No Mutations?

I found some time back that instead of washing yeast it is far easier and less introduction of other things if one were to just make a larger starter instead of washing. Is this not what the labs are doing? In essence could there be mutations over time? Or would this method keep the yeast going in their normal known traits much longer?

Mutations happen all the time in microorganism cultures or cell cultures, but they are relatively rare events in a huge population. The issue would only arise if one clone somehow mutated and outgrew the others. This can happen via genetic drift or a founder event. That being said, these are things I only worry about when culturing cancer cells for research, not yeasties for brewing.

Yup. It's a numbers game. The number of reproductively successful mutated cells you are likely to have either making a starter or washing yeast is unlikely to be high enough to make a noticeable impact on your flavor.

You're not trying to accomplish the same thing washing yeast as you are when puting them in a starter. The way you worded your post,you think it's easier to make a starter than washing yeast. Two very different things.

If mutations are such a minimal concern, why is it that it's said not to use yeast more than 10 generations?

The way I understood it was that reusing yeast can change its characteristics such as higher/lower attenuation or flocculation. Maybe even flavors too?

I meant that it's far easier to make a larger starter and set aside a portion to save vs washing yeast from a batch to save. Plus there is no concern for it having been used in a dark or hoppy beer.

I think you are talking about making a very large starter (10 ltr 15 ltr?) so you can divide up that yeast into smaller containers for multiple batches. Then use one of those to (again) make a starter so you have enough for your batch. Seems like lots of work when you get sooo much yeast from washing after you rack off your batch of beer. Plus think of all the DME you will have to use for that "big starter" you make just to pitch the liquid down the drain.... That could be beer you get to drink!

EDIT: Your reply above confirmed my thoughts. You can always plan your yeast washing brew ahead of time to get the cleanest yeast. Think of it as a 5 gallon starter you get to drink.

rodwha said:

If mutations are such a minimal concern, why is it that it's said not to use yeast more than 10 generations?

The way I understood it was that reusing yeast can change its characteristics such as higher/lower attenuation or flocculation. Maybe even flavors too?

I meant that it's far easier to make a larger starter and set aside a portion to save vs washing yeast from a batch to save. Plus there is no concern for it having been used in a dark or hoppy beer.

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I have a conical and do both. I make the larger starter from my initial vial and store a portion of it under boiled (and cooled) water for later use. Unless I am making a dark beer, I also harvest and reuse that yeast. The harvested yeast is good for developing a "house" strain, and I still have the fresh yeast from the unhopped starter to use as well. Following these methods, I can use one vial of yeast indefinitely.

What I've been doing now is making a 1.5 qt starter and saving the 1/2 qt. I'm only using 6 oz of DME instead of 4 now.

I fight over fridge space between 2 refrigerators as SWMBO buys lots of co-op fruits/vegetables. So chilling down the water in the 5 qt pot takes up lots of room.

Washing yeast wasn't terrible by any means, but making a larger starter is just so much easier, and takes up less room, and doesn't leave me with so much stuff to clean afterwards.

I do have to say that it seemed after several washes that I was getting much higher attenuation, and I noticed a similar taste in many of my beers that I figure must have been yeast related. Because of that I quit saving it (except the WLP 320) and will be restocking on yeast and trying new ones. I figure if I do it this way instead of washing there should be little chance of it changing any characteristics too, and so it ought to last longer than ~4-6 generations as mine did.

rodwha said:

If mutations are such a minimal concern, why is it that it's said not to use yeast more than 10 generations?

The way I understood it was that reusing yeast can change its characteristics such as higher/lower attenuation or flocculation. Maybe even flavors too?

I meant that it's far easier to make a larger starter and set aside a portion to save vs washing yeast from a batch to save. Plus there is no concern for it having been used in a dark or hoppy beer.

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Simple. The relevant factor here is contamination rather then mutation. You can make successive batches of starters as many times as you like and it will still work. However, you will start getting wild yeast populations in the starters. That isn't exactly a bad thing, but it won't taste the same once the wild yeast populations get large enough.

The same thing happens to sourdough starters. Over time they pick up acetobacter and yeast from wherever they are at and end up being specific to the region. For instance, San Francisco sourdough does not taste like the local sourdough from here in Denver.

Commercial yeast producers will actually go to the trouble of isolating a yeast strain, then use sterile methods of propagation for most of the processes in a batches production. That way they can insure that the level of contamination in the final product they sell is extremely low. You could do that, but it seems simpler to me to just stop propagating the yeast when it either develops an off flavor, or when it seems like you are getting to the number of generations in which that usually happens.

I'm a cheapskate, but a little yeast every 4-5 batches or more doesn't seem like a big deal to me.

And, as always, have nice day.

Leadgolem said:

You can make successive batches of starters as many times as you like and it will still work. However, you will start getting wild yeast populations in the starters. That isn't exactly a bad thing, but it won't taste the same once the wild yeast populations get large enough.

The same thing happens to sourdough starters. Over time they pick up acetobacter and yeast from wherever they are at and end up being specific to the region. For instance, San Francisco sourdough does not taste like the local sourdough from here in Denver.

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This is exactly what I am looking for. I want to develop a house strain.

BrewingGunner said:

This is exactly what I am looking for. I want to develop a house strain.

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If you are trying to do it on purpose, rinse some organic fruits and save the water. Use the water for your starter, along with your usual yeast pitch. Do a few generations off that and you will probably have something completely different then when you started. Alternately, see if you can get some unpasteurized honey. You usually have to know somebody with bees to do that. Thin it out, add some nutrients. You now have a wild yeast starter. Honey is always loaded with yeast, the sugar content is just to high for them to do much. The pasteurization of the honey does, of course, kill them off before they get to market.

Mystic Brewery just did a Vinland series where they went around the state and isolated several strains of wild yeast. I just had the saison and the yeast was so plummy...very cool idea and decent brew if you can find it