Author: Greg Foster

As an unrepentant hophead, I often find myself intrigued by the results our xBmts yield about this splendid little plant and recently found myself poring over the findings suggesting dry hop temperature produces a distinguishable difference in overall character. While seemingly expected, at least based on comments of people once the article was published, my curiosity was piqued because I’ve experienced different results with a cold dry hopping technique known as keg hopping.

What makes keg hopping unique from other dry hopping methods is the fact the hops remain suspended in the serving keg throughout the lifespan of the beer, from first to last pour. It’s basically a prolonged cold dry hop, one I’ve personally experienced as imparting great hop character. Some other advantages of keg hopping include the ability to purge oxygen from the hops as well as allowing one to force carbonate while simultaneously dry hopping. But the method has its critics with some warning that extended dry hop lengths can leech grassy off-flavors into the beer, which I’ve not personally found to be the case. Rather, I have noticed dry hopping cold beers does take a little longer to reach maximum aroma, usually peaking around day 10, which confirms the previously mentioned xBmt findings. But from that point on, my biased opinion is that keg hopping produces beers that are aromatically similar to those dry hopped warm and the aroma seems to last a bit longer.

As I pondered the findings from the dry hop temperature xBmt, I wondered if the amount of time each beer spent on the hops may have been the reason they were perceived as different. Would a slightly longer dry hop duration achieve an aroma as pungent as the more traditional warm dry hopping method? Is the cold keg hopping method I’m using as beneficial as I think?

| PURPOSE |

To evaluate the differences between two beers of the same recipe where one was dry hopped warm (72°F/22°C) in primary for 6 days and the other keg hopped cold (36°F/2°C) for the duration of serving.

| METHOD |

I’m a West Coast brewer who has little experience with NE-style ales, so in the interest of broadening my horizons, I chose to make Ed Coffey’s HopWards Pale Ale for this xBmt.

HopWards NE-Style Pale Ale

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 9 gal 60 min 57.9 IBUs 5.7 SRM 1.055 1.014 5.4 % Actuals 1.055 1.009 6.0 % Fermentables Name Amount % ESB Pale Malt (Gambrinus) 16 lbs 82.05 Oats, Flaked 3.5 lbs 17.95 Hops Name Amount Time Use Form Alpha % Magnum 17 g 60 min First Wort Pellet 12.2 Amarillo Gold 37 g 5 min Boil Pellet 8.2 Centennial 37 g 5 min Boil Pellet 10 Simcoe 37 g 5 min Boil Pellet 12.3 Amarillo Gold 37 g 20 min Aroma Pellet 8.2 Centennial 37 g 20 min Aroma Pellet 10 Simcoe 37 g 20 min Aroma Pellet 13 Amarillo Gold 114 g 5 days Dry Hop Pellet 8.5 Centennial 114 g 5 days Dry Hop Pellet 10 Simcoe 114 g 5 days Dry Hop Pellet 13 Yeast Name Lab Attenuation Temperature London Ale III (1318) Wyeast Labs 73% 64°F - 74°F

A couple days before my brew day, I split a single pack of Wyeast 1318 London Ale III yeast between two jars of pre-canned wort and got them spinning.

I weighed my salts and acid, measured out my grain, milling it on my lightning fast monster mill MM3.

Rather than go with my usual tricked-out RIMS setup, I decided to test the simpler Mash In A Bag (MIAB) approach in hopes it would make performing simultaneous mashes less complicated in the future. Still using my electric rig for all heating purposes, the added gear certainly made for an unusually crowded kitchen.

Using my HotRod heat stick, I heated the strike water in the cooler to 162°F/72°C, presumably pre-heating the MLT along the way. I then mixed in the grain and checked to see if I’d hit my target mash temperature…

What the hell?! A far cry from my target of 154°F/68°C, I was even less thrilled when a I returned a couple minutes later to find the temperature had dropped to 140°F/60°C. I pulled off a couple gallons of wort, heated it to 190°F/88°C, then stirred it back into the mash, which resulted in the temperature stabilizing at 153°F/67°C. Good enough! After a 1 hour rest, I transferred the wort into my keggle and proceeded with the 60 minute boil with hops added per the recipe, then I quickly chilled the wort to 185°F/85°C and tossed in a charge of hops for a brief hop stand.

Twenty minutes later, I finished chilling the wort to my preferred pitching temperature and took a hydrometer measurement that showed it was at a respectable 1.055 OG.

After racking the wort to a sanitized 10 gallon corny keg turned fermentor, I pitched both jars of yeast.

The beer fermented for five days at 66°F/19°C before I began to raise the temperature to 70°F/21°C, where it remained for another 9 days, at which point I took a hydrometer measurement that confirmed it was at FG.

At this point, I chilled the beer in the large fermentation keg to 50°F/10°C, which split the difference of the two target dry hop temperatures. In preparation for introducing the variable, I sanitized and oxygen purged two kegs. I then added equal portions of dry hops to two identical muslin bags that were secured to the outside of each keg with dental floss and left dangling about 7 inches above the bottom of the kegs.

Before racking the cool beer from the fermentor, I pressurized and purged each serving keg with CO2 a few more times, 20 to be exact… the local CO2 refill place does indeed love me. I used a scale to ensure each keg received the exact same quantity of beer.

The keg hopped beer was immediately placed in a 36°F/2°C fridge where it would remain for the duration of the xBmt; the more traditional warm dry hop beer was left at room temperature for a full 6 days before being pressure transferred to a fresh oxygen purged serving keg. Both kegs were hit with CO2 for force carbonation at this point. Then I did the unthinkable and let them sit in cold storage for another month. The ridiculous things I do for science. When it finally came time to gather data, both beers looked identically sludge-like. Success!

| RESULTS |

Data for this xBmt was collected at a monthly Pacific Gravity Homebrew Club meeting where 26 people of all experience levels graciously lent their taste buds to the cause.

Each participant was blindly served 1 sample of the warm dry hop beer and 2 samples of the cold keg hopped beer in different colored opaque cups then asked to identify the unique sample. In order to reach statistical significance with this sample size, 14 (p<0.05) tasters would have had to make the accurate selection. In the end, only 13 (p=0.06) tasters correctly chose the odd-beer-out, which suggests a beer dry hopped warm for 6 days then stored for a month was not reliably distinguishable from a beer that sat on the same dry hop charge in a cold environment for the entire duration.

Since the results were did not reach a statistically significant level, the following details ought to be taken with a grain of salt. Of the 13 participants who made the correct selection on the triangle test, 7 reported preferring the keg hop beer, 2 endorsed the warm dry hop beer as the one they liked most, 2 said they perceived a difference but had not preference, and 2 felt there was no difference between the samples. Moreover, after the data was gathered and before I shared the nature of xBmt, I asked many of the correct participants for their impressions on the beers, all but two stated the difference was predominantly aromatic and described the keg hopped sample as being more hoppy, dank, and fresh with a stronger aroma and less sharp flavor than the warm dry hop beer.

My impressions: Triangle tests I performed on myself proved difficult since I perceived these beers as being fairly similar, but I was ultimately able to identify the unique sample in every attempt. To me, the keg hopped beer had a stronger, hoppier aroma to it, which was the main thing I used to identify the different sample. I found it much more difficult to distinguish the beers by flavor alone. Overall, I preferred the more pronounced hop character of the keg hopped beer and didn’t notice any grassy notes or other off-flavors commonly believed to result from extended dry hopping. In fact, after over two months in contact with the dry hops, the beer was still enjoyable with no noticeable off-putting grassiness.

Ed’s HopWards recipe is fantastic and served as an excellent introduction to NE-style Pale Ales for me. I look forward to trying more and would recommend anyone tinkering with the idea of brewing this style give this a go!

| DISCUSSION |

When it comes to getting as much hop character into a beer as possible, there are a growing number of methods, all of which have their advocates and critics. Arguably the most commonly utilized of these techniques is dry hopping, which for most involves tossing a charge or two of hops into their beer toward the end of fermentation, when it’s still warm. However, those seeking even more pungent hop aroma have found success suspending bagged hops in their cold beer where it remains until the beer is gone, a method known as keg hopping. While often used in tandem, the purpose of this xBmt was to investigate the impact beer temperature and contact duration had on the hop character in a NE-style Pale Ale. Based on these results, it seems a brief warm dry hop produces a beer that is not reliably distinguishable from a similar beer that was dry hopped cold over an extended period of time.

I’ll keep both methods, regardless.

The difference between the warm dry hop and cold keg hop beers were far more subtle than I expected, but to me it was real. With my intimate understanding of the variable, I knew to focus most of my attention on aroma, which is the aspect I found most disparate between the samples. To my surprise, the beers tasted almost exactly the same, it makes sense to me that blind tasters wouldn’t be able to distinguish them. While it’s not my point to question the validity of these results, there is always the possibility of Type II error, aka a false negative, which occurs when an experiment fails to reject a false null hypothesis. Alas, there’s no good way to know for sure if that’s the case here, leaving us with one option, the only good option: exBEERiment more!

What are your thoughts on keg hopping versus standard dry hopping? Have you noticed dry hop temperature or length playing a role in how the hops are ultimately expressed. Please share your experience in the comments section below!

Grains for this xBmt were provided by:

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