Autumn.

It has gotten chilly in Chicago.

All of those Chicago Oktoberfests (including one hosted by one of my Siebel classmates) seem to have had their intended effect: a classic Midwest cold fronts moved through, fast and rowdy, on Sunday afternoon, and I've cemented my shorts and flip flops in the closet until next year. Or, I can keep my fingers crossed for a balmy Portland December.

The change of season has corresponded with an increased level of difficulty in brew school material: our instructors have taken us on a headlong dive into the biochemistry of yeast. Our class topics this week have included: "Yeast Metabolism," "Yeast Propagation," and "Yeast Morphology." What started as a cursory review of high school biology quickly became a test to remember the different chemical structures of alcohols, aldehydes, esters, acids, and ketones. The "A" groups all have "H," we determined. And then we moved into a discussion of oxidative decarboxylation, which, as it turns out, is essential to making beer taste good in two different ways. (Robin--it's both to produce acetaldehyde + ATP and to convert acetolactate into diacetyl). By noon today, one of my classmates said, "Give me a beer. If it tastes bad, I'll figured out how to fix it. I don't care about acids."

Despite the newfound challenges in class, the folks in my section of the classroom have rallied together around our common need for snacks in the classroom, inability to focus on class without coffee, and, mostly, our shared enjoyment of in-class beer tastings. Yesterday, we got to try American styles.

In one of my older posts, I talked about sensory tastings. Those are the sessions where we gain palate acuity (oh yes) by learning to pinpoint specific flavor compounds and developing a common "brewers' vocabulary" about flavor and taste. It's the way that brewers address the classic adolescent question of "How do I know if what you call 'blue' and what I call 'blue' are the same?"

Styles tastings, by contrast, serve to learn about classic brewing traditions and evaluate examples of different beer styles. Last week we tasted classics from the English/Irish/Scottish traditions--Fuller's ESB was an instant favorite and has got me thinking that maybe we should have a flagship beer after all and it will be an ESB. And yesterday, we tried "American" styles. Later in the term, we'll do Belgian and German tastings.

Now, most "American" styles of beer are just hopped up versions of classic European styles. So hoppiness, more than any specific style, is American. And there are a handful of nascent beer styles that are truly unique to the US (I think of steam lagers, American ambers, the "Belgian IPA," colonial porters, pumpkin + chile beers, fresh hop beers, double IPAs and the long list of experimental aged, strong, sour, and wild ales that are very New World). Those singularly American beers are getting easier to come by, but they don't make for much of a coherent group for tasting. So hopped up European styles it was.

We began with Michelob, which I'd never actually had before, and folks described it as grainy, sweet, sulfury, fizzy, and a little oxidized. Seven beers later we would have moved through gluten-free beers (Redbridge), fruit beers (Unibroue Ephermere), American ambers (Avery Redpoint), American pales (Sierra Nevada), American IPAs (Southern Tier's very grainy and woody offering) and, finally, onto strong ales.

A lot of friends who I've talked to since coming to Chicago have asked how my level of knowledge compares to others' in the class. And my response has consistently been that I'm right on par with most folks at Siebel: if I knew any less, I'd be swamped, and different folks in the class have different areas of particular expertise. Mine happen to be in knowledge of beer styles.

This made our tasting of the final four beer styles especially fun for me. I had the benefit of knowing what to expect, got pleasantly surprised, and got to watch many of my classmates have their first "imperial" beers.

Up first was the Double/Imperial IPA from Green Flash in San Diego. Double IPAs are strong, bitter, and boozy. Our instructor, who is also the vice president of Siebel, took a sniff after the obligatory taster's swirl and shouted "I'm from British Columbia and my god if that's not fresh BC bud!" Everyone agreed, and some noted hints of rubber, cheese (a common off-aroma with older hops), and citrus.

From there, we moved to Great Divide's Old Ruffian, an American-style Barley Wine. Barley wines don't actually have any wine in them; they're just beers "brewed to wine strength" and often has flavors more typical of digestifs. Great Divide's is one of my favorite beers of all time--it combines the viscous, sherry flavors of classic British barley wine with hop flavors and bitterness that must exceed 100 IBUs. Barley wines, in some ways, are just maltier, hoppier versions of an IPA, and Old Ruffian shows that linkage better than any other barley wine I've ever tasted.

After a quick overview of imperial stouts via Sam Adadms Imperial Stout, we moved on to the real treat of the day: Old Rasputin12th Anniversary, a bourbon-barrel aged version of North Coast's classic Old Rasputin imperial stout. Keith admitted that it had not been his intention to buy and share this special beer (which prices at $22/500 ml bottle) with the class, but when the local beer store was out of regular Old Rasputin he had no choice. I don't know that I've ever had a beer that balances barrel-aging, and the consequent vanilla + oak/woody flavors, with malt sweetness. The bourbon and coconut aromas were sweet, and the lingering bitterness and warming balanced well with the full body and creaminess of the beer. Though class was officially dismissed after we had tasted and discussed that final beer, most everyone hung on to enjoy the last of their few sips. It was enough (and too much) to send me back to studying for the evening in the naive hope that I can brew a beer so perfect.