How long does slurry stay viable?

In this article, I’ll describe a few easy tests that can give you an idea of the level of contamination in your homebrewed wort and beer. They may also be able to tell you where the contaminating microorganisms came from.

These tests can be especially helpful to homebrewers who plan on repitching their yeast to another batch of beer. A level of contamination that was undetectable by taste in an initial batch of beer may blossom in the next, leading to off flavors and aromas. Knowing the condition of your wort can help you decide whether to repitch or to start with a fresh culture of yeast.

Likewise, these tests can also help you evaluate if you are cleaning all of your equipment adequately. These days, many of us use counter-flow wort chillers. These chillers cool wort quicker and with less water than immersion chillers. However, many homebrewers worry because they cannot see inside the chiller. (With most other pieces of homebrewing equipment, you can visually inspect every surface the wort will touch.) The deep recesses of the chiller are a perfect place for bacteria to take hold and potentially be passed on to all our subsequent beers.

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Bobby_M said:

I boiled a cup of water with two teaspoons of dextrose in it and then cooled it. I pitched it into the mason jar and shook it up then left the cap on loose. 20 minutes later, it's oozing out all over the place. I guess some yeast made it.

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