How to Get Wild Yeast

[Charlotte_0'Neil]

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If you have a container of fruit juice in the back of the fridge that
has set there for weeks and the container is bulging and it has become
fizzy, that is caused by wild yeast fermentation. You can use this
liquid with yeast to make beer or anything else needed a yeast
starter.

Raisins, apple peel and lemon
Put a handful of raisins, an apple peel and the lemon juice from a
used lemon wedge into a glass of warm (about 110°F) water with sugar,
about a tablespoon of sugar for a half cup of water. Cover with a
light cloth and leave in a warm place. The top of the fridge is
usually a good place for this, as it is usually warmer than the lower
part of the room.

Potato Water
Take a cup (236 mls) of the water in which you have boiled potatoes.
Add a tablespoon of malt extract. Expose it to some yeast -- add
raisins or grapes to it or put it in a wide shallow bowl and leave it
out for a while -- and yeast should start to grow in it.

Kahm-Covered Leaves from sauerkraut
That white stuff that you worry about that forms on your other
ferments is from yeast. Add some sugar water and they will grow
happily and you will have your own house yeast starter.

Kefir grains
Rinse off some kefir grains in warm water and then put them in apple
juice for a week.(These can be returned to milk afterwards. They might
need a little extra time and perhaps some extra cream in their milk to
make up for their brief no-fat diet.) If you make water kefir, you can
use that as is as it already has an available yeast culture active in
it.

Kvass
Kvass made from kefir whey will have some yeast that grew from the
kefir and some that was airborne when it was made. If you did not use
kefir whey to start your kvass and used only salt or other kinds of
whey, there will still be some yeast fermenting in the kvass. Add
sugar and water, cover with a light cloth and keep in a warm place
until it starts to look frothy.

Liquid separated from sourdough batter
If you make sourdough bread, the liquid that collects on top if you
have not stirred it recently contains airborne yeast. If you have some
batter that you are currently planning to use to make sourdough, just
add some water, stir, wait a day and then pour off the amount of water
that you had added.

Wild yeast on growing fruit
In summer, look for yeast on fruit growing in the wild such as grapes,
blackberries, sloes, blueberries etc. This will be a brown, fuzzy down
on the fruit, either covering the entire berry or in splotches. Put
fruit into a bowl of sugar -water with a few drops of lemon juice.
Cover with a loose-woven, breathable cloth secured with a rubber band
and leave in a warm place.

Grapes
Wild yeast are naturally present on the skins of grapes, so grape
juice made from grapes you have pressed yourself will spontaneously
ferment.

Peaches
Peaches are another excellent source of wild yeast. Take a peach,
don't wash it off, cut it up with the peel on and put it in the
blender with some warm water. Add a spoonful of sugar, cover and leave
on top of the fridge or in another warm place.

Hard Cider
Unpasteurized fermented apple juice (known as "scrumpy" in the English
countryside) already has a live yeast culture in it and your work done
for you. In the US, where cider is sold as soon as it is pressed from
the apples and before it has begun to ferment, you have to keep it for
a while. Eventually, apple juice pressed from apples with nothing
added to kill the yeast will ferment. You can add some raisins to
speed up the process.

Other sources
You probably don't need to the know this, but in the interest of
intellectual honesty, you can also get yeast cultures from moldy hay,
bird droppings, feathers, insects and soil.