Refreshing your Sourdough Starter (Lievito Madre) is essential to keep it alive and provide the water and “food” necessary for the survival of wild yeasts and bacteria. When we talk about refreshing, we are referring to a very simple kneading operation involving: Starter, Flour, and Water.

In the management of Natural Yeast, we must distinguish between two types of refreshments:

• Maintenance Refreshment: Used to preserve the starter day after day. The goal here is simply to keep our yeast alive.
• Preparatory Refreshments (usually 2 or 3): Necessary to prep the yeast right before using it in a recipe. In this case, the main goal is to strengthen the yeast and stabilize its acidity.

This distinction is crucial because, as we will see, these two types of refreshments require different ratios and procedures.

How to Refresh Your Sourdough Starter: Daily Maintenance

To keep our starter healthy, you’ll need to refresh it regularly depending on how you store it. If you keep your starter at room temperature (66°F – 68°F / 19°C – 20°C), you must refresh it every day. However, if you store it in the refrigerator, you can extend its maintenance up to 7 days.

A second factor to consider is the storage method: it could be in Water (Idro) or Bound (Legato). This choice is very important because it determines a starter with very different characteristics (primarily acidity) and requires different proportions of yeast and flour.

When to Give Your Starter a “Little Bath” (Bagnetto)

Before proceeding with a maintenance refreshment, you should perform a sourdough bath, especially when the dough feels too acidic or has developed a pungent smell. The bath helps rebalance the microflora, eliminate excess acidity, and make the yeast more stable.

If you store your starter in water, the bath is done in lukewarm water at 100°F (38°C) for about 15–20 minutes. If the starter is stored bound (legato), it should be submerged in water at 68°F–72°F (20°C–22°C) for the same amount of time. In both cases, it’s best to add 2g of sugar or fructose per liter of water. After the soaking period, proceed with the refreshment according to the indicated proportions.

Water Temperature for Sourdough Refreshment

A vital aspect of performing refreshments correctly is achieving a final dough temperature of 79°F – 82°F (26°C – 28°C), ideally 79°F (26°C).

To achieve this, we adjust the water temperature using this empirical formula by Master Giambattista Montanari, whom I admire for his excellent work!

Water Temp = (Target Temp x 4) – Room Temp – Flour Temp – Starter Temp – Machine Friction (for a stand mixer, we can use 14°C/25°F).

Example: To get a 26°C (79°F) dough, assuming:

• Room Temp: 20°C (68°F)
• Flour Temp: 18°C (64°F)
• Starter Temp: 19°C (66°F)

The water temperature should be: (26×4) – 20 – 18 – 19 – 14 = 33°C (91°F)

In practice, consider these friction heat values for different machines. If using the machine at full capacity, use the higher end of the range:

• Stand Mixer (Planetary): 12-16°C (22-29°F)
• Spiral Mixer: 9-12°C (16-22°F)
• Dipping Arm Mixer: 6-9°C (11-16°F)

Refreshing Sourdough in Water (Maintenance)

In this case, we are dealing with a starter characterized by low lactic acidity (as it’s absorbed by the water) and a higher moisture content.

After the bath, squeeze the yeast and knead it with these proportions:

• 1kg Sourdough Starter
• 1kg Strong Flour W360 (approx. 14% – 15% protein)
• 300g Water at the right temperature (see above)

The dough should be well-formed, but excessive kneading isn’t necessary. Roll the starter out to about 1cm (0.4 inch) thickness and give it 3 folds to oxygenate and refine the dough. Roll it into a ball and place it in a container with cold tap water (66°F/19°C). The ideal ratio is 3 times the weight of the yeast in water. This allows you to keep the starter at room temperature (between 64°F and 72°F) for 24 hours.

Refreshing Bound Sourdough (Maintenance)

If you keep your starter bound (legato), you will have a more acidic yeast (specifically richer in lactic acidity with lower acetic acidity). Again, start with the bath in water at 68°F-72°F (20°C-22°C) with sugar for 15-20 minutes. To better dose the water for the subsequent refreshment, I suggest weighing the starter before and after the bath to know how much water was absorbed.

Once squeezed and weighed, knead with this ratio:

• 1kg Sourdough Starter
• 2kg Strong Flour W360 (approx. 14% – 15% protein)
• 920g Water (46% of flour weight) MINUS the water absorbed during the bath. Use the correct temperature (see above)

As before, roll it out, give it 3 folds, and shape into a log. Wrap it in food-grade plastic sheeting (don’t use thin cling wrap), then roll it inside a heavy-duty cotton or linen cloth, and finally bind it with a rope (like a salami), leaving it slightly loose to allow the yeast to “pull.” Once ready, leave it at room temperature (64°F-72°F) for 16 hours. To make maintenance easier, I recommend a small wine cellar where you can easily set the perfect temperature!

Preparatory Refreshments: Doses and Timing

Before using it in recipes, the starter must undergo 2 or 3 close refreshments intended to strengthen it (producing more yeast and lactic bacteria) and balance its acidity, as well as producing substances that help preserve the baked product over time.

For Large Leavened Holiday Cakes (like Panettone, Pandoro, Veneziana), it is customary to perform 3 refreshments. For “leaner” doughs like Croissants, Bread, or Pizza, 2 are enough. Even for large leavened items, if time is tight, you can stop at the second refreshment, knowing you might lose a bit of shelf life.

The first thing to consider is the starting quantity of yeast so you have the right amount for the recipe AND a reasonable amount to keep for next time. I’ve developed a simple app to help you calculate the exact amount to refresh.

Click here to access the BiancoLievito App

The 3 Refreshments for Starter in Water

After years of using a 1:0.9 ratio (1kg yeast to 900g flour), I’ve experimented with new techniques. This new method for water-based starters is based on these principles:

• Water-stored yeast often lacks lactic acidity. We must rebalance this during prep.
• The yeast-to-flour ratio determines bacterial reproduction. Too much starter and too little flour limits proliferation. Scientific data from Omnia Fermenta by G. Montanari shows the best biological conditions occur when the starter represents 10%-30% of the total refreshed mass.

What I’ve changed in this method:

1. Between refreshments, I let the starter ferment out of the water.
2. I use a starter:flour ratio of 1:1.5 (instead of 1:0.9).
3. I let the yeast grow until it reaches 2.5 times its initial volume (initial volume + 1.5).

FIRST REFRESHMENT (Water Method)

Perform the 15-20 minute bath at 100°F (38°C). Squeeze the starter and refresh as follows:

• 1kg squeezed starter
• 1.5kg Flour (W380 – 14-15% Protein)
• 690g warm water at the right temp (see above)

Knead into a firm dough, give 3 folds, and shape into a ball. Place in a large container. Cover and ferment for 3.5 hours at 86°F (30°C) until it has grown 2.5 times its volume. I recommend using a graduated container (spy) to track the level accurately.

SECOND REFRESHMENT (Water Method)

• 1kg starter from the previous refreshment
• 1.5kg Flour (W380 – 14-15% Protein)
• 690g warm water at the right temp (see above)

Knead, 3 folds, shape, and let it grow 2.5 times its volume again at 86°F (30°C) for about 3.5 hours.

THIRD REFRESHMENT (Water Method)

• 1kg starter from the previous refreshment
• 1.5kg Flour (W380 – 14-15% Protein)
• 690g warm water at the right temp (see above)

Knead and 3 folds. At this point, set aside the portion to keep and weigh the amount needed for the recipe.

• For the recipe: Shape into a ball, score the top, and let it grow 2.5 times at 86°F (30°C) for 3.5 hours. Then it’s ready to use!
• For maintenance: Submerge in cold water (66°F/19°C) and leave for 24 hours at room temp.

The 3 Refreshments for Bound Starter

Perform the bath at 68°F-72°F (20°C-22°C) with sugar for 15-20 minutes. Weigh before and after to account for absorbed water.

FIRST REFRESHMENT (Bound Method)

• 1kg Starter
• 2kg Flour (W380 – 14-15% Protein)
• 920g warm water MINUS absorbed water. Use water at the right temp (see above)

Knead, roll to 1cm, 3 folds. Shape into a tight ball, score a cross on top, and ferment for 3.5 hours at 86°F (30°C) until tripled (2.5x volume).

SECOND & THIRD REFRESHMENTS (Bound Method)

Use the same process but with a 1:1.5 ratio:

• 1kg Starter
• 1.5kg Flour (W380)
• 690g warm waterat the right temp (see above)

Once the third refreshment is kneaded, weigh the recipe portion (let it grow for 3.5 hours at 30°C) and wrap/bind the remainder for 16 hours at room temperature.