The Technical Edge: How to Kill Your Beer Yeast


Amongst that yeast, once upon a time, there was a brewer. Maybe in this case he SHOULD have killed it?

Written by Professor Goodales

Note: the Professor prefers to post, not write. This site is for you, not the Professor. But there seems to be a lack of reference material on this important topic.

Let’s say you suck at what you do: brew. You want to suck even more. What to do. What to do. You ask, “How do I kill my beer yeast?”

Well, raising acidity, or make the wort more like your filth minded uncle: more base, will do it. Beer ferments best in the 5-6 ph range. Add a lot of rhubarb, or lemon or, if you’re really determined battery acid. Do not ladle it into the wort by scooping it up with your hands; unless you hate your hands too.

Too cold can do the trick. With an ale, just get it in the 40 degree range might do the trick; though yeasties are stubborn buggers. Lager yeast is even more head strong and will ferment in the 40s. Just leave it in your freezer and do not thaw. Might not kill it but it will stop the little monsters, well stop them “cold.”

Now you could add so much fermentables that the alcohol level gets so high it strangles them in their own waste, which esentially is what alcohol is. We urinate. They expel alcohol. Leaving them, and us, well, wasted.

Some recommend Sodium Benzonate, but the Professor isn’t sure about that one.

Filtering might work, but they tend to be ornery critters and a few may sneak through. Once you have a few you may have a whole family happily fermenting again. Catholics of the more traditional flavor (See “The Cannibal’s Guide to Catholic Missionaries.”) and Mormons have nothing on beer yeast when it comes to propagation. They apparently don’t even believe in the rythm method.

One sure way to kill you beer yeast is to throw it into “the boil.” Yeast really isn’t fond of anything over 90. Of course most sane humans aren’t either.

Many claim artificial sweetners, or semi-sort of artificial sweetners like Xylitol, kill yeast but the Professor has seen no evidence of this. Beer yeast can be a little picky, so don’t be surprised if you have a very weak fermentation, or off flavors. Kind of like when neighbors move in you don’t approve of, or when your folks don’t approve of whom you are dating. Yeast can be a bit of a snob if you’re looking for a great taste off an odd fermentation source, but there probably will be a reaction: just not one you might like. Death is certainly not assured, if that is your goal, Mr. Grim-brew Reaper.

Pasteurization would work: bring it up to a high temp fast and then bring it down. The problem is good pasteurization probably requires expensive equipment. The Professor supposes a microwave might work, but remember what pasteurization does to milk: especially ultra pasteurization, makes it taste like cardboard. There’s a reason why big brewers who often have less tasty product pasteurize and craft beer brewers who don’t pasteurize offer the consumer more taste; and it’s not just the cost of the process.

However, you must ask, if you’re like the Professor and always prefer more and could care less about fitting into some style guideline; why would you want to kill the poor little beasties? Let them flirt, let them play with themselves, for yeast reproduction is achieved by budding off the same cell.

Some days when you face that spouse, boyfriend or girlfriend, don’t you wish it were that easy for you?