I made a cinnamon tincture for a Christmas stout. What I discovered is that several whole sticks in a pint of vodka for 3 weeks was either too much or too long because it got a bit astringent. I see no reason it would not last forever if you remove the spices at some point. You can filter out the solids by freezing the whole thing overnight (it will remain liquid of course, unless you have a very very cold freezer indeed) and then pouring it gently through a coffee filter or several layers of cheese cloth. stop before the gunk at the bottom pours out.
the amounts have a lot to do with taste, what spices, and what beer.
and one caveat is that a spice tincture made this way does not taste the same as spice in the boil. cooking always changes the flavor and aroma profile of a spice so if you like a spice from eating it in a dish it may not taste exactly the same when raw spice is extracted in alcohol.
In our seminar at NHC, Drew demonstrated how to make a tincture in 10 seconds using a whipper (those NO powered canisters usually used for whipped cream). Here’s an excerpt from “Experimental Homebrewing” to show how it works…
If you want to play with some other flavors, try rum or bourbon instead of vodka for complementary
extractions, such as vanilla beans.
If you have an old-fashioned whipping siphon, you can make a tincture in under ten seconds.
Load the siphon with your booze and your spice or herb. Seal the container and crack one cartridge
of CO2 or nitrous oxide into the siphon. Shake for a few seconds and then, holding the siphon with
the spout facing up, press the dispense lever and rapidly vent the pressure. Open up the siphon and
strain the infused vodka through a fine mesh sieve. This makes a great party trick to doctor one beer
in many different ways (or if you’re spiritually minded, it allows you to create an impressively varied
vodka cocktail list).
I’ve never liked the raw spice flavor I’ve gotten from tinctures.
However, when I’ve done it exactly as Mort describes (except not for three weeks). Spices in a jar with vodka, then filtered and poured (vodka) into the beer.
I also think that the vodka imparts flavor to the beer, which I did not like. I know, vodka is supposed to be flavorless. I didn’t like it. I will add my spices to the boil.
The only time I have found vodka spice extracts to be beneficial is my pumpkin beer. Spices are quite variable in strength from year to year, source, and as the spice ages. Cinnamon is a good example of this. I use the usual spices in my pumpkin beer in the kettle. If the final beer is not quite up to my flavor expectations, as is often the case, I will use additions of vodka spice extract to hit the flavor sweet spot. I am very satisfied with the beer using this method.