Tinseth formula question

So I use the Tinseth formula for finding my IBU's and I realized something that I never thought of before:

How do I calculate for hops added periodically throughout my boil?

I never calculate for any hops added with less than 15 mins left on my boil, but what about if I add hops with 60 and 30 mins left on my boil?

I know I could use an IBU calculator, but I'd prefer to do it myself.

Any input would be great, thanks!

It might be that I'm misunderstanding you, but if you're not using time as variable in the Tinseth formula, you are doing it wrong.

Your "utilization factor" is defined in terms of time and wort gravity. If you've got multiple additions, you calculate each one independently and add them together.

Is this the formula you are using? http://www.realbeer.com/hops/research.html

Yeah. That's the formula, and I was doing it wrong.

I'd just take the entire time I was boiling not just the time per hop... stupid mistake on my part heh.

Thanks

zickefoose said:

Yeah. That's the formula, and I was doing it wrong.

I'd just take the entire time I was boiling not just the time per hop... stupid mistake on my part heh.

Thanks

Click to expand...

Ah, gotcha. Yeah, I hadn't noticed that the formula is a bit unclear about that. It is definitely supposed to be addition time though. Glad it works now

One thing I did in my spreadsheet (and I'm not sure if this is correct) was to use an average wort gravity BUT to average the gravity at 60 min and flame-out (since I never add hops with more than 60 min left, other than first wort hopping). I sometimes do 100-120 minute boils and it didn't seem right to average the starting/finishing gravities because I've boiled for 40-60 minutes before adding ANY hops.

On that page Malfet linked it says:

The numbers 1.65 and 0.000125 are empirically derived to fit my data. The number 0.04 controls the shape of the utilization vs. time curve. The factor 4.15 controls the maximum utilization value--make it smaller if your kettle utilization is higher than mine.
I'd suggest fiddling with 4.15 if necessary to match your system; only play with the other three if you like to muck around. I make no guarantees if you do.

The really cool thing about these new equations is that they are easily customizable. I believe the basic form is correct; by playing with the different factors, different brewers should be able to make them fit their breweries perfectly.

Click to expand...

I've tweeked all these numbers. It seemed I was getting more utilization in general (decreased the 4.15), way more utilization from late additions (increased the .04)*, and less influence from wort gravity (decreased the 1.65 and increased the .000125).

* (edit) - by 'increased' I mean the absolute value increased but since it's a negative number it's actually a decrease.

Interesting stuff, SpanishCastleAle.

What is your take on the recent thinking that it's actually break material (rather than gravity) that impacts hop utilization? Obviously gravity is a medium-decent correlate to break material, but there are plenty of cases (like the one you are describing) where the relationship would be misleading.

Mad props to Tinseth, but I've always wanted to run some experiments to develop a new IBU formula. The need for a spectrophotometer is a bit of a barrier though. I wonder if something like this could actually be effective.

MalFet said:

Interesting stuff, SpanishCastleAle.

What is your take on the recent thinking that it's actually break material (rather than gravity) that impacts hop utilization? Obviously gravity is a medium-decent correlate to break material, but there are plenty of cases (like the one you are describing) where the relationship would be misleading.

Mad props to Tinseth, but I've always wanted to run some experiments to develop a new IBU formula. The need for a spectrophotometer is a bit of a barrier though. I wonder if something like this could actually be effective.

Click to expand...

It seems hops like to cling to everything so I'm a subscriber to the break-material-hypothesis. A couple of no-bittering-hops-but-hopbursted brews that came out way more bitter than the stock Tinseth predicted is what got me tweeking it. I'm sure I'll adjust it further.

And I thought the barcode scanner was pretty cool.