Advice on hop calcs

[matt76]

After the success of AG#1 I'm planning AG#4 to use up what I've got in the cupboard. I'd appreciate it if anyone can check my thinking here, any tips welcome...

Previously for AG#1 I used EKG hops added at the start of the boil, and Fuggles at 5 mins before the end - both of these are about 6.5% alpha, which yielded about 20-25 IBU's by my calcs.

Next, for AG#4, I plan instead to boil some leftover Simcoe hops (13.1% alpha) for 60 & 5 mins (I've also got Amarillo and Citra if anyone wants to make a recommendation there).

So if I've understood Palmer correctly then since the Simcoe hops have roughly twice the alpha units of EKG and Fuggles, I should only need half the weight of hops I used before..... err..... right?

I can do the maths as far as bittering is concerned, but am I missing anything regarding flavour. Or am I just massively overthinking things as usual? :-D

Oh, and just to keep it interesting I'm trying to get the ABV down from 6.3% to more like 4.75%, plus I'm changing the grain bill from pure MO to also include about 10% each of flaked barley, Munich and Cara Red :-D

But at least I'm gonna use the same yeast. And water. Probably ;-)

 

[MyQul]

Have you tried using any brewing software? It'll do all those calcs for you. There's a numbe of free one's. I use brewmate

 

[ACBEV]

The brewers friend recipe calc. is quite good at indicating results...

https://www.brewersfriend.com/homebrew/recipe/calculator

It looks quite complicated, but you don't need to use all its functionality. All you need to input for basic results are...

Units = Metric
Brew Method = All Grain
Batch Size (quantity of wort after boiling)
Boil Size (quantity of wort before boiling)
Select your yeast
Input mash temp
Select your fermentables and hops

This will give you a ball park estimate for OG, FG, ABV, IBU, SRM...

 

[matt76]

Yeah, I've started using Brewers Friend...

Part of the reason for doing hand calcs is I'd like to understand the science part...

But also I've tried putting my recipe for AG#1 into BF and it's some way out from what I actually got in reality - my real measured OG was somewhat higher for example, and my FG was lower. Could still be user error though!

But i think my question was really is my basic assumption right that if your hops have twice the alpha % then you'd only put roughly half as much in to get the assume kind of brew?

 

[Ghillie]

Beersmith 3 Mobile is good. Can't remember how much I paid in the app store, but it wasn't a lot. It's cool how it's always in your pocket, has loads of inbuilt calculators and a very handy brewday timer too.

 

[ACBEV]

As far as hop alpha % is concerned, I've always assumed doubling percentage will give doubling of bitterness, whether doubling the quantity of the same hop or using a hop with double alpha. The BF calc. works in this way too.

But also I've tried putting my recipe for AG#1 into BF and it's some way out from what I actually got in reality - my real measured OG was somewhat higher for example, and my FG was lower. Could still be user error though!

The BF calc. assumes 75% overall efficiency. You can change this to whatever suites you, maybe you acheived something like 80%, in which case your results for AG#1 will line up better.

I like to design recipes with the BF calc @ 75% efficiency, then brew the beer and calc. the difference. This gives me an indication of how much grain to add or subtract to hit my target the next time that beer is brewed. Assuming I have a similar efficiency. Over time you will get a better idea of your brewing efficiency, with your equipment and methods.

 

[matt76]

The BF calc. assumes 75% overall efficiency.

Where are you seeing this? When I create a new recipe it defaults, under Style, to 35% Efficiency (Brewhouse) - I'm confused...

 

[MyQul]

But also I've tried putting my recipe for AG#1 into BF and it's some way out from what I actually got in reality - my real measured OG was somewhat higher for example, and my FG was lower. Could still be user error though!

That means you got a better efficiency than what you had your calculator set at, for the OG discrepency. The attenuation of the the yeast was higher than what you had your calc set at, for the FG discrepency.
Once you've dialled in your kit and methodology you should get the same efficiency every time, so you can set your calc at that. I get 66% almost every time so know to input that in brewmate.
Attenuation can be a bit more tricky as every yeast has it's own attenuation but this can be alterted by other variables like mash temp, amount of specialty malts, etc

 

[ACBEV]

Where are you seeing this?

Make sure our brewing method is set to "All Grain". It defaults to 35% when set to "Extract". But it doesn't reset to 75% if going from Extract to All Grain. In any case set it to "All Grain" with 75% Efficiency (Brew House), which is under Boil Time.