Cooked: A Natural History of Transformation

by Michael Pollan

  In time, maltsters, as they were called, figured out that, by adjusting the cooking time and temperature in the kiln, they could take advantage of the browning reactions—Maillard and caramelization—to manipulate the flavor, aroma, and color of their beers. At the Oak Barrel, the long central aisle is lined with wooden bins with glass windows displaying more than a dozen different malts—cooked seeds of barley in colors ranging from pale gold to ebony, and giving off aromas as various and wonderful as raisin, coffee, chocolate, fresh bread, dark toast, biscuit, toffee, smoked peat, and caramel. It’s a remarkably rich palette of flavors and aromas—sense metaphors, really—to tease out of a simple, and all but tasteless, seed of grass simply by cooking it.

  But as I was about to discover, the choice of malt is only one of the daunting number of variables in brewing beer; there is also the type of hops that, depending on the strain, can impart completely different flavors (spicy, fruity, herbal, grassy, earthy, floral, citrus, or evergreen). Then there is the yeast, which helps determine exactly how sweet, bitter, fruity, or spicy your beer will be. Finally, there is the fermentation temperature and time, which can yield a crisp, light, bubbly lager at 45°F (in forty-five days) or a softer, richer ale at room temperature (in fourteen days). The first time I set foot in the Oak Barrel, I was so daunted by the sheer number of decisions that went into brewing a beer—a beer!—that I turned around and left without buying a thing.

  The second time, I bought one of the Oak Barrel’s beer-brewing kits and, with the help of Isaac, brewed my first batch of beer. We opted for an English Pale Ale. The kit makes all the hard decisions, in effect, and contains everything you need: the malt (an English type called Crystal in our case), the hops (Magnum, Sterling, and Cascade), some flavoring grains (malted Carawheat), and a bag of priming sugars we would need when it came time to bottle. But when you buy a kit, the malted grain comes in the form of a liquid extract (made by grinding the malted barley, soaking it in hot water, and then evaporating the resulting “wort” down to a sweet, black syrup), and the hops come in little pale-green pellets. As Kel packed up our purchases, I wondered, were we somehow cheating by using a kit?

  Brewing beer, even from a kit, turned out to be an enjoyable way for Isaac and me to spend a Saturday afternoon together. Being an eighteen-year-old, Isaac had an acute interest in beer, and he approached the making of it in a spirit of high seriousness. It probably didn’t hurt that fermenting alcohol was a grown-up enterprise that I knew no more about than he did, and which carried a faint whiff of outlawry. His mother wasn’t entirely sure about the advisability of this particular father-son project, which also counted in its favor. The work itself called for four hands and at least one strong back (for lifting and pouring five-gallon kettles and heavy glass carboys), all of which combined to make for an agreeable collaboration of equals. Working side by side is always a good recipe for easy conversation with a teenager, and I learned more than I probably wanted to about various other beer exploits, involving consumption rather than production.

  Following the Oak Barrel recipe, we began by boiling tap water in a five-gallon pot, poured in the malt extract, and then added the Magnum hops, a type used to bitter the beer. With a rolling pin, Isaac cracked the grains, which came in a muslin bag, and then suspended the bag in the rapidly boiling wort like a big tea bag. At the thirty-minute mark, we added the Sterling hops. After an hour, we took the kettle off the heat and added yet a third type of hops, Cascade, which is meant to contribute aroma. We cooled the liquid to room temperature, poured it through a strainer into a five-gallon glass carboy, and then “pitched” the yeast into it. The whole operation, which took slightly more than two hours from start to finish, felt a little like working from a cake mix, frankly. It might produce a decent cake, but would you be justified in calling the final product, however tasty, “homemade”?

  And yet the following morning, when Isaac and I went down to the basement to check on our carboy, we got pretty excited. Overnight, the big jug of honey-colored liquid had leapt dramatically to life. A thick layer of creamy foam had formed on the surface, like a great frothy head on a beer, and through the glass walls of the carboy we could see thick currents of brown wort circulating like powerful weather systems in time lapse. The little reservoir of water in the airlock was bubbling like crazy, releasing a damp, yeasty gas that smelled, agreeably, like an English pub. By now I knew all about yeasts and their appetite for sugars, but it was hard not to feel there was some serious magic under way down here in our basement.

  After a few days, the fermentation settled into a less hectic rhythm, the bubbles now infrequent enough to count as they formed and, one by one, slid through the airlock to perfume the room. The currents in the wort slowed, too, and a whitish-gray mass of yeast and other detritus, called “trub,” formed at the bottom of the carboy. (Only centuries of British devotion to beer making could produce such a superbly earthy vocabulary of Anglo-Saxon brewing terms: “trub,” “wort,” “pitch,” “malt,” “mash tun,” and, my favorite, “sparge.”) The instructions said we could bottle after two weeks, so, on a Saturday morning, Isaac and I together hoisted the carboy out onto the back porch, and carefully siphoned the fermented liquid into bottles, which we then sealed with metal caps. We had already added the bag of priming sugar to the beer to stimulate a last climactic bout of fermentation in the bottles; trapped under the bottle cap, the carbon dioxide produced by the yeasts would disperse in the beer as bubbles. Two weeks later, it would be ready to drink.

  Our English ale was pretty good, too. I mean, it tasted just like beer, which, at this point in my education, was good enough for me. Isaac was somewhat more discriminating. “The bubbles could definitely be livelier,” he declared, “and I could do with less hoppiness.” Befitting the English style, our ale was fairly bitter, with a pronounced hops flavor and aroma. We had brewed two whole cases of the stuff, and I wondered if we would ever get through it all. But as the weeks went by, the beer got better and better, as the hops mellowed and the warm, malty flavors came to the fore. After a month of “conditioning” in the bottle, I felt good enough about Pollan’s Pale Ale to bring a cold bottle down to Kel Alcala, at the Oak Barrel, for his professional evaluation. Kel, who is an earnest young brewer with a long blond ponytail and thick forearms tattooed with Goth-pagan imagery, poured himself a glass. He sniffed; he held it up to the light; he sipped. And then he stared at the beer for what seemed a very long time.

  “For a first effort?” Kel’s voice is a friendly growl. “I’d say this is really not bad at all.” He brought the glass of beer to his nose a second time, inhaling deeply. “But I’m getting a slight off note in the finish. Do you get that? Fresh Band-Aid. Yep, that’s it.” I took a sip and had to admit he was right. There was a faint chemical scent reminiscent of first aid. “That comes from a compound called chlorophenol. I’m guessing your fermentation was a little warmer than you probably want. Even just a few degrees can do it.”

  It’s funny how a well-chosen metaphor can, for better or worse, completely change the flavor of something. Never again could I drink Pollan’s Pale without thinking about Band-Aids. Johnson & Johnson’s Pale Ale would probably have been a better name for our first brew. But I was not discouraged. I wrote off the flaw to the fact that we had made this first batch in August; a second batch brewed over the winter turned out much better, with not even the slightest hint of hospital. Yet the Betty Crocker question still nagged at me, and when an opportunity presented itself to help brew a batch of beer truly from scratch, I grabbed it.

  I had heard that a friend I hadn’t seen in a few years, a psychiatrist whose son had gone to middle school with Isaac, had fallen deep into home brewin
g. I knew Shane MacKay to be an inveterate, if not obsessive, tinkerer and gear head (a serious guitarist, he also built his own amps and speakers from junkyard parts), and when I heard he had transformed part of his backyard into a brewery, I immediately gave him a call to see if I might assist on his next batch. I was certain Shane MacKay would not be using any kit.

  There was the unmistakable hint of the mad scientist about Shane as he proudly showed me around his backyard setup early on a Sunday morning, his white thatch uncombed, his steel-blue eyes lit up by this latest DIY fire. Shane’s teenage boys having long since lost interest in Dad’s brewing project, the alchemist seemed delighted to have an eager new apprentice. In the shade of a lean-to he’d built behind the house, Shane had erected a tall structure of steel shelving to hold, at different heights, various kettles and kegs, each atop a propane burner, and all of them linked together by clear plastic tubing that passed through various valves and spigots. Thermometers, hygrometers, jars of sanitizing chemicals, pumps, filters, funnels, carboys, bottles, airlocks, and propane tanks completed the scene. It occurred to me that, by learning to brew beer, Shane had found the perfect way to combine his engineering gifts with his professional interest in brain chemistry and how it might profitably be altered.

  With the help of some incomprehensibly elaborate brewing software, Shane had concocted a recipe for a beer modeled on a traditional Irish ale; he was calling it, for obscure reasons, “Humboldt Spingo.” As he typed into his laptop various parameters—types of malt, hops, and yeasts; temperatures and times—the software showed him exactly where the finished beer would fall along several different spectrums, including maltiness, sweetness, bitterness (measured in IBUs, or International Bittering Units), original and final “gravity” (dissolved solids), and alcohol level. Shane’s whole approach—the software, the metrics, the scrupulous sanitation—was a world away from Sandor Katz’s. Wild fermentation was the last thing Shane wanted going on in his carboys.

  Shane had picked up the ingredients at the Oak Barrel the day before: a blend of malts, dominated by an English type called Maris Otter and supplemented with smaller amounts of Victory, Biscuit, Cara Red (for color), and a few ounces of roasted (i.e., unmalted) barley. For hops (which Shane proudly showed me he had planted along his back fence), we would use U.S. Golding to supply the bitterness (but not very much—the Irish ale style is considerably less bitter than the English) and Willamette for aroma. As for yeast, we were going to divide the batch in half and pitch two different strains: an English yeast and a Scottish. Shane proposed that I take one of the carboys home to ferment in my basement, and later we could compare the effects on the beer of the different yeasts. A controlled experiment, or close to one.

  Brewing from scratch, or “all-grain” brewing, begins with the soaking of the malt in hot (but not boiling) water. Before we added the crushed grain to the water, I sampled a few of the seeds. They tasted surprisingly good, sweet and nutty, but full of cellulose, like a ridiculously high-fiber breakfast cereal. The hour-long soak allowed the enzymes in the barley to break down the grain’s carbohydrates into fermentable sugars. As we stood around the mash tun—a steel kettle with a screen at the bottom—watching the hot cereal steep, Shane asked about my brewing experiences to date. Being both a psychiatrist and a Canadian, he did a magnificent job politely masking his disdain for my Duncan Hines approach to beer making; he had started out the same way.

  But though it added a couple of hours to the brewing process, steeping the grain seemed well within my capabilities. So did the next step, which was to sparge the cooked mash. After Shane opened a valve at the bottom of the mash tun to drain the sweet brown steep water into a second kettle, he directed a stream of boiling water from a third kettle overhead down onto the mash, in order to leach, or sparge, any remaining sugars from the nearly spent grains. After this water passed through the mash, it emerged from the spigot below golden brown, warm, and fragrant. I tasted the grains again. They had been completely bleached of flavor.

  Now we had our wort—thirteen gallons of sugary brown liquid. Shane poured a few ounces of it into a glass test tube into which he floated what looked like a big fat thermometer. In fact it was a hygrometer, which measures the density, or “gravity,” of the wort: the amount of dissolved sugars in the liquid, which gives the brewer a good idea of just how much alcohol the final beer will contain. The scale on the side of the hygrometer indicated the wort had an “original gravity” of 10.50—precisely what the software had predicted. (When it dropped to 10.14, the software said, the fermentation would be complete.) Shane pronounced himself pleased. Now he rigged up a system to cool the wort as quickly as possible by submerging a spiral of copper tubing that he then connected to a cold-water line. You want to cool the wort as rapidly as possible to minimize the risk of bacterial contamination. (The addition of hops, which contains antimicrobial compounds, also helps prevent contamination.)

  Between steps, brewing beer consists mainly of hanging around watching pots boil, so there’s plenty of time for talk. (Drinking, too, though, this being a Sunday morning, we stuck mainly to coffee.) Shane and I covered many bases, catching up on family and work and other fermentation projects. He asked about this book. I told him the premise, how the four elements corresponded to the principal methods humans have devised for transforming the stuff of nature into things good to eat and drink.

  “So where does beer fit into your scheme?” Earth, I explained, since fermentation draws on the same microbial processes of destruction and creation at work in the soil. But then it occurred to me that, in fact, all four elements were represented in the beer-making process. The barley is first cooked over a fire; the grain is then boiled in water; and the beer, after fermentation, is carbonated with air. Beer is the complete four-element food. Which, I realized, is exactly the sort of insight you would expect beer to sponsor.

  When, after forty-five minutes, the temperature of the wort had fallen to our target of 70°F, we divided the liquid between two carboys and pitched the yeast, the English in one and the Scottish in the other. To aerate the yeasts, we vigorously shook and rolled the carboys till the wort began to froth. Then we plugged them with airlocks. Nearly five hours after putting the grain in to soak, we were done. Shane helped me hoist the carboy out to my car.

  On the drive home, one hand on the steering wheel and the other steadying the neck of my carboy, I thought about S. cerevisiae, the invisible single-celled creature that had been the recipient of the morning’s sustained and scrupulous attentions. “Man’s best friend”: By now, I had heard several brewers use the same phrase to describe it. But after devoting five hours of our weekend to the building of an idyllic environment for this species—a carboy full of sweet brown wort—it seemed to me it would be just as accurate to call Shane and me and all the other fermenters “Saccharomyces’ best friend.”

  “Coevolution” is a strong term, implying that both partners have been changed by their relationship. It’s not hard to demonstrate how the human desire for alcohol (bread, too) helped to redirect the evolutionary path of this particular fungus, as our species selected yeasts for their ability to ferment various substrates and produce varying amounts of alcohol or carbon dioxide. But for our relationship to this yeast to qualify as coevolution, the changes must be reciprocal. So can we make a case that S. cerevisiae changed us, too?

  I think we can. While we were altering the genome of S. cerevisiae, it was altering ours: Our ancestors evolved the metabolic pathways to detoxify ethyl alcohol in order to make use of its prodigious energy (and, conceivably, some of its other benefits). Even today, not all humans possess the required genes, and some ethnic groups, lacking the ability to produce the
necessary enzymes in their liver, have more trouble metabolizing alcohol than others. For them, alcohol remains more toxin than intoxicant. Yet the proportion of the human population that carries the genes to metabolize alcohol has almost certainly increased in the time since our species has been seriously drinking, in much the same way that the number of humans who can digest lactose as adults increased in places, such as Northern Europe, where cow’s milk was widely available. In both instances, those who carried the genes needed to take advantage of the new food source produced more offspring than those who didn’t.

  Yet the changes that alcohol wrought in our species have not been confined to the human genome or the human liver. S. cerevisiae exerted what may be an even more profound, if somewhat harder to pinpoint, effect on the plane of human culture. Precisely where genes leave off and culture begins (or vice versa) is never an easy line to draw, since eventually useful cultural practices and values influence reproductive success, and so leave their mark on our genes. And though we don’t yet know everything we would need to in order to write a comprehensive natural history of such important human traits as sociality, or religiosity, or the poetic imagination, when we do, there seems little doubt that S. cerevisiae (along with a few of the other species that produce important human intoxicants) will play a starring role. This little yeast has helped to make us who we are.