stuck fermentation

[markyv]

i tried to brew an 18% stout and it started out at1.117 and is stuck at 1.080 and still soooo sweet and i use oo1 and then added in champane yeast to try to get it to start again and nothing happend then i made a starter with sandiago super yeast and pitched that and nothing i think i dropped to 1.075. is there anything i can do or should i just dump it??????

[Bugeater]

Getting those huge beers to attenuate properly takes some careful planning. I've brewed a bunch of them ranging from 1.120 to 1.150 and have had pretty good luck.

The biggest problem is yeast health. Having the gravity that high will create quite a bit of osmotic shock. This will quite literally burst the cell walls of the yeast. Not good.

There are a couple of ways to deal with this. The first is to make sure you have enough yeast. A one or two liter starter won't work like it will for most beers. I do a five gallon starter. That is not as extreme as it sounds, though. For my 1.140 wee heavy, I first brew a batch of scottish 80 shilling (somewhere around 1.050). I time this so that I will be racking to secondary or to the keg on the brew day for the wee heavy. I pitch the wee heavy right onto the entire yeast cake (I don't bother to wash the yeast) and then heavily oxygenate it. Fermentation will take off within 8 hours and will normally bring the gravity down to around 1.025-1.030 in 3-4 weeks. Remember, the yeast will need this extra time in primary to do its job. You don't need to worry about autolysis until 6-8 weeks.

In addition to doing a huge starter, you can ease the initial stress on the yeast by doing incremental feedings of sugar during fermentation. I always use a couple pounds of sugar in my monster beers so I can get the FG to an acceptable level. Just past high krausen, just add your sugar dissolved in a little boiled water to the fermenter.

I'm not sure what you can do about your beer at this stage. I don't know how long it's been since the initial pitch, but you need to let it sit for a couple more weeks and see if the gravity drops any. As a last resort you can add some amalyse enzyme or Beano to the beer to break down the sugars to make it easier for the remaining yeast to digest them.

[spiderwrangler]

Having the gravity that high will create quite a bit of osmotic shock. This will quite literally burst the cell walls of the yeast. Not good.

Only thing I disagree with is the second statement there... since the wort has such a high concentration of sugars, it will have a lower concentration of water, and water will flow from inside the cells to outside, potentially pulling the membrane away from the cell walls (opposite of bursting). The cell walls of yeast are quite resistant to bursting, I've put them in distilled water and they still hold shape, compared to blood cells (no cell walls) that are completely obliterated by water flowing in causing them to rupture.

Was this extract or all grain? If AG, what was your mash temp?

[captain carrot]

Before dumping it you might aerate it and add a fresh pitch of yeast. Get a few packets of dry yeast and rehydrate in water. Adding some yeast nutrient to the wort may help as well.
Good Luck!

[brewinhard]

If you are going to pitch more yeast then you should most definitely make an active starter and pitch that when it has reached it's peak krausen. Otherwise the yeast won't have a chance.

[adamK]

If you are going to pitch more yeast then you should most definitely make an active starter and pitch that when it has reached it's peak krausen. Otherwise the yeast won't have a chance.

+1 to this.

[Ozwald]

It's too late for this method, but what I do brewing anything over 1.100 is to calculate my sugar additions into the original recipe & brew it w/o putting the sugar in. If it's not a lot of sugar, I wait until fermentation looks like it's almost done & add the sugar to the fermenter then by mixing it with just enough water to make a sugar slurry, bring it to a short boil & cool. If it's a bit more sugar, I'll split that into 2 & add half just before the krausen falls which will jump start the ferment for a day or 2 & then add the other half.

The idea is that if the yeast have a choice between table sugar & malt sugar, they'll eat the table sugar 1st. They can crap out early, leaving all the complex malt sugars untouched. By pitching into a wort that doesn't have all the extra table sugar in it, they're forced to eat the complex sugars first before they get introduced to all the simple sugars. Think of a big meal with children. If you put down the turkey, taters & pie at the same time, the kids are going to go straight for the pie, get full & not touch anything else. Don't give your yeast desert too early or you'll spoil their appetite.

Good luck with your current batch; I don't know if what I just said is happening in that specific batch or not, but something to think about for the next one at the very least.

[anday6]

I recently used that late sugar addition method and it worked great. ONLY 1.085 into the fermenter, and after 3 days or so I added the rest of the sugar every night. Got up to over 1.100 and was 1.025 after a week and 1.020 after 10 days and still going. All that with a pitch big enough for the whole 1.100 beer.

Doesn't help this time but now you know. Best way to save it might be to brew a small beer, below 1.050, and rack the stuck beer on the cake. It takes more time but what do you have to lose now?