[Village Taphouse]

Guys:  I often make a starter for a yeast, use the starter in batch #1 and then reuse that slurry for however many batches I envision with that yeast.  The yeast is usually used very quickly (harvested one day, used again in a day or two) and I get quick starts.  The beers are fermenting in a fridge set to about 52°.   I occasionally get a slight off-flavor and I'm trying to determine if I need to re-examine my sanitation or if reusing slurry this way is a no-no.  Can reusing slurry cause slight off-flavors because of dead yeast cells or other small mutations that may occur in the yeast?  This is not a regular thing but it does happen.  I made 7-8 batches this way using Lallemand Diamond last year and every batch was clean.  Also, this off-flavor does not seem like a contamination.  The beer is not undrinkable.  The flavor is not diacetyl or acetaldehyde.  It's more like a funky Belgian barnyard flavor but again... it's NOT pronounced.  It's subtle.  Thoughts?  Thanks guys.

[denny]

Ken, I do the same thing.  No problems attributed to it.  I don't think it's the method itself.

[Village Taphouse]

Ken, I do the same thing.  No problems attributed to it.  I don't think it's the method itself.

That would suggest I need to look closer at spots where yeast is in contact with various equipment... fermenters and flasks, specifically.  I'm alternating between Starsan and iodophor to keep bugs on the alert and I feel like my fermenter (and all it's components) and my 2L flasks are in very good shape in terms of cleaning and sanitation.  I am about to retire some 940 and I have Omega Bayern running now too but have not tasted any of those beers.  Next up here is some 838 and I'm going to be extra careful and take a belt-and-suspenders approach to see how things go.  Thanks Denny.

[ynotbrusum]

The micro flora in the air this time of year makes serial repitching a bigger concern for me.  Low level infections can exhibit what you describe, and Star San notoriously does not kill off wild yeast.  I’m not saying anything you did was wrong or ineffective, just that we have an airborne invasion in mild weather months in northern IL.

I use dry yeast typically in the summer more frequently (than making a starter with liquid yeast), avoiding too much repitching of multiple generations and the potential contamination that arises.

YMMV, too, so if your process is extremely clean, ignore my thoughts expressed above.

[Village Taphouse]

The micro flora in the air this time of year makes serial repitching a bigger concern for me.  Low level infections can exhibit what you describe, and Star San notoriously does not kill off wild yeast.  I’m not saying anything you did was wrong or ineffective, just that we have an airborne invasion in mild weather months in northern IL.

I use dry yeast typically in the summer more frequently (than making a starter with liquid yeast), avoiding too much repitching of multiple generations and the potential contamination that arises.

YMMV, too, so if your process is extremely clean, ignore my thoughts expressed above.

I was envisioning something like this.  The yeast is exposed to the air VERY rarely but it needs to go from fermenter to flask and flask to fermenter SOMETIME.  It would also explain why I see it here and there but not that often.  I may load up on 34/70, S189 and Diamond for summer use and just use it once or twice and move onto the next one.  Very interesting.  Thanks for the reply. 

[ynotbrusum]

And given the cooler fermentation temperature and cool storage of lager yeast between uses, the infection can be pretty minimal, but still noticeable.  I go with no more than 3-4 repitches in warm weather to be safe.  It seems to work, but may be pushing it, so I rarely go that many in the summer.  Hence the dry yeast approach in warm seasons.

[Village Taphouse]

I'm going to adopt that as a part of my new yeast strategy.  I'm also going to see if this tends to happen more in summer and if so, where does that point begin and end.  End would be the first frost or something?  My pitch is usually happening in my kitchen under [what I would call] controlled circumstances and my harvest is usually in my basement brew bunker where everything (flask, funnel, foil, etc) have been sitting in sanitizer for 20+ minutes. 

Btw... where are you located?  I'm in Arlington Heights. 

Also... I assume you have experienced this low-level off-flavor, correct? 

[ynotbrusum]

I have experienced the relatively rare low level phenolics of wild yeast in repitching, but for what it is worth, I once repitched 25 times with WLP 800 without incident.  So it can be done.

My location is far west of Chicago - outside of the Tri-cities area (Batavia,Geneva, and St. Charles) near Elburn.  Out in rural Kane County.

[Village Taphouse]

I have experienced the relatively rare low level phenolics of wild yeast in repitching, but for what it is worth, I once repitched 25 times with WLP 800 without incident.  So it can be done.

My location is far west of Chicago - outside of the Tri-cities area (Batavia,Geneva, and St. Charles) near Elburn.  Out in rural Kane County.

Nice.  I like it out there.

I hear you about the multiple repitching.  I have done it many times without issue.  I sometimes wonder if the issue is with the yeast (and fermenter) or later in the process like the keg or draft lines.  I have had a run where #1 was good, #2 was questionable, #3 and #4 were great and then #5 was questionable again.  That would suggest that it's not with the yeast itself but something outside of the fermenter or maybe the flask that the yeast was stored in between batches.  Cheers to you. 

[erockrph]

I have experienced the relatively rare low level phenolics of wild yeast in repitching, but for what it is worth, I once repitched 25 times with WLP 800 without incident.  So it can be done.

My location is far west of Chicago - outside of the Tri-cities area (Batavia,Geneva, and St. Charles) near Elburn.  Out in rural Kane County.

Nice.  I like it out there.

I hear you about the multiple repitching.  I have done it many times without issue.  I sometimes wonder if the issue is with the yeast (and fermenter) or later in the process like the keg or draft lines.  I have had a run where #1 was good, #2 was questionable, #3 and #4 were great and then #5 was questionable again.  That would suggest that it's not with the yeast itself but something outside of the fermenter or maybe the flask that the yeast was stored in between batches.  Cheers to you.

Yes, definitely check your draft lines. I brewed a batch of my house lager a couple of years back that tasted great at racking. I let it cold-condition in my kegerator for a couple of months, then some friends cracked into it at a party and I got rave reviews for my saison    I had been overdue for a deep clean of my draft lines, and that was certainly the culprit in my case.

[Village Taphouse]

I have experienced the relatively rare low level phenolics of wild yeast in repitching, but for what it is worth, I once repitched 25 times with WLP 800 without incident.  So it can be done.

My location is far west of Chicago - outside of the Tri-cities area (Batavia,Geneva, and St. Charles) near Elburn.  Out in rural Kane County.

Nice.  I like it out there.

I hear you about the multiple repitching.  I have done it many times without issue.  I sometimes wonder if the issue is with the yeast (and fermenter) or later in the process like the keg or draft lines.  I have had a run where #1 was good, #2 was questionable, #3 and #4 were great and then #5 was questionable again.  That would suggest that it's not with the yeast itself but something outside of the fermenter or maybe the flask that the yeast was stored in between batches.  Cheers to you.

Yes, definitely check your draft lines. I brewed a batch of my house lager a couple of years back that tasted great at racking. I let it cold-condition in my kegerator for a couple of months, then some friends cracked into it at a party and I got rave reviews for my saison    I had been overdue for a deep clean of my draft lines, and that was certainly the culprit in my case.

LOL, saison.  I know it's not funny but the way you told it was.    I actually heard another brewer mention this very thing.  I'm going to send some EasyClean + Hot water through the lines and then follow up with either Starsan solution or Iodophor.  Cheers and thanks.

[Village Taphouse]

So my concern was 'mutated or contaminated yeast' and it turned out to be DIRTY TAP LINES.  On one hand this is very good news because I have been brewing a lot and some upcoming kegs could have contained funky beer.  It appears that my cleaning, sanitation and yeast handling has been okay which is good to know.  OTOH, I clearly need to pay more attention to my draft lines.  I made a schedule and hung it up in my brew bunker.  I cleaned the lines on 7/15 and plan to do it at least once a month to make sure this doesn't happen again.  Lesson learned. 

[Saccharomyces]

Are you using Star San as your sanitizer?  Star San is darn near useless against wild and domestic yeast, which is why it should not be promoted as a do-all brewing sanitizer. You need to use an oxidizing halogen to kill wild yeast, which means diluted chlorine bleach, iodophor, or peracetic acid.  Most wild yeast are POF+, which yields the Belginesque flavors.  I waged the same war until I read up on Star San.  Star San is more accurately a bacteria killer. Star San is only attracted to positively charged cells because the killing agent, the surfactant known as dodecylbenzenesulfonic acid (phosphoric acid just lowers the pH, making the surfactant more effective), carries a positive charge. Yeast cells carry an negative charge; therefore, they repel dodecylbenzenesulfonic acid. If you are using Star San, throw it away and purchase a bottle of iodophor and learn how to use it without leaving stains all over the place.  You will thank me later.

By the way, you are more than likely picking up the wild yeast on the initial pitch.  Wild yeasts are not as strong multipliers as domesticated yeasts, but every repitch cycle gives them a chance to multiply.  Successive repitches can result in the cell count being high enough for their metabolic waste products to get about taste threshold.

[Village Taphouse]

Are you using Star San as your sanitizer?  Star San is darn near useless against wild and domestic yeast, which is why it should not be promoted as a do-all brewing sanitizer. You need to use an oxidizing halogen to kill wild yeast, which means diluted chlorine bleach, iodophor, or peracetic acid.  Most wild yeast are POF+, which yields the Belginesque flavors.  I waged the same war until I read up on Star San.  Star San is more accurately a bacteria killer. Star San is only attracted to negatively charged cells because the killing agent, the surfactant known as dodecylbenzenesulfonic acid (phosphoric acid just lowers the pH, making the surfactant more effective), carries a positive charge. Yeast cells carry a positive charge; therefore, they repel dodecylbenzenesulfonic acid. If you are using Star San, throw it away and purchase a bottle of iodophor and learn how to use it without leaving stains all over the place.  You will thank me later.

By the way, you are more than likely picking up the wild yeast on the initial pitch.  Wild yeasts are not as strong multipliers as domesticated yeasts, but every repitch cycle gives them a chance to multiply.  Successive repitches can result in the cell count being high enough for their metabolic waste products to get about taste threshold.

Thank you for all of that.  I did some homework on Starsan and Iodophor and concluded (as mentioned) that iodophor would be a good thing to get [back] into the brewery.  I used it years ago and have now returned to it.  I am on my second bottle of it now and this one is almost gone.  I will also admit that I alternate between Starsan and Iodophor... not necessarily every-other-batch but around there.  I went to order more iodophor and whichever site I was on was out of it so I ordered the Starsan version... IO-Star.  Looks and smells like the BTF stuff and dosing seems to be the same.  What I had heard about iodophor was that it was 'broader spectrum' which I suppose is just a simple way of saying what you described above. 

In related news I recently cleaned and sanitized my draft lines and I just remembered that I used Starsan for that.  I should probably do it again and use iodophor.  Thanks again.