Adjusting late hops for AA%

I have a Pils recipe that I love, and I've always used 5% Saaz hops. I now have 3% Saaz hops, and I'm wondering how I should adjust the recipe to get a similar flavor.

Previous Recipe:
9# Pils Malt -> 1.050 OG
0.3 oz 13% Magnum @ 90 min - 16 IBU
1.0 oz 5% Saaz @ FWH - 15 IBU
1.0 oz 5% Saaz @ 20 min - 11 IBU

Should I increase the amount of the FWH and 20m hops to keep the same IBUs?
Or should I keep the same weight, and increase the IBUs through the 90m hops?

Since I brew this as a 10g batch, I'm tempted to do 5 gallon each way.

Why not just proportionately add more hops for each. You have 2/3 strength (roughly) hops so you need 1/3 more You'll be fine!

I put it in Beer Smith and it's almost in direct proportion but the addition should be, add 1.34 Saaz 3% in your first wort and 1.8 Saaz 3% for 20 min.

This is what I would do.

1oz x 5% = 5aau. You need 5aau's for your FWH addition. So, you take your aau's for the addition(which is 5) and divided by the 3 from your new AA. You get 5/3 = 1.66..... oz of your new 3% hops to get the same aa.

For the next addition, 1oz x 5 = 5 aau. divide by the new 3. You get 1.66..... oz of the 3% saaz for your 20 min addition.

Hope this makes sense. Maybe someone else can explain it better.
good luck
AM

I never adjust my 15 minute or less hops. Those are for flavor and aroma, especially with low AAU hops, and I don't get much in the way of IBUs out of them anyway. The point is for flavor, and if I like an ounce for flavor, that's what I use no matter what the AAUs are. For very high AAU hops, I'd probably adjust them if they were significantly different, just to not make my beer too bitter. I'd not change the lower AAUs, though.

I WOULD change anything longer than 20 minutes, though, especially if you are using FWH.

Well, the above advice is good for the bittering, but not necessarily for the flavor and/or aroma components. Aroma and flavor are not derived from alpha acids like bittering is. Unfortunately, the amount of the relevant flavor and aroma compounds are not normally known. Chances are increasing the hops as above will result in a great beer. It just might be a little more flavorful and fragrant.

I told you someone could explain it better. At least I was 1/2 right, and I'm pretty sure my math was correct. I'll accept that.
AM

Thanks for all the feedback.

I'm going to follow Yooper's suggestion and increase the FWH hops and leave the 20m hops alone.

YooperBrew said:

I never adjust my 15 minute or less hops. Those are for flavor and aroma, especially with low AAU hops, and I don't get much in the way of IBUs out of them anyway. The point is for flavor, and if I like an ounce for flavor, that's what I use no matter what the AAUs are. For very high AAU hops, I'd probably adjust them if they were significantly different, just to not make my beer too bitter. I'd not change the lower AAUs, though.

I WOULD change anything longer than 20 minutes, though, especially if you are using FWH.

Click to expand...

This^^^^^^

According to Ray Daniels' Designing Great Beers, the AA level of hops are NOT related to their flavor and aroma compounds. The flavor and aroma of hops come from other chemical compounds within the particular hop variety and vary greatly from one variety to another. With those Saaz, I would not assume that the AA level represents their assertiveness with regards to hop flavor or aroma.

Of course, if you're concerned that the lower AA will slip you under your target IBU range, then that's an issue, but I wouldn't imagine it has a big effect.