Yeast Starter – An important first step

For my first post I thought it only fitting that I start with the first step of the brewing process: making a yeast starter.

Why should you make a yeast starter?

Yeast are the most important part of the brewing process. The goal of the whole brewing process is to extract sugars from malted barley, add hops for flavor so that you end up with a sugary liquid called wort (which tastes like a hopped grain tea, in other words not really that great). Yeast is what actually turns your wort into beer! Making a starter is useful because it:

  1. Verifies that your yeast is viable
  2. Increases cell count before pitching

Number 1 is important because you wouldn’t want to pitch yeast that was mishandled during shipping and as a result is dead. Pitching dead yeast into your beer would result in delayed fermentation (since you’d only realize the problem a day or more after pitching and you’d then have to re-pitch) and potential infection. That leads us to Number 2, pitching a large amount of healthy yeast cells ensures a quick start to fermentation which can limit the chance of infection from bacteria in the environment. A large, healthy population of yeast will outcompete any small amount of bacteria that happens to make it in after the sanitation process.

When do you need a starter?

If you’re using dry or certain types of liquid yeast a starter may be optional. In the case of dry yeast you can easily pitch high cell counts. In the case of pitchable liquid yeast, they are produced to have 70-140 billion cells and is perfect for most regular gravity beers. However, in many cases a starter is not a “nice to have” but a “need to have.” You should always make a starter if you are:

  • Making a high gravity beer (>1.070)
  • Using a “smack pack”, slant or other non-pitchable yeast
  • Using a pitchable yeast that is past its “Best Before” date
  • Making a lager with lower pitch temperatures

If you are using a pitchable yeast while it’s in date on a regular gravity beer, you don’t need a starter but there’s no harm in making one so long as you use good technique. All of this assumes you’re making a regular 5 gallon batch of beer, if you’re brewing larger volumes you definitely need to make a yeast starter every time. Right now, I only have equipment to make 5 gallon batches therefore the rest of the article will be based on making a 5 gallon batch.

How to make a starter

So you’ve decided you’d like to make a starter, what now? First you have to decide how big of a starter to make. The volume determines how many yeast cells are produced in the starter: larger volume, more resources, more yeast cells. There’s different calculators online (my favorite is Mr. Malty’s) and in brewing software packages but I usually make either a 1 quart or 2 quart starter depending on what beer I plan to brew. I use a 1 quart for most regular beers and a 2 quart starter for high gravity beers (>1.070 OG).

Now that you know how big of a starter you want to make it’s time to make it! You’re basically making a mini batch of wort for the yeast to grow in. The following recipe produces a wort with a starting gravity a little over 1.020, this should work fine.

Ingredients and equipment to make a starter.

Ingredients and equipment to make a starter.

Ingredients and Equipment

  • 1 quart water (or 2 quarts)
  • 1/2 cup Light Dried Malt Extract – DME (1 cup for 2 quart starter)
  • Yeast of choice
  • 4 quart saucepan
  • Empty growler, Erlenmeyer flask or other sanitized container that is large enough
  • Funnel (not 100% necessary but does make the pouring easier)


  1. Add water to saucepan and bring to boil.
  2. Remove from saucepan, add DME and return to boil. Note: Be careful of boil overs at this stage, boil overs are messy and you lose starter wort. Monitor the pot and if it starts to boil over quickly remove from heat until it calms back down.
  3. Once you’ve returned to a nice rolling boil, let the wort boil for 10 minutes.
  4. While your wort is boiling you can sanitize the container you’re using for the starter as well as the funnel. I use Star-San to sanitize all of my equipment, but there are plenty of other options. I like it because it takes 5 minutes and doesn’t need to be rinsed off.

    Adding hot starter wort to erlenmeyer flask.

    Adding hot starter wort to erlenmeyer flask.

  5. When the wort has finished boiling, transfer to your starter container and place container in an ice bath to cool it down. I don’t usually use a thermometer for this step. I feel the container until it is cool to the touch. The goal is to get the wort down to 70°F before pitching. If you’re going to use a thermometer make sure it is sanitized. At this point anything that comes in contact with the wort needs to be sanitized.
    Cooling starter to pitch yeast.

    Cooling starter to pitch yeast.

    Pitching yeast into starter wort.

    Pitching yeast into starter wort.

  6. Once the wort has cooled to room temperature it’s time to pitch the yeast into the wort. Sanitize the mouth of the starter container and the package of yeast (I use cheap vodka or other liquor). Add the contents of the yeast package to wort.
  7. Put a stopper of some kind on the container. I’ve used a sanitized piece of aluminum foil loosely wrapped around the top, a rubber stopper and airlock or a foam stopper. Any of these will work. It shouldn’t be air-tight since fermentation produces gas and it doesn’t need to be a sterile barrier because the starter wort will only ferment for 3-4 days in this container.

    Aerating yeast starter by swirling.

    Aerating yeast starter by swirling.

  8. Swirl starter vigorously to introduce air into the solution which the yeast need to grow.
  9. Let sit in a dry, dark place that will keep the solution at around 65-70°F. In the first two days agitate the solution again every 6 hours or so. If you have a swirl plate, put it on that and forget about it. Otherwise some swirling will do the trick. Since this is such a low volume of liquid, the fermentation can happen very quickly. So don’t worry if you don’t see any active fermentation, you probably just missed it.
  10. Let the starter sit until brew day so it can settle. On brew day, the yeast should have settled on the bottom in a nice thick cake. Carefully pour off about 80% of the liquid without disturbing the yeast cake. Then swirl the solution to get everything back in solution and pitch into your fermenter with the cooled wort you just brewed.

If everything went as planned you should see activity within 24 hours and get the best fermentation possible out of your little batch of yeast. There’s loads of information out there on the internet, here are some that I like:

One Response

  1. Scott January 29, 2016

Leave a Reply