Author: Marshall Schott

About 3 years ago, I designed an American-style Red Ale with a simple grist, bittered to 30 BU with Magnum, and finished with a moderate amount of Centennial and Cascade. When it came time to brew this beer, I realized my Magnum stock was depleted and reached for the most similar AA% hops I had available, which happened to be Chinook (Shh-nook). Despite recently learning Chinook possessed relatively high cohumulone (CoH) levels, purported to produce a harsher bitterness, my skepticism prevailed and I tossed a charge in at 60 minutes. The finished beer was good, but I’ll be damned if I didn’t experience it has possessing an unpleasantly sharp bitterness.

I’m certainly no chemist and claim no expertise on the matter, hence my deference to those much smarter than me. In For The Love of Hops: The Practical Guide to Aroma, Bitterness and the Culture of Hops, Stan Hieronymus discusses how research in the 1950’s (Rigby et al.) suggesting higher CoH levels produce harsher bitterness drastically influenced the brewing world by increasing demand for low CoH varieties, which ultimately impacted research and breeding. However, as Stan points out, later studies performed by our friends at Oregon State University demonstrated experienced tasters were unable to distinguish between beers containing differing CoH levels to a significant degree. Some have gone as far as to conclude CoH’s erroneously bad reputation is leading to some not-so-positive repercussions given findings from newer studies.

And yet, many remain concerned. Whether in the form of anecdote like my own or advice given by industry authorities, the belief that higher CoH hops produce harsher bitterness persists. As does my curiosity.

| PURPOSE |

To evaluate the differences between 2 beers of the same exact recipe bittered to the same expected level (IBU) using hops of similar AA% with either high levels of CoH or low levels of CoH.

| METHOD |

DISCLAIMER: Designing an xBmt isolating only CoH levels posed a bit of an issue– without securing pure CoH, which I couldn’t find anyway, there really was no good way of going about it that didn’t involve introducing some other variable. When testing stuff like this on the homebrew scale where access to certain shit is limited, we’re forced to make some concessions, which isn’t scientifically ideal though can still produce results applicable to the typical homebrewer. In this particular case, such a concession had to be made and I opted to compare two hop varieties similar in AA% and oil content while differing quite drastically in CoH levels. Despite efforts to reduce as much flavor and aroma impact as possible, it’s true any differences could be a function of hop characteristics other than CoH. I fully get this and have no intention of misleading anyone– if you’re concerned, view this xBmt not as a comparison of CoH levels but different bittering hops. Moving on…

I consulted with more folks than usual when designing this xBmt, all who offered great feedback. One of these people was John Palmer who suggested I replace the ESB I was planning to brew with something lighter and cleaner with a single bittering hop addition. So, I dropped the specialty malts and all but a lonely 60 minute hop charge. Exciting, eh?

British Golden Ale

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.5 gal 60 min 40.0 IBUs 5.5 SRM 1.054 1.014 5.3 % Actuals 1.054 1.014 5.3 % Fermentables Name Amount % Pale Malt, Maris Otter 10 lbs 90.91 Caramel/Crystal Malt - 15L 1 lbs 9.09 Hops Name Amount Time Use Form Alpha % Simcoe (13.8%) | Chinook (14%) 20 g 60 min Boil Pellet 13.8 Yeast Name Lab Attenuation Temperature London Ale III (1318) Wyeast Labs 73% 64°F - 74°F

Unimpressed after my first use of Wyeast 1318 London Ale III, I figured I’d give it another go and built up a start a couple days before brewing.

The evening before my planned batch sparge brew day, I collected both volumes of liquor and milled the grain while making sure my kids didn’t get run over.

Early the following morning, my tiny bottom’d assistant accompanied me to the garage where the first order of business was heating the strike water.

To reduce the introduction of extraneous variables, I opted to perform a single mash and hit my target temperature dead on.

About 10 minutes in, I pulled a small sample to confirm the mash pH was where I wanted it.

Once the mash was complete, I collected both runnings or sweet wort in a single kettle, gently stirred until well homogenized, then transferred an equal portion to a second kettle. To allow for consecutive chilling, I staggered the boil step by 15 minutes.

As the first batch was coming up to a boil, I measured out the single bittering addition of hops that would be tossed into either batch, it differed by literally 2 pellets given the closeness in AA% between them.

My decision to use Chinook and Simcoe came not without research and consultation. In fact, I wasn’t even aware Simcoe was a low CoH variety until I started designing this xBmt. My primary goal was to compare two hops with drastically different CoH levels, though I secondarily wanted to them to be similar in as many other respects as possible. My first stop on this quest was the USA Hops Variety Manual, which is where I discovered Chinook and Simcoe were at either end of the CoH spectrum. With the help of my friend Matt Chrispen from the Accidentalis blog, and utilizing Scott Janish’s awesome Hop Oils Calculator, we determined that Chinook and Simcoe share many similarities, the exceptions being CoH (woo!) and myrcene (boo!).

Myrcene is known for imparting a “green” character that’s sometimes described as mangoe-like, earthy, and to some, reminiscent of it’s danky cousin (it’s the most common terpene in weed). It’s also highly volatile, particularly in warmer environments, meaning it dissipates rapidly when used pretty much anywhere other than the dry hop. While less than ideal, Chinook and Simcoe seemed the best fit for an xBmt of this nature. To be clear, both were from the 2014 harvest season.

Each boil proceeded as normal, the first finishing 15 minutes before the second, and both were quickly chilled to my target fermentation temperature of 66°F/19°C. A refractometer measurement of both worts at this point revealed my process was consistent between the batches.

I proceeded to transfer the wort to separate 6 gallon PET carboys that were placed in my temperature controlled fermentation chamber.

The single large yeast starter was then split evenly between two clean and sanitized flasks.

Each carboy was hit with 500 mL of viable yeast slurry with signs of active fermentation showing up just 8 hours later.

Fermentation appeared the same between the batches the entire time. I began ramping the temperature to 72°F/22°C after 4 days of fermentation and at 10 days post-pitch both were seemingly done, which two hydrometer measurements taken 3 days apart supported.

Following a 2 day cold crash and fining with gelatin, I transferred the beers to kegs.

After about a week of conditioning on gas, the beers were carbonated and ready to serve! The clarity difference was rather interesting to me and remained the entire 3 weeks these beers were on tap.

| RESULTS |

A total of 23 people contributed data to this xBmt including numerous BJCP judges, experienced homebrewers, craft beer enthusiasts, and my neighbor. Each taster was blindly served 1 sample of the Simcoe/low CoH beer and 2 samples of the Chinook/CoH beer in opaque cups then asked to identify the one that was different. At this sample size, 12 accurate selections (p<0.05) would be required to imply statistical significance, and in the end exactly 12 (p=0.048) identified the unique sample, suggesting participants were able to reliably distinguish between a beer bittered with high CoH Chinook from the same beer bittered with low CoH Simcoe.

A brief comparative evaluation of only the two different beers was then completed by the 12 tasters who were correct on the triangle test. Regarding preference, five tasters chose the Chinook/high CoH beer and five selected the Simcoe/low CoH beer, the remaining two indicating they preferred neither over the other. Even more evidence to support the notion that preference is a subjective matter. The variable being investigated was then revealed to these participants and a brief explanation regarding the purported impact of CoH on bitterness perception was provided. Still blind to which beer was in which cup, tasters were instructed to select the one they believed was made with the Simcoe/low CoH hop, which resulted in seven correct and five incorrect selections.

In follow-up discussions following completion of the survey, a point at which tasters were aware of the nature of the xBmt yet still unaware of their performance, the most commonly cited factor contributing to their ability to distinguish the beers was, you guessed it, the perceived bitterness.

LAB ANALYSIS

While collecting data for this xBmt, I was contacted by Dana Garves, founder of Oregon Brew Lab, which offers brewers all sorts of rad and affordable options for beer analysis. She kindly volunteered to run lab tests for xBmts that might benefit from more objective measures. While I didn’t expect there to be much of a difference in IBU, I thought it’d be interesting to have this data available, as similar bitterness levels would provide even more support for CoH as being the most likely contributing factor to the perceived differences. Unfortunately, I impatiently packaged and shipped off samples without reading through the instructions Dana sent me, which led to the accidental combining of the Chinook/high CoH and Simcoe/low CoH samples prior to being analyzed. Fuck. Regardless, I found the results of the test rather interesting, as it showed the combined sample was at a measured 29 IBU, 11 shy of the level predicted by BeerSmith using the Tinseth calculation for both batches. Did one sample pull the other down or was the predicted IBU that far off for both? Hmm.

My Impressions: First off, my bias– I was wholly convinced these beers would be indistinguishable based not only on stuff I’ve read and heard from trusted sources, but personal experiences following my presumption formed after the Red Ale story I told above. Man, was I wrong. In all of my 5 attempts, which I completed on different days with different people serving me and various levels of inebriation, I got it right. And I mean it when I say they smelled and tasted exactly the same, the only difference I picked up was in the harshness of the bitterness. Go fucking figure. I feel like a schmuck even saying it. While pretty subtle, I found the Simcoe/low CoH beer to be characterized by a smoothness from start to finish while the Chinook/high CoH beer had more of a sharp, snappy bitter character that lingered on my palate a bit longer. It wasn’t a crazy difference, but I have no problems classifying it as noticeable.

As if that wasn’t enough, when comparing them in a “blind” side-by-side, I consistently preferred the Chinook/high CoH beer! For years, I’ve been using hops said to impart a smooth bitterness, chasing the preferences of those whose opinions I read and listened to, all the while ignoring my own desires.

| DISCUSSION |

I’ve no doubt these results will be used by some to confirm CoH levels do in fact impact the harshness of bitterness, while others will point to the “obvious fact” the differences were due the use of different hop varieties, and still some will write the xBmt off completely when they notice a p-value of 0.048 isn’t “very significant.” To be honest, I find myself waffling between all of these…

The statistics indicate a distinguishable difference… but the hops were different… but they were also really similar in so many respects… but if only 1 person’s guess was wrong instead of right… but p-values suck… but… but… but…

Ultimately, I’m left to make a decision based neither solely on the data nor my personal experience, but on a combination of both. I was able to tell a difference beyond that which might be expected if I were randomly guessing, and from this I developed a preference for the beer made with the Chinook/high CoH hop. But that doesn’t mean I’m going to recommend others adopt my perspective, what good would that do other than contribute to growth of my ego? Rather, I encourage anyone interested in this stuff to mess around with it in their own brewing, it’s a fun and relatively risk-free way to learn something new on an experiential level, which I view as being of utmost value. This xBmt certainly forced me to rethink things and you better believe it was only the first of many focusing on the impact bittering hops have on beer.

If you have any thoughts about this xBmt, please do not hesitate to share in the comments section below!

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