Is my keg infected with diacetyl?

[timrox1212]

Can this happen? I have two kegs and the one keg for the last three beers have all had this "butterscotch" taste to them. The other keg is fine. I know diacetyl is caused from the yeast but all my batches I pretty much brew the same. Use a starter, 2 week primary 1-2 week secondary/cold crash. Every beer that seems to come out of the one keg has it, the other keg dosent. What gives?

 

[mark7347]

What are your fermentation temps on the bad batches?

 

[sandyeggoxj]

I don't think the keg van be infected with diacetyl. You could have a dirty keg. How do you clean your kegs?

 

[Braufessor]

Here is a good link on diacetyl...... typically we are concerned with diacetyl as a fermentation byproduct that needs to be "cleaned up" by yeast..... I don't think that can "spread." However there are other pathways that can cause diacetyl...... mutant yeast, pedio, etc. This is a pretty good link here that goes into some of these other causes. That type of thing could be in a keg and infect new batches...
http://www.professorbeer.com/articles/diacetyl.html

 

[timrox1212]

Fermentation temp is always 62 I have a controller for that. In like 50 batches I have not had any trouble until the last 3 batches that have went into this keg. And to clean the keg I take everything apart and wash it then spray with starsan. Then soak in baking soda mixture then another spray and rinse with starsan and then water

 

[Johnnyhitch1]

Do you clean your faucets or change out beer lines?

 

[doug293cz]

Fermentation temp is always 62 I have a controller for that. In like 50 batches I have not had any trouble until the last 3 batches that have went into this keg. And to clean the keg I take everything apart and wash it then spray with starsan. Then soak in baking soda mixture then another spray and rinse with starsan and then water

Is the final StarSan rinse done immediately prior to filling the keg? The effects of StarSan don't last long after treated articles dry. You should stop rinsing after the final StarSan treatment. The rinse water is a potential vector for contamination. Have you replaced all the "O"-rings on the keg? Pedio could hide under them where your cleaning protocol might not reach it. Also, do you always use the same lines & tap with that keg? If so, all the lines plus any plastic or rubber components (gaskets, etc.) should be replaced, and all metal parts cleaned and sanitized well.

Brew on

 

[whoaru99]

Fermentation temp is always 62 I have a controller for that. In like 50 batches I have not had any trouble until the last 3 batches that have went into this keg. And to clean the keg I take everything apart and wash it then spray with starsan. Then soak in baking soda mixture then another spray and rinse with starsan and then water

I think it's not necessary to use StarSan in the intermediate cleaning steps; only for final sanitizing then no rinse and fill the keg while still wet with StarSan.

It's not hurting anything to do that intermediate sanitizing except your wallet, but I don't believe it's helping anything either. Nor, is rinsing after the final StarSan treatment.

 

[Yooper]

Sounds like a pediococcus infection in the keg or in the lines.

How do you break down and clean your kegs? What's with the baking soda?

I'd definitely tear them down well, and take off the o-rings and either replace or clean well with PBW and then rinse and then sanitize.

 

[DirtyPirate]

I would lean towards the beer lines and faucet. A good soaking with beer line cleaner. You can be sanitary as you want and those beer lines and faucets still get funky.

 

[max384]

Can this happen? I have two kegs and the one keg for the last three beers have all had this "butterscotch" taste to them. The other keg is fine. I know diacetyl is caused from the yeast but all my batches I pretty much brew the same. Use a starter, 2 week primary 1-2 week secondary/cold crash. Every beer that seems to come out of the one keg has it, the other keg dosent. What gives?

This particular keg wasn't used for root beer before, was it? I wonder if that could be the "butterscotch" taste that you're tasting. If so, try replacing all rubber pieces and giving it a very thorough cleaning.

 

[timrox1212]

I'm pretty positive it isn't my cleaning. I clean the lines and everything every batch. Could it be my yeast? Maybe too much yeast is causing this? The last 3 batches have all been +/- 5% abv and I've used washed yeast then made a starter out of it. All used white labs California ale yeast. Only other thought I could have is my Co2 line. I rarely every take this off the tank and clean it. Is that it maybe?

 

[Braufessor]

You said you ferment at 62..... do you let the it warm up at all toward the end of fermentation? Still would not explain whey it is one keg and not the other....... but, 62 is toward the cooler end of fermentation.....perhaps letting the temperature elevate to 64-66-68 after the first 4-5 days could help??

How many generations with the yeast?? could be getting some contamination in there perhaps?

CO2 line could be a possibility -especially if you have ever had beer back up into it.

I would definitely give everything a hot PBW soak, star san. Definitely don't rinse the star san as mentioned previously.