Partial Pressure Fermentation - NEIPA / London Ale III (wyeast 1318)

[Dryyourbeers]

Hi

There are several threads relating to pressure fermentation (PF) already but none of them quite get to the crux of what I'm trying to find out. The closest is the thread on pressure fermentation of ale.

I get that full PF of an ale isn't generally a good idea. However, I'm interested in trying a partial pressure fermentation. The idea being to cap the pressure at 10 psi only after adding dry hops late on, with the goal of keeping more of the aromatics in the beer. I know Scott Janish has also done an article on this but unfortunately his side-by-side comparison of PF versus normal fermentation wasn't a very fair test. He used different yeast strains and deliberately hopped the PF beer a lot less. He also used pressurised fermentation throughout the fermentation, which I don't intend to do.

What do people think of below timeline / plan? Obviously the days are approx based on gravity and yeast activity

Day 1: Pitch London Ale 3 (wyeast 1318)

End of Day 2: Drop some yeast with the trub from cold break.

Day 6.
a. Harvest the yeast from dump valve (will be cleaner because I did one drop already). Do this under pressure to avoid oxygen ingress.
b. Add CO2 to dry hop under pressure to avoid oxygen ingress. Then release C02 and add spunding valve to keep pressure at 10 PSI. The idea being a lot of the remaining CO2 (and volatile hop compounds) that are released from this point forwards will be kept in the beer, rather than losing all the aromatics. Downside = my brewing area won't have the same lovely dry hop smell when the aromatics are pushed out!

Day 7.
Second Dry hop under pressure. Again leaving under pressure afterwards

Later down the line, cold crash and keg.

Thoughts?

 

[Vale71]

I'm afraid you're making a conceptual mistake. It really doesn't matter at what point in time you spund, the total amount of gas that will escape the FV will be exactly the same and only determined by the amount of fermentable extract minus the amount required to bring the headspace up to the set pressure. Consequently the amount of hop aromatics that will be scrubbed by CO2 will be the same whether you spund right away or near the end of fermentation.

The only way to avoid CO2 scrubbing of hop aroma is to dry-hop fully fermented and spunded beer. There really is no work-around for that, sorry.

 

[Dryyourbeers]

I'm afraid you're making a conceptual mistake. It really doesn't matter at what point in time you spund, the total amount of gas that will escape the FV will be exactly the same and only determined by the amount of fermentable extract minus the amount required to bring the headspace up to the set pressure. Consequently the amount of hop aromatics that will be scrubbed by CO2 will be the same whether you spund right away or near the end of fermentation.

The only way to avoid CO2 scrubbing of hop aroma is to dry-hop fully fermented and spunded beer. There really is no work-around for that, sorry.

Thanks for your reply

I am slightly confused. To me, it seems logical that if I am keeping some of the aromatics/co2 blow off in the beer - be that 10 psi or even more with 15 psi - that is some amount of aromatics that would overwise have been lost did i not use pressure? Assuming of course i never relieve that pressure - and i have no plans to. I can completely see why some of the aromatics would blow off (once the spunding valve started venting) but surely some would remain? And that amount is additional to what would have been there were pressure not applied.

Does that make sense?

Is it wrong?

Thanks again