This is going to be a good one, with cutting edge research being presented by Jessica Young.
Title: Hop Creep Defined: Revisiting Old Culprits and Uncovering New Sugar Sources in Dry Hopping
Abstract:
Dry hopping in beer can trigger a slow, unexpected secondary fermentation known as hop creep — a problem that can extend tank times, create off-flavors, alter alcohol content, and compromise beer stability. Historically, hop creep has been attributed to simple sugars already present in hops and the activity of dextrin-degrading enzymes that break down unfermentable carbohydrates into fermentable ones.
This research builds on that foundation by identifying two previously overlooked sources of fermentable sugars in hops that may further fuel hop creep: starch-laden stores and sugars bound to plant secondary metabolites (PSMs).
Starch accumulation occurs naturally in the hop bract during daylight hours as part of the plant’s diurnal cycle. These starch reserves vary depending on harvest time and, while not fermentable on their own, can be converted into simple sugars by the same hop-derived enzymes already linked to hop creep.
The second source involves sugars chemically bound to PSMs — compounds responsible for many hop aromas and flavors. These glycosidic bonds can be broken by hop enzymes or by natural acid conditions in beer, releasing additional fermentable sugars into the fermentation.
Analytical work confirmed the presence of starch (1.5% by weight) and substantial quantities of glycosidically bound glucose, with enzymatic treatment releasing nearly three times more glucose than was present as free sugar.
To understand hop creep variability in real-world brewing, over 400 small-scale fermentations were conducted, comparing hop product type, addition quantity, growing region, and variety. Results revealed that hop creep is not only common across all hop products, but its severity depends on both biological (variety, starch content, PSM-bound sugars) and processing factors (pelletization, regional growing conditions).
By reframing hop creep as the combined result of known components (free sugars, dextrin-degrading enzymes) and newly identified ones (starch reserves, PSM-bound sugars), this work provides brewers with a more complete understanding of the phenomenon and opens the door to targeted strategies for managing its impact.