Lactose is largely unfermentable?

I'm making a caramel cream ale that calls for lactose in the secondary for added sweetness. I pitched WLP002 into a 1.075 OG wort and waited. After a week I pulled a sample and measured a 1.008 FG. Almost too low. I didn't want to go overboard on the sweetness so I boiled a lactose solution with half the recommended amount and added it to the secondary, thinking that I would add the other half at bottling if it could use more. Wait two weeks...

Today I go out to check and theres a minor krausen ring in the carboy and signs of airlock activity. I can't imagine that my 1.008 gravity beer at one week is still going two weeks later. Is it the lactose? I see the wiki says lactose is "largely unfermentable". Largely? What does that mean? Now if I add another dose of lactose at bottling am I just bomb-making? Very strange.

lactose is really not fermentable. i think what you saw in the krausen is not the lactose, but when you added the lactose, you stirred (roused) up the yeast and remaining sugars.

taste it...if you want it sweeter add more lactose!

Well, there are things that will ferment the lactose and it will leave a sour beer.

Hermit said:

Well, there are things that will ferment the lactose and it will leave a sour beer.

Click to expand...

true, but on the bright side, you might get an entry in bluebonnet in the sour beers category a couple years down the road

I didn't think 002 could attenuate from 1075 to 1008. Maybe your readings are screwed up.

"Largely unfermentable" may mean some of it, in the package, is already broken down into the constituent sugars; dextrose and galactose. It's also acid degradable, similar to sucrose, so maybe that happens a bit if it's boiled to sanitize.

Plus, the souring bacteria & yeasts, as mentioned above.

Basically Lactose is unfermentable by traditional beer brewing yeast strains. However, as other have said, there are some things that will ferment it. (ever found a jug of bad milk in your fridge?)

I double-checked the gravity this morning: 1.010. The sample from the hydrometer tube tasted like finished beer; no sourness evident. But I also got some very weak carbonation in the sample too. So I'm at three weeks, taste is good, gravity has been good for 2+ weeks, and still have signs of yeast activity? Makes me reluctant to put it in the bottle regardless of what's going on.