What is the difference between sourdough starter and natural yeast?
Sourdough starter – part one
There is an ingredient that has been helping us prepare doughs and leavened products for centuries: although not everyone knows it, the sourdough starter is extremely important in giving bread, pizza and cakes an unmistakable quality and flavour. The sourdough starter is not merely a leavening agent, but a genuine miniature ecosystem able to give baked goods a unique texture, as well as making them lighter and more digestible.
The sourdough starter was already rooted in the culinary traditions of our ancestors: it is thought to have been born in Ancient Egypt, around 3500 BC, where for the first time people began to let the dough rest before baking, thus allowing natural yeasts to ferment and leaven the dough. This practice marked the beginning of the use of sourdough starter in breadmaking, radically transforming the way bread was produced and consumed.
Before the introduction of sourdough starter, bread was essentially a flattened flatbread baked on stone, similar to today’s unleavened bread. Thanks to the discovery of sourdough starter, the ancient Egyptians were able to produce soft, fragrant bread, very similar to the one we know today. This discovery not only improves the flavour and texture of bread, but also increases its nutritional value, making it a staple food in the diets of many civilisations.
Since this is a very rich and fascinating subject, we will tackle it by answering your questions! Are you ready to put on your apron and get your hands dirty? Let’s begin!
What is the difference between sourdough starter and natural yeast?
The term natural yeast can cause confusion, since it is sometimes used as if it were a synonym for sourdough starter, but it could also refer to baker’s yeast.
The main difference between sourdough starter and natural yeast lies in their composition and in the fermentation process. The baker’s yeast consists mainly of a single strain of Saccharomyces cerevisiae, a single-celled fungus that is grown and fermented under controlled conditions and then used as an industrial leavening agent. The sourdough starter is a mixture of water and flour containing a variety of yeasts and lactic acid bacteria, such as Lactobacillus, Pediococcus and Leuconostoc, which develop naturally during the fermentation process. These microorganisms work together to ferment the dough: at low temperatures the lactic acid bacteria contribute to the development of acetic acid, which increases the shelf life of the leavened product; at high temperatures they favour the development of lactic acid, which generates the characteristic aromas of the leavened product.
The lactic acid and the acetic acid, in the right proportion (a lactic-acetic ratio of 3:1), give the dough a higher acidity than doughs containing compressed yeast, which is essential to ensure the product keeps for longer.
Is sourdough starter better than baker’s yeast?
The sourdough starter and the baker’s yeast are both leavening agents used in breadmaking, but they show some substantial differences that can influence which one to choose depending on the baked product you want to obtain.
The sourdough starter is a living organism that requires care and attention, with very long leavening times, but the result is a far more digestible and aromatic bread, thanks to the presence of bacteria and to the various families of yeasts. The sourdough starter is free from artificial additives and preservatives, which makes it more tolerable even for diabetics; moreover, the fermentation of the sourdough starter aids the absorption of essential nutrients such as antioxidants, vitamins (including folic acid), calcium, zinc, iron and magnesium.
The baker’s yeast, made up mainly of a single strain of microorganisms, is available in fresh or dry form and allows a much faster rise than sourdough starter. However, bread made with baker’s yeast can be less digestible and have a less complex flavour. Nutritionally, the baker’s yeast is known for being rich in protein, B-group vitamins and minerals such as magnesium, phosphorus, potassium, iron, calcium and selenium.
So then, which is better to use? It depends! The sourdough starter is preferable for those looking for a product with a richer flavour and greater digestibility, while the baker’s yeast is better suited to those looking for a quick and practical solution.
How can you tell when the sourdough starter is ready?
Before trying your hand at creating your sourdough starter (see article 2), check the temperature of the room where you are going to let it rest: the ideal temperature for fermentation should be between 18 and 25 °C; colder temperatures slow the process down, while warmer ones could speed it up.
To tell when the sourdough starter is ready to use, there are a few key signs to look out for:
- Visual appearance. A ready sourdough starter often shows a surface full of bubbles and foam, a sign that fermentation has taken place correctly, and a colour tending towards pale yellow.
- Doubling in volume. The sourdough starter is considered mature and ready for baking when it doubles in volume within 3–4 hours of a refreshment*: this indicates that the microorganisms inside the sourdough starter are active and able to produce the amount of gas needed to make the dough rise.
- Texture and aroma. A ready-to-use sourdough starter should have a spongy texture and a pleasant, slightly sour aroma. If the smell is too strong and sour, it may be a sign that the sourdough starter is too acidic and may need more frequent refreshments (the pH should be 4–4.5).
- Float test. Another method for testing the state of the sourdough starter is the float test: a small piece of sourdough starter should float in a glass of water if it is ready to use. This indicates that enough gas bubbles have developed inside the starter to make it light.
* Refreshing the sourdough starter is an essential process for keeping this culture of yeasts and lactic acid bacteria active and alive. During the refreshment, water and flour are added to the existing sourdough starter, thus providing new nutrients to the microorganisms present, which kick off a new fermentation. This process not only ensures the vitality of the sourdough starter but also improves its leavening and aromatic capabilities.
Remember that every sourdough starter is unique and may require a little experimentation to work out exactly when it is ready for use!
In the next article we will explain how to make sourdough starter and how to look after it, and together we will discover how to bring this fantastic ingredient to life from scratch. We will guide you step by step in creating your own sourdough starter, revealing all the secrets to nourishing and preserving it at its best. Are you ready to get your hands in the dough and become a true master baker? Don’t miss the next instalment!
