Re: [new_distillers] Aeration
- Most of my reading suggests no more than 10 generations. They hint that yeast burns out after 10 generation. It's still there, but it's weaker against wild yeast and bacteria.
From: o1bigtenor <o1bigtenor@...>
Sent: Saturday, January 19, 2013 11:21 PM
Subject: Re: [new_distillers] Aeration
On Sat, Jan 19, 2013 at 7:29 PM, Fredrick Lee <fredrick@...> wrote:Aeration is always needed. The yeast cells will consume oxygen and end up cloning themselves. Sometime shortly after the oxygen runs out, they start fuckin, which leads to mutations. The more mutation, the less control you have, the less chance you'll make that one amazing recipe again. I would use oxygenated yeast no more than 11 generations.
Why 11? D
- So how do the big breweries get consistent results with high replication numbers yeasts? D1.) House strains become accustomed to their environment and a certain flavor "profile" develops, but the yeast strains will continue to mutate until the most beneficial mutations are established. Breweries with house strains must have consistent processes and ingredients to ensure the strain remains consistent as possible.2.) Large breweries (and even small ones like ours) maintain a yeast lab where they keep a library of pure cultures of the strains (in sealed test tubes called slants). When the 11th batch goes out the door on the production line, the yeast lab prepares another pure strain from a slant on a Petri dish or culture flask, and subsequently grow it up until its big enough to pitch. In our case we grow it up to about 10 gallons, and pitch it into ~300 gallons. What comes off that 300 gallon tank is used about 10 more times. Myself and our brewmaster (and a few others) can start noticing a very subtle change in the flavor around generations 5-6. The gas chromatograph in our lab also shows these differences, but 99% of people will not be able to tell, or if they can tell, it's not too much of a difference that they'll think the beer is defective.3.) Somewhere during the culturing phase, we'll select the colony from a petri dish and make a dozen or so new slants. People also sell and trade slants. This way, we can have access to hundreds of strains from all over the world.
On Jan 20, 2013, at 9:38 AM, o1bigtenor <o1bigtenor@...> wrote:On Sun, Jan 20, 2013 at 7:14 AM, Fredrick Lee <fredrick@...> wrote:No after 16 it's changed so much that the strains are completely different you can barely even tell they were related without mitochondrial DNA testing.Thank you for clarifying!
So how do the big breweries get consistent results with high replication numbers yeasts? D
- Most people don't raise their own yeast, so they don't worry about aeration. At $0.99 per a 5g pack of yeast almost makes it not worth the effort of raising your own yeast.
From: Fredrick Lee <fredrick@...>
To: "firstname.lastname@example.org" <email@example.com>
Sent: Sunday, January 20, 2013 8:14 AM
Subject: Re: [new_distillers] Aeration
No after 16 it's changed so much that the strains are completely different you can barely even tell they were related without mitochondrial DNA testing.
On Jan 20, 2013, at 8:12 AM, o1bigtenor <o1bigtenor@...> wrote:On Sun, Jan 20, 2013 at 7:06 AM, Fredrick Lee <fredrick@...> wrote:Even with aeration, the main fermentation phase causes enough mutations that after the 11th generation, flavor traits are significantly altered. After 16 generations, the yeast cells are nearly indistinguishable from the original. That said, there are breweries that have thousands of generations on their strains, the yeast can adapt to a system and become a "house strain." Usually attenuation suffers, or lag time or some trade off occurs from the original strain, but if it works for you, then go for it. Just don't expect consistent results.
Sorry - - I asked why 11 generations and you responded its because after 11 things have changed too much. Then you say that after 16 generations there is no change. Sorry only one of the foregoing can be true. D
- In short: No. :-)
--- In firstname.lastname@example.org, "gavinflett" wrote:
> Does anyone think it's possible to aerate the wash too much to the point where it kills the ferment?