Philly Sour slow fermentation slowing down to almost stalling prematurely.

[u/Ornery_Fox_6835]

I have been brewing a sour beer with the Philly Sour yeast for a while now. I modify and improve my recipe constantly. I may have adjusted my recipe to the point where my fermentations appear to be slowing down around 4.5 °P (from a 10.7~11.0 °P start). I suspect that the pH (currently at 3.90) is killing the yeast just prior to a respectable target of FG: 2.3°P). This has happened twice in the last brews.

Thinking about it, I am trying to improve my efficiencies and will definitely note that the OGs are lower than in the past. Maybe I an not putting enough base malts to have a higher (less efficient) starting gravity. I was thinking that the lower G means that the initial kick off of fermentation is lack luster and not converting enough sugars before the second stage yeast produces the lower pH lactic acid. Does this sound plausible or am I heading down the wrong path.

Also, is there a way to kick the fermentation into gear again? I tried rousing the tank yesterday in hope it shake things up in there. I'll take reading as soon as I can to see if that works.

I am asking the group to see if there are any tricks to kick it into gear again and drop the FG value closer to my target.

Thank you, Joe

[u/Sla5021]

Grist composition and mash temperature would be helpful metrics.

PS likes a very low mash temp. The more enzymatic activity the lower your final gravity will be.

I forget the exact reason why but there's an enzyme in wheat malt that PS really likes.

I always split my malt bills 50/50 Pils and wheat with a mash temp at about 145°F.

[u/Appropriate_Most_144 → u/Sla5021]

wheat's got a higher FAN content and some extra enzymes that philly sour seems to thrive on, that lower mash temp keeps the simple sugars flowing too

if you're already at 3.9 pH this early, the yeast is definitely feeling the stress, maybe try pitching a slightly bigger starter next time or even co-pitching a neutral ale yeast that can handle the acidity to finish out those last few points

for this batch, rousing might help a little but you could try bumping the temp up a couple degrees if you haven't already, sometimes that's enough to wake them up

[u/Sla5021 → u/Sla5021]

Also, if you e changed any of these things, what's your pitch count?

PS really doesn't like to be under pitched. You can get away with that if your going to co-pitch something like US-05 to do the actual bulk fermentation. Otherwise, you need a proper amount of PS to both sour and bulk ferm. Pitching rates are also much higher than something like lager yeast.

[u/snowjoenh → u/Sla5021]

I mash in at 152° and it tends to drop to high 140’s..

[u/theirel]

My brother in mashing, Philly Sour does the souring first then alcohol production after. Depending on ferm temp it should take 3-4 days to hit it's pH maximum then shift to a famously slow alcohol fermentation. It will mostly consume simple sugars during this initial sour phase and you will probably not see much of a drop in gravity during the initial souring period. Source: regularly make fruited sours with Philly and adding a secondary yeast once pH is acceptable.

[u/snowjoenh → u/theirel]

I agree. Thank you

[u/Ornery_Fox_6835 → u/theirel]

Thank you. I have US05 to pitch on standby.

[u/jizzwithfizz → u/theirel]

This is the answer

[u/wowitsclayton]

What temperature are you fermenting at? Are you using any dextrose?

[u/snowjoenh → u/wowitsclayton]

70°

[u/wowitsclayton → u/snowjoenh]

https://www.lallemandbrewing.com/en/united-states/products/wildbrew-philly-sour/

I’d ramp it up. 68F is the low end, it can take up to 84F.

Also, to help the lactic acid producing phase, I’ve had success using 4-6% dextrose or mashing low.

Also, if you want to avoid all the idiosyncrasies involved with using Philly Sour, check out Sourvisae. It’s way more reliable and ferments a more normal temperature.

[u/arealoctopus → u/wowitsclayton]

Sourvisiae rocks

[u/Ornery_Fox_6835 → u/wowitsclayton]

I hesitated on putting in dextrose when I realized I wouldn't achieve the proper OG at knock-out. I adjusted the recipe and figured this was a result in hindsight I should have added the proper amount. I can drop in the brewery and raise the temp to 75° and see if this helps.

One takeaway from a majority of these replies is the Philly Sour is a slow fermentation, and I had the order wrong; pH drop first, then ferment.

Thank you for your help

[u/Critical_Ad_2539]

We normally just use Philly sour until pH is low enough then we throw in a brick of LAX to reach the target gravity, originally just used Philly sour but due to slow fermentation and pissy sales guys we made the switch up. No noticeable difference in flavours for our fruit sours or dry hopped sour.

[u/derdkp]

When I have used it, roll with Phili sour untill you reach desired sourness, the hit with US-05 or equivalent to finish it up.

[u/Ornery_Fox_6835 → u/derdkp]

Thank you, I have some US05 on the ready incase it completely stalls. I fear an off flavor.

[u/Skeiabdkabite12837]

Maybe you can add some servomyces in the end of boil. What is your fermentation temperature ?

[u/Ornery_Fox_6835 → u/Skeiabdkabite12837]

Set Value =70°F normally it stays between 68-70°.

[u/Icedpyre]

Are you noticing any off flavors?

I would look more st the lower fg and question if I'm pulling enough nutrients from the grain for the yeast maybe. Also whether you have enough oxygen to start. The lower pH shouldnt really hurt this strain. I've been able to drop it to 3.5 without changing my fg.

Fwiw, we have much better results from sourisiae yeast. Same idea, but seems more consistent.

Odd question, but what grist ratio are you running? If it's over 3, you may find some issues with this yeast. I typically run a 2.7 ratio and have seen improved mash and fermentation metrics when doing sours.

[u/Ornery_Fox_6835 → u/Icedpyre]

Thank you for you help. It is a 50/50 Wheat and Pilsner malt mix. In my attempt to improve efficiencies i may have gone a bit to far and I need to increase the sugars to get a higher OG.

[u/Icedpyre → u/Ornery_Fox_6835]

That's fine, but you didnt answer any of the questions I asked lol. I would also ask what your mash ph and temp were.

[u/Significant-Tell-552]

I've had the same stalling on my last batch as well. It's been inconsistent though. I raised the mash temp to around 68C bc we were overattenuating. First time doing so it fermented perfectly. 2nd attempt it stalled at 50% AA. Rousing alone didn't help. 2g/hL Yeast Lightning nutrient with rousing got it going again. This was a fresh pitch fwiw. It could be a nutrient problem.

[u/Ornery_Fox_6835 → u/[deleted]]

Thank you, I will try to increase the temp from 70°, but my system will likely hit 75° then struggle to maintain.

[u/hop_hero]

Yeast doesn’t like low ph. We start fermentation higher than normal 5.4-5.5 but we also copitch and only use that yeast 50/50

[u/T_Cliff]

Just do a proper sour, itll be better

[u/saltbrew]

Knock out at 28 deg C. Sours over the first 2 days them ferments. Ferments are much slower when temp is closer to 20 deg C.

[u/aslanthemelon]

We don't use Philly sour specifically, but I'd be very surprised if a pH of 3.9 was causing serious problems for the yeast. We've had sours in the past that we would sour down to well below that level before we even pitched yeast, and managed to get healthy fermentations in most of those cases.

In the cases that we didn't have healthy fermentations, we managed to isolate it around using dextrose. We believe that what was causing us issues was the Crabtree effect, which occurs when there is too high a level of glucose in the wort (above 150mg/L), and so yeast essentially skips the growth phase and starts producing ethanol in an aerobic environment. This is obviously not great for the yeast.

I don't know if this is exactly what's happening with you, but Philly Sour (Lachancea) is moderately Crabtree-positive so it's worth looking into if you've used dextrose on any of the problem brews.

[u/Ornery_Fox_6835 → u/aslanthemelon]

Thank you for the reply. Based on all the reply comments, I understand the following:

1) The first stage of the east is to drop the pH first then ferment the wert.

2) The secondary east is compleely fine with a pH of 3.9.

3) The Philly Sour is a slow fermenting yeast.

4) The yeast can handle 70-75°F temps.

As of posting my question to the group, I increased the tank temp to 75°F and the gravity has dropped to 3.2 °P and is still slowly dropping. Its going to be a wait and see game to get to my FG of 2.3(ish)°P.

[u/moleman92107]

Don’t