Adjusting hops for different alpha acid percentages

[foppa78]

Hello,

If I have a recipe that calls for a hop with 5.5% AA and I only have that hop in 4.5% AA will Beersmith help me to convert my recipe so that I use the correct amount of hops?

Thanks!

[UselessBrewing]

I have not seen a Converter.

What I do is take the original hops used, look at what the IBU is for the boil time, then add the substitute and adjust amounts to get it close to the original hops. If it is not close increase the boil times to get what you want out of the substitute. Don't go the other way and reduce the boil time, you may end up with cloudy beer.

Cheers

Preston

[Maine Homebrewer]

The Papazion method outlined in his books talks of taking the alpha acids, multiplying by the ounces, and getting an HBU (Homebrewer Bittering Unit) number.
For example a recipe that calls for 2oz of 5.5 alpha hops is 11 HBUs, so you'd use 11/4.5 or 2.4 oz of your 4.5% alpha hops.

Personally, I just wing it.  As an extreme IPA fan I have yet to use too much hops, and sometimes when I use less bittering than intended I just end up with more malt characteristics in the the glass.

If you keep experimenting and keep careful records you'll figure it out.
In the mean time you may accidentally stumble across a combination that you may have never seen in a recipe or thought of on your own, but really like and want to repeat.

[BeerSmith]

Hi,
  Write down the original IBUs with the original hop alpha, then change the hop alpha.  Finally just use the "adjust IBU" button to set the IBUs back to the original level you wrote down.

Cheers,
Brad

[UselessBrewing]

There you have it. Learn something every day...

Cheers

Preston