Learning Lab: Hops

As a brewer, you recognize that hops contribute bitterness, flavor, and aroma to beer. The traditional process maps directly onto this, with three steps for adding hops to the wort during the boil. Here we examine those three additions to gain a practical understanding of how each one contributes to your beer.

It takes time in the boil kettle to convert the alpha acids into their isomerized bitter form. But every minute of that time drives off and breaks down some of the aromatic oils.

The traditional three hops-addition steps are a compromise that balances this trade-off.

SO FAR, THIS SERIES has focused on what goes into beer. Now it’s time to start digging into how we use those building blocks. The first ingredient we tackled was hops, so it makes the most sense to start there.

Tradition? Tradition!

Before we dive into the steps, let’s talk briefly about hops. They have alpha and beta acids, which contribute bitterness, and they contain a complex mix of volatile aromatic oils that provide the flavor and aroma we all love. Getting all of those components into your beer can be a little tricky because of a fundamental conflict. It takes time in the boil kettle to convert the alpha acids into their isomerized bitter form. But every minute of that time drives off and breaks down some of the aromatic oils. The traditional three hops-addition steps are a compromise that balances this trade-off.

The first addition goes all in for Team Bitter. These hops are added early in the boil, spending the most time in the kettle, usually 60 minutes or more. That allows plenty of opportunity for the alpha acids (e.g., humulone, cohumulone, and adhumulone) to go into solution and be chemically converted into their bitter form. Of course, that’s also long enough to boil off the volatile hops oils and lose most of the flavor and aromatics that these hops might have provided.

The flavor-hops addition is generally made about 20–30 minutes before the end of the boil in an attempt to find a midpoint along the bitter-to-hoppy continuum. This addition will still extract some bitterness, but the important thing is what happens to the aromatics. The most volatile aromatics will be driven off, but there are plenty of flavorful compounds that can withstand the heat and lend some hoppy character.

The final aromatic addition is made either in the last few minutes of the boil or at flameout. Assuming the wort is immediately chilled, this doesn’t allow much time for isomerization, and there’s less opportunity to evaporate off hops essential oils. The net result is that very little bitterness is added, but many of the pleasant aromatics remain. As you may know from experience, the exact timing can make a big difference to the intensity and character of the beer’s aroma.

The Experiment

In the interest of better understanding that spectrum of bitterness fading over to delightful hops flavor and aroma, we’re going to sample a few isolated points and contrast them. We’ll start with a base pale-ale recipe, brewing a control batch that follows the full tradition of three hops additions. Then we’ll create a set of beers that will each have a single hops addition at various points during the boil.

Volume (after boil): 1 gallon (3.8 liters) OG: 1.055

FG: 1.014

IBUS: 43 (control batch)

ABV: 5.46%

Recipe

Grain: 1.25 lb (567 g) light dry-malt extract; 4 oz (113 g) crystal malt (30L) Hops: 0.125 oz (3.5 g) Amarillo [8.6% AA] at 60 minutes; 0.125 oz (3.5 g) Amarillo [8.6% AA] at 30 minutes; 0.125 oz (3.5 g) Amarillo [8.6% AA] at 5 minutes. (If you need to substitute a different hop, aim for about 40 IBUS in a one-gallon/3.8 l batch.) Yeast: ½ packet Safale US-05

Process Steps for Control Batch

Dissolve the DME into the initial volume of water (1 gal/3.8 l plus any make-up for the evaporation loss), then bring to a boil. Start the boil, then add the first hops addi