Pressure Fermentation Temperature Profile

[rickpbush]

Hi guys and gals, I have recently entered the world of pressure fermentation and would like to ask if anyone could chime in with any advice.

I am brewing ale. Specifically TheMaultMiller Tribute all grain kit.

I have set up a glycol chiller (home made using an oil cooler, pump, stc 1000 and freezer) and heat pad which works remarkably well at enabling me to set a temp at any given point in the fermentation and keep it there.

So, I have devised the following method for which I will now give followed by my my logic.

1. I dump the wert from the boil kettle at 30 C into my FV
2. I chill it to 20 C then pitch the yeast
3. I set my chiller/heater to 19 C and allow fermentation to proceed for about 24 hrs under atmospheric pressure just using an air lock.
4. One the krausen is about an inch thick and fermentation is fully and strongly under way, i replace the air lock with a spunding valve set to 10PSI
5. Once 10 PSI is reached, I set the temp to 24 C (the high end of my yeast is 25 C)
6. I leave it under pressure until the gravity is stable for 2 days.

Ok, so now the reasoning.

2. 20 C is 1 C above the recommended 19 C which will give the yeast a nice warm start.

3. Using atmospheric pressure to get the fermentation started seems to me to allow the yeast the best start as I've read applying pressure can stress the yeast so I want them fully established and multiply in as close to ideal conditions before I apply pressure.

4. By the time the krausen is 1 inch I guess fermentation is strong enough to take some pressure?

5. going to the high(ish) end of my yeast will result in fast fermentation I guess.

6. Seems all advice is to leave till gravity is steady for 2 days then keg, so that's what I do.

Below is a graph I drew

Is this a reasonable approach, should I be doing something different ? Any advice would be really appreciated. I am getting good results, no off flavours so I guess there are some who would say if it works for you then its all good but I'm really just looking for critique here really.

Should I go higher in temp when under pressure to get full advantage of pressure ferment speed? Is it good to use atmospheric at 19C to start etc ???

Thank you.

 

[user 263363]

Best that I can tell, your process seems solid. If not a little technical.

I know that many home brewers love to get
technical and enjoy the scientific part. This can allow them to make the best beer possible, on paper.

I, however, do not care that much. I chill my wort to room temp, pitch my yeast, pressurize my vessel enough to hold a seal (I use kegs to ferment in) and let her rip. My valve is usually set somewhere between 10 to 12 psi.

This process always nets me very clean ferments with 34/70 and US-05. I generally let them sit for two weeks regardless, but my last batch I tapped at a week and it was a bit green.

 

[Red over White]

Seems like a solid approach to run a baseline on, but you need to learn your yeast on your gear. Every yeast is different and under pressure is no different in end results. Some ale yeasts can be quite expressive ester wise under low pressure, some are very much stifled. Some lager yeasts can be quite neutral under low pressure, some kick sulfer no matter what, but typically mop it up well in lagering.

I learned by brewing my favorite beer over and over only changing one parameter in the fermenter to evaluate the effect of yeast, pressure or temperature. We go through a lot of beer here on Sunday (huge family), especially during football season, so I have to brew a lot which isn't terrible. When you apply pressure and how much can affect, esters, fusels, mouthfeel, speed to maturity, etc... keep good tasting notes especially when young until ready. They will tell you a lot as you gain experience with the process.

 

[rickpbush]

Thank you for the replies. Yes I am more scientifically minded than artistic, I tend to approach problems in a binary way hoping that precision and research can make up for my lack of creative talent.

Thanks for the advice on repeating the process altering one variable at a time, I do find that tricky as it involves much patience especially if I'm waiting possibly 3 weeks between results but that's something I need to work on. Proper note taking is also something I need to work on so thanks for that advice too.

I just read that temp should only be increased by 1c per day, any thoughts on that?

 

[Red over White]

I keep my pressure ferments in a narrow temperature range. I have a low gravity 1.040 ale I turn around in a week with Verdant I will use as an example. Pitching a 500ml vitality starter at 64° it will eventually rise to 68° at high kräusen. I let it build pressure to just 2 psi and at high kräusen I ramp to 28 psi. This let's the prominent Apricot ester develop under very low pressure and then be fully carbonated when I xfer to the keg on day 4-5. After 1 day at room temperature in the keg I put it in the keezer and on day 7-8 it is dropping clear enough with a floating dip tube to drink and boy do we love it young! The whirlpooled Cascade/Centennial hops just pop and are always the best really young. As you can see I try to work with the yeasts native temperature range and really adjust the pressure and I like that result better. You need to try it different ways and see what you like the best. I brew 10.5 gallon batches and use 2 fermenters and have tried different ways in each to learn faster. I hope this helps out a little bit.