A yeast starter is a way to multiply the number of active viable yeast cells you pitch into your wort. Underpitching, pitching too few yeast cells, can cause slow or incomplete fermentations and off flavors from strange yeast behavior. The larger your batch of beer and the higher your original gravity the more yeast you need to pitch. As a general rule of thumb we recommend two packs of yeast or doing a yeast starter for any 5 gallon batch of beer that is over 1.060 starting gravity.
To Make a 1 Liter Starter You Need:
- 4oz Light Dried Malt Extract
- 1 Liter of Water
- A small pot
- A 1 or 2 Liter Erlenmeyer Flask with Stopper
Making a yeast starter is a fairly simple process. You start by making a small amount of un-hoped wort with a gravity of approximately 1.040. For a 1 Liter starter, the size used for most 5 gallon homebrew batches the recipe is 4oz of Dried Malt Extract and 1 Liter of water. Briess Golden Light or Muntons Extra Light DME are the most common types used for this.
Combine your DME and water and bring the wort to a boil for 5 minutes. This insures your wort is sterile before pitching your yeast.
After boiling allow your wort to cool to safe yeast pitching temperatures, between 60 and 80 Degrees Fahrenheit. Using an ice bath or sealing your pot with a lid and placing it in a refrigerator can help speed the cooling process.
Once your wort has cooled pour it into a sanitized Erlenmeyer Flask. If you use a funnel for this make sure to sanitize the funnel as well. Swirl and shake the flask for 10 minutes to oxygenate the wort.
Pitch your yeast into the starter and seal with a stopper. If you have a stir bar and plate now is the time to start spinning. If you don't have a stir plate make an effort to give your flask a swirl as often and you're able to keep the yeast suspended and oxygenated.
Different yeast will take different amounts of time to kick-off and ferment the starter. Plan on a minimum of 18 hours and up to 36 hours for the starter to reach "high krousen" or the peak of fermentation activity. High Krousen is the ideal time to pitch your starter into your fermenter.
To pitch your starter remove the stopper from the flask, give the starter a good swirl to make sure all the yeast is stirred up, and pour the entire solution into your fermenter.