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Mother yeast and the ancient leavening of bread

The prerogative of a few bread lovers until a few years ago, now in vogue again, sourdough also becomes a great selling point. The sourdough remains a living product that, fermenting, allows you to grow bread and some great leavened bread such as the panettone.
Although naming it has become a factor of coolness, its use is linked above all to the awareness of the advantages and benefits, first, that of digestibility, compared to that of brewer's yeast. But what exactly is mother yeast, and how is it used?

Natural yeast or chemical yeast?

But before that, what are yeasts? In biology, they are some organisms belonging to the realm of fungi, which produce a microbial fermentation. In the kitchen, the term yeast has taken on a broader meaning, also extended to chemicals that can inflate a dough.
For this reason, there are two main categories of yeast that are used, each with its own characteristics and related uses:

  • Natural yeasts: they produce biological leavening, thanks to the intervention of organisms of a microbial nature, they are real living yeasts and bacteria. The latter, thanks to the fermentation process and the activation of heat, metabolize the carbohydrates, thus producing acids, alcohol and carbon dioxide. In this category, we find brewer's yeast (dried, fresh, powdered), and sourdough. Brewer's yeast is not a bacterium, but a fungus called Saccharomyces cerevisiae and produces only an alcoholic fermentation, while we will see that the sourdough is made of many microorganisms, such as lactic ferments, absorbed from the environment.
  • Chemical yeasts: these are dry leavening agents used to increase the volume and lighten the dough of bakery products. As the adjective "chemical" indicates, these yeasts are nothing more than combinations of one or more salts that produce carbonic gas through an acid-base reaction. The word yeast, in this case, refers only to the action of "removing". Chemical yeast: compared to biological yeast, chemical yeast has a shorter leavening time (a few minutes compared to hours) and no metabolic transformation of carbohydrates into ethyl alcohol, carbon dioxide, water and volatile compounds in general. They are not "dangerous" or unnatural agents, as you might think, but simply inert mixtures (for example tartaric acid or sodium bicarbonate) which, activated in dosed combinations, can quickly release carbon dioxide, but also have limited leavening effects.

How mother yeast is born and how it works

For a long time, sourdough was the only traditional method used to make bread rise. Its origins are older than the invention of writing and date back to the great inventors of bread: the Egyptians five thousand years ago. A discovery born from an oversight: a mixture of cereals left out of the oven began to swell under the effect of fermentation and, to avoid waste, was added to other flour to knead the bread. The final product turned out to be tastier and more digestible than the bread made until then.

Certainly, the Egyptians did not know the fermentation process and believed that this reaction was completely magical. In fact, even today it might seem a miracle that the history of sourdough is made of just two ingredients: flour and water.

This simple mixture, if left at room temperature, ferments thanks to the action of a heterogeneous culture of bacteria and yeasts called spontaneous, present in water, in the environment and in flour. Just think that in a single gram of flour there are about 13000 cells of spontaneous yeasts and 320 cells of lactic acid bacteria or lactobacillus, that's why yeast is an entirely natural and alive product.
Fermentation partially degrades the carbohydrates in the flour, thus producing substances such as carbonic gas, lactic acid, and acetic acid, which are essential for baking. In practice, some enzymes degrade the flour into maltose, and lactobacilli convert this maltose into a variety of acids, in which spontaneous yeasts can survive. Once the yeast has matured, it is added to the baking dough and left to ferment to allow the bread to rise.
Today most of us rely on the industrial bakery, where this secret has been a little forgotten and, in its place, we often find brewer's yeast or other instant yeasts. Brewer's yeast bread, more common and used in bakeries, is more marketable, because it is easier to work with. In a short time, the dough swells, making it faster and less demanding for the baker.

In recent years, we have seen a return to slow and natural leavening, along with food trends and the philosophy of self-production.

Mother yeast vs. brewer's yeast: benefits and advantages of using mother dough

With sourdough, you get bread, pizzas or cakes with intense aromatic bouquets, which then translate into higher fragrance and digestibility. Here are the details of the other properties of mother yeast, compared to another key ingredient of baking, brewer's yeast.

Gustatory differences

From an organoleptic point of view, it offers unparalleled aromas. It is a natural taste enhancer. The aromatic richness is due to the volatile compounds that form during fermentation. Depending on the type of yeast, temperature, and environment, the acids produced are variable. There is real biodiversity among yeasts, unlike bread produced in a more industrial way.

Bread has a more acidic taste and a denser texture than brewer's yeast, but still well pored.

Advantages of preservation

  • Lactobacilli, which are responsible for the acidity, also slow down the aging of the bread texture and its deterioration. Bread with sourdough can be kept for more than a week. The brewer's yeast and its faster alcoholic fermentation give a well-pored crumb, but it hardens much faster.
  • The acidity also protects against harmful moulds and microbes. Bread with sourdough does not mould.

Health benefits

  • The glycemic index is lower than for brewer's yeast bread: bacteria digest sugars and transform them into other substances (such as CO2).
  • Mother yeast pre-digests bread. The longer leavening times required to allow enzymes more time to break down proteins (such as gluten), lipid and starch macromolecules, into simple nutrients. A product obtained with sourdough is, thus, more digestible.
  • Sourdough is considered a probiotic to ease intestinal swelling problems associated with the consumption of leavened dough. On the contrary, brewer's yeast is not recommended in these cases (the effects are amplified by incomplete leavening or insufficient cooking of the product).
  • Baking with sourdough allows the body to benefit from the properties of minerals present in whole meal flours. The higher acidity produced by sourdough more easily activates the enzyme phytase which neutralizes the action of the phytic acid present in the bran of the cereal. Phytic acid is practically an "anti-nutrient" that prevents the assimilation of certain minerals such as calcium, iron, magnesium, and zinc.

Mother dough: where can I find it?

  • Mother dough and its unique aroma are the signatures of the baker who wants to express its full potential. Choosing sourdough, as a consumer or producer, means choosing slowness, believing in a sustainable bread supply chain, looking for quality raw materials and organic products.
  • Mother pasta is more than anything else a symbol of conviviality and a means of rediscovering traditions, the role of craftsmanship, the enhancement of production at the forefront of consumption. That's why today many people try their hand at the recipes that are so popular on the web, to create with sourdough, not only bread but also pizzas and cakes for all tastes, with extraordinary varieties of taste, nutritional and conservation properties.

The sourdough is a live product and must therefore be maintained regularly. We therefore talk about continuous "refreshments" that allow to invigorate the yeasts, that is the addition to the dough of other flour and water in a precise quantity.

The sourdough is a living product and for this reason, it must be maintained regularly. We, therefore, talk about continuous "refreshments" that allow invigorating the yeasts, that is the addition to the dough of other flour and water in a precise quantity.

Today, real naturally leavened bread is rather difficult to find, because new baking yeasts reduce preparation times and costs and only some bakeries are specialised. It should be noted that the term "natural leavening" may include a production with brewer's yeast (also, as we have seen, is a natural yeast). Mother yeast can be found in two forms: solid and liquid. This last variant, which is gaining a lot of ground in the home and professional field, has a higher percentage of water than the solid form and is easier to maintain.

Making homemade bread with mother yeast

Of course, to juggle at home like professional bakers you need to know how to manage several parameters: feed your yeast, know almost to the gram the rate of hydration according to the cereals used (which varies greatly if it is wheat, rye, Khorasan, spelled, barley ...), shape the dough with expert gestures, leave time to the dough to rise, form the bread and close it so that it does not open during baking (and let it rise again!).); bake in a hot oven and engrave in a clear and secure, the famous "signature of the baker. An exciting adventure, which requires a little 'patience, before the result comes through”.
Making bread is considered a relaxing activity, almost like a yoga session, and observing it is real meditation, a lesson in slowness and wisdom. We wait, and there is nothing we can do to control the process. We observe, write down, let our senses and intuition do the work. And it is a way of learning from experience, a lesson in humility. Every now and then we make mistakes, we ask questions, we observe to understand what has not worked. Tenacity, of course, is needed to avoid discouragement on the first attempt, but the second can only improve the experience.
It is a gift for all our senses: the smell of baked bread, the sensation of the dough under our hands when we need, its song (the crunch and the "empty" sound after baking), the texture of the crust and the crumb when we can finally cut it.

Putting your hands in the dough is a matter of Zen, try it to believe. And the yeast? Nothing could be easier to find or do at home. Always starting from the principle that the sourdough is obtained by the fermentation of water and flour (and time), without the need to add anything else. Otherwise, you can look for mother yeast "dealers", a network of bakers and bread lovers, who give a dose of yeast grown and maintained, to anyone who wants to make a healthy bread, along with good tips for baking.

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