how to feed sourdough: A STEP-by-STEp GUIDE

Feeding the Sourdough Starter means providing yeasts and bacteria with water and “food” necessary to survive. Refreshment is an easy operation of kneading Sourdough, flour, and Water.

When it comes to maintaining our starter, we have to distinguish 2 types of them:

• Maintaining Refreshments are used to preserve the sourdough day by day. This type of refreshment is intended to keep our starter alive.
• Preparatory Refreshments (2 or 3) are needed to get the Sourdough ready to be used in the recipe. In this case, the primary purpose is to strengthen the yeast and stabilize its acidities (lactic and acetic).

This distinction is crucial because, as we will see, the two types of refreshments have a different proportion of ingredients and procedures.

HOW TO MAINTAIN SOURDOUGH DAILY or WEEKLY

Daily (or Weekly) refreshments are essential for keeping the Sourdough alive. It will be necessary to refresh it regularly, depending on how you store it. If you keep the Sourdough at room temperature (18°C (64°F) to 22°C (71°F)), you will need to refresh it every day, whereas if you store it in the fridge (+4°C, 39°F), you can extend its storage up to 7 days.

A second factor to consider is the storage method: It may be soaked in water or tied up; this is very important because it will impact the Sourdough characteristics and require specific flour and sourdough proportions.

SOURDOUGH STORED IN WATER 

The Sourdough is characterized by a lower acidity (absorbed by water) and higher humidity when soaked in water.

The first step to refresh the Sourdough stored in this way is to soak it in warm water at 38°C (100°F), added with 2gr/liter of sugar or fructose for 15 – 20 minutes. The water will absorb the exceeding acidity released by the Sourdough during the bath.

Once this time has elapsed, squeeze the Sourdough and knead it with these proportions:

• 1kg of Sourdough
• 1kg of Bread Flour W360 (protein around 14% – 15%)
• 300g of water at 30°C (86°F)

The dough should be well-formed, but it will not need to be over-kneaded. Once ready, roll out the Sourdough to about 1cm thick. Roll it up tightly and place it in a bowl with cold tap water (19°C or 66°F).

The ideal proportion would be to soak the Sourdough in 3 times its weight of water. Now you can keep your Sourdough at room temperature (between 18°C (64°F) and 22°C (71°F)) for 24 hours.

TIED UP SOURDOUGH

This method is highly used in many bakeries in Italy. It refers to a sourdough stored into a heavy cloth and tied up with a rope.

Following this method, you will have a more acidic Sourdough (in particular, richer in lactic acidity and with less acetic acidity). 

In this case, the refreshment begins by soaking the Sourdough in the lukewarm water at 20°C (68°F) – 22°C (71°F) for 15 – 20 minutes, adding 2gr/liter of sugar or fructose.

To better control the amount of water used for the refreshment, I suggest weighing the starter before and after the bath. Hence, you know how much water has been absorbed during the bath and adjust the refreshment quantity.

Once squeezed and weighed, you can knead the Sourdough with this proportion:

• 1kg of Sourdough Starter
• 2kg of Bread Flour W360 (protein around 14% – 15%)
• 920 g Water (46% of flour weight) – the water absorbed during the soaking process.

As above, roll out the dough, and form a loaf. Then wrap it into a plastic food wrap, roll it up inside a heavy cloth and finally tie it up with a string or a rope.

I recommend leaving the cord slightly loose and allowing the Sourdough to “push” during the fermentation. Once ready, you can leave the Sourdough at room temperature (between 18°C (64°F) and 22°C (71°F)) for 16 hours.

REINFORCE THE SOURDOUGH STARTER BEFORE USING IT

Before using the Sourdough in the recipes, it needs to be fed 2 or 3 times to strengthen it (producing more yeasts and lactic acid bacteria) and balance its acidity. Moreover, it also promotes substances capable of preserving the product over time (if well packaged).

Big (and fat) leavened products (such as Panettone, Pandoro) need 2 or 3 refreshments, whereas 2 refreshments will be enough for simpler doughs such as croissants, bread, or pizza.

I will say that even for big leavened products, in case of time needs, we can stop at the second refreshment, knowing that we may slightly lose a bit in their shelf life.

When starting a recipe with Sourdough, the first thing to consider is Sourdough’s amount that we need to begin with to have the correct quantity for the recipe AND a reasonable amount to store.

That’s why I’ve developed a simple app that will help you know the exact amount of starter you need to refresh to make your recipe… and not run out of Sourdough!

Click here to access the BiancoLievito application.

An essential aspect of refreshing Sourdough is to obtain a dough at a temperature of 24°C (75°F) – 28°C (82°F), ideally 26°C (78°F).

For this, we can act on the water temperature and use this empirical formula:

Water Temp= 3 x final temp – room temp – flour temp – heat transmitted by the mixer (for a stand mixer, we can use 14°C).

!! Pls, note that this formula only works with Celsius degrees. Do the calculation in °C and then convert the result to °F !!

To obtain a dough at 26°C (78°F), imagining to have:

• Room Temp: 20°C (68°F)
• Flour Temp: 18°C (64°F)

The water temperature will be 3×26 – 20 -18 – 14 = 26°C (78°F)

REFRESHING THE SOURDOUGH STORED IN WATER – UPDATED VERSION

After several years of feeding Sourdough (with good results) using a ration sourdough to flour of 1:0.9 (1kg of Sourdough and 900gr of flour), I decided to experiment with different refreshment techniques. I’ve been inspired (and documented) by reading some texts that sparked my curiosity to put everything I had learned over the years back into play.

This new method of working starts with these primary considerations:

• Sourdough stored in the water has lower lactic acidity precisely because of its storage environment. For this reason, during the 2 or 3 preparatory refreshments, we should try to rebalance this acidity.
• The ratio between Sourdough and flour determines whether or not bacteria can reproduce. Using too much Sourdough and too little flour will result in a limited proliferation of bacteria and an unbalanced Sourdough. In the book “Omnia Fermenta” by G.Battista Montanari, you can read that the best biological conditions (scientifically proved) are obtained when the quantity of Sourdough is between 10%-30% of the total amount of fed dough. Let’s take an example with a 1:2 ratio. If I refresh 100gr of Sourdough + 200gr of flour +80gr of water, I get a total mass of 380gr, of which the Sourdough represents 26% of the total (100gr/380gr)

Here’s what I modified in this new method:

1. I let the Sourdough ferment out of the water between one refreshment and the next one, 
2. I use a sourdough to flour ratio of 1:1.5 (instead of 1:0.9)
3. I let the sourdough ferment until it reaches 2 ½ times its initial volume, i.e., initial volume +1.5 times.

Let’s see how to do it.

As a first step, soak the Sourdough in the warm water at 38°C (100°F) for 15-20 minutes, adding 2g/l of sugar or fructose. After this time, squeeze the starter and refresh as follows:

FIRST REFRESHMENT

• 1kg of starter
• 1.5kg of Bread Flour (W380 – 14-16% protein)
• 690g of lukewarm water at the correct temperature (see above).

Knead until you have a firm and compact dough, roll out to 1cm thickness and give 3 folds before forming a ball. Roll the dough tightly, score the surface to facilitate its development, and place it in a large bowl. Cover with a cloth and ferment for 3½ hours at 30°C (86°F) until it has increased 2½ times its volume (initial volume + 1.5). I suggest you place a portion of the dough into a glass, mark the initial level and use it as an indicator for following the fermentation.

The fermentation time will be long enough for the Sourdough to multiply its microbial flora. It will be essential to do the second refreshment when the Sourdough is at the peak of its development. Usually, it happens after 3½ hours, at 30°C (86°F).

SECOND REFRESHMENT

• 1kg of starter
• 1.5kg of Bread Flour (W380 – 14-16% protein)
• 690g of lukewarm water at the correct temperature (see above).

Once again, knead the ingredients, roll out the dough and form a ball and proceed as above, letting the sourdough ferment for 3½ hours at 30°C (86°F)

THIRD REFRESHMENT

• 1kg of starter
• 1.5kg of Bread Flour (W380 – 14-16% protein)
• 690g of lukewarm water at the correct temperature (see above).

Knead the ingredients until form the dough. Take the portion of Sourdough that you will store and weigh the amount needed for the recipe.

For the part that you will use in the recipe: Roll out the dough and form a ball and proceed as above, letting the sourdough ferment for 3½ hours at 30°C (86°F)

For the part that you will be storing: Soak it in cold water (19°C (66°F)) and leave 24 hours at room temperature (18°C – 22°C or 64°F to 71°F) until refreshed the next day.

After 3½ hours at 30°C, the Sourdough will be ready to be used!

HOW TO REFRESH A TIED SOURDOUGH – UPDATED VERSION

In this case, soak the Sourdough in fresh water at 20°C – 22°C (68°F – 71°F) with 2gr/liter of sugar or fructose for 15-20minutes. As mentioned above, weigh the Sourdough before and after to see how much water is absorbed during the bath.

Once ready, do the 3 refreshments using this proportion:

FIRST REFRESHMENT

• 1kg of Sourdough Starter
• 2kg of Bread Flour (W380 – 14-16% protein)
• 920g of lukewarm water at the correct temperature (see above) – the water absorbed during the soaking process

Knead the dough, and roll out to 1cm thick. Form a tight ball, incise a cross-cut on the surface, place the dough in a bowl, and ferment for 3 and a half hours at 30°C (86°F) until it has increased 2½ times its volume (initial volume + 1.5).

SECOND REFRESHMENT

Perform the same procedure as described above, but mix the Sourdough in these proportions:

• 1kg of starter
• 1.5kg of Bread Flour (W380 – 14-16% protein)
• 690g lukewarm water at the correct temperature (see above)

THIRD REFRESHMENT

Follow the same steps as the second refreshment, but use the ingredient in this proportions:

• 1kg Sourdough
• 1kg of Bread Flour (W380 – 14-16% protein)
• 460g of warm water at the correct temperature (see above).

Knead all the ingredients, weigh out the part of Sourdough needed for the recipe and let it rise again for 3½ hours at 30°C (86°F). Wrap the remaining part in a plastic sheet and then in a heavy cloth, tie it with a string and store it at room temperature for 16 hours