Who said you can reuse yeast only 5 times?

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ohad

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I've been in a tour in Carlsberg's brewery in Israel a few weeks ago.
The brewery manager said that they get their yeast shipped from Carlsberg, and they are allowed to reuse them for 10 batches in a row.

That surprised me quite a bit. Homebrewing legends speak of a terrible mutant yeast, lurking behind a single digit corner ( 4 to 6 usually).
So where does this notion come from? are ale yeast more susceptible to mutation?

there is a saying in Hebrew : "If the cedar tree caught fire, what will the moss say?" - if the big guys that care so much about flawless consistency do it, why shouldn't we?
 
I think it is also size dependent. When you are talking about the quantity of yeast that a commercial beer produces, mutations would take a long time to effect the beer.
 
ohad said:
if the big guys that care so much about flawless consistency do it, why shouldn't we?
Click to expand...

The fact that they have a cut off point at all indicates the quality degrades over multiple uses. Therefore there is no flawless consistency, rather tolerable limits. As suggested above, these large brewers are much more automated and geared toward consistent quality control than the average domestic kitchen.

If Carlsberg has a limit of ten uses, then 5 uses for myself definitely sounds like as far as I would want to risk it.

Note to self:- Remember to order new yeast with next consignment. ;)
 
I washed and reused the same London Ale yeast for a year, over something like 9 batches. I quit when it made a batch I had to dump. I stick to 5 or less uses now (or fresh dry yeast).
 
From what I've read, commerical breweries acid wash their yeast.

I'm going to wash the yeasts from my wit and IPA that are fermenting. I'm not doing so to save money so I don't see trying to stretch it out over too many batches and risk a batch of beer.
 
I did the Real Ale Brewery tour the other day and I asked that specific question. The head brewer noted they reuse their primary yeasts for 12 generations.

After the 12th fermentation, they sterilize the yeast slurry and sell it to local farmers to enrich cow feed. They also sell their spent grain by the truckload as cow feed.

So assuming sanitary practices, you should be able to reuse yeast for many generations. At $7 a vial, after 12 generations, that's $0.60 per batch for yeast. :)
 
There is a micro local to me that reported that they re-use yeast 50-60 generations.

The key is keeping the trub out of the next batch, and not allowing the cleanand pure as possible re-pitched yeast to be openly exposed. They utilized a closed system throughout their process.
 
Reusing yeast for multiple batches is a personal choice and depends on what your goals are. If you are looking to perfect a recipes and then to be able to make it over and over again and have it turn out the same, then you won't want to reuse the yeast much. If you enjoy new flavors with every batch and don't care if recipes turn out different batch to batch, then by all means, use the yeast over and over again. Batch after batch the characters of the yeast will change due to mutations and the flavors they produce will change. Mutation is a word with a lot of negative baggage attached to it. Now, it very well could be that the flavors could actually improve as the yeast mutates. Again the major determinant is do you want to have the same flavors batch afer batch? For most commercial operations, this is going to be yes. For most commercial beers, the majority of people want the beer to be the same time and time again.

The most I've personally gone is 3 batches. I like to control as many variables a possible, plus I'm set up to culture my own yeast there is minimal cost to start more yeast.
 
OK, maybe I'm slow or just confused...

How else can yeast propagation occur except by re-using yeast?

When I buy another vial of WLP300 or WLP001, is it not washed and harvested yeast?

Have Bavarian breweries not been using the same yeast strain(s) for 100's of years?

As I said, I'm just dumb, confused, or both.

Would the difference between a homebrewer and a brewery harvesting be solely in technique? If so, what?


To be clear, I'm not talking about dumping on a yeast cake ad infinitum. I'm talking about the "boiling pint mason jars and water and using the boiled water and jars to wash yeast after racking..." technique.
 
I assume this is what the big boys do. It is what we do in the lab. We have a frozen stock(s) of the yeast(s). When yeast is needed, a small sample is taken out and is then propagated to the desired density. Many thousands of batches can be started from a single small tube. Freeze up a number and you'l have the same yeast available for a very long time.
 
I had the privilege of asking this question to the Head Brewer over at Fish Tale Organic Ales in Olympia, Washington a couple of weeks ago. He is a home brewer as well, and I can't remember the exact numbers, but I think it was around 5-6 batches for home brew, and 10-12 batches in the brewery. The major difference he cited was the fact that the yeast in the brewery is never handled by human hands or really exposed to the outside environment. They can purge all tanks before transfers and keep the yeast isolated in a blanket of CO2 when it's not "on the job."
 

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