There are few human endeavors that so successfully flourish at the crossroads of art and science as brewing. Working from a palette of only four ingredients – yeast, barley, hops, and water – talented brewers can produce wildly different beers, each with distinct characteristics.
“What’s interesting to me about beer” explained Altitude chophouse head brewer Jared Long “is that there are relatively few ingredients – there’s four – but there are so many variables for those four ingredients.”
Beer owes its existence to the first ingredient: yeast. These microscopic fungi are capable of a metabolic trick called alcoholic fermentation – when there is no oxygen to power their normal mode of living, yeast break down basic sugars and produce pleasantly intoxicating ethanol as a byproduct. The yeast, however, don’t stop at just ethanol.
“Basically what happens,” explained Long, “is that some yeast strains are more prone to the production of certain esters than others.”
Yeast – like most microbes – exhibit a huge degree of genetic variability, with a multitude of distinct strains populating the earth. Each strain will produce different esters in distinct proportion to each-other. “The yeast strain I choose has massive implications for the finished beer” explained Long.
If a brewer wants a crisp, clean lager flavor, he or she will select a yeast strain that produces few and mild esters. Conversely, if a brewer is trying to craft a fruity, rich English-style ale, he would pick a yeast that is generous in its ester production.
In order for the yeast to make their contribution to the beer, they must have sugar to eat – that is where barley comes in. Barley grains are seeds, and thus packed with long sugar molecules intended for the infant plant to use in its first weeks of growth. These sugars are complex and rather inaccessible to the yeast, and they must be broken down before they are suitable for brewing.
“It’s called malting,” explained Long “and basically they’re modifying the barley to activate enzymes, which then free up the sugars for fermentation.”
The process happens in two steps. First, the barley grains are soaked in water and encouraged to germinate. As the seeds begin to come alive, they activate internal enzymes, which start to cleave the complex sugars into more usable molecules. This germination is monitored carefully, and when it has proceeded far enough, it is halted by kilning – or roasting – the grains. The kiln’s heat further breaks down the stubborn sugar polymers in a process that draws parallels to roasting coffee beans, with different roasts providing different flavor notes.
“The darker the malt is roasted, the more caramel and sweet it’s going to be,” explained Long. “Basically you’re going to go from light caramel-sweet, to really intense caramel-sweet, to then you get into the ‘chocolates’ – or the roasted barleys.”
The next component of the character of a beer is hops. Hops contain two main families of flavor compounds: alpha-acids and aromatic oils. The acids provide bitterness once altered – or “isomerized” – by the heat, while aromatic oils deliver complex notes ranging from citrus to medicinal. Hops are added to the beer during the boiling stage, and will have different effects depending on when in that stage they are added.
“If I add the hops at the beginning of the boil” said Long “I’m getting all their alpha-acids, because they’re in there for the duration. But if I add hops later in the boil, I’m going to keep a lot of their flavor and their aromatics, but not isomerize their acids, so I’m not getting a lot of bitterness out of them.”
Thus, hops intended to add bitterness are boiled at length, while aroma and flavor hops are “dry hopped,” or added at the end of the boil.
The final ingredient in beer is water. Though it seems simple, there is more to selecting the right water than one might expect. The mineral composition varies, which can have major impacts on the finished beer.
“Calcium has a lot of implications for how happy your yeast are,” elaborated Long. “If you don’t have proper calcium and zinc levels in your water going into fermentation, you’re going to have an ‘unhappy’ fermentation, and therefore not a very tasty beer.”
Each beer, whether it is a 500-year-old Belgian Trappist ale or a Budweiser, is the product of an incredibly complex interplay of factors and ingredients, each fine-tuned to exacting tolerances. Science offers insight into how only four ingredients can give rise to such a staggering variety, but it takes the artistry of brewers like Long make the leap from abstract information to delicious application.
