When active yeast -- a type of single-cell fungus -- is combined with warm water, the reaction causes bread and other baked goods to rise. Other recipes, including those for beer and wine, often call for deactivated yeast. When yeast becomes deactivated, it dies and is then used mainly as a flavoring. It is possible to create deactivated yeast at home, through a process that is time-consuming but worth the effort.
Dampen a paper towel with rubbing alcohol. Use it to wipe down the outside, inside and lids of two glass jars. Set the jars upside down on another piece of paper towel until they are ready for use.
Pour 2 pints of water into a medium-sized cooking pot. Bring the water to a hard boil for 4 to 5 minutes. Remove the water from the heat, and allow it to cool to approximately 100 degrees Fahrenheit -- as indicated on a cooking thermometer.
Pour the cooled water and two packets of dried brewer's yeasts into one of the glass jars. Stir the water with a wooden spoon until the powdered brewer's yeast is completely dissolved.
Pour 1 pint water into a medium-sized cooking pot. Bring the water to a hard boil, and add 1/4 cup dried malt extract. Stir the water and allow it to continue boiling for an additional 3 to 4 minutes.
Remove the pot from the heat, and allow it to cool to approximately 100 degrees Fahrenheit. Pour the cooled malt extract mixture into the jar that contains the brewer's yeast.
Stir the ingredients until they are well-incorporated, and cover the jar with plastic cling wrap. Allow the brewer's yeast to remain for approximately 1 hour, or until the yeast begins to show signs of life -- such as budding, churning and foaming.
Pour the entire contents of the jar into another medium-sized saucepan, and bring them to a boil over high heat. Allow the mixture to boil for at least 5 minutes. During this time, the heat deactivates the brewer's yeast. Remove the pot from the heat, and allow it to cool slightly.
Pour the deactivated yeast into the second glass jar. Cover the jar with the lid or plastic wrap and refrigerate.
Purchase brewer's yeast packages that are far away from their expiration date. This ensures the yeast is fresh and will bud effectively.