If you are not treating yeast kindly, your home brewed beers are probably a hit or miss. A yeast starter is used to provide a jump start so fermentation is a success. This is done by increasing the cell count before brewing beer. It can be compared to a runner and the preparation they go through before a race. The runner will stretch and take a few trial runs prior to the big race. This ensures strength and stamina are at 100% and helps to avoid injuries. That is exactly how your yeast works with the addition of cloning themselves. You do not want to put strain on your yeast. Unless, you want off flavors in your beer.
There are a few reasons why a yeast starter would be created:
- Original Gravity is above 1.060 (some yeast can handle higher gravity beer).
- The yeast is a little old and needs revived.
- A quicker fermentation is needed.
What do you need?
- A stir plate (you can go with a commercial grade or homemade)
- Magnetic stir bar
- Cleaner and Sanitizer
- DME (Dried Malt Extract)
- Measuring cup
- Erlenmeyer Flask (1000ml for a 5 gallon batch)
- Sauce pan
- Aluminum foil or Foam stopper
Before starting, you need to figure out what size starter needs to be created. These are ratios for 5 gallons batches. If you are brewing larger batches, just calculate the difference.
Standard 5 Gallon Starter: 2 cups water to 1/4 cup DME
Rejuvenate Old Yeast: 4 cups water to 1/2 cup DME
High Gravity Beer: 4 cups water to 1/2 cup DME
1. Before starting, sanitize everything that will come into contact with the starter. This may be slight overkill since we will boil the wort. However, it is another safety net from infection.
2. In a sauce pan, mix the needed water to DME ratios. Make sure you mix this well to break up any clumps.
3. Bring to a boil for about 10 minutes. This will sterilize anything that still needs sanitized. It will also help create a nice liquid wort.
4. Pour the solution into your Erlenmeyer Flask (the larger the batch…the larger the flask you will need) and immediately chill the solution to room temperature.
*Do not worry, these flasks will not crack. They are designed for extreme temperature swings.
5. You now have a wort with an Original Gravity of around 1.040-1.045. This is the optimal range needed for yeast growth.
6. Using a sanitized funnel, pour the yeast into the flask and cover the top with a sanitized piece of aluminum foil. This will allow CO2 the ability to escape. Do not use an airlock. The starter needs the exchange of O2.
7. Put you hand over the foil to prevent a mess and shake the mixture of wort and yeast for 30 seconds. This will oxygenate
8. Drop a sanitized magnetic stir bar into the flask and set your starter wort on the stir plate. Fire it up!
9. After about 2 days, the yeast have consumed all of the sugars/oxygen and generated new cells. Your yeast army is ready!
Brew Day Options:
Option 1 – Save For Later: If you are not going to pitch the yeast that same day, just store it in the refrigerator. However, make sure you leave the foil on. On brew day, bring the yeast to room temperature before pitching. Decant about 80% of the liquid that is sitting on top of the yeast cake. Swirl the flask to create a slurry and pitch.
Option 2 – Use It Now: Make sure it is at room temperature. Decant about 80% of the liquid that is sitting on top of the yeast cake. Swirl the flask to create a slurry and pitch. Pitch the starter right into your wort. It will start attacking immediately. Some people skip the decanting and pitch the entire starter. Just make sure you smell it first to rule out possible off flavors.