Stuck Berliner fermentation options

[toddo97]

I have a BW that's currently stuck at too high of a SG. This is one of my first AG brews so I was paying more attention to the mash temp getting too low and believe it mashed for the first half of the hour (I know--the important half ) at 156 (maybe 158 at the beginning) as opposed to the 152 it was supposed to. I'm worried that maybe there's not enough fermentable stuff because of this. I kettle soured it so it got pretty low (about 3.2 pH) prior to pitching yeast so that could be part of it. I made a 1L starter of WLP001 and the batch ended up being ~6 gallons. The OG was 1.042 and the target FG is 1.012. It's been sitting at 1.022 for a little over a week. 3 days ago, I did a slow swirl of my SS Brewbucket, that that didn't do anything. My options for this batch are:

1. Rehydrate a pack of US-05 and pour through the hole in the fermenter top through a funnel
--little bit of O2 gets in, but not much
2. Step one, but pop the top and slowly stir the gunk on the bottom with a spoon for a few seconds
--lots of O2 gets in, but best chance of getting fermentation to finish
3. Do nothing, bottle, and enjoy my low ABV, slightly 'thicker' beer than planned.

Right now, it tastes pretty good so I'm up for any of those options. A little worried that option 2 would hurt the final product, though.

 

[Kent88]

That warm of a mash shouldn't cause a 0.010 increase in gravity, although I suppose it is possible.

Do you know what a forced ferment test is? That could help you gauge how much more fermentation could happen.

I would add some US05.

 

[toddo97]

I haven't heard of a FF test, but I'll check it out--thanks. So add US05 with or without popping the top and doing some stirring?

 

[Kent88]

I wouldn't stir any more than I had to.

 

[couchsending]

Don’t stir

If you add some dry yeast make sure you rehydrate it first.

Always use a bigger pitch for kettle sours.. almost Lager pitch rates, especially with a 3.2 starting PH.

A Starter that’s actively fermenting that you even add a little of the already soured beer to would be ideal.
Acclimates the yeast to a sour environment.

 

[toddo97]

I rehydrated and pitched the US05-hopefully I’ll see some activity in the next few days. That’s good advice about overpitching for sours. Ill do twice as much when i make a gose in a few weeks.

 

[toddo97]

So after almost a week with the new yeast, I got an additional drop of zip. While doing a bit more research, I ran across some info about adding acidulated malt later in the mash. This was my first time using it and I added it right at the beginning of the mash. Next time I use it, I'll try adding it after 45 minutes or so. So it looks like I'm stuck with a good-tasting, but only ~2.5% ABV beer which I'm ok with since BW's are usually pretty low anyway. I guess my stalled fermentation was the result of :
1. Too low of a pH for the yeast to fully finish
2. Too high of a mash temp
3. Acidulated malt added too early in the mash

I've read that 3711 is a good pH tolerant yeast so I may use that.

 

[RPh_Guy]

You want your mash pH to be in the 5.2-5.6 range.
Using acidulated malt can help achieve this, rather than directly adding lactic or phosphoric acid.
If you're not using acidulated malt to adjust mash pH into range, why are you using it?

Any commercial beer yeast can ferment a sour, just pitch high and it'll be fine. Add a bit of yeast nutrient too.

 

[toddo97]

You want your mash pH to be in the 5.2-5.6 range.
Using acidulated malt can help achieve this, rather than directly adding lactic or phosphoric acid.
If you're not using acidulated malt to adjust mash pH into range, why are you using it?

Any commercial beer yeast can ferment a sour, just pitch high and it'll be fine. Add a bit of yeast nutrient too.

This was my first time using RO water+additions. Bru'n water said I needed to add lactic acid or make to lower the pH to the right level in the mashI didn't have an easy way to measure lactic acid so I used the malt. I made a started starter and added nutrient so I'm still kinda stumped about why it stalled.

 

[RPh_Guy]

You were correct to add the acid malt at the beginning since that's when you need the pH adjustment.

My guess is the mash temp is the reason for high FG. A lot of my first batches finished high before I got mash temp under control.
Hit your calculated strike temp. Insulate the mash tun as best you can. Then let it sit
Berliners are supposed to be dry. I mash low for this style.

But hey, at least it's good, right? Cheers.

 

[toddo97]

You were correct to add the acid malt at the beginning since that's when you need the pH adjustment.

My guess is the mash temp is the reason for high FG. A lot of my first batches finished high before I got mash temp under control.
Hit your calculated strike temp. Insulate the mash tun as best you can. Then let it sit
Berliners are supposed to be dry. I mash low for this style.

But hey, at least it's good, right? Cheers.

I think the rationale for adding the acid malt later is that the change in the pH too early would affect fermentability. It sounded odd, but it was another possible explanation. I think you're probably right on the cause--I was so concerned about not letting the temp drop too much that I didn't pay enough attention to the starting temp. And I guestimated a strike temp (never again!) so by the time the temp dropped to where I wanted it, the conversion was probably done.

I'm getting ready to put 3 gallons on some peaches and apricots so maybe that'll give me a half point more of ABV?

 

[RPh_Guy]

The amylase enzyme activity in the mash is affected by pH similarly to how it is affected by temperature (you want it in a particular range for optimal activity).
The only way acidulated malt would negatively impact fermentability is if the addition puts the pH out of the "correct" range (under 5.2) before conversion is complete.
You said you were using the acid malt to get the pH into range, so adding it at the beginning is right because that's when you need the pH to be correct.

Yeah, fruit juice will probably bump the ABV slightly.
Sounds good!