number of days for your homebrew to reach expressive hop character, but low to no burning. However, he warns, when it comes to buying commercial packaged beer, fresher is almost always better — since most beers have at least a few days to condition on their way to store shelves.

Here’s to many pints of juicy homebrewed IPA — without feeling the burn.