Jovial_Monk said:
That 6-10 generations is on the page for commercial brewers. As homebrewers shoot for 3 generations
Jovial Monk
Now JM, this is not a shot at you but I do get sick and tired of hearing "As homebrewers shoot for 3 generations" regarding yeast.
These comments are often based on repeated information, often an "internet" source and rarely the brewers [poster's] own practical experience.
Yeast is a living thing. It doesn't suddenly turn into C4 explosive and blow the arse out of your fermenter at generation 4.
I have an extensive yeast farm and I have used many yeast many times, and more than 3 generations.
I have a favourite at present that is up to the sixth pitching from a whitelabs 008. Zero change. If your sanitation is good, and only you can determine that, you can continue to use yeast for a very long time. In this caseI have chosen to pitch the slurry from one beer to the next rather than split a starter and brew from those. I still have some of the initial tube under water, about a fingernail worth, and that will be enough to build up for more brewing down the track. Anything up to 12 - 24 months.
The comments I make are regarding Ale yeast and although I have havested and maintained some lager strains I brew very few lagers.
George Fix wrote an interesting section in his second book where he pointed out that due to the way yeast reproduce the overall "age" of the population basically remains the same.
With Ale yeast, harvesting from the top after the first skimming will give you the most vibrant healthy yeast of the brew. That skimming will be your yeast for the next batch. and so on and so on.
Consider this ... many older breweries pitched over and over and over simply by collecting yeast from the top of the fermenter for the next beer.
If you want to use yeast for a considerable time you must learn the practical methods involved in havesting and storage. Long term storage in an old plstic container wont cut it.
Pint of Lager and Pedro, both on this list also maintain an on going yeast farm and there are many others on this list. Most brewers approach yeast farming from different angles but the common thread is sanitation.
It does involve extra work and demands time and good methodology, but if you take care you can always have more yeast on hand than you will ever need.
You as the brewer may choose not to use your yeast beyond the 3rd generation, and if you are satisfied with that well and good. But yeast are quite happy well beyond 3 generations
Steve.