Question about using Lactose

Just kegged a Tallgrass Buffallo Sweet Stout I purchsed from NB. I nailed the OG at 1.058. Pitched WLP007 and left town for the holidays. After two weeks racked to secondary and took reading of 1.023. A month later kegged at 1.022. Fermentation temp was 62-65. The recipe does not have an estimated final gravity, but I thought it would have been lower than this. Will the lactose (.375 lbs) make the final gravity high? Or did my yeast poop out? Not worried as it taste fine, just wanted to know if this is normal using lactose.

 

Lactose is unfermentable by yeast and is a gravity contributor. In a 5 gallon batch that amount would contribute between 2 and 3 gravity points.

 

If you act like the lactose isn't there your numbers would say about 65% apparent attenuation. That's a little low based on White Labs numbers for WLP007 (70-80%), but really not that bad. If the yeast is done, meaning if you've had consistent gravity readings on separate days, then it's done.

 

Thank you Hex, exactly the information I was looking for. I will make a note to create a larger starter it I brew this again.

 

An appropriate sized starter, good aeration, and good temps should get you closer to full attenuation.