Fermented Foods Part 1: Sourdough Starter

Lately I’ve been trying my hand at different types of home-fermented foods. I’ve been learning a lot and really enjoying it! So I decided to start a little mini-series on “Fermented Foods.” This post on sourdough starter will be the first installment, because the starter is where my enjoyment of home-fermenting all begins. I hope you get inspired to give some of these a try for yourself!

What is Sourdough Starter?

A sourdough starter is basically a mixture of flour and water that has accumulated the “wild” yeasts and lactobacilli (lactic acid) bacteria from the environment around it. These guys work in a symbiotic relationship. Enzymes in the flour break the starches into sugars, and the yeast and bacteria feed on these sugars. The lactobacilli break the sugars down into lactic and acetic acid (giving the sour flavor). At this point the pH drops and most microorganisms can’t survive… But this is where the wild yeasts thrive. They continue converting the sugars into carbon dioxide and ethanol. This in turn generates the bubbling fermentation (releasing CO2) that makes the dough rise.

A sourdough starter typically needs to be refreshed every 12 hours or so with more flour and water, so the fermentation process can continue. Left too long “unfed” the yeast and bacteria will convert all of the sugars, the bubbling will stop, and you will be left with a layer of ethanol on top of a goopey flour and water sludge. The alcohol smell coming from an old starter is easy to recognize. The good news is that the yeast and bacteria are still present, and with a little care they will come bubbling back to the forefront.

Sourdough starter - old
Sourdough starter – old with alcohol layer

The OTHER fact that I find super interesting about sourdough is that the flavors will differ depending on region. And much of that is due to what wild yeasts are present where the starter is “living”!

If you want to dig into the science more, there are a lot of great articles out there. Here are a few for you to start with:

Starting the Starter

The summer after Hubby and I first got married, we initiated a sourdough starter. Well, I should really say that Hubby initiated it. This was something he had dabbled with before, but with limited success. So he decided to try again. And, I am pleased to say, that same starter is still going strong today, more than 5 years later! In fact, it is more active and flavorful than ever! We hope to have it in the family for many years to come 🙂

Did you know – there are some bakeries that have been using the same sourdough starter for over 100 years?

Our starter lives in the fridge most of the time. This way, it doesn’t need to be continually refreshed. Instead, it stays dormant for a few weeks, then when we need to use it we pull it out and “wake it up”. I would go through so much flour if I tried to keep the starter out on the counter and fed. Not to mention the waste accumulating at every split. (There is no way I am industrious enough to use up every bit of left-over starter from a twice-daily split. Although I do intend to share some ideas with you on how to use those leftovers efficiently.)

By today, the starter is so healthy, that I can pull it out of the fridge, refresh it 2-3 times, and it is VERY active and ready to make bread. In fact, recently I was making a few loaves and after just about 4 hours they had over-risen and were spilling over the sides! A quick re-shaping and they had re-risen and were ready to bake in under an hour. When we first began using our starter we could sometimes let the loaves rise all day and they would still be barely large enough to bake!

Sourdough starter - bubbles/refreshed!
Sourdough starter – bubbly and refreshed!

Why Sourdough

Why sourdough, you may be asking? There are so many reasons I can think of. Some may be more inspiring to you than others, so I’ll lay out a few to see if any of them resonate…

What if you can’t find yeast?

It wasn’t until 2020 that I ever thought this would be a possibility. But with the COVID-19 pandemic that hit in early 2020, many essentials were wiped out of the grocery stores, including yeast! Thankfully for us, this wasn’t a cause for concern – we have plenty of our own yeast culturing away in our fridge.

This was a great time to share a starter with others – I read posts about people sharing fresh portions of their starter with friends and neighbors. Something I’ve also done in the past for friends that wanted to give sourdough a try. You can also spread a thin layer out on parchment, let it dry, and mail some dried starter chips! (I did this to share with a friend who lives in a different state, who couldn’t find yeast during this time.) This is also a great way to put your starter “on hold” or simply keep some as a backup. King Arthur has a great article detailing preserving a starter by drying it down, and also how to bring it back to life. Check that out here.


Did you know sourdough is easier to digest? The fermentation process the dough goes through starts breaking down the gluten in the flours. So by the time it reaches your digestive track, part of the work has already been done!

For some people with a gluten sensitivity (not an allergy), eating a true fermented sourdough may be enough for you to get back on the bread train. Another diet sourdough fits well with is the low FODMAP diet. This is a diet that I have to follow, at least in part, or else reap the painful digestive consequences. Here again, fermented sourdough breaks down those components that can be more difficult to digest, and makes the bread “gut-friendly” and low FODMAP approved!

(Kate Scarlata has a fantastic site all about the low FODMAP diet. If you have any type of digestive uncomfort, I highly recommend you investigate FODMAPs further.)

Kitchen Science

Keeping a sourdough starter, and making sourdough loaves, is a bit like a science experiment in the kitchen. So maybe it appeals to the science nerd in me… I actually feel this way about all homemade fermented foods. There’s something so fun about it!

Truly from Scratch

I don’t know about you, but I like knowing where my food comes from, and exactly what is in it. This is why I cook and bake from scratch as much as possible, using just the basic unprocessed ingredients. I’ve also been through a few health journeys where it was important that I track everything I eat, and know just what the ingredients were. So cooking/baking from scratch was really essential during these phases of life. And they are habits that I have picked up, developed, and grown to love.

Beautiful Loaves

Have you ever seen a beautiful artisan sourdough loaf? If that isn’t enough to give you some sourdough inspiration, well then there’s not much more convincing I can do :). Take a look at some of these beauties we have made over the years.

Finally – the Sourdough Starter Process

OK, finally after all that rambling of explaining science and trying to inspire you, we can get to the good stuff. The sourdough starter itself – how we started it and how we keep and use it today.

Our favorite reference for sourdough recipes and instruction is Peter Reinhart. He’s written some great bread books that we base many of our recipes on. Here are two of our favorites:

The Bread Baker’s Apprentice
Crust and Crumb

One thing to point out is that for starter and bread baking, all measurements are in grams. Gone are the cups and teaspoons of baking. Bread making is a science, and requires the correct proportion of ingredients to get the rise and crumb you are after. Weighing out those ingredients is a much more accurate way to keep tabs on things.

Beginning a Sourdough Starter

Getting started with a sourdough starter is a 2-part process. The first is to make the seed culture. From that seed culture you make the barm, which is the “starter” that you will keep, use, and refresh.

For the seed culture, mix flour and water, and let it sit out partially exposed to the air. Yep, that’s basically it! You may see some people that recommend adding fruit juice to help get the process started, but it’s not really necessary. The key is in the process – feeding regularly every 24 hours, and letting the bacteria and yeast get to work!

For the barm. You can start the barm – which is the starter you will keep and maintain hereafter, once the seed culture has doubled after the day 4 refreshment. You are still just adding more flour and water, and fermenting! See – this sourdough starter thing is super simple. The biggest requirement is a little patience :).

Below is a basic recipe, but for a detailed recipe and step-by-step instructions, as well as many more tips on sourdough and bread-baking in general, I recommend taking a look at Mr. Reinhart’s book The Bread Baker’s Apprentice (start on page 229).

Jump to recipe.

Maintaining Your Sourdough Starter

Maintenance of the starter, or barm, is pretty easy once it is established. As I mentioned earlier, we keep ours in the fridge, and I pull it out every couple of weeks to refresh it. Since I am only doing this every couple of weeks, I will typically feed it 2-4 times before either using it or putting it back in the fridge.

Sourdough starter - beginning refresh
Sourdough starter – beginning refresh
Sourdough starter - more bubbles
Sourdough starter – more bubbles

Each time is the same – take a portion of the starter, and add half its total wait in both water and bread flour, so you have doubled the weight of the starter after feeding. If it has been a while since I refreshed the starter, it will have a strong alcohol smell, and I use this as a gauge while feeding. When that alcohol smell is gone, and the yeasty smell is more predominant, I know I’ve fed it enough times that all those little yeast and bacteria guys are happy again :).

Sourdough starter - bubbles/refreshed!
Sourdough starter – fully refreshed!

I keep 400g of starter, so to refresh I typically transfer 200g to a new container, add 100g water and 100g bread flour, and mix. Sometimes, especially if the starter is older, I change this up a little. I will transfer only 100g of starter, and add 50g each water and bread flour. After ~12 hours, I will just add to this, 100g each water and bread flour, and let it ferment another 12 hours.

Sourdough starter - 100g of old
100g of old starter
Sourdough starter - add water
Add water to the starter
Sourdough starter - add flour
Add flour to the starter
Sourdough starter - mixed and ready
Sourdough starter – mixed and ready to bubble

After this point I can split it, double one half to put in the fridge for next time, and then move forward working with the other half. Depending on what I plan to make, I may just use the starter that is left, or I may double it first, use it to make a firm starter, etc. The point is, as long as you are feeding by approximate doubling on a regular schedule, the method for keeping and using a sourdough starter is fairly flexible.

Using Your Sourdough Starter

This is totally a teaser, because I am not going to give you many specifics on using the starter here. Those posts will follow. But I can tell you that aside from bread, I have tried quick breads, crackers, brownies, pancakes, energy bars, pizza crust, english muffins, and the list goes on. Sourdough starter has many uses! So if you don’t have one bubbling away on your counter or in your fridge – today is the day to get it started!

Sourdough Starter: Seed Culture and Barm

Category: Bread

Cuisine: All American

Sourdough starter - bubbles/refreshed!

Step-by-step instructions for getting your very own sourdough starter going. This is the beginning of an exciting baking adventure!


    For the Seed Culture
  • Bread flour, 18oz
  • Water, 18oz at room temperature
    For the Barm
  • Bread flour, 16oz
  • Water, 16oz at room temperature
  • Seed Culture, 7oz


    Seed Culture
    [Day 1 (Sponge)]
  1. Mix together 4.25oz bread flour with 6oz water.
  2. Cover with plastic wrap and and let ferment on the counter for 24 hours.
    [Day 2 (Feed/Ferment)]
  1. Add to Day 1 sponge 4.5oz bread flour and 4oz water.
  2. Mix until well incorporated.
  3. Cover with plastic wrap and let ferment on the counter for 24 hours.
    [Day 3 (Feed/Ferment)]
  1. Discard half of the starter.
  2. Add to the remaining half, 4.5oz bread flour and 4oz water.
  3. Mix until well incorporated.
  4. Cover with plastic wrap and let ferment on the counter for 24 hours.
    [Day 4 (Feed/Ferment/Finish)]
  1. (See Notes)
  2. Discard half of the starter.
  3. Add to the remaining half, 4.5oz bread flour and 4oz water.
  4. Mix until well incorporated.
  5. Cover with plastic wrap and let ferment on the counter until doubled (up to tripled) in size, 4-24 hours.
  1. Once the seed culture has doubled after the Day 4 feeding, you can start the barm.
  2. Mix together well the 16oz bread flour, 16oz water, and 7oz seed culture. Make sure all the flour is hydrated and the seed culture is evenly incorporated.
  3. Cover with plastic wrap and let ferment at room temperature until bubbly (~6 hours).
  4. Refrigerate at least overnight, and up to 3 days.
  5. Your barm is ready to use as your levening in a sourdough bread recipe!


Before Starting Day 4 - The sponge should have at least doubled since the previous feeding on day 2. If it has not, allow it to sit out another 12-24 hours until at least doubled, before proceeding to Day 4.

After Day 4 Fermentation - Once the starter from day 4 has at least doubled, you are ready to move on to the barm.

The barm will become more active and flavorful over time, so keep the same barm going as we have done, and it will continue to reward you with better leavening action and deeper flavors.

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