How To Make a Yeast Starter For Beer, and Simplify Your Brew Day

Jan 2022 | Last modified: September 19, 2023 | 9 min read | By Alex Goldberg

making a yeast starter

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Every beer needs yeast. It’s an instrumental, if not the most important ingredient in your beer. Because without yeast, there is no beer.

Yeast plays an important role in the aroma and flavor profile of beer more than you think. Fortunately, using a good yeast starter is an inexpensive and easy way for a homebrewer to improve the overall quality of their beer.

You can certainly use individual dry yeast packets, but the benefits of learning how to make a yeast starter will far outweigh the time and care it takes to create it.

What is a Yeast Starter?

A yeast starter is basically a small batch of unfermented beer (but don’t drink it!) with a low specific gravity.  The purpose of a yeast starter is to simply grow more healthy yeast over a period of time.

For lower gravity beers (1.040) a single dry packet of yeast can be used and is more than enough to get the job done.  But when brewing lagers and high gravity beers (1.060), a single packet of dry yeast just won’t cut it.  You could add an additional pack but it’s not recommended.

Making a yeast starter a day or two ahead of brew day will increase the cell count and ensure that you have enough healthy yeast to have a quick and complete fermentation.

Why Should You Use a Yeast Starter?

Converting wort into beer is a heavy job for yeast. It involves a lot of labor to have a quick and clean fermentation process. A yeast starter will guarantee the yeast is alive and well, which will give a boost to the fermentation to make sure the conversion is successful.

A package of dry yeast usually contains only enough yeast cells for a five gallon batch of brew, with a 1.048 original gravity reading. When the volume or gravity increases, additional yeast is necessary. The stronger the type of beer that is being made, the more yeast is needed.

In addition, the older the yeast package, the fewer number of viable yeast cells exist. For these reasons you need to make sure you have enough yeast to get the fermentation party going and keep it going.

There are many other benefits of using a yeast starter:

  • Prevent off-flavors
  • Faster fermentation
  • Saves Money
  • Unlike some dry yeast that has been sitting around dormant, this active yeast leads to healthy fermentation

Yeast Starter Ingredients

Here is a list of the ingredients that will be needed for a yeast starter:

  • Water
  • Dry malt extract (DME)
  • Yeast pack
  • Yeast nutrient

Yeast Starter Equipment

Below is a list of the yeast starter equipment that you will need:
  • Sauce pan with lid
  • Large enough vessel to hold the volume of the starter – A flask is recommended, but a glass growler, large canning jar, or even a vase
  • Sanitizer like Star San
  • Aluminum foil or foam stopper
  • Digital scale or measuring cup
  • Funnel
  • Thermometer (Optional)
  • Stir-plate (Optional)

Using DME To Make a Yeast Starter For Homebrew

Although you can use a Erlenmeyer flask to boil the wort on a stove-stop, these directions are for boiling in a separate pot and then transferring the cooled liquid to the flask.

The steps below will be the same for all starter sizes, but the amount of DME and water will vary depending on the size of the starter you are making, and the amount of beer you are brewing.  To remove the guesswork, you can use a yeast calculator to easily get the correct numbers.

But before you begin, make sure all your equipment is sanitized, including your yeast starter glass vessel, the funnel, and aluminum foil or foam stopper.

Here are the steps after determining the starter volume for a volume of 1-liter

  • 1. Measure water volume
  • 2. Measure DME/yeast nutrient
  • 3. Boil
  • 4. Cool
  • 5. Transfer
  • 6. Pitch the liquid yeast
  • 7. Stir/Shake
  • 8. Add to the wort

1) Add Water To a Sauce Pan

Start by adding approximately 1-liter of tap water to a sauce pan.  You can a little extra to make up for some boil-off evaporation that will be lost during the boil.

2) Measure DME and Yeast Nutrient

Use a digital scale and measure 3.6-ounces of Dry Malt Extract (DME). Add the DME and approximately 1/4-teaspoon of yeast nutrient to the DME, then add to the water.

Mix well.

3) Boil

Bring the DME/water mixture to a gentle boil for 15 to 20 minutes, while keeping the lid on. Keeping the lid on will help with losing too much liquid from evaporation.

Stir with a spoon or whisk and be on the look-out for boil overs.

4) Cool

Let the mix cool down until the pan is cool to the touch. You can do this by keeping it covered and waiting a few hours, or you can place the saucepan in an ice water bath and it will cool much faster.

Ideally the starter wort temperature should be between 68° and 75°F.

5) Transfer to a Flask

Pour the cooled starter wort into a clean and sanitized flask, or another sanitized glass vessel like a growler or milk jug.  If necessary, you can use a funnel to make the transfer clean and avoid a messy spills. Just make sure the funnel is sanitized too.

Cover with a piece of sanitized aluminum foil or foam stopper.  Using either one of these will prevent bacteria from getting into the wort, but will still allow for oxygenation.

6) Pitch the Liquid Yeast

Carefully pitch the liquid yeast into the flask with the wort.  Cover with a sanitized piece of aluminum foil or a sanitized foam or rubber stopper.

7) Stir, Stir, and Stir Again

Now you need to aerate and introduce oxygen to the yeast starter. These yeast cells need oxygen for the cells to reproduced.  The least expensive way is to just give your flask or vessel a good stir and shake every time you walk by.

Or for a more hands-off approach, but a more expensive option, you can purchase a stir-plate. A stir plate is electric and uses magnets to create a vortex, which automatically introduces oxygen and “stirs” the wort continuously for the 24 to 48-hours or so, while keeping the yeast in suspension.

Have a look at our review page of a few homebrewing stir plates if you need any help when you are ready to buy.

8) Add the Yeast Starter to the Wort or Store in a Refrigerator

And that’s it!

You have a few choices on how to use your starter. If you want to use it within 24 hours before you brew, you can pitch the entire starter into the beer fermenter. It is recommended that the starter be at the same temperature as the wort you are pitching into.

If you plan to wait longer than 24 hours, chill the starter in the fridge in order to drop the yeast out of suspension. When you are ready to use it, take it out, pour off (decant) most of the liquid, making sure not to dump the yeast cake with it.

Then you need to re-suspend the yeast by swirling vigorously, then allow it to come to room temperature before pouring it into fresh wort.

We don’t recommend waiting longer than a week to use this starter. Over time the yeast becomes inactive and will not serve the intended purpose. You will have to start all over again.

Frequently Asked Questions

Can You Make a Starter With Dry Yeast?

You could, but you really don’t need to. Some manufacturers of dry yeast recommends that you re-hydrate before pitching, while others recommend just pitching the dry yeast directly into the wort.

How Long Before Brewing Should I Make a Yeast Starter?

You should plan on making the starter at least 24 hours before brew day.  This will give plenty of time for the cells to reproduce and ensure a strong healthy yeast for fermentation.

How Do I Know My Yeast Starter Is Working?

Just like your normal wort during fermentation, you will see some of the same characteristics with this mini batch of beer.  You will see some bubbles and the yeast particles floating around.  Eventually there will be a layer of yeast cake at the bottom of the vessel.

Can You Make a Yeast Starter Without a Stir Plate?

Yes you can. A yeast starter need to be shaken and stirred many times during the 24-hours so it can be oxygenated so the yeast cells can grow.

A stir plate is a good idea if you often use a yeast starter when you brew.  If you don’t have a stir plate, just give the flask or vessel a good swirl every time you walk by it for the next day or so.

Final Say

While adding time to your home brewing process, making your own yeast starter allows for much more control, ensuring you have strong healthy yeast for the most complete and best possible fermentation.  Not to mention that it can save you some money in the long run.

This added step does increase the time it takes you make your own brew. Plus, it come with risks, namely an increased risk of contamination if you aren’t careful.

But if your equipment is properly sterilized, then there is no reason why making your own yeast starter wouldn’t improve the quality of your home brew.

So the next time you plan on brewing a lager or a strong, high-gravity beer, go ahead and use a yeast starter instead of the usual liquid smack packs or dry packets of yeast.

Happy Brewing!

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