To perform this experiment, I brewed a new version of my Hefehosen. After cooldown, I racked the top half of the kettle into one 3 gallon fermentor for the “clean”, non-trub half. The rest I dumped directly into an identical 3 gallon fermentor for the “dirty”, trub-ified half. I aerated each half with my aquarium pump for 15 minutes and then pitched half a vial of WLP380  into each fermentor. This didn’t look like much yeast at all, so I found an ancient (best before 9/2010) satchel of Danstar Munich yeast and added 6 grams of it to each fermentor. I then placed both fermentors side-by-side on a shelf in my cellar, to ferment at 64F.

I took a picture of their status every day. In each picture, the “clean” half is on the right, and the “dirty” half is on the left. Not that I needed to tell you that… I mean, look at them:

Right out of the kettle. The dirty half is aerating.

Later that night, the dirty half has settled pretty well.

After 1 day

Day two: the fermentations are at their peaks.

Day 3. Fermentation has slowed down.

Day 4. Fermentations almost seem to be complete.

Day 5. It's hard to tell from the photo, but the dirty half is done fermenting but the clean half is still doing a little work.

Day 6. Both are basically done fermenting.

Day 7. No fermentation activity, but the krausen on the clean half is just sitting there, inactive.

Visually, there was a big difference. The dirty half started later, but finished sooner, which makes me think that the trub is beneficial to a healthy, quick fermentation. Aromatically, the clean half was much more intense during fermentation. Whenever I would remove its tinfoil hat the smell would punch me in the face – loads of phenols and some sulfur action going on. Later on in fermenation that dropped off and was replaced with a pleasant banana character. Meanwhile, the dirty half was much less intense, but more muddied. It was hard to pick out what exactly I was smelling, although later on I did get a lot of clove.

I bottled after 10 days in the fermentor, and had my wife give me a blind triangle test 6 days after that. After watching the fermentation and smelling them, I didn’t find this to be a challenge. I easily picked out which was which. The dirty half had a very defined clove character in the nose and mouth and visually was less cloudy. The clean half had banana characteristics in the nose and mouth and was pretty cloudy. I’m thinking the dirty half’s healthier fermentation was to blame here. I have heard that if you want a clovey weizen, pitch a lot of yeast and if you want a banana-y weizen, pitch less. Although I pitched the same yeast in both fermentors, the trub provided a more ideal environment for the yeast and therefore simulated a higher pitching rate.

When I took the samples to MUGZ, I didn’t tell anyone what sample was what. I just had the mysterious labels of A and B. A being the dirty (trub-ified) half and B being the clean (no-trub) half. I asked the testers to fill out little slips of paper saying which they thought was the trub sample and which they preferred. Here are the results:

13 people thought the dirty sample (A) had the trub removed.

3 people thought the clean sample (B) had the trub removed.

5 people said they couldn’t tell.

—

6 people said they preferred the dirty sample (A)

13 people said they preferred the clean sample (B)

2 people said they didn’t have a preference

What can we get from this? For one, if the 21 testers are a good representation of the general public, then what most people think of as a “dirty” beer is wrong. On the same token, 13 people preferred the clean beer while less than half preferred the dirty beer. 5 out of 21 people couldn’t tell the difference.  Thanks to all the testers by the way!

So will this change the way I brew? Actually I think it will. Sure, the fermentation took longer in the clean half, but people obviously preferred it over a beer where you just throw all the trub in. But then again, a Hefe is all about the yeast – strain and pitching rate. I’d love to see the results from a beer where the yeast doesn’t take center stage (maybe a Stout or a Pilsner?).

The unbelievably massive Kolner Dom in Cologne. I couldn't get the entire cathedral in frame.

I’m brewing a Dusseldorf Altbier today; it’s currently in the mash tun, resting at 150F. I took Jamil’s recipe from Brewing Classic Styles and made a few slight modifications due to a shortage of two of the malts. Fortunately, I”m still within the style guidelines. Although it’s not like it really matters. Not in the US at least. I have yet to try an American made Altbier that is as good or sessionable as the examples I tasted in Dusseldorf last summer.

I’m not so much of a snob that I think you can only get good Altbier in Dusseldorf. On the contrary, I believe any beer can be made anywhere (with the exception of spontaneously fermented ales). Why there are no good American-made Altbiers has more to do with the lack of good imported examples. The precedent simply hasn’t been set on this side of the pond.  I can’t blame a brewer who has only read about Altbiers and sees them described as hoppy (by German standards) beers to then turn around and make a hoppy (by American standards) beer. Somethiing certainly gets lost in translation.

On the other hand, Altbier’s cousin, Kolsch, has scores of excellent, traditional examples in the US. I’ve been making one for a couple years that is a favorite among friends that I designed long before my stay in Cologne. I had imported Sion and locally made Summit Kolsches as my guidelines, along with the excellent Classic Styles Series book on Kolsch (all I really got from the Altbier book was that “Alt” means “old”). So why are there so many great examples of Kolsch in the US, but none of Altbier? To answer that, you need to look for something that you won’t find in a recipe or in the BJCP style guidelines. To borrow from their neighbors, it’s a certain je ne sais quois. In other words (and I just watched Moneyball yesterday), how can you not be romantic about beer?

My wife and I had been planning a trip to Europe for a few years. Initially, our plan was to go to Ireland, as we both have Irish ancestry. Sometime during those years of planning, I met a German man through work who became a close friend, so his country got bumped into first place (Ireland is on the board for our next trip now). We flew into Munich in late August and over the course of 8 days, drove all over southern Germany, spending each night in a different town, until flying out of Dusseldorf. In short, it was amazing, and I highly recommend the trip to anyone who has the time and money. We spent the second to last night in Cologne, and took a train up to Dusseldorf  the next day.

Cologne, like much of Germany, is entrenched in old and new history – less than a kilometer from our hotel was a series of ultra-modern office buildings, including a quite impressive one inhabited by Microsoft. About a kilometer beyond that was the massive 19th century Kolner Dom. In-between those two was a beautiful park along the Rhine River, dotted with the Altstadt (Old Town) buildings. The weather was beautiful the day we were there and many people were lazing out in the park and enjoying meals and drinks in the outdoor cafes.

A beautiful, fresh glass of Kolsch at the Sion pub in Cologne.

The jet lag had really thrown off our eating schedule, so we had lunch in the hotel restaurant at 3pm. If I remember correctly, the beer menu had a Pilsner, a Weizen, and a Kolsch. I ordered a Kolsch and the waitress either the waitress misheard me or I mispronounced it, so she asked “Do you mean, the city beer?”. Kolsch and Cologne are synonymous in any beer drinker’s mind, so hearing her ask if I wanted “the city beer” was beyond amusing for me. She seemed glad that’s  what I ordered. Looking around the restaurant, most people were drinking Weizens. The beer came out in the standard 25mL Stange glass. The nose was beautifully biscuity – like fresh baked bread – and was more aromatic than most commercial examples I’d tried. The taste was good, but not really any different than anything I’d had stateside. There’s not a whole lot going on in the taste of a Kolsch – it is meant to be a session beer afterall.

The session characteristics are emphasized at the Sion Brewery. It’s just a short walk from the Kolner Dom, down a narrow brick street. We found a table outside and almost immediately had a waiter ask us what we would like to drink. We ordered two Kolsches, which he pulled off of a circular platter that probably held close to two dozen stanges of Kolsch. He ticked my coaster twice with a pencil. In the hot sun of that day, our first glasses didn’t last very long. The waiter came by again and asked if we wanted more. He handed us two more and ticked my coaster twice more. Throughout our time there, the waiter would swing by, ask us “More?”, and swap out our glasses. We almost never had an empty glass. You just don’t find that kind of service in Germany, or even the US. Kolsch is low alcohol and very easy to drink. I could see it as being a very dangerous beer at a cafe with a group of friends and an attentive waiter.

This beautiful canal seemed out of place in the otherwise modern, urban downtown Dusseldorf.

The next day we took a train up to Dusseldorf. The ride was only about 45 minutes, but felt much longer due to a group of teenagers across the aisle from us that may have never bathed in their entire lives. The train moved slowly and made a few stops. We saw the rustic clean charm of Cologne turn into industrialization and urbanization. Buildings seemed newer, but were covered in graffitti (which was actually a welcome balance to their drab, gray stone exteriors. Once we checked into our hotel and began to explore, I realized the city definitely seemed more “American” than the others we had been visiting. The buildings were larger, more modern, and less charming. The streets were wider and straighter, but busier. We had to walk quite a ways to get to the Altstadt. Massive modern buildings locked the Altstadt into a few crowded blocks. This was quite a change from Cologne, which is surprising considering the short distance between the cities – they’re practically connected.

The Altbier glass is shorter, but wider than the Kolsch Stange.

Many of the cafes were filled to capacity so we eventually found one with a few tables open. The food was passable, but not great. Fortunately, they carried Altbier. It came out in a 20mL glass similar to the stange – only shorter and wider. The beer was a dark brown with only a small head. It smelled pleasantly musty and malty. It reminded me of cellars and beer aged for long periods of time – think old British Crystal malt. I didn’t get my coaster ticked, but the waiter did swing by a couple times to make sure I didn’t have an empty glass. Later that night, we had a meal at the hotel restaurant. I ordered another brand of Altbier. The waiter seemed happy that an American tourist was ordering his city’s beer. He asked me what I thought of it and whether I liked it. I told him I had never had anything like it and I loved it. He seemed very pleased at that answer. That’s when I realized that Altbier and Kolsch are very similar.

The two beers may be on different ends of the color spectrum, but they’re both easy to drink, sessionable beers. They both have a heavy emphasis on bready, biscuity flavors, but one emphasizes fresh while the other emphasizes aged. The elusive (at least for Americans) Altbier, is the older, darker cousin of the Kolsch. That hoppiness that is so often attributed to Alt comes from balancing out the caramel and Carafa. These two beers have more in common than what separates them. Of course, I’d probably get run out of whichever town I made that statement in. The residents of those two cities are fiercely proud of their beer, and for good reason – they’re both fantastic session beers. Prost!

1) there’s only one baby on the way
2) it’s a girl
3) she appears to be healthy
4) the initially predicted due date of May 15 remains

Maybe she won’t follow in her father’s footsteps and pick up the hobby, but I do plan on encouraging it.

Fast forward a few years and most of the recipes I use are of my own design. I’ve become a lot more comfortable with the ingredients and processes I use on brew day. This is familiarity is key to recipe creation, but I’m not going to cover how to create your own recipe in this article (that will come later), but I will cover how I created one recipe in particular. In this case, it’s my German Pale Ale, GPA 4.0.

I plan on doing a few of these articles. I’ll be the first to admit I’m no expert, but maybe you’ll pick up a tip or two. At the very least, you’ll get some insight into my brewing thought process.

Inspiration

On the road, you have to make do with what you have

Every recipe and therefore every beer can be traced back to a point of conception. In the case of GPA 4.0 it was in August of 2010 on a business trip to Nacogdoches, Texas. The week I was there, the daily high temperature was somewhere between 95-100F. Fortunately, I was able to find a few beers to help beat the heat. One of these was Real Ale’s Rio Blanco Pale Ale. I tried all of their year-round beers that week, and they were all fantastic, but the Rio Blanco was my favorite.

It poured lighter in color than most American Pale Ales, almost leaning more towards a Cream Ale. In the nose there was a more biscuity and spicy aroma than any APA I’ve ever had before. Sure enough, when I took a drink I knew this wasn’t an average APA. Those biscuit notes from the aroma carried into the flavor along with a soft wheat flavor I would wager was white wheat. I use white wheat malt a lot in my beers, but most prevalently in my Honey Do Honey Brew. The spiciness I smelled reminded me of light Belgian ales. My guess was Saaz – which to me is one of my favorite and most easily identifiable hops. Sure enough, the bottle’s label proudly states the beer is brewed with Saaz. It wasn’t a punch-you-in-the-face hop character many APA’s are guilty of, and it didn’t finish quite as harshly dry. The key descriptors that kept popping up in my mind were “soft” and “round”.

I wanted to brew this beer. I thought it would make the perfect warm weather brew. It would be over 6 months later before I actually did brew a similar beer.

As much as I liked the Rio Blanco Pale Ale, I didn’t want to exactly clone it. The beer was in class of its own – a new style separate from American Pale Ale. Ideas for the recipe were in the back of my mind those 6 months after I left Texas. Then a friend and fellow brewer enthusiastically told me of a beer he discovered at the Einfach Brewery in McGregor, Iowa – it was a “German Pale Ale”. For some reason finding a name of this new “style” of beer was enough for the gears in my mind to click in place and start designing a recipe.

Choosing the Ingredients

I set out thinking about what would constitute a German Pale Ale. If the style were to be added to the BJCP Guidelines tomorrow, what would be in the definition? German malts: Pilsener, Munich, and Wheat; German hops: Tettnang, Pearle, Saaz (I know it’s not truly a German hop, but it does make appearances in German style beers); a yeast that allows for a clean finish that favors malt emphasis over hops; and a flavor profile that leans towards malt-hop balance. I also need to think about the size of the beer. I want to be able to have a couple of these in a night, but I don’t want to turn this into a session beer. An average (~1.050) starting gravity should be perfect.

Grain

I should start by saying that when deciding on what grain to use, almost all of my beers adhere to the following two rules:

1) The base malt (or malts) make up at least 80% of the grist. Any less than that and there’s a good chance you won’t hit your finishing gravity and the beer will come out on the sweet side. Conversely, I have made beers with 100% base malt that have turned out very nicely.

2) There are no more than 4 different grains in any beer. In my experience, the simpler the better. The first recipes I created were monstrously complex and this complexity carried into the finished product. There is a time and a place for complexity, such as with a Robust Porter or a Saison, but most of the time you’re just muddying the waters. Pick a few quality ingredients and let them stand out.

With those rules in mind, I started looking at malts. Although this is a German-style beer, I didn’t want too much of a grainy/biscuity flavor, so that ruled out Pilsener and Munich as the base, and the more I thought about it, the more I realized what I wanted was a “German take” on an American style. Most American styles use 2-Row as their base. 2-Row by itself would make for a pretty bland beer, so I want to include a little Munich. I’ve found that adding a pound of Munich to a recipe adds a grainy/biscuit flavor that isn’t overpowering. Oh, and I don’t want to forget the white wheat that stood out in my mind when I drank the Rio Blanco.

So now I have three grains picked out. And all three of them are pretty fermentable and can be used as base malts. American Pale Ales tend to use crystal malt, so let’s throw some of that in. I originally thought Crystal 60 would be the one to use here, but it added too much color and I would imagine too much caramel flavor, so let’s go with Crystal 40.

Now I need to pick the ratios. The 2-Row and White Wheat are my main players here. Too much 2-Row and the beer could come out bland. Too much wheat and the beer will get hazy and venture into wheat beer territory. My wheat beers tend to be 60/40 barley/wheat, so I don’t want to use 40% wheat. 75/25 might be better. That calculates out to 60% US 2-Row and 20% White Wheat to start off my base. I don’t want to use a lot of crystal either, since I want this to finish dry, so we’ll keep that at 5%. There’s 15% left over, so it goes to the Munich.

So to summarize my malt bill:

60% US 2-Row

20% White Wheat

15% Munich

5%  Crystal 40

I like to use percentages when formulating recipes. It’s much easier than calculating efficiency and exact amounts. When I’ve settled on the percentages, I’ll translate those into pounds on BeerSmith and set my target starting gravity. So, in this case I’ll have 7 pounds of 2-Row, 2 pounds of white wheat, 1.5 of Munich, and 0.5 of C40. With my average efficiency sitting right around 70%, I can actually use those amounts and hit a starting gravity of 1.057. That sounds good to me.

Hops

I definitely need to use Saaz, and use it in a way that it has the dominant hop character. I don’t want to use it as the only hop, since I’ve found that this can result in a beer with a very 1-dimensional hop character. And this is a Pale Ale afterall, so hops are important. I have also found from personal experience that you generally get the best hop character by using hops from the same country or region in a recipe. I have a big bag of Pearle hops in my freezer, so let’s use that along with the Saaz. I’m a little ashamed to admit that, and its country of origin are my only reasons for using Pearle here and not another German hop.

Many published recipes give hop additions in weight (1.5oz Cascade at 60 minutes, etc) with no mention of Alpha Acid Units (AAUs), but then list a target IBU to allow you to hope for the best. The AAUs are hugely important – they are what determines the bitterness contribution of a hop. So I make sure these are correct in BeerSmith before I continue.

More important than IBUs is the MBR of a beer. I covered this in a previous article, so I won’t define it here. I found the OG, ABV, and IBUs for Rio Blanco off of the Real Ale site, so I had everything I needed to get the FG, and therefore derive their MBR, which is 44.1 (it’s interesting to note that the most famous APA, Sierra Nevada Pale Ale has a dangerously close MBR of 43.8). 44 sounds like a good number for my beer too, so I multiple .44 by my target OG+FG to get 30.8. That’s my target IBU for this recipe.

Now I just need to find a way to split up the hop additions. I really only consider 4 points for adding hops in any recipe – bitterness (90-60 minutes before KO), flavor (30-15 minutes before KO), aroma (0, Knockout), and dry hopping. I want to use all 4 in this recipe as it is at its heart, an APA. I don’t want too much at bitterness since that can cause a harsh, overly dry finish. I think most of the hop character should come at the flavor addition or later. Using BeerSmith, I spread these out across the three boil additions in 10 IBU, 15 IBU, and 5 IBU increments respectively. Keep in mind that you extract more IBUs the longer the hops isomerize, so although it looks like my biggest addition is the flavor hops, it is in fact the aroma addition. On the same note, the flavor addition isn’t 1.5x the bitterness addition, but 3x due to isomerization.

I split these out so that each addition is about 3:1 between Saaz and Pearle hops.

Yeast

Last, but certainly not least is the yeast. I debated this one for a while. I wanted to keep to the German spirit of the rest of the recipe, but I really couldn’t find a yeast that met my criteria. That criteria was: highly attenuative, highly flocculent, and favoring malt character. That combination doesn’t really exist and is a contradiction of sorts. I started searching Northern Brewer for their excellent comparative yeast statistics.

I’m a big fan of White Labs so I really only considered them. My first thought was WLP001, “California Ale” – the Chico (aka Sierra Nevada) strain. I didn’t think that would really play well with the maltiness of the Munich, so I kept looking. Ah, WLP007, Dry English Ale (or the “Bond” strain as I like to call it . It’s one of my favorites. It’s very similar to WLP001, but mutes the hops just a little in favor of malt. 70-80% attenuative, medium-high flocculation. Perfect.

Conclusion

Well, at this point I had my recipe. I brewed it last week and haven’t had the chance to try it yet, but it looks and smells amazing. I’ll keep you posted on how it turns out.

To recap, here’s the recipe

1.057 OG, 30 IBUs

60% US 2-Row

20% White Wheat

15% Munich

5%  Crystal 40

10 IBUs Pearle/Saaz @ 60

15 IBUs Pearle/Saaz @ 20

5  IBUs Pearle/Saaz @ 0

1oz Saaz and 0.5oz Pearle to dry hop

WLP007 yeast (with a starter)

Thursday:
13:00 Opening Toast
13:45 Tips & Tricks To Set Up Your Own HomeBrewery
15:00 Aged to Perfection: The Maturation of Beer
16:15 Everything I Learned About Brewing I Learned From You!

Friday:
09:00 Specialty Malts
10:15 Varietal Mead Comparison
13:30 Keynote Address
14:45 Exploring Yeast
16:00 Bottle Conditioning Like a Pro
17:15 AHA Members Meeting

Saturday:
09:00 Lesser Known and Misunderstood English Beer Styles
10:15 Starting Your Own Brewery Panel
13:30 Cellarmanship: Skills and Techniques for Serving Cask Conditioned Beer
14:45 “Plastic” Yeast Strains From Belgium and Germany: Learning to Compromise
16:00 Live Taping of Basic Brewing

I’m particularly excited about the British and cask seminars. I’m hoping the varietal mead seminar has samples!

Although I haven’t listened to the conference call mp3, the important bit is this gem of a quote:
“There’s a process for making beer — I don’t know if it’s the yeast or what it is in making beer. You can put those microscopic things on oil and they die, and all you’ve got is some methane gas left.”

I haven’t the slightest idea what he’s talking about. Is he suggesting we ferment the ocean? I won’t say he’s wrong, but I don’t understand how this could possibly work. Is he saying yeast would consume the oil, convert it to methane, and die in the process? Is there any actual science to his suggestion?

I created a handout for the talk which I will post soon.

At any rate, my newest experiment was to test if the variety of hop used for bittering had any effect other than bitterness in the boil, fermentation, and finally, the taste of the beer. Often times, when I brew from a recipe found in a book or magazine, I don’t have the correct bittering hop on hand, so I substitute it with another hop by changing the volume of the addition to match the same IBU. We’re taught that this shouldn’t make a difference. I find it odd that if it really doesn’t make any difference why do British recipes insist on British bittering hops, German recipes insist on German bittering hops, and so on. On top of that, what about the popularity of hop extract, like HopShot, where the hops the extract came from doesn’t even really matter.

To test this, I picked a recipe that was mild enough that any difference in hop character should be easily noticeable. Since my experiment concerned bittering hops, I wanted a recipe that didn’t use any flavor or aroma hops. I settled on a British Mild – well, somewhere between that and a Bitter – I wasn’t trying to win a BJCP medal here. 32 IBUs is a little high, making a MBR of .6 repeating, but not undrinkable. I didn’t want a lot of beer sitting around if the beer turned out less than palatable, so I decided on making a 2-gallon batch, split into two 1-gallon boils. Here’s the recipe:

2 gallons All-Grain @ 70% efficiency
1.040 OG / 1.009 FG / 32 IBU
1.14kg Maris Otter
60g Crystal 60
60g Flaked Barley

Mashed at 152F for 60 minutes.
2g Safale US-05 between each gallon.
Fermented @ 64F for two weeks in primary, no secondary
Carbonated using 1 Coopers Carb Drop per bottle

Pardon my mixing of metric and imperial measurements. Grams and kilograms tend to make more sense to me in recipes, and as you’ll see soon, was almost necessary when measuring the hops. I’m slowly transitioning to using all metric in my recipes, but that’s another post for another day.

So let’s talk hops. I wanted a big difference between the two hops used. I settled on some Willamette @ 3.4% AAU and Summit @ 18% AAU. To equal 32 IBUs at 60 minutes, using Tinseth (by way of Beersmith), the additions were 13.2g Willamette and a measly 2.5g Summit.

Summit on the left, Willamette on the right

I had two kettles set up on separate burners on the stove top going at the same time. Hops were added at the same time and burners were turned off at the same time. Nothing to note between the boils other than the not-surprising fact that I was busier preventing a boil over with the Willamette batch than the Summit batch. Both kettles cooled down in an ice bath afterwards.

The worts were poured into separate 1-gallon glass carboys and shaken vigorously for a couple minutes each. The 2 grams of yeast each were pitched and each carboy was shaken again briefly. Here they are right after shaking:

Low AAU (Willamette) batch on the left, High AAU (Summit) batch on the right

I stuck them in my brew closet, which stays at a steady 64F during the winter. I started taking pictures every 12 hours.

Low AAU (Willamette) batch on the left, High AAU (Summit) batch on the right

It looks like the Willamette batch started fermenting before the Summit batch. It finished sooner too. Both finished at a gravity of 1.009.

I bottled in 12oz bottles and added one Cooper’s Carbonation Drop to each bottle. This was probably overkill given the style and the low gravity, but I think they’re a must for experimentation. It would be very easy to get inconsistent carbonation and therefore inconsistent results by mixing the priming solution into the entire batch and I wasn’t willing to put one gallon on keg and force carbonate.

Here is a few ounces of each prior to bottling.

High AAU (Summit) batch on the left, Low AAU (Willamette) batch on the right

There’s a significant difference in the clarity between the two samples. It appears that more hop matter means more cloudiness in the finished beer (something that shouldn’t be surprising to anyone who has ever brewed an IPA).

Here they are after carbonating in the bottle for 8 days.

Low AAU (Willamette) batch on the left, High AAU (Summit) batch on the right

Unsurprisingly, nothing changed in the bottle. The differences in clarity were still very visible after sitting out for an hour at room temperature as well.

Now, the important part – taste. I did this blind (as in with my eyes closed) with the help of my lovely research assistant wife. She poured me four ounces of each in clean (glass) beer flight glasses. The bitterness did appear to be identical between the samples, but the flavor and aroma had an ever-so-slight difference between them. One didn’t smell or taste as clean as the other, but that’s really splitting hairs. If you were to hand me a pint of one and then a pint of the other without telling me anything was different between them I may not notice the difference (other than in appearance). However, after having a couple of one in a row and then a couple of the other in one night (which I had to do of course… for science!), I did notice a slight difference and the Summit batch was preferred. I had my wife taste the samples and she didn’t notice a difference. I had the rest of the bottles out at a party without telling anyone about the experiment and no one commented or seemed to prefer one over the other.

So in conclusion, I say go ahead and substitute one bittering hop for another as long as they’re not TOO different. Willamette and Summit are probably too different. A 5% AAU hop and a 7% AAU hop probably aren’t. If you’re concerned about clarity and making a sparkling clean beer, use a high AAU hop. I should add that I made an Irish Red Ale with only hop extract once and it seemed TOO clean. The EKG batch I made following that seemed preferable, but that’s a bit inconclusive as they were brewed weeks apart.

I may try this experiment sometime again in the future with a very hoppy beer to see if the flavor and aroma hops cover any difference in bittering hops, but until then I’m happy knowing that subbing one hop over another is important, but only if the hops are wildly different.