Time to move on to the next part of brewing: bittering agents. The oldest known bittering agents were herb blends (the most famous being gruit), the modern bittering agent of choice is hops. The herbal beers are still being made today (but not a lot of it) by some of the American craft brewers looking to revive old styles and flavors. There’s lots of options for brewing with herbs instead of hops, here’s an article that talks about the various herbs, and how to use them.
We’re in the modern age now, which in the beer making world means almost a thousand years of history. So that means hops are the primary bittering agent. The bittering component of the hops is known as Alpha Acids, and any hops you buy from the homebrew shop will have an AA% on them. These get measured in a final beer by a scale called IBU (International Bittering Units). IBU’s aren’t the final determination in how bitter a beer tastes though, as that will depend on the residual (or non-fermentable) sugars left in the beer.
If you’re looking to replicate a recipe exactly, the AA% will be important to you. Most recipes will have the variety of hops, listed with an AAU number. That number is just the AA% times the weight in ounces. So, for an AAU of 30, you would need two ounces of 15 AA% hops.
Hops add a lot more flavors then just bitterness, and these flavors can lend themselves to different styles. One way of classifying hops is by the most frequent use for them:
- Bittering – These are hops that are being used primarily for their AA% and to bitter the beer, they will be added at the beginning of the boil, and be boiled for 45 minutes or more. This will drive out most of the flavor and aromatic components of the hop.
- Flavor – These are hops that are used with 30 – 15 minutes or so of time remaining in the boil. These will add some flavor, but most of the aroma notes from the hops will be driven off.
- Aroma – These are hops added towards the end of the boil, or even after the boil has ended (either in a whirlpool or through dry hopping). These will add little to no bitterness, but will retain all of their aroma and flavor notes.
Another type of hops are the Noble hops. This is a special category of four different varieties of hops (Hallertau, Saaz, Spalt, and Tettnang). The term just came into being in the past couple of decades, and the hops from their original regions are generally in high demand. These classifications are more of guidelines, as any hop can be a bittering hop if enough of it is used, and some bittering hops have some very good flavor and aroma notes. Hops can have a wide variety of flavors, with the most common being: earthy, pine, citrus, spice, grapefruit, and tropical fruit.
Another use for hops is dry hopping. This is when hops are added to the beer after the yeast has been pitched, and will add no bitterness, but will add tons of aroma. There are even some beers being released now called 0 IBU beers where all of the hops are added at the beers flameout, or used as dry hops.
New and experimental hops are being cultivated every year for new characteristics, such as disease resistance, flavor, and high alpha acid percentage. These are generally released in small batches to breweries and home brew shops. At this point they’ll generally have letters and/or a number to identify them, only getting a name when they go into wide scale production.
If you say you don’t like hops, it can help to learn the varieties so you can learn which ones you don’t like. There are also several hops that can add negative qualities to beer if used with too heavy of a hand (garlic, catty, vegetal, etc.). Good brewers will avoid this, but not all breweries use good brewers.