I've probably brewed too many NEIPA's for my own good and thought I would share some of my findings and look studies regarding the subject of biotransformation. This article isn't to discourage you from anything, but rather to shed some light on the subject and encourage everyone to be conscious of what biotransformation does and make a case for why your second dry hop should be post-fermentation.
This is an article based on my extensive experience and sensory evaluations conducted on the matter.
If you ever listened to Craft Beer & Brewing podcasts, there are a number of breweries that hop their IPA's after fermentation completes. As a matter of fact, they drop out the yeast by cold crashing to about 50-60F, harvest the slurry, and then add their dry hop. Here are some examples of temperatures at which some of the most successful commercial breweries dry hop:
There are other breweries that ferment at lower temperatures, these are just the specific ones that mentioned their dry hopping schedule on the podcast. So far, it looks like almost all of them dry hop post-fermentation.
Let's look into some studies. This graphic was part of a webinar by Yakima Chief Hops on Dry Hopping Techniques.
Comparison of three beers, one with whirlpool hops only, one hopped during, and one after fermentation.AFDH - Active Fermentation Dry Hop
PFDH - Post Fermentation Dry Hop
Beyond the flavor intensity noted in each beer by the sensory panel (graph), observe the final ppb (parts per billion) in the table above. Specifically, the Final Beer values of various compounds demonstrate the effect various hopping methods have.
WP Only (Whirlpool) - values are the lowest throughout.
AFDH - Active fermentation values are much higher than whirlpool addition only.
PFDH - Post fermentation values for Final Beer Linaloon and Geraniol are noticably larger than AFDH values. In case of Geraniol, these values are over two times larger.
Concluding this study, it's evident that the ppb values of the post-fermentation dry hop beer far exceeded the Active fermentation beer. For the full details on this study, I recommend watching the webinar linked above. It's insightful and has interesting tips from the kind folks at YCH.
Moving on to another piece from the YCH webinars, is a graphic demonstrating the amount of specific hop pounds, and the amount of each, present within different hops. I won't get into the specifics of the study as YCH and Scott Janish do a much better job than I ever could, but I would like to point out that not all hops have the compounds that can survive fermentation.
Many of these hop compounds bind to proteins and yeast cells, and in turn drop out at the end of fermentation. You'll find these on the right side of the chart, while hops with highest amounts of "survivable" compounds are more toward the left side of the chart. I've personally been a big fan of dry hopping with Mosaic and Sabro in mid-to-late fermentation, and these, as well as Idaho 7, are all fantastic in Whirlpool as well.
YCH Webinar on Hop Survivables can be found here.One of the thing I had to learn the hard way is what hop burn is. As it turns out, Scott Janish has a very interesting article supporting multiple points from this article in his recent piece titled "A Case for Short and Cool Dry Hopping. There, he covers multiple aspects of cool dry hopping and how cooler and shorter dry hops lead to less hop creep and help prevent polyphenol extraction (hop burn).
...the temperature of the dry hop significantly increased polyphenol extraction. When dry hopping at 66°F (19°C) compared to 39°F (4°C), there was an increase in polyphenol concentrations of nearly two-fold for the low-alpha hop and nearly 2.5-fold for the high alpha hop
I have certainly experienced this first-hand when dry hopping at high krausen or during fermentation at all. Anytime I use a very high alpha hop like Galaxy above 65F, the hop burn resulting from the use is very strong. Yes, the burn goes away after a few weeks, but sometimes some of the perceived harshness remains in the beer. Why compromise your beer for 2-3 weeks if this can be avoided altogether?
Having read The New IPA, I was swayed and went all in to fermentation dry hopping, like many others. While I've had some success, my practices began to evolve over time after my beers weren't quite reaching their full potential. Since then, I've had much better experiences with the following:
While my process remained the same over time (closed transfers, fermentation control, hop quality and technique), I have found that moving the dry hops to later stages in fermentation and introducing multiple dry hops have drastically increased the hop saturation and overall quality of my NEIPA.
Here's the dry hop schedule that I have found to give the most impact in terms of juiciness and hop utilization. The base of the IPA includes 70% 2-row, 20% Malted Oats and 10% White Wheat. For a full recipe, take a look at my Hop Butcher clone recipe.
OG: 1.072, FG: 1.016
Yeast: London Ale III or Imperial A24 Dry Hop
2oz Citra @ Whirlpool
2oz Mosaic @ Whirlpool
2.5oz Citra @ 8 days in Primary for 48 hours
2.5oz Mosaic @ 8 days in Primary for 48 hours
Cold crash to 58F for 48 hours, and transfer to dry hop keg
2.5oz Citra @ ~11 days in Dry Hop Keg for 48 hours
2.5oz Mosaic @ ~11 days in Dry Hop Keg for 48 hours
While dry hopping procedures become more standardized in the industry and (hopefully) in the homebrewing circles, there are still many factors that remain unexplored. I'm personally curious about hop saturation levels and whether there is such a thing as "too much hops". Could using less hops per gallon add more flavor? Can muslin bags hinder hop extraction? If you have any experiences or fun stories about this, feel free to reach out and follow me on Instagram.
Useful link - Northeast IPA thread (350 pages and counting) is a fantastic thread with experienced brewers sharing their feedback and personal findings on the subject of NEIPA, I highly recommend it.
