One major issue with dry hopping is quite a new one. Well, sort of. As brewers and beer drinkers alike have begun to crave the more fruity and fresh hop strains, hop processors have started reducing the time and temperature at which the fresh hops are dried, ready for breweries to use. Whilst this helps to preserve a better and fresher hop character, it’s created an issue where enzymes present in the hops that would normally be deactivated by a temperature spike in processing are now present in hops in larger quantities than before. These enzymes have a nasty habit of breaking down complex sugars into simple ones. So, if you add a vast quantity of hops to a beer that has finished fermenting, the enzymes in the hops can spring into action and start to break down sugars that were previously unfermentable into fermentable sugars. Some breweries adapt to this by having a lengthy warm rest after the dry hop, to accommodate for any extra fermentation that might occur due to dry hopping. Other breweries have reacted by reducing their dry hopping temperatures to inhibit the enzymes, however this makes dry hopping even less efficient flavour/aroma-wise. Another way to combat this is to reduce the contact time between the hops and the beer, which is another cause for the growth in popularity of purpose-built dry-hopping equipment, since the reduction of contact time between the beer and the hops means less time for the enzymes to hang around and get up to mischief.
This phenomenon in modern times has been called “hop creep”. At best, it can be negated with careful monitoring and process management, but at the expense of some hop character extraction efficiency. Sometimes breweries will simply add to their process time to accommodate this issue, which is fine, but time is money in small, busy breweries, and even a couple of extra days of tank residency is costly over the course of a year. At worst, if left unchecked, hop creep can lead to refermentation once the beer is packed, leading to exciting things such as non-pourable kegs and exploding/gushing cans and bottles.
However hop creep isn’t anything new. It was written about extensively over 100 years ago, at a time when it was commonplace for landlords to keep hops at their pub. When a beer started to taste off or old, they simply dry hopped the barrel to give the beer a DIY face-lift. This led to hop creep being identified and studied long before the NEIPA was even a glint in a brewer’s eye. The reason it was forgotten about for so long is tied up in the history of beer and society as a whole. Over the course of the last century, due to two world wars and the associated economic hardships, hoppier beers were made and drank less frequently. Then after the wars, palettes moved towards ‘Euro-fizz’ (as a more Brexity writer might term it), and the beer industry as a whole moved away from dry hopped beers and wooden casks, in favour of sealed steel kegs and lagers that wouldn’t know a hop if it jumped inside it mid-fermentation and used it’s previously dormant enzymes to break down long chain sugars into shorter more fermentable sugars restarting fermentation in a manner that greatly displeases the brewer (sorry). It’s only since the beer world as a whole has moved back towards using real hops, and using them in vast quantities (employing techniques such as dry hopping that were previously consigned to history) that hop creep has begun to rear its ugly head again.
At Mammoth Beer, our process has been built around finding a balance between all of these conundrums. Typically, we allow primary fermentation to finish. We then chill the beer to 12°C, which takes a day or so. This temperature change makes the yeast drop out of suspension more readily and settle in the bottom of the cone of the tank. At this point we harvest the yeast, and dry hop immediately after. After the hops are added, we allow an hour for the hops to break apart, before chilling the beer to 0°C, and bubbling the beer with CO2 to a higher pressure. This bubbling helps carbonate the beer, and mix the hops with the beer. Over the next 24 hours the hops will drop to the bottom of the tank due to the temperature drop, giving them some good contact time, but not enough contact time for the enzymes to have a drastic effect. Once the beer is cold, we dump all of the hop matter from the bottom of the tank, before bubbling the tank more to finish carbonating the beer.
Who knew juicy IPAs were such a pain in the arse?