Pitch new yeast? NB Chocolate Milk Stout

[jskennedy1979]

I brewed NB's Chocolate Milk Stout on 2/15 (LME with specialty grains). OG was 1.049 per hydrometer and 1.052 on the refractometer. Target gravity was 1.051 so I felt good about this batch. I took a refractometer reading on 2/20 at 1.033 (70°). Tonight, 2/22 I had the same 1.033 reading. Is this a stuck fermentation? I have read that the pound of lactose could change the final gravity but it seems like many who have brewed this finished in the 1.025 range.

Should I pitch new yeast? I have a vial of a local strain of yeast that is similar to Wyeast 1056. I also have 1272 AA II that needs to be used soon. If you did pitch, which would you use?

I plan on taking a hydrometer reading Monday night to compare to the refractometer. Thanks for the insight.

 

[Gavin C]

With alcohol in the wort you need to corect your refractometer reading.http://www.brewersfriend.com/refractometer-calculator/

This gives you a FG of 1.019 assuming a starting gravity of 1.051

 

[jskennedy1979]

Thank you so much for the response, Gavin! I actually had the same problem with my last batch and just re ran my readings for both beers and feel a lot better.

 

[Gavin C]

No worries. Glad to help. This issue comes up all the time with refractometer usage.

 

[BigFloyd]

Also, milk stout contains unfermentable lactose (milk sugar). A pound of lactose in a 5-gallon batch means that your FG will be .07 higher than if you had no lactose.

For grins, I ran a comparison one time between hydro and refract readings on a batch that was finishing. Hydrometer = 1.017, Refractometer = 1.035

 

[supermutantbrewmaster]

I just bottled my own version of a Milk Chocolate Stout last night. I came out at 1.032 which was not unexpected. I wondered if it was gonna be 1.024 like predicted because when I added the lactose to the fermentables section, the prediction didn't change. Honestly I think if its a thick milk stout, it will probably be shelf stable at 1.033.

 

[jskennedy1979]

Also, milk stout contains unfermentable lactose (milk sugar). A pound of lactose in a 5-gallon batch means that your FG will be .07 higher than if you had no lactose.

For grins, I ran a comparison one time between hydro and refract readings on a batch that was finishing. Hydrometer = 1.017, Refractometer = 1.035

Before I posted, I read a little about results with this kit and the lactose "offset" seemed to be a common theme. Still, when I saw 1.033 as a FG I was concerned that at best I was around 1.026 with lactose considered. Everything makes sense now that Gavin showed me the Brewer's Friend calculator.

I didn't want to pull another thief from the fermenter (especially now that I am confident primary is probably done) but I think I may to compare my hydro vs refract measurements. Thanks for the input!

 

[Gavin C]

I just bottled my own version of a Milk Chocolate Stout last night. I came out at 1.032 which was not unexpected. I wondered if it was gonna be 1.024 like predicted because when I added the lactose to the fermentables section, the prediction didn't change. Honestly I think if its a thick milk stout, it will probably be shelf stable at 1.033.

A final gravity this high would be inconsistent with a milk stout. Even an imperial stout or a big Barleywine would most likely finish below 1.030.

On a milk stout if the FG is 1.033 there are a few possibilities

1: measurement error (as was the case for the OP)
2: mashed way to high with little fermentable sugars being produced
3: adequate fermentabeles but insufficient yeast both in health and/or numbers

Again assuming measurement error is not the case there would need to be a seriously flawed process to have a FG of greater than 1.03 for a milk stout.

 

[supermutantbrewmaster]

Hmm. The guys at my LHBS suggested that it was fine due to the lactose and cocoa powder content. I'm not worried as the green beer tasted fine, no noticeable sweetness or anything that would indicate it was totally off. I used S04 for it which tends to attenuate out pretty high anyway.

Also I checked with my hydrometer and not a refractometer at 64F or so. I mashed at 152 which dipped a little at the end to 150. It was a 2.5 gallon batch with 0.4 lbs lactose and 0.25 lbs cocoa powder. Fermentation started up in 12 hours after pitching 11 g rehydrated S04. Active fermentation lasted 3 days reaching a max temp of 66F and then it was allowed to sit in primary for another 11 days.

 

[newfiebrew]

My milk stout is acting similar as my OG was 1.070 and after a week is at 1.030 using Nottingham. My temp is only about 62 degrees so I am wondering if it's too cold? What temp are you fermenting at? Maybe increasing the temp a little would stimulate the yeast???

 

[jskennedy1979]

Are you using the same kit as I did? 1.070 seems a bit high. Did you mix the wort and the top-off water before you took your reading?

My temp stayed really steady between 69-70°. I used my swamp cooler once to counter the high temps at start. Never was above 72 or below 68°.

 

[BigFloyd]

My milk stout is acting similar as my OG was 1.070 and after a week is at 1.030 using Nottingham. My temp is only about 62 degrees so I am wondering if it's too cold? What temp are you fermenting at? Maybe increasing the temp a little would stimulate the yeast???

62*F is fine for Nottingham. It doesn't mind the cooler temps (I've used it as low as 55*F successfully), but can produce some nasty funk if you let it get too warm (68*F or higher) during active fermentation.

A final gravity this high would be inconsistent with a milk stout. Even an imperial stout or a big Barleywine would most likely finish below 1.030.

On a milk stout if the FG is 1.033 there are a few possibilities

1: measurement error (as was the case for the OP)
2: mashed way to high with little fermentable sugars being produced
3: adequate fermentabeles but insufficient yeast both in health and/or numbers

Again assuming measurement error is not the case there would need to be a seriously flawed process to have a FG of greater than 1.03 for a milk stout.

Agreed.