Best way to add lactose, vanilla, and cold brew coffee post fermentation

[boredstate]

Turning our pumpkin spice porter into a Basic B**ch Pumpkin Spice Latte porter. Trying to minimize cold side oxidation. Got about 5ish gallons of a 1.060 OG, now 1.014, porter we want to add the aforementioned ingredients to post fermentation. Poor planning led to this post-ferm doctoring idea.

To keep the beer from getting too watery by boiling water, throwing in lactose, then adding cold brew, my thinking is make a small batch of cold brew concentrate, maybe 1 pint, heat it up enough to dissolve in lactose (1/2 lb maybe?) and let stand long enough to kill anything and drive off some O2. Or do I boil water, throw in lactose, let cool then use that liquor to make the cold brew??

I also have 2 Madagascar vanilla beans, but I'm trying to have this on for thanksgiving. Should I go vanilla extract, or soak the beans in vodka for a few days then add to taste? In my 10 years of brewing, I've never used vanilla beans. Comments, suggestions, advice? What would your process look like?? TYIA!

EDIT: I know I could just add the coffee straight to the beer in a nylon bag and steep it for a day, but fresh roasted beans have a ton of O2 in them, right? Just worried about that aspect of it.

 

[FromZwolle]

Bottling or kegging?

 

[boredstate]

Kegging.

 

[FromZwolle]

Turning our pumpkin spice porter into a Basic B**ch Pumpkin Spice Latte porter. Trying to minimize cold side oxidation.

I wouldn't worry much about this at all. a porter in a keg can stand a bit of oxidation.

To keep the beer from getting too watery by boiling water, throwing in lactose, then adding cold brew, my thinking is make a small batch of cold brew concentrate, maybe 1 pint, heat it up enough to dissolve in lactose (1/2 lb maybe?) and let stand long enough to kill anything and drive off some O2. Or do I boil water, throw in lactose, let cool then use that liquor to make the cold brew??

I usually pull a pint of beer and heat it up to add lactose/maltodextrine, but this sounds just fine. just dump the cold brew into the keg before you transfer the beer into it. I have done this without the lactose with great results. However,

EDIT: I know I could just add the coffee straight to the beer in a nylon bag and steep it for a day, but fresh roasted beans have a ton of O2 in them, right? Just worried about that aspect of it.

I've heard that this is the best way to get the nicest coffee flavor, even better than cold brew. From what i gather the beans should be in contact with the beer for no more than 48 hrs, 24-30hrs being the recommended amount.

Since you're kegging, I would do this part in the keg, you can go for a round 2 if you feel the flavor isn't there. If you're really worried about the oxidation, you can toss a few grams of ascorbic acid in there to minimize any uptake of additional o2.