Ethyl Acetate Fault - Fixable?

[Brian Drake]

First, I promise that I spent a good hour searching for 'film yeast' and 'ethyl acetate faults' in this forum, as well as elsewhere before deciding to post.  There are a number of posts on film yeast and how to manage proactively, but nothing that really spoke to how to recover a batch gone south.  I have kegged my first three 15L batches and one of the three has a detectable ethyl acetate fault.

Primary: Mar-18

Batch#1 was pitched w/ Safbrew T-58 (ale yeast)

Batch#2 - wild ferment

Batch#3 - Lalvin EC-1118

SG_init wasn't measured, but was commercial culls (Honeycrisp/Gala blend).  All 3 had pH corrected to 3.4 and dosed with a 1/2 dose of KMBS 48-hours prior to pitch.

May-18: All 3 batches were racked (a bit late) into 5-gal buckets w/ silicon spin lids and sat in keezer @ c. 2C for 2 months.  Didn't add any KMBS at racking.

late Jul-18: All 3 were pulled out and sat in garage.  Temps ranged from 10 up to 20C for another 5 months.

early Dec-18: All 3 were kegged into corny kegs & carbonated.  SG_final = c. 1.000 for all three and all nicely clarified.  Noticed a chunky 'plasticky' film that shattered when disturbed on Batch#2 (wild) but didn't have any context for what it was.  Took a picture, shrugged and moved on with the process.  Other two batches didn't have anything similar.  Noticed an off-flavor reminiscent of acetone in #2 and luckily found Andrew Lea's 'The Science of Cidermaking, Part 5: When Things Go Wrong' and got a quick and definitive diagnosis.  (Thanks!)  The other two are relatively boring, but perfectly drinkable.

Now that I know what it is and what contributed to it, there are some things that I'll make sure I do differently, namely making sure oxygen isn't present (stay away from secondary in plastic buckets)

Question: what do I do with this batch?  Will the ethyl acetate (?) dissipate in keg over time?  Does SO2 help at this point whatsoever?  I suspect "No" to both of these..

Andrew's book mentioned a tactic to deal with acetobacter by rolling it in w/ fresh pomace and re-fermenting.  The note mentioned that this may work with film yeast faults as well.  Since ethyl acetate is a VA, will an active ferment quickly blow it off and allow me a 'reset' button?  Fine by me - I'm in R&D mode, so I was perfectly happy to have a 'problem' and interested to see if there's any solution here.

If that's correct and I don't have any decent apples to work with this time of year, what about re-dosing with KBMS, topping up with honey, some yeast nutrient, wait a couple of days and pitch a Sacc yeast for a cyser?  Worth a shot?  It's cold in the garage (10C), so if this approach has any merit, any tips on an appropriate yeast?  Any advantage for calculating a honey addition for an ABV >X% to inhibit a repeat on film yeast?  I ask this because what I've read indicates that film yeast seems to withstand SO2 pretty well... curious if the group has a feel for what its threshold for ethanol is?

Sorry for the long post and thanks in advance for your input!

Best,

Brian

OOLLC

[Andrew Lea]

Generally speaking ethyl acetate will not age out. It’s fairly stable chemically once formed. Nor will SO2 help you once it’s formed. However, in smallish quantities it can be re-metabolised by yeast (but not “blown off”) and hence re-fermentation as you suggest is a possible though not foolproof way to deal with it. Ethyl acetate is not a VA, it’s an ester. However, its microbiological formation is often accompanied by acetic acid hence it gets lumped in with so called VA and often makes the major sensory contribution to what is perceived as VA. 

Andrew

Wittenham Hill Cider Portal
www.cider.org.uk

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[Dan Samek]

worst case you can distill it and age with oak chips a nd have nice two bottles of calvados two yeras later :-)

Dne středa 19. prosince 2018 7:58:39 UTC+1 Brian Drake napsal(a):

[Wes Cherry]

I know VA isn’t considered a fault that you can age out but I have one contrary datapoint:

A couple years ago I made a Malbec wine that ended up with pronounced VA.  I blended it into another wine at about 20% ratio.  Upon bottling (with cork if that is relevant),  it still had a distinct VA nose.  After aging it has mellowed considerably.  It still tastes a bit off and weirdly fruity but the strong VA has diminished considerably.

The one time I had a cider batch with excessive VA, I blended it out (5-10% iirc) such that it was subtle enough to be perceived as fruity and was quite drinkable.

-'//es Cherry

Dragon's Head Cider

Vashon Island, Wa US

www.dragonsheadcider.com

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[Miguel Pereda]

Brian Drake
In the cider galaxy there are many worlds and sometimes the tips that are valid for one type of cider are not applicable at all to other styles and can not be generalized. For this reason, and from my experience, I will tell you that in some type of cider the main responsible for the formation of ethyl acetate are the no-saccharomyces yeasts, called oxidatives, which can have uncontrolled growths at the beginning of fermentation due to high temperatures, lack of cleanliness or slow extraction of the must.
Greetings.
Miguel A. Pereda

[Brian Drake]

For anyone who might be interested..

To my 4gal of 1.000 dry cider (w/ ethyl acetate fault), I diluted with another 2 gallons (mix of fresh juice, water, 4# honey, plus juice stewed off 4# strawberries and 3# rhubarb).  pH was c. 3.8, corrected to c. 3.5 w/ malic acid, sulfited to c. 100ppm and then pitched w/ a D47 starter (2-3 day on magstir plate).  Ferment started rolling within 8hrs at warmer temps (c. 72F/22C) and after several days, moved to the garage.  I was on the upper end of D47's temperature range in the house and I was concerned about producing ethyl acetate again... Moved to garage (50F/10C) which put the brakes on the fermentation (actually well below D47's sweet spot)  After another 10 days, racked off (1.002 SG) into corny keg. 

Apricot color, tart.. some strawberry/rhubarb character present (but more subtle than I'd thought) and touch of sweetness (maybe some unfermentable sugars in the honey?)  My first cyser/malomel, so not certain.  The ethyl acetate character is gone.  Whether diluted, masked, or blown off ... I couldn't say.  It's in the keezer now under CO2 pressure and I'll sample as it ages.

I like the idea of secondary/maturation in corny keg, but wasn't certain if cold temp (36F/2C) and CO2 would inhibit maturation or not.  I didn't expect I would approach 1.000 so quickly.

I didn't get a good SG measurement before pitching yeast, but I've calculated sum-of-sugars and should be right in ballpark of 9.0%.

Thanks for advice - scored my first 'save'! :)

Brian

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[Gloria Bell]

Thanks Brian!

I find a referment and dilution does help!  I had to do that this year too.  Not sure where the off flavour came from as it was low temps ect but I didn't sulfite off the hop - so may have been with the apples.  This worked for me as well - didn't make it a magical cider - but sure blew off 90% of it.  Also sulfited to 100-125 I believe.  Original pH was 3.31 on mine so didn't need to adjust.

Thanks for posting!