Should I use 60 or 90 minute hops additions?

by | Inside Fermentarium

Transcript for Should I use 60 or 90 minute hops additions?

Almost every homebrew recipe says to add bittering hops for 60 minutes. Is 90 minutes better? Maybe it should be less? That’s what we’re going to investigate next.

The bitterness in our beer comes from the bitter resins in the yellow lupulin glands. These are known as the alpha, beta, and gamma acids. The important one is the alpha acids, and that’s why that’s the only acid we typically see listed on our homebrew hops. The beta acids can contribute bitterness to our beer if they get oxidized, but the flavor isn’t great. Gamma acids don’t contribute any bitterness to our beer.

The bitterness in our beer is created by converting the alpha acids. This conversion is called isomerization. That’s a fancy word, but it just means we rearrange the organization of a molecule, but we don’t change the atoms in the molecule. This new molecule happens when we boil our beer over time, and its what makes our beer bitter.

How to measure bitterness

In order to determine how much bitterness is contributed to our beer, we use the IBU equation. IBU stands for International Bitterness Unit.

W is the weight of our hops, in ounces. V is the volume of wort in gallons. A is the percentage of alpha acids in our hops. That’s usually listed on the package of hops when you buy them. That leaves one variable left to calculate IBUs. The U is for hop utilization.

Hop utilization

Hop utilization is how well we convert the alpha acids to bitter flavors in our beer. This process takes time and heat. It’s never 100%, and there’s many factors that can reduce the amount of bittering in your beer. For this video, we’re just going to focus on how boil time affects our final product.

If we throw in our hops, and stop the boil right away, not many acids will be converted. We’ll just get the aroma and flavor, but no bittering. The reason is the alpha acid content in hops is only soluble in boiling water, and it takes time.

The simple thinking would be, more is better, so the longer we boil hops, the more of the hoppy goodness gets to our glass. Unfortunately it doesn’t work that way.

For starters, the process can go both ways. It’s like going backwards and starting over. There are also competing processes which cause the hops to oxidize into humulinic acids. Even worse, the isomerized alpha acids can get broken down. These contribute to reducing the overall bitterness in our beer.

This is using the Rager method (used for estimating hop utilization). Other methods have similar curves. While we’re adding bitterness there are competing forces removing it. When we’re starting out, there’s plenty of alpha acids to convert. The competing processes aren’t contributing as much to your beer flavor. The longer we boil, the less alpha acids there are and the reduction forces start to work against us. The magic number for homebrewers seems to be around 60 minutes.

What happens beyond 90 minutes?

What happens beyond 90 minutes? Well we’re expending alot of energy for little advancement in our bitterness efficiency. Once you get past 45 minutes, you’re not getting much bitterness for your time. There are some reports that we’ll also get a nasty vegetive flavor past 90 minutes, but I couldn’t find a good source for that. We’ll leave that as anecdotal until I can find a better reference.

Should you do boil hops for 90 minutes?

And all that said, Dogfish has a 90 and a 120 minute IPA. These are very popular beers, so they must be doing something right. Tough call. I think the best reason to not go past 60 minutes is there isn’t much value in doing so. As the chart showed earlier, it’s an asymptotic curve.

I won’t boil my hops past 60 minutes. I’d love to hear other homebrewer experiences. What are you seeing in your boil times?

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And with that, I’ll see you next week!

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Credits and Links



DJ Spiess

DJ Spiess

Beer buddy

I live in Denver, Colorado. This blog is everything about beer, wine, cider, mead and other spirits.
I am a avid homebrewer and winemaker. I’ve been making my own beer and wine for many years. I started making beer when I was in college (mostly because the drinking age in the United States is 21). My first few beers were horrible. The beers are much better now, and I often supply my neighborhood with free beer! It is a great hobby! If you’re into computer programming, you might want to check out my programming site,