Old yeast didn't ferment all the sugars

[Shawn Lewis]

Hey, All,

I made the mistake of brewing with old yeast. I will not do that again. Initial ferment was 4 weeks. It's been stuck at 1.02 for a week.

I bottled without adding extra sugar because I didn't want to take the chance that the yeast would not ferment the extra sugar and I would end up with not just weak beer, but too-sweet beer.

I'm fine with my decision, but I'm curious what others' experience is with this issue.

 

[Hoppy2bmerry]

How old is old? Was it liquid? Did you make a starter? I’ve used “old” yeast many times. Dry yeast stored properly in the fridge can be a year past the date and be fine. Liquid yeast I’ve used packs 6-9 months past their date with a starter.

 

[mirthfuldragon]

Making starters is a game-changer when it comes to using old yeast. I used some harvested 3787 slurry from an overbuilt starter from April 2019; it has been in the fridge sitting in a sanitized pint mason jar. Built a 1L starter of 1.030 wort, which acted sluggish. I let it go for about four days, then pitched it and crossed my fingers. 3787 is notorious for blowing out airlocks, and this one was true to that - it decided even a blowoff tube was for chumps.
From 1.051 to 1.012 in about 80 hours, including the standard post-pitch lag phase.
Honestly, I might go top-crop it today and use it again.

For the OP, 1.020 could be a lot of residual sugar, depending on the style and yeast strain. Priming sugar is around 0.002 to 0.003 SG, so adding more sugar to that leaves the potential for bottle bombs. Be careful here. What style and strain did you use?

 

[bucketnative]

The priming sugar would have most likely fermented, because it is a simple sugar (assuming you used dextrose or the like).

FYI - There are certain strains that will not ferment maltotriose, and without knowing your full recipe, process, yeast strain and fermentation; it's too early to conclude that old yeast was the problem.

 

[Shawn Lewis]

How old is old? Was it liquid? Did you make a starter? I’ve used “old” yeast many times. Dry yeast stored properly in the fridge can be a year past the date and be fine. Liquid yeast I’ve used packs 6-9 months past their date with a starter.

I don't know what the date was, but it sat in my fridge in a plastic bag for 9-ish months.

 

[Shawn Lewis]

Making starters is a game-changer when it comes to using old yeast. I used some harvested 3787 slurry from an overbuilt starter from April 2019; it has been in the fridge sitting in a sanitized pint mason jar. Built a 1L starter of 1.030 wort, which acted sluggish. I let it go for about four days, then pitched it and crossed my fingers. 3787 is notorious for blowing out airlocks, and this one was true to that - it decided even a blowoff tube was for chumps.
From 1.051 to 1.012 in about 80 hours, including the standard post-pitch lag phase.
Honestly, I might go top-crop it today and use it again.

For the OP, 1.020 could be a lot of residual sugar, depending on the style and yeast strain. Priming sugar is around 0.002 to 0.003 SG, so adding more sugar to that leaves the potential for bottle bombs. Be careful here. What style and strain did you use?

It was 1/2 packet of Safale-05 for 1.5 gallons of wort.

Re: starters, I will do some research, but do you mind sharing what you did to make your starter?

 

[bracconiere]

what did you use to check your FG? refractometer or hydrometer? (just thought i'd ask)

 

[Shawn Lewis]

what did you use to check your FG? refractometer or hydrometer? (just thought i'd ask)

Hydrometer

 

[bracconiere]

out of curiosity, what was the OG? i've heard that for big beers, 1.02 isn't unheard of as a FG...


and also what was your mash temp?

 

[mirthfuldragon]

Re: starters, I will do some research, but do you mind sharing what you did to make your starter?

There are two ways I use: boil 100g of DME in 1L of water, chill, and add yeast, put it on a stir plate, and wait a couple of days. I use a $15 Amazon erlenmeyer flask. Stir plate is optional - you could just shake it every couple of hours.

The other way is that I will pressure-can sweet wort (from a pale ale, etc) , which is effectively sterile and can be used straight-up with yeast. About once a year I'll do a 10g batch and then can off a case or two of quart jars. Starters really become necessary when getting into lagers.

**********
Also, a half packet of S-05 is a big over-pitch in a 1.5g batch - was it old, previously opened, or stored warm? If you're doing a big imperial stout, then like @bracconiere said, 1.020 could be final gravity.

 

[ncbrewer]

I don't know what the date was, but it sat in my fridge in a plastic bag for 9-ish months.

If it was in the factory sealed packet, it's probably fine. If previously opened, probably not, at least according to most yeast companies. But I've read accounts of opened yeast packets being stored for later.

 

[RM-MN]

If it was in the factory sealed packet, it's probably fine. If previously opened, probably not, at least according to most yeast companies. But I've read accounts of opened yeast packets being stored for later.

Yeast companies are making sure you don't blame them for a problem of your own making, plus they sell more yeast if you discard the opened package. With dry yeast I store opened packet to use later although I prefer to use them within 3 or 4 months.

I made the mistake of brewing with old yeast. I will not do that again. Initial ferment was 4 weeks. It's been stuck at 1.02 for a week.

Assuming you are brewing from an extract kit the yeast probably did all it could. Depending on the ingredients and how you treated the yeast during the fermentation period it isn't uncommon for an extract batch to stop fermenting at 1.020. By leaving it for 4 weeks you should have been fine to add the priming sugar. I fear you will have bottles of flat beer.

 

[bracconiere]

plus they sell more yeast if you discard the opened package.

i miss the old days when a packet of dry yeast was $1......

 

[bucketnative]

i miss the old days when a packet of dry yeast was $1......

Switch to wine

 

[bracconiere]

Switch to wine

been seriously considering it....

https://www.ebay.com/itm/WINE-YEAST...:SSEAAOSwHMJYFP3p:sc:USPSPriority!85650!US!-1

but not sure if it will flocculate as well...hell i'd use baker's yeast if it would floc good....

 

[Shawn Lewis]

out of curiosity, what was the OG? i've heard that for big beers, 1.02 isn't unheard of as a FG...


and also what was your mash temp?

OG 1.054
It's an extract brew not from a kit. Specialty grains were steeped at 158 - 164 degrees.
I'm not brewing with a style in mind.

water 1.5gal
pale lme 3 pounds
fuggle hops 5 grams - boiled separately, strained out and hops water added
carapils 2 oz
20L crystal/caramel 2 oz
malted oats 2 oz
Safale-05 yeast 1/2 packet

 

[McKnuckle]

Hmm, Safale US-05 is, of course, a ubiquitous dry yeast. Sitting in a fridge for 9 months is child's play for it (or any dry yeast). Perhaps you might reveal your mash temperatures?

[Edit - you posted just before I did. Okay, 158-164. Definitely at the high end and above. You achieved 63% attenuation, which is not a shock to me.]

I have a 1.048 stout that finished at 1.020 thanks to some erratic high alpha range mashing. It's definitely finished, too. Checked with a refractometer AND a hydrometer.

 

[Shawn Lewis]

Yeast companies are making sure you don't blame them for a problem of your own making, plus they sell more yeast if you discard the opened package. With dry yeast I store opened packet to use later although I prefer to use them within 3 or 4 months.



Assuming you are brewing from an extract kit the yeast probably did all it could. Depending on the ingredients and how you treated the yeast during the fermentation period it isn't uncommon for an extract batch to stop fermenting at 1.020. By leaving it for 4 weeks you should have been fine to add the priming sugar. I fear you will have bottles of flat beer.

Now that I've made my own mead and beer, flat room-temp beer doesn't bother me at all.

 

[Shawn Lewis]

Hmm, Safale US-05 is, of course, a ubiquitous dry yeast. Sitting in a fridge for 9 months is child's play for it (or any dry yeast). Perhaps you might reveal your mash temperatures?

[Edit - you posted just before I did. Okay, 158-164. Definitely at the high end and above. You achieved 63% attenuation, which is not a shock to me.]

I have a 1.048 stout that finished at 1.020 thanks to some erratic high alpha range mashing. It's definitely finished, too. Checked with a refractometer AND a hydrometer.

So you think my FG is pretty normal? What do you have to do to get it down closer to 1.00?

I was shooting for close to 1.00, then going to back-sweeten and add sugar for carbonation.

 

[ncbrewer]

[Edit - you posted just before I did. Okay, 158-164. Definitely at the high end and above. You achieved 63% attenuation, which is not a shock to me.]

You might have misread. This was an extract batch, with specialty grains steeped at 158 - 164.

 

[bracconiere]

So you think my FG is pretty normal? What do you have to do to get it down closer to 1.00?

I was shooting for close to 1.00, then going to back-sweeten and add sugar for carbonation.

now i feel like i'm being trolled, lol....


GLUCOAMYLASE! brewhaus.com is where i get mine by the pound

 

[bracconiere]

You might have misread. This was an extract batch, with specialty grains steeped at 158 - 164.

?? malted oats? that's not a already converted crystal malt, and i don't know about the carapils.....

 

[Shawn Lewis]

?? malted oats? that's not a already converted crystal malt, and i don't know about the carapils.....

Carapils for mouthfeel. Malted oats also for mouthfeel but an experiment.

 

[dwhite60]

I've used four year old dry least without a problem.

Your beer is probably just done.

Bottle it and move on. I would keep them contained somehow, in a plastic tub, just in case you have bottle bombs.

All the Best,
D. White

 

[BrewnWKopperKat]

Depending on the ingredients and how you treated the yeast during the fermentation period it isn't uncommon for an extract batch to stop fermenting at 1.020.

So, depending upon the recipe and the yeast used, the resulting beer can end up at 1.020 - maybe higher, maybe lower.

This is the beginners brewing forum. I'd prefer that people not misread what your wrote and start mindlessly parroting that all extract beers have a FG of 1.020.

 

[BrewnWKopperKat]

If it was in the factory sealed packet, it's probably fine. If previously opened, probably not, at least according to most yeast companies. But I've read accounts of opened yeast packets being stored for later.

it sat in my fridge in a plastic bag for 9-ish months.

A packet open for nine months is probably outside the 'experience range' of almost everyone in the forum. I tend to use my open packages within two months.

That being said, recipe, rather than open yeast packages probably accounts for most of the FG. measurement.

Did you use recipe software to estimate FG?

 

[rburrelli]

So far everyone has assumed that the yeast came from an already opened package. I don’t see where the OP stated that.

Yeast from a nine month old unopened package of US-05 should be fine. In most cases.

 

[BrewnWKopperKat]

So far everyone has assumed that the yeast came from an already opened package. I don’t see where the OP stated that.

Good observation. This ...

I don't know what the date was, but it sat in my fridge in a plastic bag for 9-ish months.

... is what lead me to understand that it was an open package.

 

[Shawn Lewis]

A packet open for nine months is probably outside the 'experience range' of almost everyone in the forum. I tend to use my open packages within two months.

That being said, recipe, rather than open yeast packages probably accounts for most of the FG. measurement.

Did you use recipe software to estimate FG?

No. I used a hydrometer. I think the yeast package had been opened and used once before.

 

[Shawn Lewis]

Sounds like the yeast worked more or less fine. I'm content with that. Thanks, everyone!

 

[rburrelli]

Good observation. This ...



... is what lead me to understand that it was an open package.

Disregard. OP responded while I was typing.