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How to fix hop creep? with Jessica Young
Jessica Young “Let’s start by defining hop creep: the unintended secondary fermentation that comes from adding hops on the cold side. There are a lot of symptoms we associate with hop creep (i.e. diacetyl), but that is the runny nose to your flu. The reason that diacetyl increases again is that the yeast restarts fermentation. There are other negatives that can come with hop creep such as increased CO₂, increased alcohol, decreased residual sugar, and increased perceived bitterness. This means not only is the beer going to be out of targets for what you have on your package label, but also it is no longer going to be in balance flavor wise.” To build on this, we interviewed Jessica Young to give you practical insights from her latest research on hop creep. See her answers below.
Your work shows that hop creep is influenced far more by variety, product type, and growing region, rather than by hop quantity. What are the top 3-5 things brewers should change or incorporate in their dry hopping decisions if they want predictable fermentations and stable thiol forward beers?
Variety and product type are the most influential factors when choosing hops. Variety has time and time again shown a difference in the amount of hop creep with certain ones creeping more than others – however they all will have hop creep. The same is with product types. T90 can exhibit some of the most amount of hop creep, but importantly, it provides the most consistency. Consistency and knowing what to expect from one fermentation to the next is sometimes more important than what produces more or less hop creep.
The good news is dry hopping earlier with active yeast also goes hand in hand with releasing bound thiols. These thiols are conjugated and need to be released. The best way to execute that release is via yeast with β-lyase activity that cleaves the bond and releases the thiol. The yeast must be active to provide thiol release and drive through hop creep, so this leans towards early and warm dry hops. Importantly, thiols are one piece of the picture on hop aroma and usually need to be conjugated with other aroma attributes to create that fruity character brewers are after.
Based on your findings, what are the simplest early warning indicators brewers can monitor (gravity shifts, VDK, specific hop traits) to detect hop-driven secondary fermentation before it becomes a packaging risk?
Hop creep is always going to happen, but it’s about allowing it to happen in the fermentation vessel rather than in the package. If you dry hop early and warm, you’re allowing the primary fermentation to coincide with the unintended secondary fermentation (hop creep). That will reduce your tank timeline versus dry hopping cold at the end of fermentation. This is extended both because of temperature and because of the timing of the yeast life cycle. You essentially just told the yeast to go to sleep and then introduced more sugar, all while moving at a snail’s pace.
However, if you choose to dry hop, it’s important to know your process well. You need to at least allow a couple of tanks to sit slightly longer than you normally would to make sure you’ve reached the end of all fermentation whenever you test a new recipe or get new lots of hops. The best way to monitor hop creep is daily gravity. If you dry hop warm, 3 days of repeat gravity is sufficient, but if you dry hop cold I would recommend quite a bit longer. If you see movement, do not move the beer forward.
I also recommend taking package samples and saving them (both a hot and cold sample) for several months. There are several ways to test for hop creep in packaged product. I found the most reliable to be CO₂ increase or alcohol increase, but those can be pricy pieces of equipment. You can check for a drop in gravity, but make sure to degas your sample! This will allow you to understand if your cellar processes are in fact strong enough.
If a brewer wants to release more thiols while minimizing hop creep volatility, which combination of hop format, timing, and yeast behavior offers the best balance today?
Hop creep and thiol release intersect at the same point in the process: both are driven by enzymatic activity during dry hopping in the presence of active yeast. As a result, the conditions that maximize thiol biotransformation also increase the likelihood of hop creep occurring more quickly. You want active yeast that has the ability to cleave bonds and is ready to metabolize a new influx of sugar from hop creep.
What are the 4 or 5 parameters/takeaways that brewers should consider if they are worried about hop creep (a checklist for brewers, perhaps)?
- Gravity decrease is more important that diacetyl clearance and it will take longer to see than drop at colder temps at the end of fermentation.
- Have good systems in place to track fermentations and make sure your methods work. Double-check your process is good enough by saving the packaged product and checking it over time. If you see any change in gravity, CO₂, or alcohol – you could have a hop creep problem and need to increase your tank residency.
- Know your process and system so that you know when things are going awry. Dry hopping warm and early can provide benefits of allowing primary and secondary fermentation to occur simultaneously as well as the yeast being more active.
- Never rush the beer and give the beer the time it needs, always. Hop creep can still be unpredictable. It’s more important to keep your beer in the tank and let the fermentation take the time it needs.
About Jessica Young
Jessica Young is a brewing scientist and consultant with a background spanning production brewing, quality, and sensory.
She began her career in Asheville and then moved to Bearded Iris Brewing in Nashville, ultimately advancing to production manager. Jessica holds a degree in Cell and Molecular Biology, completed the Master Brewers’ Program at UC Davis, and is now a regular lecturer in the program.
Published Mar 27, 2026 | Updated Apr 14, 2026