Another wild yeast fermentation

[TimT]

Putting down a pale the other day I thought I'd also try to start a wild yeast fermentation from the peel of one of our apples. I set aside a bit of wort in a jar I'd just boiled and chucked some fresh apple peel in.

It took three days but it's definitely started fermentation. Looks respectable enough (ie, can't see signs of a bacterial fermentation - no kahm yeast or lacto-bacilli web, etc - just some froth/bubbles on top indicating a yeast is making CO2).

Since I've never done this before I'm suddenly not sure what I should do, so I thought I'd field some questions. My aim is to cultivate the wild yeast and pitch it into another ale, maybe an experimental 2.5 litre batch, possibly a light beer.

- It's in a sealed jar at the moment. Obviously this is not tenable if I want to encourage it to get to full strength. Open the lid and risk stuff getting in? I could pitch it at the bottom of a demijohn but that's a lot of oxygen to a very little bit of yeast.

- Should I slow the yeast down by putting the jar in the fridge?

- Wait until it's at full strength before pitching it into another beer? Or not bother waiting?

(Thought I'd start up a new thread rather than revive an old one).

 

[TimT]

I've risked opening the jar lid - probably a good thing; there was the sound of gas escaping and I caught a whiff of it too. Sulfury, a bit like chickpeas actually.

 

[rockeye84]

So wild yeast lives on apple skins? And other fruit too? Cool of you could capture your own strain..

 

[TimT]

Oh yeah definitely. If you're a yeast - what's not to like? Balls of sugar and nutrient just dangling there on the tree, waiting for you to drift by. PS - could quite possibly be a yeast from the kitchen anyway, since that's where the apple was sitting - so maybe just a brewer yeast or a bread yeast!

 

[Midnight Brew]

TimT I came across this: http://www.homebrewtalk.com/collecting-wild-yeast.html

I think even on AHB maybe but a good read. Really eager to try it but doing so many other brewing things at the moment. Good time of year for it according to the page. I've kept some left over wort from the last batch frozen in the freezer to give it a try. I'm going to try it with about 50ml then step it up when I do actually get around to it. I dont have those handy little petri dishes but they'd be handy in selecting and isolating the strain from the other organisms in the ferment. Then it's just a matter of fermenting and getting the yeast to where you want it. Time consuming and fun by the looks of it.

Subscribed. Keep us updated.

 

[Not For Horses]

Check out a company in the states called South Yeast Labs. They're doing some cool stuff with fruit and flowers and stuff. Right up your alley TimT.

I've done a wild yeast capture from some apricots. All went well, got it in a starter and stepped it up then into a 3L batch. Only problem was it was super low attenuating. Went from 1.045 to 1.030. So I guess not all wild strains will be suitable for brewing.
I've not been dettered though and nor should you!

 

[TimT]

Thanks Not for Horses - the possibility of low attenuation is why I'm thinking it might be good to give it a go on a mild, light beer. I think you shared a South Yeast Labs link with me before - it's quite possible. They pretty much recommended doing what I'm doing.

Cool link, Midnight Brew, and very helpful. So my plan is probably cover the jar with foil or glad wrap - minimise infection from outside, though gas will still escape round the corners - and wait until I get a nice yeast cake. I have no gelatin or petri dishes though I could definitely work a variation on the method there, by making a solution with malt extract, boiling to kill bacteria, adding a bit of lemon juice to acidify the environment slightly, and pitching the yeast cake into that, and perhaps start an experimental wild yeast brew mid to late next week.

 

[TimT]

This one's a write off. Most of the yeast dropped out of suspension yesterday and a generic mould took over. Bad fungus! Bad bad fungus! I made an attempt to salvage the yeast cake by filtering it out through a cloth but of course caught most of the bad fungus as well as the good fungus. An SG test also revealed the gravity hadn't dropped appreciably - maybe two points or so.

Still, while there's life (and apples), there's hope. I've got a malt extract-water solution cooling down in the fridge and I'll have another go at nurturing a wild yeast colony with some more peel this evening; I'll let folks know if there are more exciting developments!

 

[TheWiggman]

I've gotta say Tim I'm a fan of your experimental and out-of-the box approach to brewing, you've more than one thread like this. At least if your beer's no good you can just say "it was experimental".

 

[Not For Horses]

You inspired me today TimT so this was the result:
Sloe berries covered in powerdery white yeasty (hopefully) goodness harvested from the back roads of Evandale dropped into a 1.040ish starter made from yesterday's leftover wort.

 

[TimT]

Nice. Erlenmeyer flask might be just the thing for this sort of fermentation - I'm going to try it again soon and I want something I can put it in that can be fitted with an airlock. Not full demijohn sized though!

 

[Not For Horses]

2L Glass juice bottles work well too. Plus you get 2L of juice as a bonus!

 

[TimT]

I like your thinking. I have a few 2.5 L bottles, not sure if the seal would be perfect though? I'll have another look.

 

[n87]

you can buy a kit of bottle tops for various sized bottles with a airlock hole and seal.
i saw it Saturday at one of the home brew stores, they use it for cider.

 

[TimT]

Thanks. I'll have a look round.

 

[TimT]

Take No. 2. I peeled another apple and made a mixture of malt extract, water, and a bit of vinegar, with the hope the slight acidity will deter the various non-yeast beasts that are interested in taking part. It's in a 2.4 L juice bottle which I cleaned with a sodium metabiusulfite solution. It's on the heat pad. There's various tell-tale bubbles around the surface already and when the bottle starts feeling too tight I'll pop an airlock on it. Touch wood!

 

[Mutaneer]

Questions
where are you getting the apples from?
Where are you doing the peeling.?

If you're not picking them from the tree in an orchard, and peeling them on the spot you're going to introduce a lot of nasties.

After a long discussion with both the head brewer at Two Metre Tall brewery here in Tassie (they use wild yeasts a lot in their brews and brew "sour style" beers) and the brewers at Lark Distillery regarding wild yeasts, they are abundant absolutely everywhere.
The lark guys will crack their large fermenters and lift the lid the smallest amount for half a day to a couple of days to introduce a small amount of wild yeast,
but in the height of spring they will only need it open for a couple of hours to introduce sufficient wild yeast.

So anything that's travelled any great distance or been in any store around people, animals, other fresh produce, cheese, dairy products, etc is likely to be covered in rubbish that will just turn to mould.

Wild yeast that's contained within fresh, unpasteurised juice would be the best option to cultivate,
it's picked, and pressed on the farm, keeping the exposure to nasty "foreign" yeasts to a minimum.

I've done exactly that, kept some juice aside from a batch, stuck it in a sterilised 500ml bottle and airlocked it,
it bubbles away after a few days, then calms down, then goes off again.
I'm assuming as it produces alcohol, it is killed off, but then the strong ones grow again, then die off.
so by the end of it, hopefully the yeast that is left is a high-alcohol-tolerant wild yeast that can be washed out and cultivated.

I haven't tasted any of the results yet, but it's an interesting experiment anyway

 

[TimT]

Apples from my trees out front. Probably a bit of lead from the cars going by as well....

If anything bacteria is even more prolific than wild yeast so there's always that risk as well. Ah well. We'll see how we go.

 

[TimT]

Hey, I could be wrong on this - need to check my cider book - but I think the 'second' fermentation that a wild fermented cider goes through is the malo-lactic one: basically, the yeast, having got in there and chomped up some of the goodies, dies down - giving lacto-bacilli a chance to get to work. I'll check up on that.

UPDATE: Yep, that seems to be the indication from my cider book: the initial fermentation is yeast driven; the second is bacteria driven. Yeast as we all know likes to start off with a bang and then dies down after that; bacteria is a slower, more patient beast.

Malo-lactic fermentation helps to mellow out the cider if it's too sharply acidic, turning the malic acid into lactic acid and CO2.

However, not being very familiar with wild yeast fermentation it's entirely possible some yeasts might like to have a go twice over, as you suggest.

 

[Mutaneer]

Yeah, I'd just expect that the amount of good yeast around and on the Apples from a few trees is far less in proportion to the bad than the fruit in a large orchard in the country.
As for MLF, Mine isn't at a secondary ferment stage yet.