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Reusing Yeast

I’m finally going to try and reuse some yeast and want to try two different yeasts. But I have some questions:

  1. I have a stout in primary right now with Wyeast 1084 - Irish Ale and OG of 1.040. So what are my options for the next beer? Does it have to be a stout (which I’m OK with and will probably end up doing)? Are there some simple rules for picking the next beer?

  2. For the other beers I’m planning on using Wyeast 1728 - Scottish Ale. I’m thinking of starting with the NB Spiced Winter Ale and then doing the NB Scottish Wee Heavy. But I’m wondering if the Mulling Spices in the Spiced Winter Ale will carry over to the Wee Heavy. Am I going to end up with a Wee Heavy that has a mulled flavor?

Also, in both cases I’m planning on reusing the full yeast cake. I talked to another brewer recently who said that whenever he reuses yeast he just does it all in one day and moves the first beer to secondary/keg, leaves the yeast cake in the fermenter, and pours the next beer on top. Seems like the easiest thing to do. Any major drawbacks?

  1. You have a few options depending on your method. If you plan to rack onto the cake as you suggested, you usually want to move from lower OG to higher OG. Because you’re also keeping the last batch’s trub and dead yeast, you will want to go from lower IBU to higher IBU. Also try and stay within similar styles. Don’t pour a kölsch on the cake from stout. If you rinse your yeast then these guidelines are much more lax simply because you are removing trub and dead yeast.

  2. Are the spices in the boil? Are they added after fermentation like a dryhop? If the latter, then rack the beer off the cake, and add the spices. If the former, then you will probably get flavor contributions. As stated above, if you rinse the yeast, you will not have to worry about the flavor contributions.

My process is to remove the yeast from the fermenting vessel and split it into 3 jars, rinsing twice. This allows me to get mostly good, healthy yeast and also allows me to clean and re-sanitize my carboy. You could use the whole cake, pour the new wort in your old batch’s dirty carboy but you are basically wasting 2/3 of your yeast. If you save your yeast you can potentially get 121 batches from one pack of yeast. There are no major drawbacks and the process you suggest is the easiest way to go about it.

Personally I only used rinsed yeast. It’s fairly easy to do and it gets all the other crap out. A general rule is to only reuse yeast for equal or higher gravity beers. Meaning you wouldn’t want to go from a high gravity beer to a low gravity beer with the 2nd gen yeast. People will tell you they’ve done it with success, but I’ve done a lot of reading about this topic and most will recommend to not do it. Also if you rinse yeast, you can usually get enough yeast for another 2-4 beers.

If you’re pitching right on top of a yeast cake (which I would recommend against) you should be careful about what is in that cake. I made a pumpkin ale with a lot of spices and there’s no way I would brew and pour another type of beer onto that yeast cake with all the spices in it. I would think hops in the yeast could also create an issue.

Rinsing yeast is very easy to do. Just need a little patience and have good sanitizing practices.
This video breaks it down very easily.

Hey mvsawer… seems like whenever someone asks a question like this it’s always you and I with similar responses. Great minds think alike?

For sure! Besides consuming my creations, yeast is my favorite part of the “sport”!

I hear that. I love rinsing yeast and getting 3-4 healthy jars. That’s like $21-$28 worth of yeast. I’ll often trade yeast for grains or hops with other members of my beer club. I also get pissed when a yeast won’t cooperate when rinsing. I’ve had a few that just don’t separate well from the trub. I end up getting only a jar or even just dumping all of it. That makes me sad.

Do you guys strain your wort before adding it to the fermenter?

I do not rinse my yeast and have not noticed a lot of trub.

I probably dump the first 1/3 that comes out of the fermenter and is runny. I then dump the thick stuff into mason jars.

I seem to have had fairy good success the past year and the viability of the yeast seems to exceed Mr. Malty’s predictions

Any good links to yeast washing?

I do strain the wort. And the first 1/3 that you’re pouring off is the healthiest yeast still in suspension. Even with a lot of trub, you will have a good amount of yeast. Also, if you’re not shaking the yeast to get everything in suspension, you may not get a distinct layer of trub. One more thing, if you pour off the liquid and then just separate the middle layer in your fermenter, that’s rinsing your yeast. Fermentation does a pretty good job of stirring stuff up, but a good cold crash will get you a very nice layer of viable yeast. I watched a bunch of Youtube videos, and read articles online. Search youtube and google for yeast rinsing, yeast washing, and yeast ranching.

This breaks it down. Very easy.

Dumping the top layer off is dumping off the yeast. The bottom is the trub. You don’t want that. Click the link and check out the video.

The trub sinks to the bottom first and is more tan or brown. The yeast stays in suspension longer and drops later. Sometimes only after a few days in the fridge. But when you have a layer of tan trub and white yeast on top, you’ll definitely know the difference.

Thanks for the great info. I’ll definitely give rinsing a try. If I didn’t want to have to make a starter for a beer over 1.060 (like the wee heavy which is 1.083), can I just use 1 jar or should I use 2 jars? I guess I’m trying to figure out how the jars equate to a starter. And does the answer change if I use the yeast after only a few days versus a few weeks?

If you use it within a few weeks of harvesting/rinsing you could use just 1 jar. Yeast viability will deteriorate over time, so if it’s stored for a month (in the fridge) make a starter. Don’t store your yeast at room temperature and make sure its under beer or sterile water.

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