How long can yeast survive 6 months?

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How long can yeast survive 6 months?

Postby Indian » Mon Dec 04, 2006 2:58 am

I interviewed a local micro Brewer whom claims that with out infection he never has problems and often reuses yeast up to 5 and even 6 months. Sounds like he is pulling my leg. Any comments invited!
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Postby brewer13210 » Mon Dec 04, 2006 11:15 am

Depending on how the yeast is stored, you can keep it viable for very long periods of time. If the brewer knows what they are doing, then 6-months is very possible.

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How long can yeast survive

Postby Indian » Mon Dec 04, 2006 10:13 pm

Unless I misunderstood him we were not discussing storage but reuse.

Yeast cells, as I understand are complex, in reproduction, decay, and infection.

The kind folks at Fermentis yeast responded with the following,
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Postby brewer13210 » Tue Dec 05, 2006 11:28 am

Both the brewer and Fermentis are incorrect.

First, unless a sample is massively infected, it's unlikely that anyone will be able to smell or see the bacteria; it has to be plated on media to see what grows. Very small infection rates can be big problems in a brewery, and the only way to discover it before it becomes a problem is with a basic lab and someone who knows how to use the equipment (skills and good professional brewer should have).

Secondly, if a brewer practices proper sanitation in the brewery, and times the batches so that healthy viable yeast is repitched, then it's unlikely that the yeast will become infected.

As for a "pure" culture, yeast is a living organism, and over many generations will mutate based on the conditions in the brewery, and some strains of yeast will mutate faster than others. If the yeast is treated well, it may develop "house flavors", but remain a strong fermenter. In a case like that, the brewer may decide to keep the yeast as the flavors distinguish his beers from others.

In the city I live in, there is a microbrewery that has been using the same strain of yeast for over 10 years. It was originally a Ringwood strain, and in that time, it has developed a strong diacetyl character that the brewer likes, so it has remained without being discarded for a fresh strain.

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How long can yeast survive 6 months GREAT ANSWER!

Postby Indian » Tue Dec 05, 2006 9:49 pm

Great answer!

Can you recommend a good book on basic brewing lab skills, (yeast / bacteria / infection identification? A source for the obligatory lab poster with yeast strains (Ringworm) would be cool too.

I ask because my company's lab will be erected long before my dream of a pilot brewery.

Maybe I could hone some basic lab skills in the interim period with other breweries yeast, a sort of Forest Gump of microbiology if you will.

Thanks Todd great answer!
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Postby brewer13210 » Wed Dec 06, 2006 8:02 am

"An Analysis of Brewing Techniques" by George and Laurie Fix is a good starting point. I also took a few courses at The American Brewers Guild.

The biggest help I had was knowing someone who worked in the lab of a local pharmaceutical company, who was able to give me some very good pointers on setting up a lab and giving me some hands-on training.

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Diplomats use yeast too.

Postby Indian » Wed Dec 06, 2006 9:43 pm

Sweet!

I will try to get a copy in my travels next month. You have been very helpful.

I have one example of a micro brewer whom claims that it is better to fly in liquid yeast from France every two weeks or so because he was not confident of the local skills whom he was training to follow all procedures when he departs. Maybe he is right, or has a deal the yeast supplier.

In fact, this is the second
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Postby brewer13210 » Thu Dec 07, 2006 7:27 am

These are very real issues between dry and liquid yeasts. The dry yeasts are very easy to use and fairly inexpensive, but the liquid yeasts come in a much wider variety.

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