9 Steps To Culture Yeast From A Bottle

Every once in a while I get asked how to culture yeast from a bottle of beer.  It’s not that hard, but it is time-consuming.  If you are interested in culturing your own yeast this is the post that you need to read.

Which Beers Can Be Culture

When choosing the beers that you want to culture yeast from, know that there are some that are going to be off-limits; or impossible.  If there was pasteurization before bottling, it’s just not going to happen.  Commercial beers, ya don’t even waste your time – there will be no yeast.  The easiest ones are if they were bottle conditioned, easiest way to tell if it was bottle conditioned is, see if there is any yeast sediment.  If there is sediment, assume yes.

Different Yeast Strain In The Bottle

Another thing that some breweries do is that they use a different yeast strain when they are the bottle conditioning.  The yeast will be different from the one which they used for the fermentation process.  You will find this with a lot of hefeweizens with an exception of Schneider Weisse.  If it’s a British beer, generally they are bottled with the same yeast strain as what they were fermented with.   This is something to consider because you may culture yeast, but just not the yeast which was intended to be cultured.

Multiple Yeast Strains For Fermentation

Some breweries will use multiple strains of yeast in the fermentation process.  So when you culture, you may not be getting the same exact yeast that you want.  I’ve heard that  Saison Dupont is an example of this, they have 3 strains of yeast.  Just something to consider.

Stack Your Odds

If you want to increase your odds of getting a good culture, you want to get a beer that isn’t stored too cold or is extremely alcoholic.

You got to stack your odds

What You Are Trying To Do

Essentially when you are culturing yeast you are trying to get yeast at the bottom of the bottle which is in poor condition to wake up, and then grow into something that you can use.  Sanitation is a must on this because the yeast is weak and you don’t want other critters growing when your feeding this weak yeast.  Once it grows to viable numbers then you can use it!  So this is how you can culture your own yeast in just 9 steps.

9 Easy Steps

Step 1

Sanitation is a must for this process.  For myself, I’m really not a bit sanitation nut, but if you decide to go a culture yeast you’re going to have to find some OCD in you or it’s going to be a waste of time.  So with that said, before you even open the bottle you want to sanitize the outside of the bottle.  You don’t want any bacteria touching this bottle in process.

Step 2

Pour most of the beer into a glass, and leave the bottom part of the beer so that the yeast in not disturbed  At this point, take a lighter and flame the rim of the bottle a bit.  It should kill any bacteria that is present.  Any bacteria that was under the lid of the bottle cap is now dead.

Step 3

Take the bottle and set it down.  Put foil over the top to prevent any contamination and let it warm up to room temp.

Step 4

Pour a bit of wort into the bottle.  2ml or 3 ml is plenty at this point.  Once that is done flame the lid of the bottle again and put a stopper in it with an air lock.  It’s gonna take a little of time for the yeast to wake up depending on how much viable yeast there really was.  I recommend putting it on top of your refrigerator for about 3 days.  After 3 days of so you should start to see some signs of fermentation (foaming of a little cloudy is acceptable).

Fire Is Our Friend For This

Step 5

Now that there is fermentation or that 3 days has passed, it’s time to transfer it and add  fresh wort.  You will use about 15ml of wort for this process.  Just sterilize another 12 oz bottle and add the 15ml of wort to it.   To transfer, just flame the bottle with yeast in it and pour into the new bottle.  Flame the tip of the new bottle and repeat with the stopper and air lock.

Note: If you are wondering what 15ml looks like, it’s a bout .5 of a fluid ounce.

Step 6

In about another 3 days you should see some signs of fermentation.  If you see this, we’re in the clear.  At this point, you can really start to step it up and will be ready for the next big culturing part before you can use it.

Step 7

You are going to do another step up for this step.  This time you are going to get your wort to have a gravity of 1.030 for 5 fl oz (150ml).  So make more wort, put it into another 12 oz bottle, add 1/2 tsp of yeast nutrient and then proceed with the same sanitation steps as listed before.  You will pour transfer the yeast once again.  This time wait about 5 days.

Step 8

At this point it’s time to figure out if the yeast that you have is actually good enough to use.  I know, all this time you are going on a hunch that you can use it.  But this is the big moment.  Look to see that there has been kraeusen that has risen and fallen (that’s the head), that’s a sign that the yeast actually worked.  What is in that bottle should taste very much like beer.  If it does, we’re good, if not – well it failed.

The way that we figure this out is, put your bottle into the refrigerator over night.  The yeast will seperate from the wort over night and then pour yourself a little t glass or a small container.  Taste it, if it taste like beer kinda then you’re good. If not it’s time to try again.  If it taste good, on to the next step.

Step 9

Time to make a big starter if your beer is good.  I use a 1 gallon glass jug for this with a #6 stopper.  You will want to sanitize the jug and the stopper, that’s a must.  Then make a big starter, half a gallon.

Since your yeast has separated because it was in the refrigerator, I pour off the liquid and only add the yeast to the bigger starter.  The reason that I do this is because I don’t want to pitch any mutant yeast, or yeast that hare not flocculant.

Once the half-gallon starter shows some activity it is ready to pitch in to you beer that you want to make!

Conclusion:

I know there are plenty of other ways to do it out there, but this one has worked for me pretty well.  I really don’t do too many yeast cultures from bottles anymore, I use to when I first got into homebrewing.  It’s a bit of work but if you are aiming to use a yeast strain that you like, this is the method that has worked best for me.

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