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Hop water absorption rate and fermenter to keg loss #616

Open Drevi opened 3 years ago

Drevi commented 3 years ago

After some head scratching when a pretty hoppy brew that came almost a liter short, I figured I did not account for the absorption rate of hops. I sacrificed some to test and came with 7ml/g of absorption. Others like https://www.youtube.com/watch?v=PDQeRuBlAvA get even more at 12ml/g. For now I'm just adding extra "kettle to fermenter loss" based on total hops (kettle and dry hop) to compensate this, but would be cool if this absorption rate could be added to the equipment tab.

Another minor feature missing is the fermenter to keg loss. Most brewing software/spreadsheets "batch size" refers to the volume going into keg/bottles. This is not as inconvenient as the hops, since the loss is fixed you can just increase the batch size once and never think about it again. It's just a consistency thing.

matty0ung commented 3 years ago

Interesting. Is there any difference between absorption rates for leaf and pellet hops?

Drevi commented 3 years ago

AFAIK, yes. But I'm seeing people claiming less, and more. For example this https://www.homebrewtalk.com/threads/leaf-hop-absorption-measured.241469/ claims 5ml/g. While I've read various others claiming 16ml/g. I would test it myself to give a default rate but I don't have any leaf hops (not even sure I can get around here).

Having both absorption rates to input would be great, so people using mixed types of hops could have an accurate calculation.

mattiasmaahl commented 3 years ago

Initially I don't see much trouble implementing this, although have not dived into the details of what would be required. Some data would be nice if we are to use "standard" values, other way to go would be to let user input the absorbtion values and just do the calculation. @matty0ung are you planning to look at this? Otherwise I can have a look when I'm back from vacation.

Drevi commented 3 years ago

I've just kegged that beer. The dry hop matter came at 620g, it was originally around 90g of hops (don't have exact values as this was not intended as a test). That puts it near the 7ml/g of my other test. Seems like a good baseline rate for pellets.

matty0ung commented 3 years ago

@mattiasmaahl Happy for you to look at it. I'm still polishing the new database layer.

mattiasmaahl commented 3 years ago

Ok, then I'll have a look when I'm back at work. 😊