Sudden Recurring Diacetyl Problem

[Mike Lachelt]

Hi all,

I’ve been in business a number of years now without ever noticing diacetyl in my ciders. But suddenly a good portion of my tanks are developing diacetyl. The effect is nearly undrinkable. Here are some relevant facts:

1. At the end of fermentation in IBC tanks, the cider has no noticeable diacetyl flavour. Everything seems healthy and normal.

2. Diacetyl develops only once the cider has been racked into a BIB for storage.

3. We use sulfite prior to fermentation at different levels depending on the Ph of the juice (usually 50-75ppm), and then add 30ppm at racking. Diacetyl creeps in within one month during aging.

4. All of the tanks that have developed diacetyl were frozen as juice during storage, thawed, and then fermented. Our process in this regard has been the same as in previous years, when no such problem occurred. But perhaps the initial sulfite added after juicing became ineffective after months in freezing? (But again, we had no problems in previous years).

4. This may have begun when a few tanks of cider got FAR too warm in the cidery last winter. We dealt with those tanks, but now we are noticing diacetyl in numerous other tanks fermented long since the temperature was under control.

5. We are in the process of discarding all of our lines and replacing them with new ones. (Since the problem only shows itself in the ageing tank, perhaps the cause is in the pump or in the lines?). Should I be discarding the pump too? (Seems crazy).

6. I have been using peracetic acid to sanitize our pump, lines, and bottling tank. I use a combo of S02 and citric acid to sanitize my IBC’s. Perhaps I should be using PAA on my IBC’s instead? (A guy from a wine lab I just spoke with says he thinks the cause is my use of so2 and citric acid to sanitize our IBC’s, which, he thinks, will not kill the lactic acid bacteria that is responsible for diacetyl...). The tanks and lines are cleaned with PBW.

7. I am always struggling to keep the cidery cool enough in the summer. Fermentations get a bit too warm, and aging tanks are kept a bit too warm as well. Doing my best...

This is certainly very concerning! I keep hearing how rare it is to have diacetyl problems...and yet here we are. If anyone has any suggestions, I’d love to hear them.

Thanks all,

Mike

[Andrew Lea]

It sounds to me as if you have unluckily caught a wild strain or species of lactic acid bacteria which has a propensity toward diacetyl production. Your addition of citric acid also rings alarm bells since this is a known precursor to diacetyl (in perries for instance).  I’d guess the problem may have originated during the warm spells but the bacteria are now happily endemic in your IBCs and the occasional burst of citrate will just encourage them. Also I suggest that 30 ppm total SO2 added at racking may not be enough - usual advice is to maintain 20 ppm free SO2 at all times. And even so, you may now have something of a sulphite resistant strain. 

I would have thought a serious deep clean / CIP would be the answer to take you back to where you were before.  IBCs have rough internal surfaces where microbes can lurk. And no, acidified SO2 is not a very good sanitiser. You need to use some proprietary chlorine or oxygen based sanitiser / cleaner designed for winery use that can really get in and zap those surfaces. Plus all the pipe work as you suggest. I’ll leave others on your continent to suggest the best ones to use. 

Good luck,

Andrew

Wittenham Hill Cider Portal
www.cider.org.uk

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[Wes Cherry]

Also beware that there’s many mL of void in IBC ball valves that is quite difficult clean.   Work the valve back and forth multiple times while cleaner and then sanitizer are being pumped past.    Or don’t use the valves except for CIP cleaning.   Rack and fill with a racking cane instead.

IBCs are cheap compared to their contents so getting new IBC bottles would be prudent.

End user hose-clamped hoses can harbor microbes between the hose and the end fitting.   Commercial cideries should use professionally swaged hoses.  I like Goodyear/contitech vintners hose.   I order through processhose.com

Also, as Andrew suggests, higher doses of sulfites may be in order.   Don’t be afraid to hit them hard with 75ppm free or more.    Shocks of high levels of so2 have been shown to be better than consistent levels at controlling microbes.  A month or so in the ibc and free so2 levels will drop quite fast.

Higher pH ciders will also require more sulfites to get sufficient microbial suppression.

-'//es Cherry

Dragon's Head Cider

Vashon Island, Wa US

www.dragonsheadcider.com

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[Mike Lachelt]

Hi Wes, thanks for the advice. I’ve got a large number of IBCs so I think I will try to sanitize them with PAA and monitor the results closely before trying to replace them all at great expense. (My choice of acidified so2 was based on its greater longevity, but I see now this was a terrible choice). I wonder: what sort of strength for PAA would you recommend? I have been using 100ppm on my lines and bright tank, but perhaps a stronger dilution is now appropriate for my IBC’s, given the severity of the condition. (I would say stronger must be better...but one must also consider the residue of the sanitizer and it’s effect on the incoming juice. Do you think 250ppm would be too strong?

(I wish I could simply ask my chemical company, but I have only the chemical, and no company rep to call for advice. This is “Purisan” peracetic acid, 5.25% peroxyacetic acid and 22% hydrogen peroxide, with he rest being “inert ingredients”).

Thanks again for your help. I sure hope I can get away without replacing all my totes...but it’s nerve racking.

Mike

[Wes Cherry]

It’s been years since I used PAA, but I don’t see a problem with higher concentrations as long as you purge any remnants - could even use normal concentration PAA to rinse the high conc. residual.

The Purisan label says it’s ok to use up to 500ppm on food contact polyethylene.

http://cru66.cahe.wsu.edu/~picol/pdf/OR/61318.pdf

And 2700ppm on other hard surfaces including polyethylene.

Purisan is a wesmar product.    You could give them a call too.

You might also look at using lysozyme as insurance.

-'//es Cherry

Dragon's Head Cider

Vashon Island, Wa US

www.dragonsheadcider.com

[Mike Lachelt]

Hi Andrew,

Thanks again for your thoughts. I guess so2 and citric was a pretty bad idea, residual from my introduction to cidermaking! Fortunately I have some peracetic acid that may help. I spent the day rinsing out tanks previously sanitized with so2 and citric, and then re-sanitizing them with 200ppm of PAA, which I have on hand. And now my fingers are crossed...

Cheers and thanks,
Mike

[Mike Lachelt]

I've read that label a number of times and never noticed the reference to polyethylene!  Thanks for the tip about lysozyme :)

m

[Richard Anderson]

I have been following this thread with interest thinking diacetyl was naturally occurring  in cider and often thought to be beneficial, at least in small quantities adding some buttery flavors as well as self-limiting. However it appears that it is getting out of hand in out in our cidery. We have about 900 liters in one  ss tank that is over the top for most people when we started to bottle 2017 cider in April.  I thought at first we had a case of spontaneous malo lactic fermentation since TA the was low according to lab tests and thinking it might mellow out to be a really interesting cider. Unfortunately it has not changed  for the better over the summer. It will be distilled. I have always used PAA as a sanitizer and am wondering if we are just creating a  vigorous lactic bacteria? Any thoughts on this.

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[Wes Cherry]

I agree a little diacetyl in bittersweet ciders is quit nice, giving butterscotch flavors.   In other ciders, absent the backbone of bittersweets, I find diacetyl insipid.

and am wondering if we are just creating a  vigorous lactic bacteria? Any thoughts on this.

Just like with any pesticide, it’s probably a good practice to rotate sanitizers to avoid breeding resistant strains.

-'//es Cherry

Dragon's Head Cider

Vashon Island, Wa US

www.dragonsheadcider.com

[Mike Lachelt]

Hi Wes,

You were saying you no longer use PAA. Can I ask why? What do you use instead? (I do find it difficult to have to re-make a new batch of it every day). As a general practice, I am going to rotate different sanitizers. Is there a reason PAA isn’t in your rotation? (I had initially worried about introducing acetic acid, but have come to the understanding that this fear is unwarranted). Is there reason to avoid it?

Thanks,
Mike

[Wes Cherry]

It can oxidize cider. Short life too. Searching the archives for PAA and my name should give several posts on it and why I use triple San now.

-'//es Cherry
Dragon's Head Cider
Vashon Island, Wa US
www.dragonsheadcider.com

[Mike Lachelt]

Thanks Wes. I have also noticed the problems you discuss with PAA (oxidation, browning of the cider, and short life) but will deal with these until I can source a preferable alternative. Cheers,
Mike

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[Brendan Kearns]

...somewhat related, can anyone throw in an answer for cip temp of caustic that IBCs can tolerate? Longer cycle lower temp than ss? Or can I use 70C water? 

Cheers

Brendan