Homebrew Recipe: Harvesting Yeast From Beer Bottle Dregs

Last week I shared how to get yeast from potato boil water. This week it’s all about how to get yeast out of the bottom of a bottle of beer. Harvesting yeast is a green choice but also lends itself to really exciting experimentation. This is also a great way to cultivate a yeast you particularly like.

How To Cultivate Beer Yeast From Bottles

Here’s the process. Up front: this does not work with mass produced beer. This is a great method for local craft beers and friends’ homebrews.

The Process

Sanitize

Don’t open the bottle from which you want to harvest. Instead, sanitize the entire unopened bottle and place where it will not get contaminated. Sanitize your opener, too, along with a small square of aluminum foil.

Open the bottle and spritz with a solution of sanitizer and water. Dump most of the beer, leaving the sediment at the bottom (the “dregs”). Spritz again.

Cover the bottle with the dregs in it with the sanitized square of foil. Allow to warm up to room temperature. You’ll know you’re at the right temp when the bottle doesn’t feel cold to the touch. Always touch test where the dregs are, not higher on the bottle.

Start

Use a sanitized funnel and spoon to transfer about a teaspoon of wort onto the dregs. Plug using a stopper with an airlock. You should see fermentation in no more than 80 hours.

Transfer and Cultivate

After three days, and once you can see that fermentation has started, sterilize a second beer bottle. Pour in a tablespoon of fresh worth. Spritz the bottle that is holding your yeast and then pour it into the new bottle. Pop the stopper and lock into this bottle after sanitizing.

Wait three days. Make more wort, put it into a santized beer bottle and add a half teaspoon of nutrient. Transfer again by pouring using the sanitation directions above.

Wait five days and check for a head. If you’ve got a foamy head you’re good to taste test. The liquid in the bottle should taste like beer. If it doesn’t, you’ll need to toss your experiment. But if it tastes like beer you can move onto the next, and final, stage.

Put the beer bottle in the fridge and allow it to separate over night.

Sanitize a one gallon carboy and stopper. Make a half gallon starter. Pour the liquid off the yeast and only add the yeast to your starter. Pop in the stopper and airlock. Once you have activity you can pitch this into your next batch of homebrew.

Recipe modified from: Jay’s Brewing

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