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Stalled fermentation What did i miss?

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william_shakes_beer

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Here's the situation:

2 weeks ago I brewed a batch of pumpkin ale, something I have done many times before. 10# base malt, 2 pounds specialty malt, 1 lb. brown sugar. 1 oz. hops, spices as required. OG 1.065 on the refractometer. Put in the ferm chamber at 77F. Stirred vigorously with a sanitized spoon to aerate. Pitched WLP550 and let it sit for a week. Opened the bucket a week later, no krausen ring, no foam, no signs there was ever yeast in there at all. Refractometer says 1.056. Crap. Got out the power drill and a sanitized paint stirrer, aerated the F*&^ out of it, checked to verify the actual wort temp was the same as the temp controller was reading. Spot on. Left another coupe days still no love. Went back t the LHBS, purchased a fresh packet of WLP 550, pitched and aerated again. End of the third week, still no krausen ring, Refractometer still says 1.056. Bought some iodine to do a starch test and verify conversion was successful. No purple.

Now, here's my dilemma:

I have another batch i was preparing to brew. It's exactly the same yeast, hopps, spices and grains. Only difference is addition of molasses to make it xmas beer. In fact I bought the gran for both batches in the same order. I looked at the 10 pounds in the basement and the crush looks good.

1. Should I trash the pumpkin batch or keg it after another week in the ferm chamber and see how it carbs?

When I brew the second batch, what should I change?

The only thing I can think of is the strike water was a bit warm (170F) when I doughed in. However, the iodine test tells me conversion took place.

I am at a loss.
 

IslandLizard

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First off:
When using a refractometer for gravity readings when alcohol is present, you need to use a correction formula:
Refractometer Calculator - Sean Terrill or
Brewer's Friend Refractometer Calc

Now a reading of 1.056 is damn high, 1.025-1.035 is a much more common raw reading for "refractometer FG" when everything has been working fine actually. So indeed, something is way, way off!

I gather you didn't make a yeast starter in either case? That could be the issue, pitching mostly dead yeast.
How about taking an old fashioned hydrometer reading? That will tell ya.

A few other thoughts:
Have you checked your mash thermometer lately?
Did you add any Sorbitol, unintentionally?
Do you see a yeast layer?
Have you checked the pH of the beer?

I'm surprised it's not infected after 3 weeks.
Did you taste it?
 
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william_shakes_beer

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I did not make a yeast starter. I pitched a pure pitch pack I had recently purchased from the LHBS.

I understand the refractometer isn't *supposed* to be accurate when alcohol is present. I was merely attempting to confirm what I suspected from the look of the wort: that fermentation has stalled. When I did the second pitch I again purchase a fresh packet of pure pitch from the LHBS. Both packets had an expiration date of the middle of 2021.

When i checked the ferm temp I threw the mash thermometer into the bucket and the temp matched the temp controller within one degree ( ferm sensor is on the outside of the bucked while mash therm was i the wort, so a degree isn't much) Also, during brew day, each time after I pull the bag I return the mash therm to the pot and it reads 212 about the same time its at the beginning of active boiling. To me those 2 data points mean the therm is accurate. Also, the iodine test tells me that conversion has taken place.

The mash temp began at approx 170 but over the curse of the hour mash it dropped to approx 156F. IMHO sufficient range to ensure both enzymes have an active period.

When I did the iodine test, alcohol was present ( the initial ferm brought the wort from 1.065 to 1.056, which I attribute to the brown sugar fermenting out). Does the presence of alcohol affect the iodine test simalarly to how it affects refractometer readings?

The only possible source of sorbitol or any other preservatives is the spices I added. McCormics ground allspice, ginger, nutmeg, cinnamon, and whole cloves. Only the ginger lists an additional, ingredient, sulphur dioxide ( added to retain color). the quantity is 2 tbsp
 

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The mash temp began at approx 170 but over the curse of the hour mash it dropped to approx 156F. IMHO sufficient range to ensure both enzymes have an active period.
Good thought but with a starting temp of 170 the enzymes were destroyed before the temperature fell. They never had a chance to work within their active range.
 

wsmith1625

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You should consider keeping dry yeast as a backup. Great shelf life and ready to pitch in cases such as this. US05 or BRY97 get the job done. I've also heard US04 if good, but I haven't tried it myself yet.

EDIT: Dry yeast can't fix unfermentable sugar.
 

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Both packets had an expiration date of the middle of 2021.
Unless they changed it recently, White Labs' PurePitch yeast packs do not list an exp. date.

There are a MFG: date and Best By: date listed. The "Best by" date is 6 months out from the MFG date.
In that packaging, stored in the refrigerator, never been mishandled, viability is expected to decline by 3% per month over the first 3 months, around 8-10% per month for the next 3 months:

I'm not sure where LHBSs get their yeast from, and how it's transported. Some may be better than others.
Now lots of things can happen after it leaves White Labs. Usually during transport, exposure to (very) high or very low, freezing temps are most common. The time of exposure plays a big role too. A few days to a week on a truck in hot or freezing weather can create havoc for yeast, decreasing viability (cells dying) faster than the refrigerated storage curve.

On average, yeast bought at an LHBS is 2-4 months old. If yours was packaged a week before you bought it (that's highly unlikely), the "Best by" date would lie somewhere in February or March 2021.

Making yeast starters is encouraged to:
a) prove and improve viability,
b) ramp up cell count, and
c) by overbuilding, you can save some out for a next batch.

BrewUnited's Yeast Calculator
 

IslandLizard

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Only the ginger lists an additional, ingredient, sulphur dioxide ( added to retain color). the quantity is 2 tbsp
That may be something to investigate...

Sulfur Dioxide is what is released by K-Meta (Campden). It's used in wine production to kill off or prevent wild yeasts from growing, and prevent oxidation.
It retards yeast growth. Now if that was added with 10 minutes left in the boil, most of the SO2 should have been driven off. I doubt there was a lot of it present anyway, it being used as a preservative, ginger still being the main ingredient. But who knows?

IIRC, they fumigate ginger (and certain dried fruits, such as raisins, dates, etc.) with SO2. Those are generally not suitable for fermentation, un-sulphurized fruit should be used instead.
 

IslandLizard

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You should consider keeping dry yeast as a backup. Great shelf life and ready to pitch in cases such as this. US05 or BRY97 get the job done. I've also heard US04 if good, but I haven't tried it myself yet.

EDIT: Dry yeast can't fix unfermentable sugar.
Yeah, that's almost a given. Unless you make starters from liquid yeast, ahead of time, it's a toss up how healthy (viable) she is.

Besides, a fresh pack of White Labs or WYeast only contains 100 billion cells at packaging, which is already an insufficient pitch rate for most 5 gallon batches over 1.030! As it gets older, it's downhill from there.
 

VikeMan

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Unless they changed it recently, White Labs' PurePitch yeast packs do not list an exp. date.
White Labs actually has changed to a "Best Before" date. I think there was also a brief period where they were printing both a packaging date and a best before date, but they removed the packaging date so that they could avoid confusing us each time they change their mind about shelf life, or (less jaded view), as they acquire more data on shelf life.

ETA: I almost forgot to get up on my soapbox and state that a specific "Best Before" date is almost meaningless. Two days after that date, there will be a number of cells very close to what there were 2 days before that date. And a lot less than at packaging.
 

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I almost forgot to get up on my soapbox and state that a specific "Best Before" date is almost meaningless.
Yeah, don't get me started either...

I think there was also a brief period where they were printing both a packaging date and a best before date,
For over 2 years on their PurePitch packs.
The last yeast I bought was in April 2019 (White Labs), been living on stock since.

but they removed the packaging date
As long as we know packaging is 6 months before Best by date, we can date or count back. We're still able to do that, not so sure about the general capabilities of our next generation... ;)
 
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william_shakes_beer

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Unless they changed it recently, White Labs' PurePitch yeast packs do not list an exp. date.
Right you are, I was working from memory. The packets were both best buy 09 Jan 2021. Lot number 11381220, as is the pouch in the frige for my upcoming batch.

When I was ranching yeast, I routinely made viable and healthy starters from sample in a preform that as 6-7months old. Unfortunately, i took a hiatus of a couple years and as a result i pitched my entire ranch ( pun intended )and plan to purchase for each batch, since I am no longer brewing 12 times a year as before. Is the wisdom of the community telling me I should return to making starters?

If the high strike temp denatured the enzymes, wouldn't the starch test tell me that?
 

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Welcome back to brewing! It's a nice and rewarding hobby, not a life's mission for everyone.

Is the wisdom of the community telling me I should return to making starters?
Absolutely! For the 3 reasons I mentioned before.

a) The most important one is proving viability.
b) And while you're at it, you may as well grow a proper pitch amount, it's usually accomplished in a single, 2 liter (or 1.5 liter) step for most beers under 1.070.
c) If you want to use the yeast again, and enjoy saving some money ranching, grow a little more, for keeps. Alternatively, save some yeast cake from the previous batch. Some yeasts do indeed seem to get better with repeated use.

I save my ranched slurries in 4 oz (sometimes 8 oz) mason/jelly jars, after cold crashing and decanting. They live in a box of just the right size on a shelf in the kitchen fridge.

If you don't have a stir plate, look up shaken-not-stirred yeast starters. You'll like it, it fits your nym to a T.
One of those gallon brew store jugs and a screw lid is all you'd need. And yeast and some DME.
In a pitch, you can use a growler or 1/2 gallon jug.
 

IslandLizard

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If the high strike temp denatured the enzymes, wouldn't the starch test tell me that?
Not sure if an Iodine starch test can tell you that after the boil.

An Iodine test is typically done on a small (deep) dip sample from the mash tun. You actually want the sample to include a few grain pieces, and the Iodine to touch them.

But an OG of 1.065 tells you, you've got sugar, not starch! It maybe high in dextrins, but there will be plenty of sugar.

[...] with a starting temp of 170 the enzymes were destroyed before the temperature fell. They never had a chance to work within their active range.
Enzymes don't get denatured that quickly, they're locked up in starch granules, not hydrated yet.

When room temp grist is added to 170F strike water, the overall temp of the whole mash system drops quickly when stirred and mixed together. It may have settled at 157F after a few minutes. There are calculators for that, to review where it could have been.
Brew365 is one of my favs.

For illustration:
I often underlet grist with 174F strike water in my (non-preheated) converted cooler mash tun. Yes, I stir well and quickly, and it will settle at 154F after 2-3 minutes, exactly where I want it to be.
 

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This is very similar to what just happened with my Stout. Too high strike water around 74c. When I added the grain it took a long time to cool down to 65c. Started fermenting quickly within a couple of hours at OG 1065 and stopped at 1042 confirmed by 2 readings 3 days apart . So around 3%.
It isn't the yeast. I added some sugar after the 2nd reading and it fermented vigorously straightaway.

Beer is therefore full of unfermentable sugars. Inc some lactose I added to the boil.

Question is I should now have a 4 % beer rather than a 3% but will it be worth drinking?
 
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william_shakes_beer

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Sorry, I missed the mention of strike water and only saw the mash temp. Now, which was it? What was the initial mash temp?
To be clear:

1. I do brew in a bag.
2. filled kettle with water, (7.5 gallons for a 5 gallon batch) looped bag around rim, lit burner
3. water raised to 173F. Cut burner, removed lid, stirred and waited
4. when the stirred water read 170F, i dumped the grains, stirred them to mix, put the lid on and went inside to get breakfast.

I thought denaturing didn't begin until 175F? Nowhere in this process did I ever reach or exceed 175F.
 

VikeMan

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To be clear:

1. I do brew in a bag.
2. filled kettle with water, (7.5 gallons for a 5 gallon batch) looped bag around rim, lit burner
3. water raised to 173F. Cut burner, removed lid, stirred and waited
4. when the stirred water read 170F, i dumped the grains, stirred them to mix, put the lid on and went inside to get breakfast.

I thought denaturing didn't begin until 175F? Nowhere in this process did I ever reach or exceed 175F.
Denaturing is happening at all temps. But 170F is a commonly accepted milepost for a sharp upturn in the curve. It's the temperature at which many people "mash out."

If I'm following along correctly, you added 12 lbs of grain to 7.5 gallons of 170F water. Ignoring the heat capacity of your kettle (probably near enough to 0 for this calculation anyway), the mash would have landed at about 163F. This would result in a relatively unfermentable wort.
 

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I dont want to derail the thread but I'm curious, what happens now? Can OP re-pitch and just start fermenting again? Or is now ready for the next step?
 

VikeMan

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I dont want to derail the thread but I'm curious, what happens now? Can OP re-pitch and just start fermenting again? Or is now ready for the next step?
If the problem is a relatively unfermentable wort (which I suspect it is), pitching more yeast isn't going to help, unless he wants to pitch a much more attenuative strain (e.g. a diastaticus strain).
 

VikeMan

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So it cant be salvaged at all?
It could, but the beer won't much resemble the original intent. He could pitch a saison strain (and thus get some saison character), or just drink it as is.

Or he could pitch some enzymes, I guess.
 

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When I did the iodine test, alcohol was present ( the initial ferm brought the wort from 1.065 to 1.056, which I attribute to the brown sugar fermenting out). Does the presence of alcohol affect the iodine test simalarly to how it affects refractometer readings?
Actually per previous statements you went from 1.065 OG to 1.056 "on the refractometer". Using the BF refractometer correction calculator you are probably about 1.038. This is still as seriously high stuck fermentation but the good news is you have about 3.5% ABV in there which would be some protection from contamination. However all that stirring and mixing has me worried about oxidation but a little oxidation could be ok in a spiced beer.

I'd look to enzymes to fix it. Maybe a gram or two of glucoamylase and let it sit. The alcohol in there will not have killed the yeast you should not need any more. Get another sample and taste it when you add the gluco to make sure it doesn't have some obvious signs of contamination or oxidation.
 
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william_shakes_beer

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i pulled out my hydrometer this morning, cooled a sample to 60F and dropped it in. I'm at 1.026. Then I tasted it. I don't like flat beer, but the taste was reasonable. Not what I was going for and the spices are muted but i'm going to keg it and punish myself by drinking it and every glass say "pay more attention to mash temp dummy"
 

MountainHighYeast

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i pulled out my hydrometer this morning, cooled a sample to 60F and dropped it in. I'm at 1.026. Then I tasted it. I don't like flat beer, but the taste was reasonable. Not what I was going for and the spices are muted but i'm going to keg it and punish myself by drinking it and every glass say "pay more attention to mash temp dummy"
If it makes you feel better, I definetly wont be making this mistake and learned from it. I'd drink one with you.
 
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william_shakes_beer

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That batch is in the keg, i'm prepping for my next one. Just for fun I plugged my particulars into this Mash Infusion and Rest Schedule Calculator - Brewer's Friend mash calculator to determine my initial dough temp. . It said I should dough in at 72.1F WTF? we all know from my experience that that will result in an unfermentable wort. Has the whole world gone mad???
 

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william_shakes_beer

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At the OP yo can see that the stalled batch started with a dough in at 170 which resulted in a stalled fement caued by unfermentable wort.
 

VikeMan

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It's telling you to use strike water at 172.1F because the rest temperature is set to 165F. That rest temperature is user input.
At the OP yo can see that the stalled batch started with a dough in at 170 which resulted in a stalled fement caued by unfermentable wort.
And again I say: the reason it's telling you to use strike water at 172F is because you have the rest temperature (i.e. the mash temperature) set to 165F. It's not a calculator gone mad. It's the correct answer given the input.
 
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