Wed Mar 02, 2011 10:33 pm
Actually what I would suggest is getting your smoked porter together and then play with the vanilla flavor. Buy a nice-quality vanilla extract bottle (from your local shishi market or williams sonoma). Add about an eighth-teaspoon to a bottle of your porter and drink. Add a quarter teaspon, and so on. I've been doing that with a stout I quite like, so I can figure out about how much vanilla to put into the secondary when I brew it again. As it happens, somewhere around 3/16ths of a teaspoon (about 1 mL) per 12 oz bottle is about where I like it. That works out to just about 1.7 fl oz per 5.5 gal batch, give or take. Turns out, I'll probably just add liquid vanilla extract at that dosing level at bottling time next time I brew this stuff (maybe to only half the stout) rather than mess around with vanilla beans.
That said, the next-best thing to do is split your batch, age half of it on two or three beans in the secondary, and leave the other half alone. Figure out which ratio of the two is best-tasting, and you know how many vanilla beans to add. But in my (not extensive, but not limited) experience in cooking and baking with vanilla beans there's a fair amount of variability in the quality and strength of vanilla beans. At the very least, you should measure by bean weight, rather than by number of beans, and you'll still have variability based on where the beans are from and how old they are. That's why I like the extract.
The even more heretical thing to say is that blind tastings of various vanillas in most baked applications (cookies, etc) tend to be unable to discern actual high-quality vanilla from the artificial stuff. I'd bet you could use artificial stuff here, since you're really only after the one note of *vanilla* in there (vanillin, which is an aldehyde) rather than the rounded subtle flavors that causes people to select one variety of vanilla over another. Most of that subtle stuff will get buried under your smoked porter.
Doubly-interesting, you might want to think about oaking the beer a little bit. Oak can add some vanilla flavors (which come from actual vanillin) as well.
