What Is Beer Made Of? A Look Inside the Brewing Process

Beer is an alcoholic beverage made of fermented grains. Different combinations of cereal grains go through various stages of treatment and fermentation, resulting in a carbonated drink ranging from lightly golden to dark amber to nearly black.

The four typical main ingredients of beer include water, barley, hops, and yeast.

• Barley: Barley is a cereal grain (or true grain) used to brew beer since the third millennium BCE, in Egypt, Babylon, and Sumeria. Barley is the preferred grain for making beer because it generates a lot of starch-digesting enzymes, forming fermentable sugars that then become alcohol. In beer-making, the germination of barley grains is called malting. Barley is one of many grains (in addition to rice, oats, corn, millet, sorghum, and wheat) that brewers use to brew beer.
• Hops: Soft, green hop cones are the flowers of the hop plant (Humulus lupulus), a perennial plant cultivated as far back as the ninth century. The alpha acids in hops are the primary bittering agent in beer; a compound in the cones called lupulin informs the aromatics and flavor notes in the finished brew, such as pine, citrus, or banana. The oil extracted from lupulin glands also suppresses bacterial growth, allowing yeast to flourish. The hop bitterness is necessary to balance out the sweetness of the malt, and all forms of beer contain hops. Learn how to grow hops at home.
• Yeast: Yeast is a single-cell fungus and a powerful leavening agent that causes bread to rise by digesting the sugars in the flour and releasing carbon dioxide as a byproduct. Brewers may use active dry yeast, lager yeast, ale yeast, and liquid yeast strains to make various beers. The yeast affects the beer flavor when it breaks down the sugars into ethanol, forming other metabolites that further influence the aroma and flavor.

There are various types of beer brewed all over the world, including:

1. 1. Ales: Ale is a type of beer brewed with Saccharomyces cerevisiae, a species of top-fermenting yeast and a foundational ingredient in baking, wine-making, and brewing. Top-fermenting yeast rises to the surface of the wort (the beer starter) during the brewing process, creating a thick head of foam known as krausen that brewers use to gauge the progress of the fermentation. Ale yeast brews in warm temperatures and produces a significant amount of esters and metabolites as it ferments, creating a more flavorful, fuller-body beer with distinct fruitiness, bitterness, and strong hop flavor. Ales tend to be darker and cloudier in appearance, with higher alcohol content. Learn the differences between ale and lager.
2. 2. Belgian beer: Inspired by British pale ales, Belgian-style beers are malted ales with slightly bitter and fruity yeast notes, brewed with both malted barley and unmalted wheat. They have a complex flavor, sometimes containing wheat, herbs, and floral spices, such as coriander. Belgian beers typically have higher alcohol content (around six percent or higher), and brewers usually describe them as cloudy, thick, or creamy.
3. 3. India pale ales (IPAs): Historians believe British breweries altered the pale ale brewing process to meet export needs, developing the India pale ale in the early eighteenth century. The IPA variety acquired a more robust hop flavor by adding more hops while increasing the alcohol content. Nowadays, most IPA recipes use a variety of American hops, like Citra, Cascade, and Centennial, to complement the bitter hoppiness with a juicy citrus kick. Learn the differences between pale ales and IPAs.
4. 4. Lagers: A lager is a kind of beer made with a yeast type suited to bottom-fermenting at cold temperatures. The lager style varies in how dark or light it is and the alcohol by volume range for each beer type. Many well-known international beer manufacturers and specialized craft beer companies produce lagers in mass-market quantities. They are generally less hoppy than ale-style beers. This category includes American lagers, dark lagers, amber lagers, and bock beers, such as doppelbock (“double bock”) and maibock (“spring bock”).
5. 5. Pale ales: In the early 1700s, English brewers began experimenting with recipes using lighter malts, which produced a more bitter beer style with a hoppier flavor profile than dark and malty beer styles of that era—earning them the nickname “bitters.” Compared to an India pale ale, or IPA, a pale ale generally has lower alcohol content. Popular types of pale include American pale ale, English pale ale, amber ale, and blonde ale.
6. 6. Pilsners: A pilsner (referred to as “pilsener” in some locales, or “pils” as slang) is a type of pale lager beer that originated in the Czech Republic city of Plzeň. Bavarian brewer Josef Groll is believed to have developed the first pilsner beer in the nineteenth century. This brewer from Bavaria hit upon a specific lager recipe made with soft water, malty barley, and Saaz hops. This specific noble hop flavor gives pilsner-style lagers their spicy flavor. Learn the difference between pilsners and lagers.
7. 7. Porter: A porter is a dark beer developed in London, England, in the 1700s. Porters are made of malted barley and often brewed and top-fermented with ale yeast, meaning their fermentation occurs near the top of the tank. Porters were initially hopped brown ales brewed with brown malt. Brewers continued to refine their processes as the drink increased in popularity (and as malt taxes increased and laws on beer production became stricter). Today, porters are made with dark malts and range in color from dark brown to black, providing a robust flavor with aroma notes of dark chocolate, coffee, or caramel.
8. 8. Sour beer: Sour beers have a tart, acidic flavor with a hint of sweetness from the wild yeast and bacteria used during the brewing process. Brewers may add acidulated malt or fruits to bring that signature sour flavor. Sour beers use a small amount of aged hops in the brewing process, boiling the wort, which is either exposed to the air or infused with a bacterial culture. Sour beers have a range of ABVs and contain between two and nine percent.
9. 9. Stout beer: Initially referred to as a stout porter, this dark ale is made with hops, roasted barley, yeast, and water. Stout beer has a deep and full roasted flavor, with a thick and creamy mouthfeel. Though experts dispute the exact origin of stout (the first usage of the word appeared in the 1600s), the first version was a porter beer with higher alcohol by volume, giving it a heavy-bodied taste. There are many different stouts, including Irish stouts, milk stouts, oatmeal stouts, and imperial stouts.
10. 10. Wheat beer: Wheat beer refers to any beer that uses wheat as the primary grain in its brewing process. Wheat beers are top-fermented, with German and Belgian styles among the most popular. (They are often lighter and sweeter than other beers.) Due to their citrusy notes, wheat beers pair well with garnishes like fruit slices. Wheat beers have a low ABV percentage, generally between two to five percent. This creamy beer has a full mouthfeel while also providing notes of breadiness or lemon and cloves.

After the brewers decide which grains to use, they send them through a brewing process where they eventually become the alcoholic drink known as beer. The steps of a typical brewing process include:

1. 1. Milling: Milling is the process of heating and cracking open the grains (often barley and wheat) so that the mash liquor can easily access them. Milled malt—crushed germinated barley kernels—are essentially the beer’s “grounds” (similar to coffee grounds), which will create the body of the beer. Brewers don’t usually need to mill grains like corn or oats for beer brewing.
2. 2. Mashing: Brewers mix the crushed malt with hot water inside a mash tun—a brewing vessel that mixes water with the ground malt—activating the enzymes created by the broken-down endosperms. This process converts the malt starches into maltose and dextrins (sugars).
3. 3. Boiling: The liquid created from the mashing process—known as wort—gets boiled at a high temperature for a certain amount of time, depending on the beer style. For instance, sixty to ninety minutes is often the range for porters and stouts, whereas brewers can boil IPAs for as little as thirty (but up to ninety). Brewers can boil strong ales like barley wine for up to 120 minutes. The boiling process, which pasteurizes the wort, eliminating harmful bacteria, is also when brewers add hops and other spices. The amount of hops depends on the desired bitterness of the beer.
4. 4. Fermenting: The wort passes through a lauter tun—lautering is the process of separating the wort from the spent grain bed—where the brewer adds yeast, which feeds on the sugar from the malted grain, starting the fermentation process. As the mixture ferments, it produces alcohol and carbon dioxide, then gets cooled again.
5. 5. Filtering: After the mixture cools, brewers filter it again either directly or in a pressure- and temperature-controlled mechanism called a “brite tank” (sometimes spelled “bright tank”). Brewers may also add carbonation during this stage. While carbonation naturally occurs during fermentation, forced carbonation (where carbon dioxide gets pumped into the beer) can also be necessary to provide the right bubbles.
6. 6. Packaging: After getting cooled and filtered, the finished beer is ready for bottling, canning, or put into kegs for distribution. Some brewers transfer the beer into barrels (such as imperial stouts) or casks (such as real ale) for aging before distributing it as the final product.

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