Sacks of grain patiently await the start of the brewing process.
If there’s any lesson at all in the manufacture of gruel-beer, it’s that beer must be easy to make. It is. Of course, as the long history of beer demonstrates, making good beer is a different matter entirely. Nevertheless, the process hasn’t changed a great deal since it began. Modern commercial malting and brewing employs a lot of technology to ensure consistency and precision in the process, but brewers still go through the same basic steps. A medieval brewer visiting a twenty-first-century brewery might be confused by the computers and electronics, but the tuns, kettles, and vats would all be instantly recognizable.
Making beer always starts with the grain and hops and other adjuncts. A recipe may be made with as few as four ingredients or as many as a dozen or more. Employing these building blocks involves the same basic method whether the brewer is using a five-gallon home setup or working in thousand-barrel batches. Depending on the style, the beer will be handled differently, but in the end it’s all just variations on a theme. Even with the use of computers and sophisticated mechanics, brewing beer remains an elegantly straightforward process. ■
NO MATTER HOW complex the recipe, beer is made up of four basic elements: a solution (water), a source of sugars (grain, either alone or with fruit or raw sugar), and spice (usually, but not always, hops). Yeast, the fourth, is the agent of fermentation.
In a nutshell, here’s how everything works together: Malted grains are steeped in water to make them edible to the yeast that will be added later. This creates a sweet tea known as “wort” (rhymes with shirt) that’s rich in simple sugars. Yeast would happily dive into the wort and make beer, but the result would be as sticky and sweet as honey. So brewers bring the wort to a boil and add spices to offset the sweetness of the malt. (Beer drinkers of the Dark Ages enjoyed good health not because beer was inherently wholesome—though that goes without saying—but because the process of boiling it killed all the deadly bacteria often found in the water.) Finally, brewers cool the beer down and add yeast, which does the rest, turning sugars into alcohol, and wort into beer. In most modern beers, the recipe employs barley, hops, water, and yeast; a sizable minority use other malts, sugars, fruits, and spices in addition to these basic ingredients. ■
SUGARS FERMENT EASILY. They are predisposed to fermentation, and yeasts crowd around, waiting for the opportunity to strike. The process is so natural that ripe fruit will ferment while still hanging on the tree. Monkeys know this, and look for “alcohol plumes” that alert them to boozy fruit. The result, even in its still-on-the-vine form, is considered a wine—though humans have refined the process considerably. When grains provide the fermentable sugars, we call the resulting beverage a beer.
Grain is, beyond a source of sugar, the body of a beer, offering the flavor and aroma that characterize its nature. Beer has been called “liquid bread,” and anyone who has swirled it around her mouth knows exactly why. A beer may start with a whiff of wheat or barley and continue along with the homey, familiar flavors of cracker, biscuit, or cookie. Sometimes more exotic grains round out the flavor—the spice of rye, the creaminess of oats. Without grain, you don’t have a recognizable beer.
Sacks of grain patiently await the start of the brewing process.
Malt is the principal source of fermentable sugars in beer. It’s a little different from grain, though the words are often used interchangeably. Unlike fruit, raw grains won’t ferment well—their sugars, which start out as carbohydrates and proteins, are too rough and indigestible for yeast to eat. The grain must be malted first, a process of awakening the seeds so they begin to sprout. This creates chemical changes in the grain that convert the carbohydrates into simple sugars that make a tasty meal for yeast.
Beyond the flavors and aromas grains contribute, they offer these other essential elements.
Two-Row Versus Six-Row. Barley comes in many varieties, but the two most common categories are two-row and six-row. Both are used in brewing. The number refers to the way the kernels cluster around the center stalk (not, as some people assume, how the grain is planted in the field). In two-row, the kernels grow on either side of the stalk; in six-row, they circle it like petals on a flower.
Two-row barley is generally favored for base malts because the kernels are plumper—the way they grow on the stalk gives them more room to spread out—and offer the greatest amount of carbohydrates for yeasts to work with during fermentation.
Because of its higher protein content, six-row barley browns more easily. This makes specialty malts taste slightly different when made with six-row barley—a flavor preferred by some breweries. Six-row is also used in darkly malted roasts where carbohydrate yield is irrelevant and where flavors and colors are the same for both types of barley.
■ Fermentable sugars. The sugars and carbohydrates that yeasts consider edible start out locked up inside the seed of the grain, stored there until they’re called on to nurture the shoots of a new plant. Grain needs to be malted first—a process that converts proteins and carbohydrates into fermentable sugar.
■ Color. In preparation for brewing, malt is kilned and roasted. Unmalted grains may also be roasted. This imparts a color, ranging from straw to jet, and that color is in turn imparted to the beer.
■ Body and mouthfeel. Beer is thicker than water—sometimes much more so. This is known as “body,” and it comes from unfermented proteins and caramelized sugars that the yeast couldn’t convert to alcohol. The caramelized sugars, dextrines, are often intentionally left in—some malts are rich in them—and they increase a beer’s viscosity.
■ Protein. In addition to adding body and mouthfeel, protein interacts with the natural carbonation in beer and is responsible for the head. Other alcoholic beverages—cider and Champagne, for example—also bubble up when they’re poured, but lacking protein, they can’t maintain the glamorous head that tops a fresh pint of beer.
A mash tun at Brewery Dubuisson in Pipaix, Belgium
Kilning (drying) and roasting are the final stages, and they play an important role in the flavor and aroma of a finished beer. Much as coffee can be roasted lightly or to an oily, midnight black to create different kinds of flavors, so malt can be roasted to different levels. As with coffee, roasting affects the flavor—but to an even greater degree. Some light roasts produce a warm toastiness, others a sweeter hint of dark fruit, and some a French roast–like bitterness. Some malts, known as “base malts,” are kilned at relatively low temperatures and emerge a very pale color. Specialty malts are dried for longer periods of time and then roasted. When a brewer assembles a recipe, he uses a selection of malts in the “grain bill” that will provide color, aroma, and flavor specific to style.
Designing a grain bill for a beer is like creating the recipe for a cake. Whether you’re making a white cake or a chocolate cake, the main ingredient is flour. In a grain bill, base malts are the main ingredient. These pale malts are the foundation of any beer; they’re loaded with simple sugars and enzymes that will convert easily to alcohol. Even in the darkest beers, the majority of malt will be base malt—just like flour forms the basis of even the darkest chocolate cake.
Another important category are the crystal or caramel malts. This class of malts is created by roasting still-moist grain before kiln-drying it. During the process, sugars caramelize. The resulting malt is brittle and crumbly; the sugars, which form longer chains during caramelization, can’t be consumed by yeast and so are used to enhance body. True to its name, caramel malt contributes a pronounced toffee flavor; in larger amounts, it produces dark fruit notes; and in unbalanced proportions, it will lend the beer unwanted tannins. Once crystallized, these malts are roasted and may be quite light for use in pale ales, or very dark for use in darker ales.
Next are the dark malts used in schwarzbiers, stouts, and porters, and specialty malts that accent different styles. Dark malts add color, but their effect on flavor varies. Some add roastiness, some sweetness, others coffee-like bitterness. Specialty malts contribute accent notes that fill out the flavor of a beer—a touch of honey, toast, or smoke.
Finally, malts from grains other than barley are occasionally used to give a beer different character. Wheat can be used as a base malt and adds a soft, bready flavor as in weizens and witbiers. Rye is a versatile grain that can add an earthy spiciness to darker beers or a spritzy, minty freshness to light beers. Unmalted roasted barley, used primarily in stouts, contributes less of the coffee-like sharpness of black malt; instead, the character is more rootlike and sour. Oats add body and mouthfeel, while corn and rice, used mainly in industrial lagers, lighten the body of a beer without adding much flavor.
PILSNER |
The lightest malt available. Imparts a slight flavor—sweet and gently grain-y. Despite the name, pilsner malt can be used in any style of beer. |
PALE |
Kilned slightly darker than pilsner, pale malt gives the beer a more bready flavor; typically used in ales. |
VIENNA |
Slightly darker than pale malt; used to produce light amber beers like bock and Oktoberfest. |
MUNICH |
Roughly twice as dark as Vienna, with an amber hue that heads toward red. It is prized for its rich, caramel flavor with hints of toast and nuts. |
CARAMEL/CRYSTAL |
This category of malts includes examples that are quite light (for use in pale ales), medium, or almost brown (for use in darker ales). |
CHOCOLATE |
Used in porters and stouts; when combined with lighter, sweeter malts, its gentle bitterness can indeed closely resemble cacao. |
BLACK MALT |
Akin to espresso: intense bitter flavor, sometimes even charred. Adds depth and complexity to a beer as well as balancing sweeter malts in high-gravity recipes. |
ROASTED BARLEY |
Used primarily in stouts, it provides the deep, roasted flavor that characterizes Irish stouts like Guinness. |
WHEAT |
In some styles, the protein in wheat stays in suspension and clouds a beer, and works with certain yeasts to produce banana and clove flavors. |
RYE |
Rye thrives in poor soil, so its use in both bread and beer has been concentrated in colder, harsher regions. Finns and Russians used it to make their traditional beers, sahti and kvass. |
OATS |
Oats are used to enhance a beer’s texture, creating a silky, creamy quality that works well in both stouts and pale ales. |
Sugar in your beer? In Belgium and England, brewers regularly and proudly use it—many styles can’t be made without added sugar. But in Germany, using sugar is absolutely verboten; this appears to be an almost moral issue with brewers there. Americans also hold a mild prejudice, associating the use of sugar with industrial lager production. Yet as people become more aware of the full range of beer styles, old biases are starting to die out. (Well, not in Germany.)
Sugar performs two roles in beer: It boosts alcohol, and adds flavor. Unlike malt, which never fully ferments out, sugar converts almost entirely to alcohol. This is useful for brewers who want to increase alcohol without adding body. Brewers use sugar to make tripels, for example, which rise to 8 to 9% alcohol but remain light-bodied. Compare these to all-malt barley wines of roughly the same strength; these beers are so dense and viscous their mouthfeel is as rich as a mocha’s.
Brewers commonly use refined sugar (sucrose) to boost alcohol strength. In Belgium, brewers once used “candi” sugar, a form of sucrose crystallized into lumps like hard candy. Now almost all use sugar syrup, another form of sucrose. When Belgians use dark candy sugar, this is a caramelized form of sucrose that adds both color and a bit of caramel flavor. Caramel sugar is also a traditional ingredient in British ales, notably mild ales, used for the same reason. The British also use invert sugar, a variant of sucrose, wherein the constituent parts of glucose and fructose have been chemically split in two. Some breweries believe invert sugar is easier for yeast to ferment than straight sucrose.
Finally, brewers occasionally use less-refined sugars to add flavor as well as alcohol to their beer. Molasses, maple syrup, brown sugar, and honey all provide fermentables for yeast to munch on, but each also leaves traces of its distinctive flavor after fermentation. ■
MAN CANNOT LIVE by bread alone, and neither can beer be made solely with malt. The very sugars that make grain the body of beer also make it overly sweet; a beer is not complete without spices to balance the malt, to scent it and bring it alive. Hops now perform this role in most beers, but it wasn’t always so. Their regular use in beer is less than a millennium old; before that, brewers used a dazzling variety of other spices—as always, based on what was available locally.
Archaeologists have been most useful in documenting old recipes. By scraping residue from the inside of pots, they have been able to identify the grains and spices brewers used in the earliest beers. From these reports, we know that the Egyptians used coriander, the Chinese chrysanthemums, Scots favored heather and meadowsweet (a perennial herb in the rose family), and throughout Scandinavia brewers spiced their beer with juniper and sweet gale. It’s safe to say that nearly every herb and root used in cooking has at one time or another been thrown into a brew kettle.
Spiced ales continued well after brewers began using hops, and this oft-quoted recipe from John Houghton in 1683 attests to the diversity of spices brewers once added to beer.
To produce 42 gallons of mum start with seven bushels of wheat malt, one bushel of oat malt, and one bushel of beans. Once fermentation begins thirteen flavorings are added, including three pounds of the inner rind of a fir tree; one pound each of fir and birch tree tips; three handfuls of ‘Carduus Benedictus,’ or blessed thistle; two handfuls of ‘flowers of the Rosa Solis’ or sundew; the insect eating bogplant, which has a bitter, caustic taste; elderflower; betony; wild thyme; cardamom; and pennyroyal.
Eventually, of course, hops were discovered. Much of the credit for hops goes to the Roman naturalist Pliny the Elder, said to have first named them—though this account is disputed. In any case, the first documented use of hops as a beer ingredient didn’t come until 822, when an abbot in Northern France mentioned them in a manual of abbey rules. It took hundreds of years for hops to catch on—they tasted weird and were hard to use—but ultimately, recognition of their antibacterial properties led to their adoption. Other spices may have tasted good, but they couldn’t match the preservative quality of Humulus lupulus.
In common language, hops are the cones that form on female hop vines. (Technically, they’re actually strobiles, not cones, which is their informal name, and bines, not vines—bines climb by encircling a vertical object, while vines send out tendrils to latch on.) They are remarkably energetic herbaceous perennials that can grow a foot a day and cover entire trees in the wild—but only in certain conditions. Hops require at least fifteen hours of daylight and therefore can only be grown between 35 and 55 degrees latitude. They do better in drier climates, but require a lot of water; hops are also subject to a number of diseases and infestations. As a consequence, commercial production is isolated in just a few regions—over 85 percent of the world’s output is grown in Germany, the U.S., China, and the Czech Republic. In the United States, nearly all commercial hops are grown in the Northwest. The newest region to excite beer fans is the southern hop band in Australia and especially New Zealand.
European Skunks. Many people are familiar with the “skunky” aroma of many European beers—sometimes thinking this is the house character of those beers. It’s not. Beer takes on a skunky flavor when exposed to light, a chemical reaction resulting from the decomposition of certain chemical compounds in the hop’s isohumulones. The offending compounds are so strong humans can detect them in parts per billion. When it happens, a beer is said to be “lightstruck.”
The main culprits are the green bottles many European breweries use, which are more light permeable. It is possible to purchase a hop distillate immune to becoming lightstruck—that’s what American breweries use for their clear-bottle-packaged lagers—but the distillate lacks the character of fresh hops. For beer protection, brown bottles are better, and cans and kegs better still.
THE ANATOMY OF A HOP
In beer, hops are no ordinary spice. Through the alchemy of the brewing process, their acids are transmuted to what humans perceive as bitterness. Beyond bitterness, brewers can harness them to produce flavors of mango in one beer or black pepper in another; hops can scent a beer with the freshness of pine or the softness of jasmine. It is no wonder that they have replaced other spices, nor that they have beguiled so many beer drinkers; their character is so mutable that just by changing a single hop in a recipe—or by changing the moment the same hops are added to the boil—a beer’s nature can be transformed.
So what’s in a hop that allows it to express such personality? The hop cone looks a bit like a papery, green pinecone, but under each petal are not seeds but globules of yellow resin called lupulin. The resin is where important acids and essential oils are located—those elements responsible for all the flavors and aromas hops contribute. The central function of the hop, bittering, comes from a group of five acids collectively called alpha acids or humulones. In their native form, alpha acids are insoluble. In order to unlock their bittering potential, they have to go through a chemical change.
Core samples taken from the center of hop bales
Brewers at Fuller’s select hops for the coming year.
“Noble” Hops. Among the best-regarded hops are four that claim regal heritage: German Mittelfrüh from the Hallertau region; Spalt Spalter south of Nuremburg; Tettnanger, which take their name from the region around Tettnang; and Saaz or Žatec from Bohemia. Collectively, they came to be known as “noble” hops for that most ignoble of reasons: because that’s what the salesmen started calling them in the 1980s.
They are widely considered outstanding hops, however, and their gentle, balanced qualities were thought to account for this. Other hops with similar qualities tried to join the club (Fuggle and East Kent Golding) with more or less success; partisans of the original nobles were reluctant to expand membership.
But over time, other excellent hybrids emerged that didn’t have the same configuration of acids and oils. As time has gone on and research tells us more about hop chemistry, the “noble” designation seems like a relic of an earlier age. In the democratic scrum of the modern hop market, the old nobility hold on to their titles more out of ceremony than need. They are great hops, but now they have lots of company.
Hop Terroir. In winemaking, the concept of terroir is used to discuss the natural environment that produces the grape—the soil and climate of the vineyard. Brewers have less concern for terroir—they can make adjustments for water and grain variation, effectively removing environmental variables from the calculation.
Hops, on the other hand, seem very sensitive to terroir. Several famous varieties are associated with their small regions of origin, and in turn define certain styles or families of beers. Interestingly, when rhizomes of these very plants are moved to other regions, the hops they produce don’t taste the same. Something about the soil, the quality of sun, the summer temperature, and the length of days makes an American-grown East Kent Golding taste different from one from East Kent. So for a truly authentic-tasting pilsner, brewers can’t use locally grown Saaz; they must go to the source.
Boiling them causes this change (called isomerization), but it takes a long time. The longer the hops bob in boiling wort, the more bitterness they’ll produce. Alpha acids are present in different levels in each hop type, ranging from 1 to 20 percent, so each variety has a different maximum potential for producing bitterness.
Another class of bittering agents in hops are beta acids. Unlike alpha acids, beta acids are immediately soluble in wort, but behave differently in finished beer. Isomerized alpha acids slowly lose their bittering capacity, but beta acids oxidize with time, growing in intensity and contributing a different quality of bitterness to aged beers.
Hops also contain essential oils, the compounds so important to the aroma and flavor of the beer. Of lupulin’s entire makeup, just a tiny proportion—1 to 4 percent—is essential oils. Yet these oils exert a mighty influence on the way a hop smells and tastes. Brewers will often hand-select their hops from dealers, rubbing them together to burst the lupulin and expose the essential oils. What they glean from the scent comes primarily from a mixture of four oils: myrcene, farnesene, caryophyllene, and humulene, usually accounting for 80 to 90 percent of the total. These four are also present in other botanicals, and it is tempting to make associations between those spices and the aromas we find in hops. Myrcene is found in bay leaves, thyme, and ylang-ylang; farnesene in gardenias; caryophyllene in cloves, rosemary, and black pepper; and humulene in Cannabis sativa (that is, marijuana), to which hops are closely related.
After drying, hops are baled and stored at near-freezing temperatures to preserve their delicate oils and acids.
“Dwarf” or “hedgerow” hops only grow to eight feet, and can be harvested so the bines are left intact. The result, some researchers believe, are hardier, healthier plants.
Dr. David Gent of the USDA stands in front of experimental fields of pesticide-free hops that employ varying techniques to control pests and blight.
But here comes the mystery. These oils are volatile, and they are easily driven off. When hops are added early to the boil, very little of the oils survive. Even later additions, from which their characteristic flavor and aroma are drawn, are just as lethal. These oils remain only when a beer is dry-hopped, and yet their character is clearly present even when they are added fairly early during the boil. The aroma that rises from the crushed hops in a brewer’s hand is similar to the aroma that rises from a pint glass (sometimes: “rubbings” are not an exact science)—even after those volatile oils have been subjected to boiling wort and active yeasts. So how does the character survive when the oils do not? This is a mystery that scientists have yet to decode. Hops contain more than 400 aroma compounds, and some of them survive the boil and are unlocked during fermentation. There are even a few compounds that aren’t released until they’re worked on by the enzymes in the mouth. It’s a very tricky matter, this hop aroma and flavor business, and we have lots more to learn about how it works.
Like any spice, hops contribute different qualities depending on variety and method of use. The earlier hops are added in the brewing process, the more bitterness they contribute; the later they are added, the more aroma. Somewhere in between they start adding interesting fruity-tasting compounds and other flavor elements, a process that continues along through fermentation. Because of their chemistry, hops are generally grouped by type: aroma or bittering. Hops useful for bittering should produce a clean, sharp flavor without harshness. Aroma hops provide distinctive scents full of floral, peppery, or citrus notes. Brewers tend to use high-alpha hops to bitter a beer (because of the alpha acid content, it means they don’t have to use as many pounds of hops), and lower-alpha hops for aroma, but this isn’t always true. Where hops are concerned, “bittering” and “aroma” are general categories.
Not all hops are used in whole form. Because whole hops have a great deal of surface area, they are the least stable form and most subject to degradation during storage. Many breweries use hop pel-lets instead; these are made by crushing whole hops into a powder and molding them into beads the size and shape of a pencil eraser. In most cases, pellets are more stable than whole hops, but some breweries believe the process of crushing changes the way they are converted during the boil. (Despite the ardor of their partisans, there’s no evidence either form is superior.) Pellets and whole hops are used interchangeably in the brewing process, and many brewers use both depending on the situation. Among nonindustrial breweries, only a small minority use hop extract, a product that contributes a somewhat different quality; even more rare are hop oils, used to enhance aroma.
A recent list of hop types included more than 100 varieties from around the world, including several rare and new ones. Yet it surely understates the total, which expands by the year. Learning to recognize hop types isn’t critical in beer appreciation, but it can help one isolate examples to pursue or avoid. The Appendix contains a list of major hop varieties with descriptions of their flavor and aroma.
Immediately after harvest, hops are quickly dried before packaging. Drying and cooling stabilizes the hop components, but it also changes them. Because dried hops are the standard, all the information breweries use when creating recipes—oil amounts, acid levels—has been based on dried hops. When we talk about brewing hops, we’re talking about dried hops.
About twenty years ago, English and American breweries began experimenting with hops fresh from the bine. In order to capture the most evanescent volatile elements, brewers collect hops from the fields and race them back to waiting kettles. The length of time between picking and brewing is never more than a few hours. The products of this process are known as “fresh-hop” or “wet-hop” beers, and they smell and taste quite a bit different from their regular hop cousins. The Pacific Northwest, where most of the nation’s commercial hop fields are located, has a decided advantage in making these beers. Many are produced for draft sales, but a few, like Deschutes Hop Trip and Rogue Wet Hop Ale, are sent farther afield in bottles.
A pantry’s worth of spices—like this sampling from Brewery Ommegang—can be used in brewing.
Wet hops are unpredictable. They don’t uniformly produce fresher, more vibrant versions of their dried selves. Some do, but the acids and oils exhibit their character capriciously. In others, the hop produces different flavors from those expected, and in some unfortunate examples, they result in very unpleasant flavors. (I’ve tried fresh-hopped Hallertauers—that famous “noble” hop—that tasted like sour beef. Sauerbraten is lovely with a nice amber lager; it is less so in an amber lager.)
So far, researchers haven’t looked into how wet and dry hops affect beer differently. In research on other herbs like oregano and peppermint, scientists have found sharply differing levels of oils and acids. Interestingly, the differences weren’t consistent across herbs, so it’s not clear whether hops all behave the same way, either. Perhaps this is why some varieties lend themselves to wet hopping while others do not.
Hops are not likely to be displaced anytime soon as the spice of choice in beer, but they weren’t always the only option. Before hops came into widespread usage, brewers used local ingredients like juniper berries, heather, sweet gale, or yarrow. A few traditional beers are still made in the old way (Finland’s Lammin Sahti with juniper is a good example). Revivals like Williams Brothers Fraoch Heather Ale from Scotland, Jopen Koyt [Gruit] beer from the Netherlands (a mixture of herbs), and France’s Lancelot Bonnet Rouge, with elderberries, are some examples. American craft breweries have concocted New World unhopped ales with other spices, as well.
Far more common is the use of spice to enhance hopped beer. While the rest of the world catches up, Belgium’s breweries continue to use spices even after they adopted hops hundreds of years ago. It is so common that Belgian breweries often don’t mention it (did you know that Rochefort adds a dash of coriander?), leaving drinkers to wonder if that black pepper note comes from the spice or is a product of fermentation. Belgians regularly add orange peel, hibiscus, dandelion, paradise seeds, ginger, and cumin—to name just a few.
British brewers once had nearly the same affinity for adjuncts, putting everything from licorice and rosehips to oysters and spruce tips into their beer. The practice was very common until two or three hundred years ago when laws changed to regularize brewing ingredients, and trailed off substantially after the world wars.
How Much Is Enough? The average brewery takes eight gallons of water to produce a single gallon of beer. For larger breweries, this can mean running through millions of gallons of water a year. Efficiencies can cut water use in half, but tuns, kettles, and tanks will always need to be cleaned out. As the planet warms, water availability—more than water quality—may one day dictate where breweries can be located. Craft breweries are on the leading edge of water and energy conservation, and some have cut that ratio down as far as 2:1.
With the rise of craft brewing, new breweries have taken up old practices, and now spiced ales are common. Many of the old spices have been rediscovered, including vanilla, elderberries, cinnamon, lavender, star anise, chamomile, sarsaparilla, cardamom, sweet gale, ginger, mugwort, and yarrow. Beyond tradition, modern breweries have experimented widely, adding things like tea, coffee, chocolate, chile peppers, and even exotica like cactus, persimmon, and palm nut. One of the more memorable beers I’ve tried came about when a brewer, inspired by a branch from an evergreen in his backyard, decided to cut it off, needles and all. He threw it into a porter, to surprisingly successful effect. If a brewer has been enchanted by an ingredient, he’s probably tried to brew with it. ■
IN TWENTY-FIRST–CENTURY BREWING, the quality and composition of water is of little concern to breweries; they can easily adjust its pH and compensate for the presence of unwanted minerals. Water is now effectively just a blank canvas for the colorful play of malt and hops.
This wasn’t always the case. Until they mastered chemistry in the twentieth century, brewers were at the mercy of their local water source. It was a definitive ingredient, and the most fixed. While hops and barley could travel a few miles, water was difficult to transport, so breweries were sited to take advantage of rivers, springs, or deep wells. Brewing consumes huge amounts of water, so the source had to be bountiful and reliable. But because it was fixed and immutable, local water exerted an unseen force on the beers made with it. Some water had lots of minerals, others had very little—and these conditions dictated that certain styles would be more successful than others. Stouts may have been a good fit for the chill, dreary rain of Dublin, but it was the water, not the weather, that made the style successful. Likewise, the pilsners of Pilsen, the pale ales of Burton, and the amber lagers of Vienna.
Discovering Yeast. For centuries, brewers regarded fermentation with wonder, attributing it variously to God or magic. The roiling tuns seemed to be enchanted—or perhaps imbued with the Holy Spirit. (Brewing has long been a monastic pursuit.) Amazingly, yeast wasn’t actually identified until the 1800s. Before then, brewers had only the general sense that the dregs from the last batch, when dumped into a freshly brewed wort, made the resulting beer less harsh and vinegary. Brewers domesticated yeast without ever knowing exactly what it was.
It was Louis Pasteur who finally identified yeasts as living organisms in 1857, but yeast science really didn’t get rolling until nearly the dawn of the twentieth century. For example, it was only in 1903 that Carlsberg Laboratory discovered that what made English beers funky at the time was the presence of a wild yeast strain, Brettanomyces. (Interestingly, it’s now absent from English beers, and associated with Belgian ones instead.) This was surprisingly late in the game—by this time, breweries were already refrigerating and shipping their beer on rail lines.
The reason is chemistry—and this also explains why water is now relatively unimportant in the brewing process. When a beer is in the mashing phase, the pH of the beer will dictate what elements are drawn from the malt. Dublin has a lot of bicarbonate in its water, making it hard and alkaline. This draws the tannins from the grain husks. When Irish breweries used a mash made solely of pale malts, the hard water produced a harsh beer. The addition of acidic roasted malts, however, balanced the mash, bringing it into more appropriate pH. Voilà!—fantastic Dublin stout.
On the opposite end of the spectrum, Pilsen, Czech Republic, has soft water with almost no dissolved minerals—and less than 1 percent the bicarbonate of Dublin. This water is especially suited to pale malts, needing none of the acidic dark malts to produce an appropriate pH. And so from this water, Czech brewers were able to brew the pale lagers that took the town’s name. ■
THE WORD “YEAST” comes from the Old English gist, which means “boil.” To see a day-old vat of beer is to understand why: The wort turns milky and sends up a mighty cloud of froth that heaves and bubbles like a witch’s cauldron. It sends off waves of carbon dioxide. Even the temperature rises—if left on their own, the trillions of active yeast cells would boost the temperature of the beer by ten to twenty degrees Fahrenheit. Boil indeed.
Yet yeast is a modest being—a ubiquitous single-celled fungus that floats through the air, coats surfaces of fruit, and lives on certain other organisms, notably insects. (There’s even a variety that lives between human toes.) Yeasts have been enormously valuable to people, too, who’ve harnessed them to make bread, wine, and beer. All three of these products are made with the same broad category of yeast, Saccharomyces cerevisiae.
By the end of the boiling process, lots of chemistry has already taken place in the wort. Malt starches have been converted to sugars, hop acids and oils have been put into solution and isomerized. It’s during fermentation that the yeast cells perform the final acts of chemistry, turning sugars to alcohol, and it is here that beer is finally made.
Fermentation is fairly simple: Yeasts begin by consuming all the available oxygen suspended in the wort. If there is more oxygen than yeast (and in wort, there always is), the cells reproduce by budding, sending their children off to collect the remaining available oxygen. Once all the oxygen is gone, yeasts begin the chemical conversion that makes beer. They take in sugars, starting with the most digestible kind first, and work their way along until they’ve consumed everything they can. The gobbled sugars go through the yeast cells and are excreted as alcohol and carbon dioxide. Within a day of the introduction of yeast, the beer will begin its transformation into bubbling cauldron, a process that peters out after a few days, as yeasts conclude their gorging frenzy and begin settling to the bottom of the tank, sated and still.
It’s a mistake, however, to think that yeast’s sole contribution to beer is alcohol production. Yeast cells are essentially miniature chemical plants, and in addition to alcohol and carbon dioxide, they produce other compounds like esters and phenols. For the brewer, these other byproducts are nearly as important, for they make a profound contribution to the final character of the beer. Yeast can create flavors that mimic other ingredients like fruit and spice, they can make a beer taste drier, sweeter, or more alcoholic—all by the way they metabolize the malt.
Following are the four major categories of by-products that yeast may produce.
“Double, double, toil and trouble”—yeast in action
“Marmite: Love It or Hate It.” In the early 1900s, a German scientist determined that spent brewing yeast was edible—and nutritious. An English company decided to monetize this information and Marmite was born. Spread on toast for more than 100 years, it remains a cherished product—albeit not by everyone. In the U.S., craft breweries feed their spent yeast to cows.
■ Esters. These compounds create the fruity aromas and flavors that characterize ales. Ester formation varies from strain to strain, so the effect on beers varies. Commonly, esters express themselves as apple, berry, pear, or banana, but may also be spicy.
■ Phenols. These compounds produce smoky aromas and flavors that may taste like cloves or plastic, or contribute an almost medicinal quality. Traditional German weizens and some Belgian beers have overtly phenolic qualities.
■ Diacetyl. All yeast produces diacetyl, a substance with a flavor so like butter that it is used to flavor candy and theater popcorn. Yeast eventually reabsorbs diacetyl, but sometimes breweries package their beer before the process is complete.
■ Fusel alcohols. In addition to ethyl alcohol, yeast can produce heavier alcohols that add sharp, hot notes. More common in stronger beers, they add complexity and warming sensations.
In addition to creating these flavor and aroma compounds, different yeasts metabolize sugars differently, too. Some are very efficient, consuming lots of sugars and drying a beer out. Some are less efficient and leave sugars floating in the beer, making it sweeter. And some are just weird; the yeast used by Moortgat to make Duvel, for example, generates an amazing amount of carbon dioxide, giving the beer dense, fluffy clouds of foam when it’s poured from a bottle.
Conditions also exert a powerful effect on yeast. Some strains work best in temperatures just above freezing, while others like warmth. Even things that seem like they couldn’t possibly affect yeast, do: In squat, wide tanks, yeasts produce different compounds than they do in taller, narrow ones. Breweries once regularly used open tanks to ferment their beer, which allowed yeast floating by in the air to drop in. Most modern breweries abandoned this as an anachronistic and unnecessarily dangerous method and prefer to keep their beer safely behind a sheet of steel, where no wild yeasts can find it. But research has shown that the numbers of phenols and esters produced in open fermenters, even using the same yeast, vary substantially. Indeed, when Orval switched from open fermenters to tall, closed cylindroconical fermenters, it took three years to re-create the Orval signature taste in the new tanks. Yeast is a living organism, and beer is its natural environment. Like any other ecosystem, the conditions affect yeast’s behavior, and their behavior in turn affects the beer.
The most important condition in determining how a yeast will behave is temperature—and temperature is what divides the two main categories of yeasts between ale and lager. Ale yeasts prefer temperatures above 60°F, and many do best at room temperature or higher. Lager yeasts thrive at cooler temperatures around 50°F or lower. Low temperatures inhibit the production of chemical by-products, so lager yeasts create a much “cleaner” beer with little in the way of esters, phenols, or diacetyl. Because ales are fermented warmer, they do produce these by-products; the warmer the fermentation temperature, the more by-products they produce.
The differences in yeasts evolved only after centuries of domestication, as breweries repitched their house yeast over and over again, creating “house character.” Eventually, the lines became distinct from each other as they adapted to their native environment—in this case, a particular brewhouse. (If a brewery borrows yeast from another and reuses that yeast, over time it will behave differently than it did in the brewery of origin.)
The technique of lagering dates back possibly as far as the 1400s in Bavaria, to a time when people had only a rudimentary understanding of yeast’s nature. Bavarian brewers had isolated a yeast that didn’t behave like the regular strains; it fell to the bottom of the fermenter and worked best at cooler temperatures. The same type of yeast didn’t work well in warmer climates, but Bavarian brewers were utilizing deep, cool caves and cellars so they could use this yeast during the cold months. In the nineteenth century, Louis Pasteur confirmed what those old Bavarians knew: Chill temperatures inhibited wild yeasts that could spoil beer. Within a few decades, these qualities would be so prized that the majority of breweries in continental Europe had switched to lager yeasts. With this strain’s emergence, so evolved many of the famous beers that now define German and Czech brewing.
Hefeners. Sometimes you read that the old brewers didn’t know yeast existed. They didn’t understand what it was, but they definitely knew it existed. Schlenkerla Brewery’s Matthias Trum, who studied the history of brewing, explained how medieval Germans understood it:
The yeast is in fact not mentioned, that is correct. You have to put yourself in the mind of a medieval brewer. In the Middle Ages, they had a profession called the “hefener,” so they knew exactly. [In German, hefe means “yeast.”] The purity law lists ingredients, right? Yeast I put in the beer and I get more out of it. I harvest the yeast at the end and I put it into the next batch. And that was actually the job of the hefener …. The hefener’s job was to harvest the yeast from the batches, to press out as much remaining beer as possible, which was sold at a low price to the poor, and then the yeast was added to the next batch. You started with a smaller amount of yeast and then you ended with a bigger amount of yeast.
Gravity Measurements. Expressing a beer’s original and terminal gravities requires a scale, and unfortunately, breweries have adopted different versions. The Plato scale represents the measure as the amount of solids in suspension. On this scale, if wort is measured at 15° Plato, it has 15 percent sugars in suspension. Another compares the weight of water to wort. The scale assigns a value of 1 to water, so a wort of 1.050 specific gravity (sp. gr.) is 1.05 times as heavy as water. Low-gravity beer falls below 1.032 sp. gr./8° Plato, and high-gravity beer begins around 1.060 sp. gr./15° Plato and goes above 1.110 sp. gr./26° Plato.
Type of Beer |
Original Gravity |
Terminal Gravity |
ABV |
||
Specific |
Plato |
Specific |
Plato |
||
Berliner weisse |
1.030 |
7.5°P |
1.002 |
0.5°P |
3.9% |
Pale ale |
1.050 |
12.5°P |
1.012 |
3°P |
5.0% |
Barley wine |
1.106 |
25°P |
1.020 |
5°P |
11.3% |
It is important to emphasize something here. For decades, otherwise well-informed scientists believed that ale and lager yeasts were taxonomically different; not only did they behave differently, but they were different kinds of yeasts. Cats and dogs. However, in the past decade, mycologists working with mitochondrial DNA have found that lager yeasts aren’t pure. The lines cross and merge, and it appears that lager yeasts have ale as well as lager ancestors. The current thinking—and given how fast discoveries are being made, it should be considered a provisional finding—is that there are two separate hybrid lager yeasts, both with some ale parentage, but from different lines. It turns out they’re more like different breeds of dogs.
Read a book on brewing written more than five years ago, and ale and lager yeasts will be described as genetically distinct. Now we know they’re not, but this isn’t a major mistake—lager and ale yeasts really do behave differently and belong in separate categories. Instead of distinguishing between yeasts based on type, though, it’s more useful to distinguish them by function. They may not have a different genome, but ale and lager strains behave differently, and the beers they make taste different, too.
Wild Yeasts and Bacteria. The tart category is a small niche in the spectrum of beer—just a few examples from Germany and Belgium (and lately, the U.S.), with very little total barrelage to speak of. This is a recent development, though; until breweries began to domesticate yeast, soured ales were the norm. They were common in Britain into the twentieth century. A few traditional styles remain, and most beer drinkers regard them as anachronisms. But for some connoisseurs, they remain the pinnacle of the brewer’s art.
Sourness may be tart and clean as in Berliner weisse, funky yet dry and austere as in lambics, or vinegary as in Flemish reds. These different qualities come principally from three major organisms—the wild yeast Brettanomyces and the bacteria Lactobacillus and Pediococcus. Other minor organisms, like Acetobacter, Enterobacter, and caproic acid also contribute to a sour or acid profile.
In some soured beers, bacteria are introduced and controlled, adding a tangy, sometimes sharp sourness. In some, like lambic, the experiment is wholly uncontrolled, and all the wild yeasts and bacteria jump into the beer and create a little ecosystem where they contribute different amounts and different types of souring compounds and flavors. Below is a list of the principal agents.
■ BRETTANOMYCES. This wild yeast inspires the most awe and fear among brewers. It will eat anything, including dextrins and sugars that other yeasts find unpalatable, achieving nearly 100 percent apparent attenuation—far more than regular yeast. (Brewers joke that it will start eating the bottle if you leave it long enough.) By contrast, standard ale and lager yeast strains attenuate at between 70 and 80 percent. Brettanomyces will produce both acetic and lactic acids, but the former only under certain circumstances. This extreme attenuation will eventually make a beer taste almost dusty in its dryness. There are many species of Brettanomyces and many strains within each. The most common is Brettanomyces bruxellensis, which is particularly funky, often described as having a “horse blanket” aroma.
■ LACTOBACILLUS. Lactobacillus gives tart Flanders ales their character, as it does some German ales like gose and Berliner weisse. As the name suggests, this bacteria produces lactic acid; it is far more finicky than Brettanomyces. It prefers warm temperatures, a low-oxygen environment, and low levels of hop acids. Brewers can control Lactobacillus, allowing it to turn a beer very sour or just tweak it only slightly. Lactic-soured beers are tart and refreshing—for those who appreciate this quality.
■ PEDIOCOCCUS. Pediococcus is the beastie that gives lambics their lactic tang, not Lactobacillus. This is mainly a function of the life cycle of a lambic. Pediococcus ferments in beer with little or no oxygen; likewise, it gives off no carbon dioxide. The Pediococcus gets active when the lambic warms up, creating long slimy strands on top of the wort. You can drink the beer at this stage, but it’s oily and known as the “sick” stage. But from that unappetizing sickness comes the lactic acid, and eventually, the slime is reabsorbed as the Brettanomyces begins gobbling up everything that remains.
Two concepts related to the action of yeast are attenuation and gravity. Attenuation represents the degree to which yeasts have consumed fermentable sugars. Breweries measure this, based on a scale of gravity, by comparing the wort and the finished beer to pure water. Using water as a baseline, brewers can measure how much dissolved sugars are in solution. Sugars are more dense than water, but alcohol is less dense. So when yeast begins converting sugars to alcohol, the gravity drops. By measuring the difference between the readings taken before the yeast is added (the “original gravity”) and after the yeast is done (the “final” or “terminal” gravity), breweries are able to calculate the alcohol percentage.
When they make these calculations, brewers also see the attenuation, or how efficient the yeast was in consuming sugars. The lower the figure, the higher the attenuation, and the drier the beer will taste. This doesn’t always correspond directly to a perception of sweetness, because esters may make a dry beer taste sweeter—but it’s a useful guide to understanding how dry a beer is. In brewing jargon, the terms for high-/low-alcohol beers are often used synonymously with high-/low-gravity beers. Yet the two aren’t identical, because if a yeast is poorly attenuated, a higher-gravity beer may not be as alcoholic as the original gravity suggested. So while it’s useful to know the alcohol percentage of a beer, it’s even more useful if you know both the alcohol percentage and the original gravity. ■
AT A CONCEPTUAL LEVEL, brewing beer is easy to grasp: Malted grain is soaked in water to extract fermentable sugars, boiled with hops, cooled, fermented with yeast, and packaged. More detailed descriptions, particularly accounting for the procedures practiced differently in Germany, Belgium, and the U.K., could fill volumes. Fortunately, unless one is interested in actually brewing, a simple description is more than adequate to understand the nuts and bolts of commercial brewing.
Modern malthouses are wonders of technology where kernels of grain are subjected to constant analysis to ensure that they maintain optimal moisture and temperature levels and come out of the kiln plump and enzyme rich. They produce malt meeting the rigid specifications that brewers require to produce consistent batches of beer. Yet for all that, grain is still malted the same way it was thousands of years ago.
Essentially, grains (the seeds of the plant) are first steeped like tea in vats of water, a process that stimulates the kernel’s embryo and begins the production of enzymes. Each grain needs to become sodden, and will be soaked and drained and soaked again over the course of a couple days. The seed is rousing itself to reproduce and begins important chemical changes, ultimately resulting in the first nubbin of a shoot, known as a “chit” in the trade. Next, the wet chitted grain is left out to germinate. This is the critical moment when those unfermentable proteins are broken down as the seed shifts into its growth cycle, a process known as “modification.” The starches in each kernel exist to sustain this process, and the plant would quickly exhaust them if left to grow. Instead, after four or five days, the maltster dries the grain to stop germination and preserve the starches.
Breweries store malted grain until they’re ready to brew a beer. The first step is crushing (milling) the malt to prepare it for mashing. Much like grinding coffee, grain can be milled coarse or fine. Finely ground malt will release more sugars into the wort, but if it’s ground into powder, the grain will clump and the husks will be too fine to create an adequate bed for running off. Brewery equipment dictates how fine the grist can be: Breweries with separate lauter tuns can use a finer grind than those using their mash tun as a filter; if a brewery uses a mash filter, the grind can be extremely fine.
The mash process looks much like making breakfast porridge, but it functions more like making a huge kettle of tea. Malt and water are mixed together at temperatures designed to stimulate enzymes that will break down starches and proteins; liberated from the grain, starches and sugars will be rinsed off to make the barley-tea– like wort. There are essentially two ways to do this: either in a successive series of steps where the temperature of the wort starts lower and is raised and held; or with a single infusion of water (called “hot liquor”) at a temperature that averages out the advantages of the step process.
Homebrewing. Of all the ways to learn about beer, none recommends itself quite as well as homebrewing. The process of formulating a recipe, observing the brewing process, and tasting the results reveals levels of subtlety that are hard—though certainly not impossible—for the nonbrewer to apprehend. But homebrewing is also tricky and laborious and, like mastering the skills of car mechanics, not worth the trouble for many people—and far too detailed a process to cover comprehensively in this book. Take heart: There are several excellent books available (see the bibliography), and you can brew a one-gallon test batch in an afternoon and for as little as fifty dollars. I suggest you try it at least once; the more you brew, the more you understand what makes beer taste like it does.
THE BREWING PROCESS
Modern breweries use the first process, called “temperature-programmed mashing.” British and some American breweries use the second, called “infusion mashing.” There’s a third, much older practice called “decoction” that was a precursor to temperature-programmed mashing. Still regularly practiced in the Czech Republic and in some breweries in Germany—particularly Bavaria—it’s a laborious process of removing some of the wort from the mash tun, heating and returning it to raise the temperature of the overall mash to the next step.
In lautering, breweries remove their barley tea from the sticky mash porridge. In older systems, breweries have to lauter from their mash tuns, but modern systems avail themselves of a separate vessel known as a “lauter tun.” In these systems, the entire contents of the mash tun are flushed to the lauter tun, a similar-looking vessel that contains a series of rakes and blades. The contents of the mash are heated to reduce viscosity, and the blades and rakes separate out the wort, which is collected underneath a mesh bottom. While they chop and plow, an arm inside the tun sprinkles water over the grain bed to continue to rinse the malt of sugar—the process known as “sparging.” Finally, the accumulated wort goes to the kettle for boiling.
Boiling has several virtues, but the most important is converting hop acids so they can become soluble in wort. The process takes a while, so breweries boil the wort for sixty to ninety minutes on average (and never for less than an hour). Hops also add flavor and aroma, but the compounds that contribute these qualities are delicate. To infuse flavor, additional hops are added twenty to thirty minutes from the end of the boil. Aroma compounds are especially fragile, so aroma hops are added in the last few minutes.
Beyond hop extraction, boiling sterilizes the wort, removes unwanted volatile compounds, and precipitates out chunky protein molecules to clarify the beer. Most brew kettles (“coppers” in Britain) are heated by steam jackets or heater tubes (“calandria”), but a few older breweries still use direct-fired kettles. The hot spots created by open flames caramelize the wort, adding a toffee flavor and darkening the beer.
Chilling beer quickly was an important innovation that allowed breweries to pitch yeast quickly to avoid contamination. In modern breweries, heat exchangers do the work—and save energy along the way. These devices work by using cold water to flow across plates next to the hot wort. The two liquids come to equilibrium, and the now-warmed “cool water” goes to the hot liquor tank where it requires less energy to reach mash temperatures.
The magic happens inside fermenters, where yeast converts sugar into alcohol, esters, and phenols. While most brewhouses look similar, fermentation systems vary substantially. The shape of and temperature in the fermenter has a huge influence on the way yeast behaves. Primary fermentation takes just a few days for ales and up to ten days for lagers. Once it’s complete, the beer will be sent on to conditioning tanks to ripen. In lager breweries, this may take weeks or months; in ale breweries, just days or weeks. The one exception is cask ale, which is transferred to casks before it has completely finished fermenting. It will complete its fermentation in the cask, creating natural carbonation along the way.
Floor Malting. In modern malthouses, germinating grains are carefully regulated and tended by machine. An older, more traditional method is known as “floor malting.” This involves spreading the steeped grain out in the warehouse-like open spaces in the malthouse.
Germinating grain is fussy. The activity produces heat; maltsters regulate the temperature by both adjusting the depth of the grain bed and raking it. In earlier times, the master maltster monitored the process by hand and feel, and the job was regarded as a high art, equivalent in importance to the master brewer—critical if beer was to be palatable. Breweries themselves maintained their own maltings (a dangerous job that often led to fires). Because germination temperatures were so important, malting could only be done during the five or six coolest months of the year—which was true with brewing, as well.
As the brewing industry became more sophisticated, specialized companies took up malting and eventually most breweries abandoned the traditional method. It survives in Britain and the Czech Republic, where some brewers still prefer floor-malted grain for the rounded, malty flavor it gives their beer.
Not all beer is filtered—some breweries like their product served au naturel. Filtering has the advantage of adding clarity to beer; more important, it removes staling particles, like dead yeast, that limit shelf life. Some breweries take the additional step of pasteurizing their beer to prevent spoilage. The trade-off is that pasteurization requires beer to be heated—either for a short time at high temperatures, or a few minutes at lower temperatures—which accelerates the staling process. Most smaller traditional and craft breweries don’t pasteurize.
Bottling, canning, casking, or kegging is the final step before beer leaves the brewery. The type of container is dictated somewhat by cost—bottling lines are very expensive, canning lines cheaper, keg fillers the cheapest of all—but also by beer style. Real ale must go into a specially designed cask. Many Belgian and French styles of beer require refermentation in the bottle and so they’re not kegged. ■
