Consistent Homebrew Beer: Bitterness from Hops

Hop cone in the Hallertau, Germany, hop yard

Hop cone in the Hallertau, Germany, hop yard (Photo credit: Wikipedia)

I’m not much of a fan of big hop flavours in beer. This led to a monumentally stupid mistake on my part – not paying much attention to hops when home brewing.

Yes, I use hops in my beers, but I have never fully appreciated or given hops the right amount of respect. That’s changing.

I think part of my ill-placed mistrust or disinterest in hops came from the current hops/alcohol arms race going on between some brewers. I’m sure you know what I mean. Brewers that seem to chase the “World’s Most Hoppiest/Strongest Beer” accolade. The title that seems more  marketing gimmick than anything else. 

Consistent Homebrew

Anyway… recently I’ve been thinking about my own homebrewing (which has been far less frequent that I initially planned this year) and how I want to keep the bitter levels consistent when I make something I really enjoy.

So to the forums and books (mainly How to Brew: Everything You Need To Know To Brew Beer Right The First Time by John Palmer – a must have if you don’t already own it) I went.

One of the key components which I had not considered before was hops. When I say hops, I don’t mean just simply using the same amount of hops, but the amount of Alpha Acid (AA) present in the hops.

Note: There are a number of factors to consider, but in this post I’m focusing on hops and their AA levels.

What is Alpha Acid?

Alpha Acid is a chemical compound which is important for producing beer. It is found within a hop’s resin gland and are the source of bitterness. Each harvest year the AA % of a hop plant can vary depending on how good/bad a season has been.

What this means is that you can buy the same hop variety from one year to the next and depending on the level of AA in the plant, the bitterness of your beer can change if you don’t take that into account.

When I realised this I slapped my balding forehead with my palm (not really… I just wanted to make it seem more dramatic). However, it was a moment where I realised I’d been taking my hops for granted.

Hops: Getting the Maths Right

digital kitchen scale

Weight Isn’t As Important As You Think (Photo credit: .m.e.c.)

So, say you like the way your homebrew has turned out, particularly the level of bitterness. If you want to replicate the batch, it isn’t simply a case of just adding the same weight as last time.

Let’s say you used 57 grams (2 oz) of Cluster hops in your last batch and that year’s AA was 6.00%. Now you want to get the same bitterness in your next batch but you’ve bought some more Cluster hops. However, your new Cluster hops are from a different harvest year and they have an AA of 5.50%. If you add the same weight, the bitterness of batch 2 will differ.

Working out how much Alpha Acid Units (AAU) will go into your homebrew means you will no longer need to worry about hitting the same weight and focus on getting the right AAU in the future.

The AAU is the AA% multiplied by the weight (in ounces). So with the above example of Cluster hops, the first batch’s AAU would be:

2 (the number of oz) x 6 (the % of AA) = 12 AAU.

To match this with the second batch you need to increase the amount of hops used to 2.18 oz (12 / 5.5).

This is also important if you want to increase/decrease the bitterness more accurately, or, if you have to substitute in a different hop, with a different AA%.

Note: This is just one look at one part of brewing which affect consistency – but it should help. Other factors include temperature of fermentation, hop boil time, etc.

Anyway, I don’t know about you, but I am now going to start paying attention and noting down the AA of the hops I use – not just ignoring it, hopefully my brewing will only improve for it.

I’m still learning, so if you see anything in this post that I’ve not got right, please feel free to let me know. I’m always keen to learn!

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