Stuck fermentation ad nauseam

[RedCat]

Good evening all, long-time reader, first-time poster.

I have been brewing on and off for the last 15 years or so, but in the last two years, I've been brewing probably every two weeks or so, and we have stopped buying beer at home. Everything is made at home now (much to the delight of my wife, who much prefers an ale to a lager, and the ales on offer in Spain are not the greatest). So, I'm not a novice, but I still have a lot to learn.

Recently, I have found that my last four batches ended up with a final gravity of around 1.028 – way too high. This hasn't really happened before. I normally just leave a batch to ferment for two to three weeks, bottle it and onto the next one. But these last few batches, whilst they have tasted OK, are nowhere near as alcoholic as they should be. So, clearly, something is not quite right.

For added information, all of these batches have been different recipes, and all have stopped around about the 1.027-1.028 mark. They've all had an OG of somewhere between 1.043 and 1.050.

My mash temperatures are pretty consistently at around 67 °C (I haven't really started experimenting with that yet). I ferment all my batches in a dedicated fridge with a temperature controller and a heater inside. It basically oscillates between 19.5 and 20° C at all times (sorry, I have no idea what that is in Fahrenheit). I normally make a yeast starter according to the basic instructions in John Palmer's book, and I usually give the batch a bit of a back and forth to aerate it before putting it in the fridge to ferment.

So, my question to my fellow homebrewers is: what am I missing, or what could I do to try and eliminate this issue? Because it's clearly a process problem if it's affected the last four batches in a row.

All contributions and suggestions welcome. Many thanks!
Chris

 

[Minbari]

67c(152F) is on the high end. At 155F the enzymes that convert are dying and the feementabilty of the wort is going to lower, so it will finish sweeter. On your next batch try 64c(146F) and see if that helps.

Also, how is your yeast health? Yeast nutrients? Yeast is in date?

Last item, have you checked your hydrometer just to rule out false readings?

 

[RedCat]

Hey Minbari, thanks for a swift reply!

So, I'm going to make a new batch of porter on Sunday. I'll try mashing a little lower and see what happens. As for your other questions, I use dry yeast and rehydrate it during the brew stage so it's ready once the wort is chilled, but I don't make a starter using DME or anything like that, so maybe that's something I could look at. I don't use any yeast nutrients. Is there anything in particular you would recommend?

As for oxygenation, I normally pour some wort into the fermentor and then some back in the pot a couple of times to aerate it, but nothing more advanced than that.

I have taken readings with a hydrometer and refractometer and both say the same thing, so I feel confident about the readings at least.

Many thanks!

 

[Bigbre04]

As @Minbari said, i shoot for 147-151(63.8-66.1) for all of my batches. I also overpitch with dry yeast.

Dont do starters, they are not needed with dry yeast. if you are propping up yeast from a previous batch, that is different.

i add O2 to all of my batches at knockout. Also a good quality yeast nutrient is a good addition(i use yeast X).

Double check your thermometers to be sure you didnt transfer too hot and kill off your yeast!

likely if you were repitching and reusing yeast, you may have gone too many generations or something happened to the yeast(too long between batches, infections, strange mutations, etc.) There are a lot of variables involved in repitching yeast. I dont bother with it because yeast is so cheap for me($25/batch).

 

[RedCat]

Hey @Bigbre04 !

Thanks for your suggestions. I think trying a lower-temperature mash might be the first thing to try. I'll have a look into yeast nutrients, but at least for the next two batches I'll try a lower mash temperature and see what happens. If I try too much at once, I might draw the wrong conclusion!

 

[Bigbre04]

Hey @Bigbre04 !

Thanks for your suggestions. I think trying a lower-temperature mash might be the first thing to try. I'll have a look into yeast nutrients, but at least for the next two batches I'll try a lower mash temperature and see what happens. If I try too much at once, I might draw the wrong conclusion!

Good call!

What yeast are you using? Are you repitching it?

 

[RedCat]

I just use the SafAle-04 sachets. I haven't harvested yeast yet, though obviously it's something I'm interested in.

 

[Donoroto]

Welcome to Brewers Friend, at least to the ‘posting’ side. We like helping, sometimes with 10 different opinions for six responses…

Lower mash temperature is a good and easy thing to try.

S04 dry yeast need not be rehydrated, and this dry yeast does not need oxygenated wort. You can just sprinkle it into the fermenter. Read the Fermentis data sheet for details.

19.5-20 (67-68F) is a bit cool for this yeast - within normal range, but cool. Try starting at 20 and increasing to 22-23 on day 2-1/2 (or when bubbles start to slow). This gives the yeast more energy to finish the job. Alternative is to start at 21-22 then increase to 23-24 when bubbles start to slow. The yeast is happy from 10 to 26.

Good luck, let us know if any of this helps.

 

[Craigerrr]

You should have no issues pitch a packet of S-04 into that gravity wort. No need to hydrate it first, and no need to oxygenate the wort. I got this directly from a Fermentis rep who was giving presentation at our brew club. I haven't hydrated, or aerate for years...
Although your mash temperature is a little high, In my opinion it is not too high. Im wondering if you maybe have a mash pH issue.
For this Porter you are going to do, I think you want a slightly higher mash temperature...

 

[Bigbre04]

You should have no issues pitch a packet of S-04 into that gravity wort. No need to hydrate it first, and no need to oxygenate the wort. I got this directly from a Fermentis rep who was giving presentation at our brew club. I haven't hydrated, or aerate for years...
Although your mash temperature is a little high, In my opinion it is not too high. Im wondering if you maybe have a mash pH issue.
For this Porter you are going to do, I think you want a slightly higher mash temperature...

dark beers should be between 5.3 and 5.4ph! knocking out my raspberry chocolate stout right now! way overshot my grav 15.85p! target was 15.3 @ 82%

 

[RedCat]

Hi @Craigerrr and thanks for your contribution!

It's interesting that you raise pH, because it was actually something that I really wrestled with when I first started brewing over here in Spain. I grew up in the Cotswolds in the UK, where the water is, well, hard. But nothing could prepare me for the water report here in La Mancha, and frankly, it's just no good for brewing, at least not out of the tap. Anyway, I got myself a fancy pH meter and some extra additives and I now pretty much hit 5.2-5.3 without too much effort if I use water from the supermarket. But it's definitely a factor that's worth considering if the mash temperature change doesn't resolve anything.

I'm no expert by any means, but my wife is an oenologist, and she's very much partial to the idea that yeast will do what yeast does, you just have to create the right conditions. So, I'm ready to believe that the mash is the culprit before anything else. I'll take on @Bigbre04 's comment about the mash pH and aim for something a little higher this weekend.

 

[Bigbre04]

Hi @Craigerrr and thanks for your contribution!

It's interesting that you raise pH, because it was actually something that I really wrestled with when I first started brewing over here in Spain. I grew up in the Cotswolds in the UK, where the water is, well, hard. But nothing could prepare me for the water report here in La Mancha, and frankly, it's just no good for brewing, at least not out of the tap. Anyway, I got myself a fancy pH meter and some extra additives and I now pretty much hit 5.2-5.3 without too much effort if I use water from the supermarket. But it's definitely a factor that's worth considering if the mash temperature change doesn't resolve anything.

I'm no expert by any means, but my wife is an oenologist, and she's very much partial to the idea that yeast will do what yeast does, you just have to create the right conditions. So, I'm ready to believe that the mash is the culprit before anything else. I'll take on @Bigbre04 's comment about the mash pH and aim for something a little higher this weekend.

Cant argue with the yeast comment, but proper conditions are needed for yeast to do thier best work. Over pitching is really a game changer to be honest. Especially with lager yeast. The cost is relatively minor compared to a very consistent fermentation every time. i pitch 250g into roughly 76 gals of wort. im over by a fair amount(yeast dependent), but i also get very consistent and fast fermentations. Those things being said, i am not really a homebrewer. I am batman.

 

[Dave Y]

For added information, all of these batches have been different recipes, and all have stopped around about the 1.027-1.028 mark. They've all had an OG of somewhere between 1.043 and 1.050.

what is your water source?
1.027-1.028... That should be pretty sweet in terms of beer. I'm wondering if your water source recently changed additives. Chlorine and chloramine (?) work against yeast.

If your source water hasn't been tested, you need to either switch to a known source - like reverse osmosis water and add chemicals and adjust pH to desired levels or, well maybe it's a good idea anyway because you indicate this is persistent and onset about 4 batches ago.

If the yeast isn't finishing up, it doesn't have enough to feed on, it's being inhibited by temperature or contamination or it's not viable enough to begin with.

- how are you measuring the mash temp? 152F / 67C is spot on for a single infusion. However, how are you measuring to know you're at 67c? Is that method confirmed accurate? <-- Know this before you make any changes to process or procedures.

- for that matter, how are you measuring your starting and final gravity, and have you calibrated it? Recently.

No amount of mash temperature deviation is going to stall you out at 50% through the fermentation or less.

- Are you recirculating wort through the mash?
- what are you doing to clean and sanitize everything in the post boil process?

Some of us muppets do yeast starter cultures even when it's not needed. Why? Because it's better to have too much horsepower, than not enough. You could double pitch also, but I suspect you wouldn't get much further or at least not in the 'beer' range 1.010-1.018-ish..
Throw shade on yeast starters all you want, but my 4 day in the fermenter at 61F is at 1.018 already from a SG of 1.083.

I would personally start with
1) everything I think is clean and sanitized, gets cleaned and sanitized again.
2) validate my thermometer, refractometer, hydrometer/tilt are accurate. if you don't have a quick acting thermometer, get a few. you may find your mash temp reading is not wholly accurate.
3) For a porter, a single infusion at 152F is again, spot on. Depending on style and preferences, you could go few degrees higher if you want a sweeter beer. I'd use distilled water, adding chemicals using Brewer's Friend's handy-dandy calculator, set the pH and go. I use R/O water, so close to the same process, but several houses back, when I'd use tap water, even filtered, my yeast would stall at 1.018-1.022.
4) make sure your yeast is still within the date range. I'd do a starter myself, because the world is divided into 2 distinct groups.
People who do yeast starter cultures for their brewing
and
The great unwashed muppet peasantry.


If you are determined to make it work without any of that, I'd consider a different source for your yeast; you may have gotten some that wasn't handled or stored properly. Who knows.

Brew it. Ferment it. Report back with results.

 

[Sandy Feet]

Nothing wrong with the fermentation temperatures or the mash temperatures. 20C is 68F. Just shy of that should be perfect for S-04.
It won't hurt to mash a little lower, but 152 should be fine. My guess would be the yeast, and I always overpitch the dry yeast. I use 2 packs in 5 gallons for an ale. I use about double that in a lager. I usually shoot for something between 1.050 and 1.060 OG.
Check your dates and maybe try to buy some fresh packs (maybe from another source) to see if that makes a difference. I didn't think about the water, but yes, that would make a difference too.
Shit, I just thought about one other thing: Are you milling the grains, or is someone else doing it?

 

[Minbari]

Late to the reply party, but i use wyeast nutrient. Easy to find and works very well

 

[RedCat]

Morning all! I wasn't expecting such a great response, but thanks to all of you for your contributions.

There's a lot to go at here, so I think I'm going to have to note it all down and try things one step at a time. I don't really have enough equipment to do a full factorial design, and I haven't done a Gauge R&R on any of my equipment either. So, one thing at a time is probably best. I've recently bought some small demijohns so I can do small batch experiments, so maybe I can do 2 or 3 batches on the same day, varying a couple of things and see what happens.

Something I forgot to mention is that I measure the gravity of the first runnings, pre-boil and post-boil every time. And these always come out exactly spot on. It's only after fermentation that the figures are off. So I guess either there are too many unfermentable sugars, or the yeast isn't able to do its job properly.

Oh, and I buy my grain pre-milled. I'm not likely to buy a mill this side of Christmas, but it's something I intend to do.

I'll try out a few things over the next couple of weeks and get back to you once I get a change in results!

Chris

 

[Minbari]

Morning all! I wasn't expecting such a great response, but thanks to all of you for your contributions.

There's a lot to go at here, so I think I'm going to have to note it all down and try things one step at a time. I don't really have enough equipment to do a full factorial design, and I haven't done a Gauge R&R on any of my equipment either. So, one thing at a time is probably best. I've recently bought some small demijohns so I can do small batch experiments, so maybe I can do 2 or 3 batches on the same day, varying a couple of things and see what happens.

Something I forgot to mention is that I measure the gravity of the first runnings, pre-boil and post-boil every time. And these always come out exactly spot on. It's only after fermentation that the figures are off. So I guess either there are too many unfermentable sugars, or the yeast isn't able to do its job properly.

Oh, and I buy my grain pre-milled. I'm not likely to buy a mill this side of Christmas, but it's something I intend to do.

I'll try out a few things over the next couple of weeks and get back to you once I get a change in results!

Chris

Always best to change one variable at a time. While yeast can effect what you are seeing, i have my doubts that it would happen on all 4 batches.

Once you bottle condition it, does it carb up ok? Do you add yeast at bottling or just let residual yeast do the job?

 

[RedCat]

Always best to change one variable at a time. While yeast can effect what you are seeing, i have my doubts that it would happen on all 4 batches.

Once you bottle condition it, does it carb up ok? Do you add yeast at bottling or just let residual yeast do the job?

I don't add extra yeast when bottling and (so far) there's been no problem with carbonation.

 

[Minbari]

I don't add extra yeast when bottling and (so far) there's been no problem with carbonation.

Ok, then i would assume your yeast is ok. First thing i would try is lower mash temp and see how that goes.

I purposely step mash higher to get unfermentable sugars for sweeter finish beer.

 

[Megary]

Good evening all, long-time reader, first-time poster.

I have been brewing on and off for the last 15 years or so, but in the last two years, I've been brewing probably every two weeks or so, and we have stopped buying beer at home. Everything is made at home now (much to the delight of my wife, who much prefers an ale to a lager, and the ales on offer in Spain are not the greatest). So, I'm not a novice, but I still have a lot to learn.

Recently, I have found that my last four batches ended up with a final gravity of around 1.028 – way too high. This hasn't really happened before. I normally just leave a batch to ferment for two to three weeks, bottle it and onto the next one. But these last few batches, whilst they have tasted OK, are nowhere near as alcoholic as they should be. So, clearly, something is not quite right.

For added information, all of these batches have been different recipes, and all have stopped around about the 1.027-1.028 mark. They've all had an OG of somewhere between 1.043 and 1.050.

My mash temperatures are pretty consistently at around 67 °C (I haven't really started experimenting with that yet). I ferment all my batches in a dedicated fridge with a temperature controller and a heater inside. It basically oscillates between 19.5 and 20° C at all times (sorry, I have no idea what that is in Fahrenheit). I normally make a yeast starter according to the basic instructions in John Palmer's book, and I usually give the batch a bit of a back and forth to aerate it before putting it in the fridge to ferment.

So, my question to my fellow homebrewers is: what am I missing, or what could I do to try and eliminate this issue? Because it's clearly a process problem if it's affected the last four batches in a row.

All contributions and suggestions welcome. Many thanks!
Chris

My .02. And most of this has been stated already.

Your mash temperature is fine. I wouldn't worry about that. 67C/152F is pretty much the go to temperature. Maybe you could squeeze another gravity point or two by mashing lower, but this does not explain missing your Final Gravity by such a margin.

The obvious question I have is...how are you measuring Final Gravity? If you have a hydrometer, that's all you need. Put the refractometer away once alcohol is present because you won't get an accurate reading. There are correction factors for measuring FG with a refractometer and they will get you close, but they won't be as accurate as using a hydrometer.

Assuming you are using a hydrometer to measure FG, do you know if it's accurate? Does it measure 1.000 in distilled water at room temp?

Assuming all that is good to go, then your most likely causes for poor attenuation are:
1. Poor yeast health or (severe) under or over pitching.
2. Improper fermentation temperature. Are you sure your fermentation temperature is correct? You are on the low end for S-04 and if your temp is off by a few degrees, it could cause under-attenuation.
3. Are you sure fermentation is complete? Same gravity readings a few days apart? I'm assuming it is because you haven't had any bottle bombs.
4. Your grain bill is filled with too many adjuncts or unfermentable sugars. Can you post a typical recipe?

After making sure my equipment (hydrometer, fermentation temp) was accurate and my grain bill is fermentable, the first thing I would try is to set the temperature of fermentation to ≈20-21C for the initial busy part of fermentation and then raise it to ≈22-23C for an additional week allowing the yeast to completely finish the job.

Interesting post. Good luck with everything!