How Beer Is Made: The Brewing Process Step by Step

How BeerIs Made

Beer is made by turning grain starch into sugar, boiling that sugary liquid with hops, and letting yeast ferment the sugar into alcohol and carbon dioxide. Everything else in brewing is a refinement of those three moves: make sugar, add bitterness and aroma, ferment.

The ingredient list is short. Malted grain (usually barley), water, hops and yeast cover nearly every beer on the shelf. What separates a pale lager from a stout is how each of those ingredients is chosen and handled at each step below.

Raw barley is mostly locked-up starch that yeast cannot use. Malting fixes that. The grain is soaked in water, allowed to sprout for a few days, then dried in a kiln to stop growth. Sprouting builds the enzymes that will later break starch into sugar, and kilning sets the malt's color and flavor. A lightly kilned malt tastes like crackers; a heavily roasted one tastes like coffee. Most breweries buy malt from specialized maltsters rather than doing this themselves. For the full story, see malt explained.

The malt is cracked in a mill so water can reach the starchy interior, then mixed with hot water in a vessel called a mash tun. This porridge is the mash. Held at the right temperature for about an hour, the malt's own enzymes cut starch into sugars.

Temperature is a steering wheel here. Beta amylase works best in roughly the 131 to 150°F range and produces highly fermentable sugar, which leads to a drier, lighter beer. Alpha amylase prefers roughly 145 to 162°F and leaves more unfermentable dextrins, which means more body. Brewers pick a rest temperature to land somewhere between those two outcomes. Mash pH matters too; the target is roughly 5.2 to 5.5, and the water a brewery uses has a lot to do with hitting it.

Lautering separates the sweet liquid, now called wort, from the spent grain husks. The husks settle into a natural filter bed, the wort is drained off, and hot water is sprinkled over the grain (sparging) to rinse out remaining sugar. Spent grain often ends up as livestock feed.

The wort goes into a kettle and boils, usually for about an hour. The boil sterilizes the wort, drives off unwanted compounds and concentrates the sugars. It is also where hops come in.

Hops added early in the boil supply bitterness, because heat converts their alpha acids into iso-alpha acids, which dissolve in beer and taste bitter. Most of that conversion happens during the first hour. Hops added in the last few minutes, or after the boil in a whirlpool, contribute aroma instead, because their delicate oils have less time to evaporate. The deeper explanation lives in hops explained, and the numbers on the label are decoded in ABV and IBU explained.

Hot wort would kill yeast, so it is chilled quickly, typically through a heat exchanger, to a yeast-friendly temperature. For many ales that is around 60 to 70°F; lagers go colder. Fast cooling also limits the window for contamination.

The cooled wort moves to a fermenter and yeast is added (brewers say "pitched"). Yeast eats the sugar and produces alcohol, carbon dioxide and a long list of flavor compounds. This is where an ale becomes an ale and a lager becomes a lager.

Ale yeast works warmer, roughly 60 to 70°F for clean styles, and can throw fruity esters and spicy phenols. Lager yeast works cooler, roughly 48 to 58°F, and tends to taste cleaner. Primary fermentation can finish in under a week for a simple ale or take a few weeks for a lager. See beer yeast: ale vs lager for the full picture.

Some beers get hops during or after fermentation as well. That is dry hopping, and it adds aroma with little added bitterness.

Freshly fermented beer is called green beer, and it usually needs a rest. During conditioning the yeast cleans up byproducts, flavors smooth out and solids settle. Ales may condition for days to a couple of weeks. Lagers get "lagered": held cold, near 32°F, for at least 2 to 3 weeks so yeast and proteins drop out and the finish turns crisp. Some beers take a much longer detour into oak; see barrel-aged beer.

Many beers are filtered or centrifuged for clarity; hazy styles skip it. The beer is carbonated, either by injecting carbon dioxide or by letting a little extra fermentation happen in a sealed tank, keg or bottle. Some brewers pasteurize for shelf stability. Then it goes into kegs, cans or bottles. The trade-offs between those containers are in cans vs bottles.

From here, the brewery's job is done and yours begins. Heat, light and time all wear beer down, so how you store it matters more than most people think.