For the sake of furthering your scientific research (and because this thread deserves to be resurrected, again), I would suggest pasteurizing the prepared kava in a sous vide machine at 140 F for 2 or 3 hours, rather than boiling it. Just put it in a sealed container and submerge it into the water bath. I believe I have read that at least some of the kavalactones can be destroyed at close to boiling temperatures. 140 F for several hours will kill as many germs as 10 minutes of boiling, without reaching a temperature that harms the good stuff.