I tried following the recipe here to try to create a Sichuan peppercorn simple syrup. The recipe is basically to add slightly crushed peppercorn to sugar and water, allow to simmer, take off the heat, and repeat. The end result was tasty, but it did not have the same mouth numbing effect that I was hoping for except for with the leftover peppercorn in the syrup.
How can I get the mouth numbing effect into a syrup, and why did the above method not work? The Wikipedia article on hydroxy alpha sanshool suggests you can extract it with a distillation method although that seems like a bit of overkill when I am just trying to make cocktails at home (and when I don't own a condenser or distillation flask).
Best Answer
The reason you didn't get the numbing effect is because the hydroxy alpha sanshool is an alcohol that is largely soluble in oils not water.
When boiled it will come off in the steam and escape the boiling process in that manner. If you distill it, it will collect as an oil not as an ethanol/water soluble product. I doubt that putting the lid on the pot will collect significant amounts, or if they do collect enough to form droplets, they will be as fine oil layer on the surface of the liquid or on the lid of the pot.
I note that the extraction protocol mentioned on its wikipedia page includes ethanol and notes that the yield is low (~60%) of the available chemical. Boiling alone in water is not sufficient to extract any significant quantity.