Maintaining yeast

That is the method I use and have been pleased with results. My guess is you are not getting autolysis, as once you chill your extra yeast it becomes dormant. I try to use it or re-start it within 4 months, always adjusting the quantity available due to aging. My process usually gives 4 - 5 cycles before I notice a change to characteristics. As careful as I am, it still seems some little "bug" will enter the group and start to take over.

Regarding autolysis; here's Palmer's take on the subject:
http://howtobrew.com/book/section-1/what-is-different-for-brewing-lager-beer/autolysis

 

Personally, I never use yeast that is older than two weeks old after harvesting. After one week if I need to store it longer for a second week, I'll feed my yeast a wort concentrate so it has nutrients in storage. Yeast does live longer, but the vitality drops drastically in storage.

That said, using the word spicy makes me think you are getting phenols which would indicate a contamination of wild yeast. Another theory would be that you have a cross contamination from a previous yeast strain. French Saison yeast is notorious for causing issues quickly. To me, French Saison yeast is far scarier than Brett is, but for some reason not a lot of brewers treat it with the same precautions.

 

Also to add, bottom cropping yeast should be harvested from beer as soon as the beer reaches terminal gravity for optimal performance. This is particularly difficult without a conical since buckets and carboys don't do much to facilitate flocculation. Top cropping yeast should be harvested on the second day of fermentation after skimming the beer on the first day.

 

Weedy, I have numerous times brewed with French Saison yeast strains and at those times I had no knowledge that they were var. diastaticus and the potential issues associated with it. I just performed my regular cleaning and sanitizing processes and I personally never experienced any contamination issues on subsequent batches.

I have also brewed a few batches with Brett (a co-pitch with Sacch in the primary) and I did the same as above - regular cleaning and sanitizing processes with no contamination issues.

Based upon these experiences it seems to me that as long as the homebrewer conscientiously cleans and sanitizes then everything will be OK. Or was I just lucky (on multiple occasions)?

Cheers!

 

It is true that Brett and French Saison yeast are still yeast that gets cleaned and killed with good sanitation practices, however, it is highly unlikely that there would be no cross contamination at all (this is true for cross contamination of Sacch strains too). You mentioned a while back that you don't reuse yeast. It wouldn't be surprising to learn that you had cross contaminations but that the contaminating yeast strain didn't have time to take over or create off flavors. When I had cross contamination issues at Blue Pants, it never was apparent in the first or second generation, but by the third generation, we would have phenols and highly attenuated beer and sometimes bottle bombs. Our first lab results showed that the beer was "free" of contaminations. At that time, I wasn't sure if yeast could evolve to become POF+ (it can't) and my theory was we were not selecting the healthiest yeast. We fought that issue for about 6 months in my first year there and it was very confusing. It took multiple lab screenings, eventually with PCR testing to find French Saison yeast was taking over. We actually found contaminating yeast directly in the culture we were purchasing from the yeast lab we used to use and they denied it. It took a few generations for the saison yeast to grow enough to actually make it apparent. At that time, I stopped using Saison yeast, which meant discontinuing a very popular beer, and switched yeast labs. We went way overboard for a week with our cleaning procedures and the issue was resolved.

 

I suppose that could be possible but if the previous contaminating yeast strain doesn't present off flavors then it is pretty much a non-issue for me and my homebrewery.

Cheers!