Exploring Dry Hopping: Its Benefits and Why You Might Want to Give It a Try
Brewing beer is a straightforward process that involves extracting compounds from crushed grain, sterilizing and flavoring them through boiling in the presence of hops, and finally, allowing yeast to ferment the mixture. However, the brewing process also allows for a wide variety of recipes that create numerous styles of beer. The brewer is like a chef, and the brewery is their kitchen.
Unfortunately, many of the delicate, aromatic compounds we're after are lost during brewing, particularly the hot side processes. To preserve the flavor profile we desire, these delicate flavors must be added back in.
Dry hopping is a technique for adding these lost flavors to the beer. It's a cold extraction process, carried out at temperatures between 4-20°C, that extracts non-volatile and volatile chemicals from hops into an alcoholic solution without increasing product bitterness. By using dry hopping, we prevent isomerization of hop α- and β- acids, resulting in a hop addition that preserves the fresh, fruity aroma compounds present in the plant material while limiting bitterness.
Let's break it down:
What's Dry Hopping, and Why the Hell Do We Need It?
Dry hopping aims to add flavors and enhance aromas in post-fermented beer. The delicate hop aroma compounds, which would otherwise be lost during the boiling phase, are extracted and added back into the beer through dry hopping, rounding out the flavor profile and intensifying the overall hop character.
How the Hell Does Dry Hopping Affect Taste?
Scientific research shows that dry hopping influences the taste of beer by bolstering the assertive hop base flavor. By evaluating hop volatile analysis in beer samples, we can see that increasing dry hop doses lead to higher levels of various volatile compounds like β-caryophyllene (spicy, woody), α-humulene (spicy), terpinen-4-ol (menthol), α-terpineol (citrus), linalool (floral, fruity, citrus), nerol (rose-like), geraniol (floral, rose-like), and geranial (green/grassy, floral).
So, you might think that more is better when it comes to dry hopping, right? Well, not quite. Research indicates that overall hop aroma and intensity, and citrus characteristics, favor a non-linear relationship with diminishing returns beyond 800g/hL. Beyond this concentration, herbal/tea notes dominate.
The Risks of Dry Hopping
Over-attenuation (aka "hop creep")
Adding hops when you think fermentation is complete can lead to your final gravity reading continuing to drop, a phenomenon known as hop creep. Dry hopping can promote after fermentation by releasing fermentable sugars due to enzymatic processes within the hop plant material. Preventing hop creep can be challenging, but strategies like "soft crashing" the beer below the ideal temperature threshold of the yeast and removing yeast from fermentation vessels might help.
Increased Bitterness
Research has shown that dry hopping can lead to increased extraction rates of non-volatiles, contributing to perceived bitterness in the final beer in the absence of isomerization.
Oxidation
Oxygen is the enemy of highly dry-hopped beer. It's proposed that the production of reactive oxygen species (ROS) in wort is the driving mechanism in the degradation of beer matrix compounds, leading to off-flavors and discoloration. Consider methods such as hop dosing under CO2, using a CO2-saturated hop doser, or dosing hops during active fermentation to consume excess oxygen.
pH
Beer's pH can have a drastic effect on various characteristics, including stability, flavor profile, and infection risk. Dry hopping can cause beer with higher dry hop doses to be at increased risk of pH drift.
Contact Time, Temperature, and Agitation
Variables such as hop contact time, dry hop temperature, and agitation can influence the dissolution of hop aroma compounds. In general, 24 hours of contact time may result in near-complete saturation of beer with hop-derived flavour compounds, but the temperature and agitation may also play a role in aroma extraction.
Dry Hop Like a Damned Pro
Variable control and understanding the factors affecting hot hop compounds extraction can only help your brewing process. The homebrewing experience is personal, so do whatever the hell you want!
Scientist, cyclist, and avid homebrewer, Sam Gilchrist, began his homebrew journey during the COVID lockdown, fulfilling a long-standing desire. As a proud Spike Solo System owner, his scientific mind and methodological approach have significantly impacted his brewing methodology, rekindling his love of biology and the odd compulsion to control variables.
- Dry hopping is a post-fermentation technique used to enhance the aromas and flavors in beer, as it allows for the addition of delicate hop aroma compounds that are otherwise lost during the boiling phase.
- Scientific studies indicate that dry hopping affects the taste of beer by amplifying the assertive hop base flavor, causing increases in various volatile compounds like β-caryophyllene, α-humulene, terpinen-4-ol, α-terpineol, linalool, nerol, geraniol, and geranial, resulting in a more intensified hop character.
- Although dry hopping can offer numerous benefits to the flavor profile and aroma of beer, it also has potential risks such as over-attenuation (or "hop creep"), increased bitterness, oxidation, pH changes, and the need for careful control of contact time, temperature, and agitation to optimize the extraction of hop aroma compounds.
