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Bitterns calculations


Sep 24, 2013
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Hello, I am having problems with the bitterns calculations in Beersmith. My recipe calculates a 62 IBU . But in reality it's much higher. Everything was working fine , but my last two batches I had to not ad most of the hops because after first addition it was already too bitter.
You are not alone in trying to figure out the relationship between a bitterness model and your sensory perception.

The models used to ESTIMATE bitterness are all subject to the type of hops used (raw material), the boil vigor of the process, boil off rate (process related), time to chill (process), altitude (location), wort gravity (recipe/process), boil time (recipe), yeast strain (recipe/raw material), among other parameters.

To add more confusion, there are a number of IBU models (Tinseth, Rager, Garetz being the most popular) and each of the models have been developed using a different process, in different ambient environments, different raw materials, etc. When you follow a recipe, you do not necessarily know what model the author of the recipe is using for their IBU calculations.

Lastly, each person has their own taste sensitivity. I am very sensitive to bitterness and many very bitter IPAs are essentially undrinkable to me.

So, what should you do? First, use the IBU calculation as a guideline for your process.

Next, do a few basic experiments to determine how close your bitterness is to a commercial beer. This will allow you to judge how to adjust your recipe to get the same bitterness sensation and the associated bitterness calculation for your process.

One of my go-to commercial beers for this is Sierra Nevada Pale Ale. They have a strong QA program, actually test their IBU instead of relying on a calculation, and are exceptionally consistent. Plus they have published their recipe, so it is easy to duplicate the recipe with confidence. Do a side by side tasting and comparison of bitterness. Match up their published IBU (38) to the model you choose to use use in BeerSmith and figure out how far off you might be based upon your sensory evaluation.

Just to tie this up with a bow, Denny Conn and Drew Beechum wrote a nice experimental result from comparing how many different brewers made the same recipe with the same ingredients and the measured IBU as compared to the model they used for calculation in the recipe. You can find their article at https://www.experimentalbrew.com/2017/01/18/episode-32-the-ibu-is-a-lie/
Thank you for your Reply. I have been home brewing with Beersmith for years and it has always been right on or at least I was pleased with the final results. What changed or did Y change some setting?