Ethyl Acetate in Starter

[Scrumpy-]

In preparation for a wild ferment, I isolated the rotting fruit from my sweating apples, shredded them, added water and sugar to get a SG of 1.035 and checked the pH which was 3.5.  I added 1 teaspoon of FermMax to this 7 liter ferment and let it warm to 20 deg overnight.  This morning, the airlock is bubbling nicely.  I assume that I have a viable culture dominated by apiculate yeast (no microscope so can't be sure).

There is a distinct aroma of nail polish remover which I assume is ethyl acetate.  I am worried about pitching this starter into my must. I ran across a comment in the literature this morning that advises against feeding nutrients to apiculate yeast so that it does not over produce ethyl acetate. There is also a comment that in this case, the succeeding population of saccharomyces will not be strong enough to scrub the ethyl acetate from the must.

My plan was to rack the clear must off the plant debris in this first ferment and inoculate a cleaner must to grow a larger starter.  I would then pitch this starter into my main fermentation after adding 50% of the recommended sulfite.  Now I really wonder if this is such a good idea.  

Does ethyl acetate disperse or react to form compounds that are more agreeable to the palate during fermentation or aging? 

Should I culture a new starter but not add any yeast nutrients?

Since the first culture is derived from the apples I am about to mill, can I expect the same ethyl acetate production if I just let the must self start?

Can I expect the bugs in the starter to produce similar levels of ethyl acetate in my main fermentation if I do not add nutrients?

Thanks for your comments and advice.

[Andrew Lea]

Whatever else you do, I think it is a huge mistake to start with rotting apples! You will not only have apiculate yeasts in your culture, you will have any number of lactic and acetic acid bacteria, many of them very adverse and some of them generating very strong SO2 binding compounds which will make your later use of SO2 close to ineffective. They will also likely be high producers of ethyl acetate. 

If you plan to make a starter culture, please start with good sound fruit. 

Andrew 

Wittenham Hill Cider Portal
www.cider.org.uk

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[Scrumpy-]

Thanks Andrew,

I think I have fermented up a Devil's brew given the strong aroma. 

I'll abandon the starter plan and just let the must spontaneously start after treating it with a half dose of sulfite.  Do you recommend addition of yeast nutrients in a wild ferment?

[Andrew Lea]

On 11/11/2016 15:16, Scrumpy- wrote:

> I'll abandon the starter plan and just let the must spontaneously start
> after treating it with a half dose of sulfite.

Note Wes's previous comments on this issue. You may prefer to use say
25% of 'official' sulphite* which will give you a shorter lag phase.

> Do you recommend addition of yeast nutrients in a wild ferment?

No, because it defeats the object, which is a long slow cool
fermentation using a succession of wild but hopefully beneficial
organisms. Adding nutrients negates that and alters the microbial
ecology. I would only add nutrients to a wild fermentation if it
'sticks' late in the day and you want it fully dry. (In that case I
would add thiamine on its own to begin with and only add DAP if that
didn't work).

*I must (yet again) raise the issue of 'official' sulphite levels, for
instance those I quote in my book or on my website. I must stress again
that they were worked out empirically, to give around 0.5 - 1.0 ppm
molecular SO2, in the 1960's and 70's at the Long Ashton Research
Station in the UK for our West Country fruit harvested off the ground in
typically rural cidermaking conditions and sweated before use. As a
result the microbial load and SO2 binders were quite high, and this is
built into the recommended SO2 figures.

Those recommended SO2 levels do not necessarily apply to clean hand
harvested dessert fruit in the New World. You guys need to establish
your own SO2 binding curves, and not rely on British data from 50 years
ago which was established for conditions quite different from yours.

You also need to realise that the level of wild apiculate yeasts in
clean hand harvested dessert fruit (or ex CA store) will be much lower
than in sweated cider fruit because there will have been less time and
opportunity for the yeast to multiply inside the fruit. Remember also
that the apiculate yeasts are primarily associated with fruit flesh,
while the Saccharomyces are primarily associated with non-orchard
sources such as previously used mills, cloths and other equipment.

It is obvious from posts in the last few days that people really haven't
taken these issues on board when thinking about the nature and
succession of wild yeast fermentations.

Andrew

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near Oxford, UK

[Claude Jolicoeur]

Le vendredi 11 novembre 2016 10:16:42 UTC-5, Scrumpy- a écrit :

Do you recommend addition of yeast nutrients in a wild ferment?

I would say no.
Adding nutrients would favor the growth of a larger initial yeast population, and possibly later a higher risk of H2S production.
If you choose to add nutrients, then make sure you also add some "slow release" nutrients to prevent this risk (i.e. nutrients from organic nature).
Claude

[Scrumpy-]

Thanks again for your advice.

I gathered fruit from the ground and picked some in approximately equal proportions under conditions that closely resemble the historic West Country environment you describe. The various apple batches have been sweating for 4-6 weeks.  Most are starting to go soft and test negative for starch using an iodine test.  It sounds like a 50% sulfite treatment is the best approach.

The safe thing to do would be what I always do, sulfite to kill everything then pitch commercial yeast.  I'm ready for a new approach this year and will roll the dice on a wild ferment.

[Andrew Lea]

Great! Sounds like you do have something close to  'traditional West Country" conditions there! In which case the Long Ashton recommendations for sulphite addition would indeed be applicable, and yes I agree with you that 50% of those levels would be good for a sulphite directed wild ferment. Under those conditions you should be getting around 0.5 ppm molecular SO2 in the juice which should allow wild Saccharomyces and some apiculates to survive. Good Luck!

[That is the strategy I have used in my own cider making for the last 25 years and it works for me. I get a lovely mixed yeast population as I can tell by looking at it under a microscope. And a much more interesting result in flavour terms than using EC 1118 or any of its one dimensional stablemates. Yes I am prejudiced on this issue and I don't care who knows it ;-) ]

Andrew 

Wittenham Hill Cider Portal
www.cider.org.uk

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