Does ranching select for most flocculant cells

[william_shakes_beer]

I have been ranching 6 strains for about 3 years. Using each strain once or twice per year, so I'm looking at between 3-6 generations.

I have noticed my ferments becoming less vigorous. Also, long term bottled product is becoming overcarbonated.

1. Is it possible that in the process of decanting starters into preforms, I have been selecting for the most flocculant cells?

2. Is cell tendency to flocculate early vs late a genetic mutation that can be accidentally selected, or is it a function of physical forces on a uniform yeast strain?

4. Is there a way I can examine my samples (say under a microscope) and evaluate tendency to flocculate? What would I look for?

None of my strains are anything special, they are easily purchased fresh

 

[Homercidal]

I have been ranching 6 strains for about 3 years. Using each strain once or twice per year, so I'm looking at between 3-6 generations.

I have noticed my ferments becoming less vigorous. Also, long term bottled product is becoming overcarbonated.

1. Is it possible that in the process of decanting starters into preforms, I have been selecting for the most flocculant cells?

2. Is cell tendency to flocculate early vs late a genetic mutation that can be accidentally selected, or is it a function of physical forces on a uniform yeast strain?

4. Is there a way I can examine my samples (say under a microscope) and evaluate tendency to flocculate? What would I look for?

None of my strains are anything special, they are easily purchased fresh

Ok, I'll try again after reading your post more carefully.

After 3-6 generations you shouldn't see too much change in yeast behaviour. I think that is about the point where a lot of people refresh their production yeast, though, so it may not be out of line with industry (homebrewers) practices.

Anyway it's simple to understand that your method of collecting samples may be the cause for any change in yeast characteristics, especially flocculation. If you aren't thoughtful and careful, you may only be getting yeast with more or less flocculation characteristics, not both. I don't know your method, so I can only make an assumption, but harvesting early, or late is one way a yeast strain can be nudged to flocc more or less. You may be doing this.

In your case, if you aren't purposely working towards new yeast characteristics, I'd just start over fresh. Yeast is pretty cheap if you only buy every 3-4 batches. You may look into freezing some in a yeast bank and building it up from very small samples, but that's work and IMO isn't worth the cost if you only brew once a month or so.

 

[william_shakes_beer]

Here's my ranching regime:

1. Prepare starter wort using 4C water to 1C pilsen dme
2. Boil, cool, innoculate with 2 vials of slurrey collected from step (12) below
3. spin in 2L eflask, foil covered, on stir plate 48-72 hours, til krausen falls.
4. Cold crash til brew day
5. brew day: remove flask from frige to warm to room temp
6. brew batch, cool to pitching temp
7. swirl up starter and pitch, reserving 1/4C+- of slurrey
8. refeed starter, repeating steps 1,3,and 4.
9. Decant eflask once
10. collect 2 preforms of swirled slurrey, cold crash preforms and eflask 24 hours
11. decant preforms only
12. repeat steps 10 and 11 til flask is empty