Stuck fermentation or high final gravity?

I brewed my first milk stout 6 days ago and I'm now worried the fermentation is stuck but it could just be an unusually high final gravity due to the lactose.. I would like to hear some experienced opinions.

Here is the recipe:
Yield = 11 gal
OG was 1.061

17.5 Lb 2-Row
2 Lb Lactose
2 Lb C60
1.25 Lb Munich
1.25 Lb Oats
1 Lb Roasted
1 Lb Chocolate
1 oz Magnum 60 mins
1 oz Golding 20 mins
Fermax yeast nutrient added at 5 mins of boil
2 tsp Calcium Chloride added to mash water
100% RO Water

I pitched 2 packets of Safale US-05 and aerated for 20 mins with a pump and stone. Fermentation is temp controlled in a conical at 69*.

The fermentation was vigorous only 12 hours after pitching and settled down like normal over a few days. Only the gravity is at 1.022!! That just seems way too high for a terminal gravity to me..

Any insight would be greatly appreciated. I have extra Safale US-05 on hand but would rather not pitch it if 1.022 is acceptable for the style.

It's only been six day. give it another week and see what the gravity is then. If you had any yeast lag time, which could be up to 72 hours then in actuality your beer has only been for example fermenting for 3 day....The largest push or fermentation may be done, but that doesn't mean the yeast still isn't slowly breaking down the last of the fermentable sugars.

Your mash temps could have something to do with it. But as Revvy said, give it time..

The lactose is added for sweetness and isn't fermentable. It will show up in your gravity reading. Not sure how much 2 lbs would alter the gravity. Check into that to get a true reading.

I have made many a AG stouts that seemed to have a High FG 1.017( No lactose). They turned out to taste great. Sometimes you have to just say to hell with it and not worry about FG. If fermentation is done, it is done. "It's beer, just drink it" as my buddy says.

That S-05 is going to do its job, I wouldn't pitch another. That yeast is pretty damn consistent. Just give it another week and see where your gravity is at. If it hasn't changed, just ignore the gravity. It is what it is. Sometimes we put too much emphasis on technicals. Get the final product and let your taste buds tell you if it is good.

Thanks for the replies. Gravity is still at 1.022 but I will relax and give it a few days. I did move the temp up to 72* just now in hopes of helping the yeast finish. I'll give it a few days at 72* and if it is still 1.022 I'll cold chrash and transfer to the keg. Worse case scenario; I'll call it an extra sweet milk stout.

I'm pretty sure in Palmer's book he states that lactose is 40 ppg. So adding 2 lbs would give you somewhere around 16 extra gravity points at 5 gallons. This would give you an adjusted gravity of 1.006 after you account for the added lactose. Seems like a good amount of attenuation to me!

It's an 11 gal batch, so 80 ppg / 11 = 7points. So you are at 1.015 without the lactose. Sounds quite acceptable - I've had milk stout finish at 1.022 and you don't notice it.

Cheers!

the milk stout in my keg is real close to that. 1lb lactose for 5 gal. i'd say everything is fine.

frazier said:

It's an 11 gal batch, so 80 ppg / 11 = 7points. So you are at 1.015 without the lactose. Sounds quite acceptable - I've had milk stout finish at 1.022 and you don't notice it.

Cheers!

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Heh, thanks for the correction!

Thanks for all the great replies. The target of 1.016 must have excluded the impact of the lactose altogether or have considered it fermentable. Either way I wrote the author of the software (Brewtaret) to confirm. It would be interesting to see if other software programs are also lactose intolerant.

Based on the replies I think I'll go ahead and cold crash it and move it to kegs. It's still sitting at 1.022 so I think the yeast were already complete after just a few days, as usual.

llama_boy said:

It would be interesting to see if other software programs are also lactose intolerant.

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GET OFF THE STAGE!! *throws tomatoe

Just to follow-up, the beer came out just fine. After a month in the keg it has dropped clear and is a very drinkable brew.

Here's what isn't perfect about the beer and how I would hope to correct it:
1) Too sweet for me and I would say it is on the high side of the style.
Reduce the lactose by ~30% and increase the hops a little
2) A little uninspiring
Change the yeast strain to something more appropriate for the style
Also the beer could use more malt complexity, maybe a little a Melanoiden
Also the water profile could be modified more toward style
3) Not "roasty" enough
Increase the dark malts a little
4) Poor head retention
Swap a little 2-row for wheat


I'm saving this as Sweet Stout v2. When I brew it again I'll post it in the recipe section.

Yield = 11 gal
OG was 1.061

17.5 Lb 2-Row
1.33 Lb Lactose
1.5 Lb C60
1.5 Lb Roasted
1.25 Lb Munich
1.25 Lb Oats
1 Lb Wheat
1 Lb Chocolate
1 oz Magnum 60 mins
1 oz Golding 30 mins
1 oz Golding 15 mins

Water recipe still outstanding but targeting something like London.
Wyeast 1728 (currently taking a deep dive on this strain)