Fusel issue

[beerbeer95648]

Last couple batches of IPA's have been full of fusels. We are casting 20 barrels into single batch tanks at 68 degrees. We have a knockout of about 30 minutes of which we run 02 at 1.5 L per minute the whole time. Wort goes through about 90 feet of pipe before hitting the tank. According to the DO meter we tested from Gusmer we are getting 12 ppm at the tank with this setup. We are pitching 2 to 3 pounds per barrel of slurry. We add 2 tablets of MicroElements in the kettle as per Gusmer. We add a blend of CaS04 and CaCl2 to get our CA to 70ppm. Our fermentations last about 4 to 5 days. Gravitates range 1.066-1.072. Any thoughts? Can the nutrients be hurting us with the additional Amino acid load? Pitch rate? Any input is appreciated.

[Randy.Cockerell]

Sorry to hear you are having the issues. For me I'm interested in how well you trust the temp regulators on your tank, while they are probably fine maybe try taking a temperature manually. Your pitch sounds generous given that your yeast slurry is at least 40% solids, do you test for that? Others thoughts are to ask how many generations you have been using this strain and if you are pitching from another beer how was that beer and was that beer a high gravity. It's possible that it could be some sort of infection, do you have a way to check for that? Lets us know what you think

[mmussen]

My First thought is that its a yeast health issue. Do you know if you're getting enough Zn in the wort? Also how are you storing your yeast before pitching? How many Generations are you running the yeast? 2 - 3 lbs sounds like a lot more yeast than you need - Are you guys doing cell counts? Too high of a pitch rate can increase your production of fusel alcohols.

[beerbeer95648]

Sorry about the disjointed response, writing this in a hurry, but want to say thank you guys for taking the time to respond.

Anyway,

I am losing sleep over this one. This is generation 5 currently, strain is Cal Ale. The donor tank (1.055 sg) tastes clean as does the other tank that was pitched from the same harvest. We dont currently run micro on our beers, we are only on batch 19 and have not had the luxury yet to get a mini lab set up. However, we are very stringent with sanitation. We are harvesting into clean 1/2 bbl kegs which first have the spear pulled and then everything is steamed. The harvested kegs are stored in our cold room for 0-7 days max with no head pressure. We add zinc containing nutrient tabs in the boil. We have not had good luck getting accurate cell counts at pitch, but this last tank I counted was pitched at 2lb/bbl, and at 12 hours after pitch was sitting at 30 mil/ml. I am having someone take another count here soon today to see what the true high krausen count was. Obviously, without the initial cell count the high krausen number doesn't tell the whole story. We have not been measuring solids as of yet, but would be very surprised if we weren't sitting at 40%+ as we try and use a qualitative description of the thickness as we harvest. In my past experience I have always had much more reliable ways of measuring pitch rate. Pitching at 2lb/bbl is new to me, but it is what I have heard others use as well as what was recommended by wyeast? Is it really all that high? I have had a gut feeling that maybe it was a touch high, but we have only had this issue with the IPA and Double IPA which started making me think it was too low for those beers (double got 3lb/bbl). We have struggled with random late onset sulfur production as well that gasses off, but adds time to the residence time in the cellar, so not sure if these issues are related. Other than the fusel in the IPA and occasional sulfur there has been no indication of poor fermentation. All of our beers finish in around 4.5-6 days and go to completion based on our forced fermentation samples. In the near future we should be set up with some methylene blue, and a bit further down the road set up for plating.

[kugeman]

Is this happening in the same fermenters every time? Are you sure that your temperature readings are accurate? The simplest explanation would be an overly warm fermentation. You'd definitely get fusels with calif. ale yeast.

[beerbeer95648]

Is this happening in the same fermenters every time? Are you sure that your temperature readings are accurate? The simplest explanation would be an overly warm fermentation. You'd definitely get fusels with calif. ale yeast.

Different tanks, but both in single batch tanks. The cooling temp at the heat X matches the tank, as does the temp coming out of the zwickle when putting a temp probe in the stream? But, I will check it again soon. I keep thinking it is pitch related, but I work a government job 40 hours a week and brew and take care of cellar tanks in the evenings and weekends. We are running 2x20bbl FV's and 2x40bbl FV's along with 3 brites, and we are ordering 3 more 40's this week. Hence the lacking data on cell counts. I really wish I had counts for those tanks. The first 17 beers were clean as could be, except honestly I thing the first 2 batches of IPA showed very slight fusel so maybe this beer was on the border with whatever variable is lacking/over abundant? So stressful since we have had a really good response from those around us and want to honor their trust in the products we are serving them. Quick edit: Most recent cell count on new tank is 44mil/ml at 46 hours having oxygenated to 12ppm and pitched 2lb/bbl. Like I mentioned, without a tank full count this doesnt tell me a whole lot but hints at around 10mil/ml pitch?

[AT-JeffT]

Why not pitch the next one at 65F or so?

A targeted pitch of 1.0mil/ml/P in 20bbl(are you knocking out slightly over 20bbl?) of 17P beer by my calculations would require 92lbs of yeast @ 1mil/ml and 95% viability. Does that sound about like what you are pitching?

[beerbeer95648]

Why not pitch the next one at 65F or so?

A targeted pitch of 1.0mil/ml/P in 20bbl(are you knocking out slightly over 20bbl?) of 17P beer by my calculations would require 92lbs of yeast @ 1mil/ml and 95% viability. Does that sound about like what you are pitching?

Just cooled in a 17 plato beer last night and am trying just that as far as temp. But not pitching anywhere near 92lbs. We calc'ed needing about 4 gallons of slurry at 9.6# per gallon for a total of about 40 lbs. Knockout is about 21 bbls currently. We always have very active fermentation less than 12 hours after pitch? So, still not sure if we are under or over.

[AT-JeffT]

Just cooled in a 17 plato beer last night and am trying just that as far as temp. But not pitching anywhere near 92lbs. We calc'ed needing about 4 gallons of slurry at 9.6# per gallon for a total of about 40 lbs. Knockout is about 21 bbls currently. We always have very active fermentation less than 12 hours after pitch? So, still not sure if we are under or over.

What is your pitching cell density?

[beerbeer95648]

What is your pitching cell density?

Haven't been able to get a good number yet as we don't get thorough mixing when pitching. We're basing everything on high krausen count. That tends to be between 40 and 60 million.

[beerbeer95648]

Why not pitch the next one at 65F or so?

A targeted pitch of 1.0mil/ml/P in 20bbl(are you knocking out slightly over 20bbl?) of 17P beer by my calculations would require 92lbs of yeast @ 1mil/ml and 95% viability. Does that sound about like what you are pitching?

I think you're on the right path with your numbers. Put our numbers into a spreadsheet, and we are under pitching by about 25% based on my last slurry count. We made a change this week in doing our cell counts based on weight as opposed to volume. So where does everybody get the 1 to 2 pounds per barrel from? Really thick cold harvests? All the published numbers from the current suppliers says between 1 and 1 1/2 billion cells per milliliter for the average 40% solid slurry. That is about what I'm getting with these most recent counts. But every time I've mentioned to people we pitch 2 pounds per barrel we've been told that was high?

[Swags]

Low pitch rate = fusel

The Wyeast website says low pitch rate produces fusel. I just dumped 12 bbls. Of our IPA for the fusel smell. The previous batch was a little bit off too so i am considering temperature stratification in the tank as a possibility and potentially yeast was not as viable.

[AT-JeffT]

I think you're on the right path with your numbers. Put our numbers into a spreadsheet, and we are under pitching by about 25% based on my last slurry count. We made a change this week in doing our cell counts based on weight as opposed to volume. So where does everybody get the 1 to 2 pounds per barrel from? Really thick cold harvests? All the published numbers from the current suppliers says between 1 and 1 1/2 billion cells per milliliter for the average 40% solid slurry. That is about what I'm getting with these most recent counts. But every time I've mentioned to people we pitch 2 pounds per barrel we've been told that was high?

I've wondered that too. We harvest at fermentation temps so I've always assumed that number was based on cold, more dense harvests.

Fermentation performance and flavor profile are the goal here so whatever amount of yeast gets you there.

Through analysis of a brewpub that typically underpitched, I've found that more than a 15% underpitch will cause issues.