ideas how to keep a kettle sour warm?

[user 204491]

I know this is an old thread, but I have one follow-up about keeping temperature during the kettle souring process.

Based on the advice from this thread, I just purchased a fermwrap and temp controller, so I will be fine keeping ~115 during the lacto fermentation. I plan on doing so in a corny keg covered by two fermenting buckets. I am going to crimp the dip tube to create a thermowell and control based on that temp.

My question is how to keep the starter warm enough with the same equipment. The volume of the starter will be less than 2 liters. The corny keg will provide the most control, but I feel like there will be too much headspace in it for the starter to keep temp.

Do you think I should let the starter sit for a few days in an erlenmeyer flask with the ferm wrap loosely wrapped around it? This approach will minimize headspace. Another approach is to let the starter sit in the 5 gallon stock pot that I'll be boiling in. The stock pot won't fit in the fermenting buckets, so I'll have to rest them in a keg bucket. The flask and stock pot both involve my temperature probe coming into contact with the starter, which I am trying to avoid.

What approach have you guys used for the 2-3 day starter heat hold? Keg? Erlenmeyer flask? Stock pot?

I may be overthinking this. It is my first sour, so I want to make sure it pays off.

Well, I hate to be the guy that answers your question about thing A by instead telling you to try thing B, but if alternatively you could do away with that extra equipment, making a starter, all the hassle, and even save some money and just go with a strain that sours well in a short time without needing to be heated.

Lactobacillus Plantarum will do the trick in 24-48 hours at lower temps and even works at room temp as well. It's available in a large number of probiotics. I particularly like the Swanson's Inner Bowel support capsules. They are $10 for 30 capsules (on sale currently BOGO), and I use 1 per gallon of wort, which even that is a bit of overkill.

You just open them up and toss them in. No starter required. Also, it's a pure strain of Lacto you're working with here, so you don't have to purge with CO2, and you don't have to worry about the death stench. I usually chill my wort down to 100F, pitch the pills, and then just let the temp free fall for 24-48 hours while the pH rises. Works ever time and will go terminal at about 3.1 - 3.2 pH.

One word of caution - Plantarum is pretty hop sensitive so be sure you are doing this in unhopped wort. I do fermenter sours, don't even boil and generally only do dry hops, but if you're going to add hops you'll want to do it after you've soured.