I recently did an all grain Oatmeal Stout. Grain Bill was about 9.5lbs, so it was never going to be a big beer.
I nailed the OG around 1.043, which is around what I was shooting for.
I pitched the safale s-04 and it fermented hard for about 5 days and then tapered off. Fermentation was in my basement which fluctuates between 69-74 degrees, so I’m not sure if the temp would have had a huge impact.
After 8 days I went to rack it into a secondary (corny keg) and was going to let it sit for another few weeks, but when I checked my gravity it was at 1.022, which is not what I was looking for at all. Was hoping to get down to around 1.010.
I’m not sure what I could have done differently, but I ended up racking to a secondary at pitching new yeast (same safale s-04.
Did I just not leave it in the primary long enough? Should I have added yeast nutrient? Was it a problem with my mashing temp? Fermentation temp?
Let’s start with a few questions…did you measure FG with a hydrometer or refractometer? What we your recipe and mash temp? Have you made this recipe before? Did you rehydrate the yeast or just pitch it in dry?
No, I’ve not made this recipe before. I copied it down off of a Northern Brewer recipe kit. It had been about a year since I’ve been able to brew anything, so I wanted something fairly simple to get back in the swing of things.
Used a hydrometer. I don’t have a refractometer (yet). Hydrometer was 1.042-1.043, which is what the recipe kit indicated should be the OG.
Recipe was 6.5lb maris, 1lb flaked oats, .5lb roasted barley, .5lb chocolate, .5lb dark crystal, 1oz Glacier hops, safale s04 dry ale yeast.
Mash temp was around 152-154. Was going for 153. I didn’t have a great probe thermometer, but I got my strike water up to around 165-170 before mashing in. So, it should have been around desired mash temp.
I wouldn’t immediately guess that the yeast is a problem. The manufacturer’s recommendation is to direct pitch this yeast dry. I’ve done so and watched it rip right through fermentations in three days. At your ambient temperatures, the ferment would have been at least in the upper 70s, maybe low 80s, higher than ideal but not high enough to kill the yeast off. You might have overshot the mash temperature a bit (you say the thermometer was not great.) With a high mash temperature and some crystal and roast, you might have actually reached the attenuation limit of your wort. You could test this idea by calibrating your thermometer: check it by placing it in the stream of steam coming from a tea kettle, and in crushed ice. While you’re at it, calibrate your hydrometer, too: in distilled water at the temperature marked on the stem (usually 60°F,) it should read 1.000. If either instrument is off, you’ll know by how much and you can compensate in your future readings.
Well, two things that have come out of this for me is I need to add a weldless thermometer to my mash tun. I bought all of the parts to do that and a 6” thermometer with 1/2” threaded male part on the dial. So, that will definitely help get a more accurate temperature reading while mashing/sparging.
The other thing is I really need a fermentation chamber. The ambient temperature in my basement is in the low 70’s in the summer and the high 50’s/low 60’s in the winter.
That’s a good point about the ambient temp. Just because the outside air temp and bucket exterior is reading 70, 71, or so doesn’t mean the fermenting liquid is at that temp.
Well, some yeasts are sensitive to temperatures lower than 115°, some will crap out at 90°, but ambient the 70s is just going to get you to fermentation temperatures that give off flavors, not dead yeast. The point is spot on that you should have seen accelerated a activity. I don’t think it’s a yeast issue here. But temperature control is still one of the most valuable additions you can make to your brewery. Should come before all the other bells and whistles.
Yeah, that would do it, but he fairly good verification on both strike water and mash temp. Although if his thermometer was massively off, it could be. Kinda seems like a long shot, though.
I think pretty much any lager yeast will stop at 90° but I’m being a bit pedantic there I guess. Nobody’s likely to be in that situation, except maybe in propagation. Which would then stop being propagation. I don’t know if any ale strains would shut down before they’re dead. But not many will make beer you want to drink under those conditions. Sorry to distract.
(One old test to differentiate ale and lager yeast was to incubate them at 90°, and if they didn’t die, they were ale yeast!)
OK, now I’m gonna be guilty of diversion…I’m not aware of any lager strain that will shut down at 90F. But that’s exact;y what I mean…I’m not aware. I’ll see if I can get any info from my friends at Wyeast. I’ll also see Chris White in Australia in a couple weeks and I’ll try to remember to ask him.
I believe the yeast did exactly what it was bred to do. As most English strains, S-04 does not process maltotriose so it leaves undigestible sugars therefore leaves the gravity ‘high’. You have to plan for high FG when using this yeast.
I believe repitching the same yeast will not produce any difference in FG. If a yeast that can digest maltotriose was re pitched I believe a change in FG will be seen.
True. They list it as “highly attenuative” but I find with typical worts mashed around 150°, 70% is about what you can actually expect. A high mash temperature would bring this down significantly. Check that thermometer.