Capturing wild yeast

Yeast has been used for fermentation and baking throughout history. In fact, it is likely one of the world’s first domesticated organisms. There are pictograms of ancient Egyptians making leavened bread and brewing beer that date back thousands of years! It probably seemed like magic back then. All you have to do is leave out flour and water and it creates this amazing substance that allows you to make things like leavened bread and fermented drinks such as beer and wine. It wasn’t until 1857 that Louis Pasteur discovered that yeast was actually a living organism.

Yeasts are very common in the environment, but they are most prolific around sugar. It naturally occurs on the skin of certain fruits and berries. For example, it is a natural yeast on the skins of grapes that allow for the fermentation that is necessary to create wine. The yeast you need to make bread and beer though, usually come right out of the air. See? Just like magic!

Now, of course, you can just go buy yeast in the store. This domesticated yeast is standardized and reliable, unlike wild yeast. However, if you want to see what kind of yeast you can cultivate at home just out of curiosity, then here is the way to do it.

To catch wild yeast you will need:

• A container, preferably with a loose-fitting lid
• A wooden spoon
• A piece of cheesecloth
• Flour
• Water

To start a culture, mix two cups of flour and two cups of water in a non-metal bowl. Lay the cheesecloth over the top to keep out bugs and debris and leave it on your windowsill.

The next day pour off about a cup of the mixture and feed it with another cup of flour and another cup of water. In a few days, the mixture will become bubbly - the yeast is growing! The bubbles are caused by the carbon dioxide that the yeast is generating. There is also lactobacilli growing in this starter. This is what makes the slightly acidic flavor of a good sourdough bread.

You might be wondering why the flour doesn’t get moldy and disgusting when you leave it out like this. It turns out that the starch in bread flour is something that not a lot of bacteria can easily handle. Yeast, however, creates special enzymes to deal with starch. The yeast and lactobacilli together poison the culture with the alcohol and lactic acid they both produce, which keeps other bacteria out. Neat, huh?

Leave the bowl on the kitchen counter for about five days. As the mixture ferments, it will develop a strong bread-like aroma that may be a little off-putting at first if you are not used to how yeast smells. Feed it every day or two by dividing it in half and adding another cup of flour and another cup of water to one half of it. The other half can be thrown away. When you see a watery substance floating to the top, stir it. After about a week the starter should look a little like pancake batter - thick and yellowish.

At this point you can do one of two things:

1. You can store it in the refrigerator to slow down the yeast. Then you will only have to feed it every five or six days.

2. Or keep it on the counter and feed it every day or two like you did this week. This, of course, is how it used to be done, but they didn’t have reliable refrigeration back then! They also made bread pretty much every day.

When you are ready to bake your own bread, add a cup of your yeast mixture to the dough to provide the yeast needed to leaven the bread. Don’t forget to replace what you took out! It will likely take longer to rise than if you used commercial yeast. Collecting yeast from the air creates random results - you may get a good one, you may not. If you really don’t like how it turned out, you can always try again and see what you get next time! Your chances are better if you live close enough to an existing bakery or brewery to be able to smell their yeast. If you can smell it, it is definitely in the air and ready to be captured for your own use.

This experiment can be fun! Play around with it, try a few different cultures, and see what kind of magic you can create!