aidan

Recipes 

I've just read on some forums that the standard conventions and calculations regarding hops utilisation as a factor of BG might actually be wrong. i.e. BG has no effect on hops utilisation

A search on this forum shows that it's been discussed here too - http://www.homebrewtalk.com/f37/late-addition-hop-utilization-188394/#post2186025

What has me baffled is, if this is true, how could this have gone unnoticed for so long? Tools like BeerSmith, which so many brewers rely on, would guide brewers to use much more hops if they are boiling all their extract in a portion of the water. Wouldn't all these brewers have noticed that their beers are overly hoppy?

Just wondering what's your own personal experiences on this?

david_42

Recipes 

First, hoppy and bitter are two different factors. Second, very few people can detect an IBU difference of less than 10. I suspect the main problem is simply that high beginning gravities often have high bittering levels and the concentration of the bittering chemicals does impact utilization. So, it was easy to make a wrong assumption.

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aidan

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So what you're saying is that boil volume affects hops utilisation and SG of the boil doesn't, is that right?

Do you reckon the best approach for using BeerSmith (or similar) to calculate quantities for a partial extract boil is to enter it in as a full boil to get your numbers?

Yuri_Rage

Recipes 

This has come up a few times recently, and there is a valid argument that specific gravity does not impact hop utilization as directly as most of us expect. However, after lengthy debates and equations, the end result is always fairly similar: the Tinseth formula (BeerSmith's default) is still a valid means by which to approximate IBUs in small brew lengths.

So, keep using BeerSmith in the intuitive manner that it was meant to be used. Most importantly, use the same means to estimate IBUs for all of your recipes. That way, you'll have a baseline "feel" for what those numbers mean in your brewhouse, even if they aren't as accurate as lab results.

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Hermit

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I think you may have answered your own question here. This type of brew science is pretty old stuff and I'm sure has been studied and verified more than once. Way to many batches brewed to assume it doesn't work.