Harvesting Yeast From The Wild

 

It’s easy to harvest wild yeast and to make your own yeast culture, for brewing or for baking, or to use in the wild for backwoodsman cooking. It might not perform quite as well as the super yeasts bred by specialists in expensive factories, but it’s the yeast our ancestors used for thousands of years, harvested from the wild. The main difference is speed. The yeasts you buy are designed to start acting fast because our modern society lacks the patience of our ancestors. Wild yeasts take a bit longer to get up to speed. Other than that I can see little difference. My bread rises the same and my wine and mead are just as alcoholic. The way around this is simply to have your own living culture to hand, ready to pour into whatever you are making. See details below.

Yeast occurs naturally, on everything, even on your skin, and also on the skins of most fruits (dried or fresh) and on herbs or other vegetation. Mead and wine makers of old did not add yeast but relied instead on the wild yeasts, those which were already living on the fruit, or floating around in the air. Many English cider makers today still allow fermentation to occur naturally, from the wild yeasts on apple skins.

I’m a beekeeper, and if you leave uncapped stores, or wet frames hanging around for a while, particularly in a damp place (like a shed), then you can sometimes pick up the smell of fermentation beginning to take place. That’s why bees concentrate their gathered nectar down from 80% moisture content to 20% moisture, or less, to prevent fermentation taking place. In damp air the exposed honey absorbs moisture until it is above 20% and then fermentation can take place. Whilst mead, (the name we give to fermented honey) is wonderful for us, it is fatal for the bees. I make use of this naturally occurring yeast in my mead and to create a culture to use in other wines.

If you are interested in using wild yeasts for wine or mead making then perhaps you should have a read of another article on this web site called ‘Easy Mead Making’. Also my first attempt as cider making, using wild yeast on the apples, is also documented on this site. See: ‘My First Attempt at Cider Making’.

Mead being fermented from wild yeasts found already fermenting in open cells of nectar in a honey comb from a beehive.

 

So wild yeasts are everywhere.

 

Can we use this yeast used for fermentation for baking?
Surplus yeast created by the beer brewing process, is known as ‘barm’, and was once commonly used by bakers for making ‘barm cakes’. Barm cakes can still be bought in Lancashire though they are no longer made with barm, and so the name survives as simply a local name for a bread roll.
So the same yeasts can be used for brewing or baking, one straight after the other if you like, like they used to do.

 

How to Get Your Yeast
The first step is achieved by gathering fruit, either cultivated or wild. It’s best to use older fruit, even damaged, the blemished stuff you might normally discard. Clean, perfect fruit has a smooth surface which can easily be washed by rain whereas older, less than perfect fruit will have wrinkles or breaks where yeast will gather and fermentation may have already begun on the ripe inner via breaks in the skin.

The last pick of the year with a mixture of good and sub standard fruit (normally discarded).

 

I’ve deliberately selected the older, wrinkled or damaged gooseberries for wild yeast making.

 

Don’t use supermarket fruit because it may have been washed or polished clean, waxed, or sprayed with anti fungal chemicals, or with worse. I once tried to make marmalade wine from cheap supermarket marmalade and the chemicals within the jars killed the yeast within a couple of days, and all attempts to re-start it failed. You are after wild natural yeasts and these aren’t found in abundance in modern sterile growing conditions, or in the packaging centres of large scale production, in fact they are deliberately eliminated.

Dried fruits can also be used, and at any time of the year as yeasts survive on them for quite a while. If you are reading this when your own fruits aren’t available, and are encouraged to have a go, then you could give it a try by using bought dried fruits.

 

To make your starter yeast culture:

1 – Place the fruit (or herbs) in a jar up to about half full. Be sure not to wash the fruit, or to take the skin off, as this is where the yeasts will be. Sweet ripe fruits are best, (and even more important if you are in a situation where you have no sugar or honey).
Use a large jar if you want to use some of the yeast soon, but if you also intend to keep the culture going for next time.
In my two examples below I have used rhubarb and gooseberries from my allotment.

 

2 – Add water, or weak sugar syrup until you are about three quarters of the way full.

Sugary water (syrup) goes into the gooseberries

 

Freshly sliced, but not washed, rhubarb in a jar, awaiting sugar.

 

3 – Add a couple of teaspoons of sugar or honey if you haven’t added syrup. It may work without a sweetener if the fruit is ripe, but it will be much faster and more vigorous with. Give the jar a shake to dissolve the sugar, no need if you added syrup. If you are a brewer or wine maker you will probably have yeast nutrient and you can add a little now if you wish. You could also test the specific gravity and adjust accordingly, but I don’t bother at this stage.

 

4 – Put the lid loosely on the jar and leave in a warm place. If you screw down the lid the jar will explode. In as little as 24 hours bubbles may begin to form on the fruit.

Bubbles begin to form on the fruit after 24 hours

 

I usually give the jar a little shake now and then to hasten the transfer of yeast into the liquid. After 3 or 4 days a good amount of bubbles should start to appear and a froth may begin to gather on the surface, depending on the fruit you used. The bubbles indicate that the yeast is reacting with the ingredients in your mix, in other words it’s multiplying, making yeast (and alcohol).

The water will turn from clear to cloudy as the yeast multiplies.

Bubbles gather on the surface and the liquid begins to go cloudy, good signs.

 

The same thing is happening here with the gooseberries on day 4. You can no longer see through the yeasty liquid and bubbles are rising from the liquid and are passing up through the fruit.

 

5 – Once you are sure that the yeast is living in the sugary water (usually after 3 or 4 days) then discard the solids and keep the liquid. If left in the jar the solids will disintegrate, turn to mush, and will be difficult to remove later, especially soft fruit like rhubarb.

The liquid gets cloudier each day until the fruit can be discarded

 

Add another spoonful of sugar or honey to keep the yeast fed. The liquid will continue to go even more milky, and a fine foam may form on top as the yeast multiplies. Excellent progress!

Day 7 and the yeast water is even more cloudy but the fruit is colouring the water too. Time to get rid of the fruit.

 

The fruit is removed and the jar topped up with sugar water to create enough yeast culture to experiment with.

 

6 – Once the liquid is milky and fermenting vigorously then you can use the yeast water for brewing, or in bread making (or other recipes).
Keep the fermentation going by the occasional addition of honey (honey contains more nutrients than sugar) and topping up with water. If left alone the yeast will eventually use up all the ingredients, and then die.
You can slow down the fermentation by keeping the culture somewhere cool.

If you have no immediate use for the yeast water, and the jar is full, you can keep the yeast vigorous by tipping half of it away and by adding more sugar or honey, and water, to keep the yeast fed and active. Or pour the mix into a bigger container and add more water and sugar.

This never ending fermenting process was once commonly used with sour dough for oatcakes in Britain, and was kept going in remote communities for years, possibly centuries, evolving over time, sometimes giving unique local tastes to oatcakes, which were loved by locals who grew up with it, but sometimes considered almost inedible by outsiders.

 

Testing your yeast.
Brewing
– If you are an experienced brewer, or wine maker, then you should be able to tell from the smell or taste if things are going in the right direction, or just test the specific gravity.

A demi-john of cider made using the naturally occurring wild yeasts.

 

Baking – For bread making there’s only one way to find out and that’s to make some bread. Remember that wild yeast is not the super yeast you may be used to and things may take a little longer to get going. And just as brewers ‘barm’ yeast gave a distinctive flavour to barm cakes then your yeast may also contribute to the flavour, but there’s no telling how until you try it.

On day 6 I mixed a little of the yeasty liquid with plain flour to a batter like consistency, to create a type of sour dough. After 3 days the yeast activity was obvious so I carried out a simple test.

The bubbles form in the batter and gently rise to the surface

 

I subject a spoonful of the mix, unchanged, to gentle heat in a frying pan to see if it would rise during cooking, and it did.

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A test sample to see how the mix reacts to gentle heat

So I turned on the oven and put a big spoonful in a hoop (to stop it spreading).

 

It rose nicely

Commercial yeasts are bred to give consistent bubbles whereas a collection of wild yeasts will give different bubble sizes producing interesting patterns and textures. The cross section below shows this. The flour culture needs more time to really get going, for the yeast count to increase, but as you can see, after only a few days there are encouraging results.

When sliced open the bubbles are revealed. Not a bad start, edible and nice, but a more consistent texture would be better.

 

The sour dough culture was topped up with strong bread flour, and water, and left to build up the yeast count so that I can experiment with larger quantities.
The liquid culture was also topped up with sugar water, and continues to bubble away, also gently increasing its yeast count.

More experiments to follow.

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Experiment 2 – Sourdough pan loaf

Once the sourdough culture was bubbling well I split it in two. The culture was topped up with strong white bread flour and water and left to continue bubbling.
The other half had flour added to it to increase the amount and was left to rise in a jug for a day.

 

More flour was then added to make quite a soft dough which was kneaded and then placed in a round pan to rise, then baked.

The dough in this test was too wet and floppy and bubbles escaped preventing the bread from rising properly.

 

But the texture was more bread like. Getting there. Notice that the bubble size difference isn’t now as great probably as some yeast strains become more dominant as time goes on.

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Experiment 3 – Small sourdough loaf

The next loaf was made with a much drier and firmer dough and left overnight to prove.

A stronger white bread flour, and a drier dough rose better. This loaf had been left overnight to prove.

 

After baking. Looking good.

 

Much better results and tasted great

 

 

Its easy! All you need is an old jam jar and some old fruit.

Sourdough bread from wild yeast!

And wine, cider and mead from wild yeasts!

 

Andrew

 

My First Attempt At Making Cider (using wild yeasts) – Article on this web site >
Easy Mead Making (Using bought and wild yeasts) – Article on this web site >

 

p.s. I’ve been experimenting, for a couple of years, with making vinegars from naturally occurring bacteria, added to my naturally brewed mead and wines. Once I have concluded my experiments, and perfected my technique, I’ll put my findings on this web site.

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