Uncorking Nature's Brew: A Guide To Wild Yeast Beer Capture

Capturing wild yeast for beer is a magical process that can lead to delicious results. Homebrewers can find, harvest, and grow their own yeast, which can be used to make a full batch of beer. The process involves setting wort under a tree, covering it with cheesecloth, and waiting for wild yeasts to find their way into the wort, feed on the sugars, and create carbon dioxide and alcohol.

Set wort under a tree

To capture wild yeast for beer, you can set your wort under a tree, especially a fruit tree, since yeast loves to hang out on sweet fruit. Cover the wort with a cheesecloth to keep anything larger than yeast out. Hungry, wild yeasts will find their way into the wort, feast on the sugars in it, and create carbon dioxide and alcohol.

Start with 250ml of 1.040 santised wort and add your captured yeast. Keep it at a good temperature, aerate it, let the CO2 escape, and treat it as you would any starter. After 2 days, you should have around 3.3 billion cells. Then, make a 1.5l 1.040 wort and top up the 500ml wort with the new wort. After another 2 days, you should have around 40 billion cells. If you need more than that, leave the bottle in a fridge so that the yeast will form a sediment at the bottom. After about 48 hours, you can decant the old wort and top up with 1750ml of fresh wort.

Once you’ve grown up a starter, carefully smell and taste it. Imagine what beer style it could work with. If it has a clove or pepper character, consider trying a saison or Belgian style beer. At this point, it is safe to taste the starter. Pull a small sample from below the surface and taste. If it tastes mild, fruity, or lemony, you should be good to go. Any bad flavor is not a good sign. Also, if the starter beer has dropped clear, that’s a great sign of a healthy fermentation.

Cover with cheesecloth

Once you’ve grown up a starter, carefully smell and taste it. Imagine what beer style it could work with. If it has a clove or pepper character, consider trying a saison or Belgian style beer. If it tastes mild, fruity, or lemony, you should be good to go. Any bad flavor is not a good sign. Also, if the starter beer has dropped clear, that’s a great sign of a healthy fermentation. You’ve now captured and grown your very own wild yeast and are almost at the point where you can use it to make a full batch of beer. The next step is to make a starter with your new yeast. Follow our guide on how to make a starter to grow your wild yeast into a pitchable size.

Some American brewers experiment with spontaneous fermentation, too: John told me that you can do this by setting your wort (the "starter" of beer, a sort of sweet solution that you add yeast to) under a tree—especially a fruit tree, since one of yeast's favorite places to hang out is on sweet fruit—cover it with a cheesecloth to keep anything larger than yeast out, and wait. Hungry, wild yeasts find their way into the wort, feast on the sugars in it, and create carbon dioxide and alcohol.

Wait for hungry yeasts

Homebrewers generally have the DIY ethos. Why not take it to the next level by finding, harvesting, and growing your own yeast? Capturing wild yeast will get you closer to finding the ultimate local beer.

Homebrewers generally have the DIY ethos. Why not take it to the next level by finding, harvesting, and growing your own yeast? Capturing wild yeast will get you closer to finding the ultimate local beer.

Wild yeasts find their way into the wort, feast on the sugars in it, and create carbon dioxide and alcohol. Some American brewers experiment with spontaneous fermentation, too: John told me that you can do this by setting your wort (the "starter" of beer, a sort of sweet solution that you add yeast to) under a tree—especially a fruit tree, since one of yeast's favorite places to hang out is on sweet fruit—cover it with a cheesecloth to keep anything larger than yeast out, and wait. Hungry, wild yeasts find their way into the wort, feast on the sugars in it, and create carbon dioxide and alcohol.

Once you’ve grown up a starter, carefully smell and taste it. Imagine what beer style it could work with. If it has a clove or pepper character, consider trying a saison or Belgian style beer. At this point, it is safe to taste the starter. Pull a small sample from below the surface and taste. If it tastes mild, fruity, or lemony, you should be good to go. Any bad flavor is not a good sign. Also, if the starter beer has dropped clear, that’s a great sign of a healthy fermentation. You’ve now captured and grown your very own wild yeast and are almost at the point where you can use it to make a full batch of beer. The next step is to make a starter with your new yeast. Follow our guide on how to make a starter to grow your wild yeast into a pitchable size.

Keep starter at a good temperature

Capturing wild yeast for beer is an exciting process that can lead to unique and delicious beer styles. Once you've captured your yeast, it's crucial to maintain its health and activity by keeping the starter at a good temperature. Here are some detailed instructions to guide you through this step:

• Maintain a Consistent Temperature: Wild yeast is sensitive to temperature changes, so it's essential to keep the starter at a consistent temperature. The ideal temperature range for yeast growth is typically between 68-72°F (20-22°C). Avoid drastic temperature fluctuations, as they can slow down or halt yeast activity.
• Use a Fermentation Lock: Consider using a fermentation lock or airlock on your starter vessel. This allows for the release of carbon dioxide while preventing other contaminants from entering. Regularly check the airlock to ensure it's functioning correctly and bubbling.
• Aerate the Starter: Yeast requires oxygen to thrive. Aerate your starter by gently swirling the mixture or using a small, clean stick to stir it. This process helps distribute nutrients and oxygen throughout the starter, promoting healthy yeast growth.
• Monitor and Taste: Regularly monitor your starter's progress by tasting small samples. If the starter tastes mild, fruity, or lemony, it's a positive sign. Any off-flavors may indicate issues with temperature control or other factors. Remember, the goal is to capture and grow healthy, active yeast.
• Avoid Contamination: Keep your starter clean and sterile to prevent contamination. Use sanitized equipment and utensils, and ensure your workspace is clean. Contamination can lead to off-flavors and a failure to capture the desired wild yeast.
• Patience is Key: Yeast growth takes time, so be patient throughout the process. Allow the starter to ferment and mature, and remember that the temperature control is a critical factor in its success.

Decant old wort after 48 hours

After 48 hours, you can decant the old wort and top up with 1750ml of fresh wort.

Start with 250ml 1.040 santised wort and add your captured yeast. Keep it at a good temperature, aerate it, let the CO2 escape, and treat it as you would any starter. After 2 days, you should have around 3.3 billion cells. Then make a 1.5l 1.040 wort and top up the 500ml wort with the new wort. After another 2 days, you should have around 40 billion cells. If you need more than that, leave the bottle in a fridge so that the yeast will form a sediment at the bottom.

Frequently asked questions