Brewer’s Art – Generative AI

© 2022, Randy Mosher / Craft Beer & Brewing Magazine

Like living organisms, the evolution of beer styles follows a principle called “punctuated equilibrium.” This states that as long as conditions remain unchanging, there is little evolutionary change other than random drift. But when conditions change, entities either adapt or radiates to fit changing niches or gets pruned back as unfit. With long-dormant American beer, changes started in the 1970s.

Pioneered by home- and craft-brewers, the explosion of artisanal beer continues today. The earliest of these beers were inspired by European ones, especially British ales. Perhaps it’s an expression of the American character to turn a glassful of inspiration into something new and different, but the beers were more reimaginings of European standards than painstaking facsimiles. The die was cast by Anchor brewing with their 1972 total remake of their historic Steam Beer: switch to all-malt, toss some exotic crystal in the recipe, then balance it with the weirdest hop you can find at the time, a new variety called Northern Brewer. This outline has become the rule for most pale ales, IPAs, barley wines and others in the family ever since. In 1975, Anchor followed up with an American IPA (AIPA), the first in modern history. 

For a reference from IPA’s historical heyday, let’s look at an East India Pale Ale in George Amsinck’s 1868 Practical Brewings. It’s a two-ingredient (SMASH) beer, using “New Burton white malt,” and “East- and Mid-Kent” hops. This, he says, “was brewed by my instructor…in olden times, when the Ales, from that locality, were perfect in every sense of the word.” This would put it somewhere around the 1820 to 1830 time period, maybe earlier. Gravity was 1.067 and terminal was 1.031, giving a calculated alcohol content of just 4.8 %/vol, pretty rich, but a good foil for the hops: nearly 13 oz (370 g) per 5-gallons (5 lbs/US bbl) in the kettle with another another 3 oz (85 g) per batch (1.2 lbs/US bbl). The high terminal gravity is explained by a “too hot” mash, as Amsinck says, at 165 °F/73.9 °C. It’s plenty bitter: a calculated 100+ IBU even if you assume that Goldings in those days were at only 2% alpha. 

Modern drinkers would recognize it as an IPA, but there are clear differences from classic American IPAs. First, AIPAs used plenty of crystal/caramel malt. Although they had been around in the UK for many decades, crystal malts don’t appear to have been common in British pale ales until their gravities dropped precipitously, starting with WWI. My theory on its prevalence here is that it was used to boost aroma in homebrews made from malt extract that had been stripped of aroma by the vacuum-concentration process. Later, its use became habitual, needed or not. It’s bold, but it’s also a beast that can overwhelm a beer and cause it to age prematurely. 

The reasons are in its chemistry. Because crystal/caramel malt is steeped whole at mash temperatures, a lot of the starch is converted into sugar before it goes into the roaster. This dramatically changes the chemistry compared to other malts. When roasting of these “steeped” malts begins, it’s syrupy rather than dry. This means the Maillard browning pathways are different, so instead of bready, toasty and roasty notes, there’s a lot more caramel, jam and toffee. There’s also a lot of caramelization, a different chemical process than the Maillard browning that dominates dry-kilned or roasted malts. A class of oxygen-containing chemicals called furans and furfurals brings different flavors: cotton candy, caramelized sugar and burnt marshmallow. A chemical called beta-damascenone may add date/raisin/prune character, although it is also evident in over-aged hoppy beers. 

These unique, intense flavors can take over a pale beer pretty easily. Drinkers thirsting for something really bold certainly got it with the first generation of AIPAs, but they’re a little heavy for modern tastes and also contain a lot of unfermentables that fill you up. American IPAs had been slowly moving away from this rich style even before the advent of the haze craze. 

There’s also an issue with flavor stability. Beers with crystal malts, especially those in the middle of the color range, tend to age quickly, presenting a kind of  “saddle leather” character reminiscent of sherry, but less pleasant. In some trials, one large Chicago craft brewer found the worst of this graceless aging was with 60 Lovibond (120 EBC) crystal. They always tried to avoid it afterwards. As a general rule, Maillard-derived compounds have some antioxidant qualities, but for complex reasons, some crystal malts actually contain reactive oxidative compounds that can transform amino acids into the aldehydes responsible for staling flavors, once the reactive oxidant chemicals further break them down. 

Modern pale ale malt is not really a blank slate either, with a bit of a sharp, cracker-like toastiness. In stronger IPAs and especially doubles, it can be a little much. There’s no law stating that IPAs have to be mostly pale ale malt, especially since we know paler malts were at least sometimes used in IPAs historically. Raw sugar from India and the Caribbean was sometimes used after 1846, which will certainly lighten the body.

So what do we love about old-school AIPAs and what could we improve on? Their bold, mouth-filling flavors are great. Same for the in-your-face West Coast hops with their pungent floral notes. What’s not to like? Well, the aforementioned over-reliance on crystal malts, with their heavy flavors and and poor aging. Those early “C-hops” (Cascade, Centennial, etc.) can be a little one-dimensional, so it would be nice to overlay them with some more fun and modern fruity notes rather than replace them altogether. 

On the grain bill, my recommendation is to be subtle. Maybe mix down the pale with some lager malt. A little crystal 20, perhaps for that clean pure caramel flavor, maybe a pinch of crystal 80 for some old-school toasted raisin notes—but just a suggestion. If you want a bit of sweetness you can use a higher mash temperature and bump up the grain bill by a few percent to compensate for the lower attenuation and still hit the alcohol target. 

What if we could unlock some of the fruity, tropical hop aromas hidden in even the most utilitarian of hops? It turns out we can. A new group of CRISPR gene-edited hops incorporates more plentiful and effective versions of enzymes that liberate thiols—potent sulfur-bearing aroma compounds found in grapefruit, passionfruit and others. They’re also present in many of the newer, highly desirable hop varieties. 

Chicago-based Omega yeast now has two products, and one—Star Party, based on the workhorse Chico strain (originally from Ballantines)—is perfect for our purposes. Besides Omega’s other offering, at least one other so-called “thiolized” yeast is on the market, and my guess is that others will be coming soon. To get the best results, there are some unusual brewing requirements, including mash-hopping and paying attention to the amount of bound thiol precursors present. Omega suggests Saaz for this, but Cascade, Calypso, Nugget, Perle and Hallertau have high enough levels to work. Whirlpool hops add more potential.

Surprisingly, malt itself has a fairly high level of thiol precursors. Omega’s brewing trials in unhopped wort verified this, so these strains might be useful for lightly hopped fruit beers as well. Whoever’s yeast you use, be sure to pay attention to their instructions. Other than that, the fermentation procedure is perfectly normal. 

All in all, it should be possible to use these new yeast strains to overlay fresher, brighter aromas onto a classic AIPA. Provided you lighten up the heavier elements of the grain bill, the result should be an updated throwback that lets you truly enjoy the best of both worlds.


Batch Size: 5 gallons (19 liters)
Mash efficiency: 72%
OG: 1.066
FG: 1.015
IBUs: 65
ABV: 6.8%

7.5 lb (3.4 kg) pale ale
3.5 lb (1.6 kg) lager malt
11 oz (312 g) crystal 20
10 oz (283 g) Vienna
4.5 oz (128 g) crystal 80

1.9 oz (54 g) Cascade at mash hops [7 IBUs]
1.9 oz (54 g) Cascade at 60 minutes [35 IBUs]
1.4 oz (40 g) Calypso at whirlpool [23 IBUs]
1 oz (28 g) Chinook at dry hop

Omega OYL-404 Star Party Ale

Mill the grains, add the mash hops, and mash at 153°F (67°C) for 60 minutes. Raise to 165°F (74°C) for mash out, recirculate until the runnings are clear, then run off into the kettle. Sparge and top up as necessary to get about 6 gallons (23 liters) of wort, depending on your evaporation rate. Boil for 60 minutes, adding hops according to the schedule. After the boil, do a whirlpool step: Stir or recirculate to create a vortex for 10 minutes, then add the whirlpool hops, allowing 30 minutes to steep. Chill to 65°F (18°C), aerate well, and pitch the yeast. Ferment at 68°F (20°C) until complete and gravity has stabilized, then add dry hops for 3–5 days. Crash, remove or rack off sediment, package, and carbonate.

Replace pale ale and pilsner malts with 7 lb (3.2 kg) pale dry malt extract (DME) and replace other grains with 1.1 lb (500 g) dextrin malt, 1.1 lb (500 g) crystal 20, and 8 oz (227 g) crystal 80. Mill the grains and place them in a mesh grain bag. Steep in 1 gallon (3.8 liters) of 153°F (67°C) water for 30 minutes, then raise the temperature to 168°F (76°C). Remove the bag, rinse the grains, add 5 more gallons (19 liters) of water to your kettle, and bring to a boil. Turn off the heat and add the DME in batches, being careful not to scorch. Return the heat and achieve a rolling boil. Boil for 60 minutes, following directions as above.