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Feed your gut with sourdough

Ask the Dietitan, General health, Gut microbiome health

Feed your gut with sourdough

If you take care of your sourdough properly, it can live forever!

This guest post is written by Moe Brandi who holds an MSc in Food Innovation and Health and specializes in bioactive components in foods that improve human health. Her work centers around natural ingredients and a strong belief that food can be healthy, delicious, and gratifying at the same time.
Sourdough is something everyone is talking about right now. It's a historic bread-making technique, and we are now more than ever seeking the very fundamental cooking practices, life giving, and comforting foods.




Introducing sourdough

Sourdough bread is a mix of science, craft, and a little bit of magic. Your sourdough starter is made from only two basal ingredients, flour and water (+ patience). When combined, these two ingredients will attract yeast from the surrounding air over a few days of fermentation. 

As mentioned above, sourdough is essentially fermented flour. More specifically, it is an active culture of both lactic acid bacteria and wild yeast from the environment. This culture creates an airy baked bread, but also provides a welcoming wine-like acidity (from the lactic acid produced by the bacteria) that counteracts the sweetness from the flour perfectly. 

If fermented properly with the right balance of yeast to lactic acid bacteria (fermentation time matters), the sourdough will provide elasticity to your dough and an open crumb (i.e. air pockets and less dough per inch). An open crumb is often what defines sourdough bread in comparison to bread fermented with commercial yeast - an ingredient that will make your dough rise very predictably and quickly. 

We will go through the basics of making your own sourdough in this blog post, from understanding the basic principles to successfully creating light, moist, and flavor-balanced bread. We hope that this blog post will kickstart your interest in home-baked bread, and will give you the knowledge to evaluate and improve your baking.


Choosing the right flour

Flour is the essential ingredient in baking. We recommend that you look for high extraction flours with a protein content between 10-14%. 

The extraction rate is the percentage by weight that is extracted from the whole grain to make flour. This means whole wheat flour contains 100% extraction of the whole grain and white flour is about 70% extraction. A lower extraction (i.e. white flour) makes your dough more elastic and easier to handle in the mixing and shaping process.  

In comparison, whole wheat flour contains the nutritious gem and fibrous layers of the grain, but will also contain less gluten, which could result in a flat and sticky bread in the beginning, if you are not an experienced baker. Whole wheat flour also enhances the activity of the sourdough, which can therefore make it difficult to control to obtain the right flavor and texture balances. 

If possible, look for the highest quality, organic, and local flour. Not only will you be supporting local farmers, but also increase the nutritional value of your bread.


Sourdough and diabetes

Sourdough bread is overall a better choice to include in diets for diabetes in comparison to other bread fermented with commercial yeast. This is because sourdough bread is considered easier to digest, contains nutrients beyond the ingredients themselves due to the fermentation, it has a lower glycemic index (and lower FODMAP score) and is therefore less likely to spike your blood sugar. 

Going a little bit more into detail, the lactic acid produced by the bacteria in your sourdough starter culture may neutralize phytates present in the whole wheat flour, which will increase the absorption of nutrients during digestion.

Furthermore, it’s shown that lactic acid produced during the fermentation can lower the postprandial glucose and insulin responses in humans. It may also change the gluten protein formation, making it easier to digest than regular bread made without a sourdough starter, but more evidence is needed to fully back up this statement.

If you want to read more about the differences between sourdough and commercial yeast when it comes to your health and digestion, read here


Sourdough equipment list (adapted from Gotzbread): 

Must-haves to start baking:

      • Oven
      • Mixing bowl
      • Small glass jar or container for your sourdough.
      • Bread knife or blade
      • 1.5 - 2.5 liter airtight containers to ferment your dough (at least one)
      • Measuring scale


Necessary equipment to get the best results:

    • A baking stone, baking steel or an iron cast pan
  • Pastry card
  • Proofing/bread basket 
  • Baking cloth
  • A cheap kitchen/food scale (10kg/1g) can be found at Amazon or Target. 

  • Starting your mother sourdough 

    NOTE: If possible, we highly recommend measuring your ingredients by weight (grams or ounces) using a kitchen/food scale; this will be more precise than measuring with cups. When it comes to baking, accuracy in measurements is critical to success, and the single most accurate way to measure your ingredients is by weight. The more precise, the better fermentation and first-time experience.

    The approximate corresponding amounts in cups are added in parentheses below, without taking into account the difference between dry and liquid measurements in the conversion. Therefore, if you decide to use cups, we recommend that you spend some more time evaluating the consistency of the sourdough, the development of the sourdough/fermentation, and the consistency of the final dough.

    Weight and measurements in the recipes below are inspired by Gotzbread (Lille Bakery located in Copenhagen). 

    Day 1:

    Use your fingers to mix together flour and water until thoroughly combined (you can use other amounts than mentioned in this recipe, as long as you keep the proportion of flour to water 1:1):

        • 25g whole wheat flour (⅛ cup)
        • 25g wheat flour (⅛ cup)
        • 50g water at ~ 80 degrees and filtered if possible (¼ cup)

    When done mixing flour and water together (it should have the consistency of a thick paste or batter similar to peanut butter), place the lid lightly on top. It should not be completely enclosed - you can also choose to cover the container with a towel instead. Let sit at room temperature on the kitchen counter for 24-48 hours. 

    Following day(s):

    Check your sourdough every 24 hours. After a couple of days, the sourdough will start to bubble lightly - it will have a sour smell and taste. When you see the bubbles (a sign of culture activity) it is time to refresh or re-feed your sourdough,

    Refreshing/refeeding your sourdough

    If you want to make sure that the sourdough is ready for refreshing, taste it with your fingertip. If it is not sour, it is not ready to be refreshed. If it does taste sour, follow the simple instructions below: 

        • 1g of your mother sourdough (0.035 ounce or a fingertip)
        • 40g water (⅓ cup)
        • 40g wheat flour (⅓ cup) 

    Mix sourdough, water, and wheat flour together with your pointing finger and let sit for another 12-18hours (best to do this refreshing step in the afternoon or evening - then the sourdough is ready next morning)

    The sourdough cycle: how to maintain it

    If you do not bake often, put your sourdough in the fridge after mixing your final bread dough (see below). When you are ready to bake, you will have to take your sourdough out from the fridge and refresh it. Then it will be ready for the following day. After refreshing a sourdough stored in the fridge, you can discard the rest. 
    If you do bake often, we recommend that you keep your dough at room temperature and refresh it daily using the recipe above. 

    The sourdough cycle is defined as the way that you refresh, wait, and prepare your sourdough starter to make your final bread dough. 

    Mixing your dough

    After the refreshed sourdough has fermented for another 12-18hours, you will have to make it ready to mix into your final bread dough. Follow the instructions below:

        • The sourdough after 12-18hours
        • 40g lukewarm water (⅓ cup)
        • 40g white wheat flour (⅓ cup)

    Mix all the ingredients together and let sit for 1-2 hours. When it begins to lightly bubble, your sourdough is ready and you have ~ 160g. 

    See ingredients for the final bread dough below (serving size: 2 loafs or 12 buns):

        • 930g wheat flour (7 ½ cups)
        • 90g whole wheat flour (¾ cup)
        • 730g (80 degrees F) water (3 cups)
        • 120g of your (160g) sourdough (1 cup)
        • 12-24g salt (~ 1 - 1.4 tablespoons)

    Measure out the water first. Add your sourdough (it should float). Mix the flour and salt in and mix your dough together with your hands until it is evenly mixed. The dough should feel lukewarm. It is helpful to have some water ready on your side to remove the dough from your fingers after mixing. Leave the dough in the bowl at the counter with a wet towel covering it. 

    For the next three hours, you need to fold your dough every hour. This is done by first stretching the dough, then folding it over itself very gently. You should do this 4 times, for all 4 corners: 

        • 1st hour after you have mixed your dough: Fold it!
        • 2nd hour after you have mixed your dough: Fold it! 
        • 3rd hour after you have mixed your dough: Fold it! 
        • 4th hour after you have mixed your dough: Add a little neutral oil to two containers. Divide the dough in two parts and put every part in two separate containers. Fold the dough again gently so it becomes like a ball in the container. Store away in the refrigerator overnight at 39.2 degrees F (airtight, with completely sealed containers).  


    Baking sourdough buns 

    1. The following day, begin by turning on the oven at 475 degrees F - it should be very hot when you put your buns in. Make sure to have your baking stone or steel in the middle of the oven when you turn it on and a baking tray in the bottom of the oven. Your baking stone or steel will make sure to retain the heat in the oven when you add your buns or bread.

    2. Sprinkle flour on the table. Next, open your containers with the dough stored in the fridge from yesterday and add flour on top of it as well. Release the dough from the sides of the container with the pastry card, turn the container upside down so the dough lands on the table with the flour side down. 

    Depending on the size of your container, divide the dough in two halves with your bread knife. Every half, you cut into 3 buns (square shaped) - no need to form them by hand.

    3. When you are ready to bake your buns, turn off the fan of the oven and then slide your buns on to the hot baking stone or steel. 

    Add a little water into the tray in the bottom of the oven, this will create a lot of steam and make sure that the surface of your buns will not dry out - thereby, your buns are able to rise properly.

    4. Open the oven after 10 min of baking so the steam can get out and caramelization/browning of the buns can begin. Close it again and continue to bake the buns for another ~ 5 to 10 min until they look ready (light brown to darker brown, whatever suits your taste and eye).

    If you want to make bread loaves, follow the same procedure for the buns, but shape your loaf using the bread basket with a baking cloth in it (sprinkled with flour) - let it rest in the basket for 5-10 min before baking. 

    Remember to use your bread knife or blade to score your dough - this will allow it to expand during baking. Bake it for a little longer than the buns after releasing the steam from the oven. 

    When you are getting more experienced, you can easily play around with adding seeds (sesame and pumpkin seeds are some of my favorites), porridge, other types of heirloom wheat varieties like Oland wheat, Emmer wheat, Spelt, Kamut or rye.

    Evaluating your bread

    Cut your finished buns or bread and take a look inside.

    If the fermentation went well, your buns will have air bubbles (open crumb), meaning that the gluten protein bonds have not been broken down entirely by the sourdough culture. Flat and very sour tasting bread are a sign of over-fermentation and too many lactic acid bacteria. 

    The balance between yeast and lactic acid bacteria is very important and also why you have to continue to refresh your mother sourdough - you don’t want to have too many lactic acid bacteria. If you have too many lactic acid bacteria in your sourdough for the final baking, you will get an excessively sour bread. 
    The slow fermentation in the fridge before shaping the bread also helps create gas and an open, delicious crumb.

    Due to the steam in the oven, the surface of the bread will not dry out during the first 10 min of baking. This will allow that the bread can continue to expand and give you that desirable thin and crispy crust/surface.