The current industrial yeast makes the dough rise (by producing CO2), but no deep transformation of the dough takes place: gluten remains unchanged, and the nutritional value is very low. Even the aromas must be manually added to make the bread "edible" and visually "sellable."

Two hundred years ago, bakers used to get fresh brewer’s yeast from brewers. It was fine and creamy, providing natural fermentation to the bread. Bakers would then make a "dough starter" (a fermented dough) that they reused from batch to batch. This was real bread, made with real baker’s yeast and a fermented dough aged for several days. This starter had a rich flora of natural yeasts and lactic acid bacteria. Lactic fermentation occurred after alcoholic fermentation, making the bread not only tasty but also beneficial for health. Making bread took time…

However, industrialists had other plans. They realized that yeast alone was enough to break down sugars into alcohol and produce CO2, making the dough rise and resulting in fluffy, airy bread. This was sufficient for them because the bread was edible and filled stomachs. It didn’t matter that the bread was hard to digest and had little nutritional value. The goal was to produce more, faster, and more often because famine and war required cheap bread for the people in as little time as possible. Industrial yeast became the new standard in baking.

The use of yeast in its industrial and commercial form, as we know it today (fresh yeast cubes, dry yeast, etc.), dates back to 1857 when Louis Pasteur discovered the fermentation process. Since then, it has been selectively bred in laboratories, isolated, and modified to withstand all kinds of stress (heat, freezing, etc.). It has become highly concentrated to work quickly and make bread effortlessly. It is now omnipresent in the food industry (bread, pastries, alcohol, beer, but also meats, prepared foods, sauces, etc.). It acts both as a ferment and as a preservative in the entire food industry. It is also boosted with ultra-refined flours full of sugars to speed up results. These fast-rising yeasts significantly increase the glycaemic index.

Before this period, sourdough was the norm, used by bakers worldwide for over 3,000 years. Real sourdough had ideal, natural proportions: 100 times more lactic acid bacteria than yeast. This allowed for a true, deep transformation of the dough—real fermentation. The bread was nourishing and healthy.

Why was sourdough replaced by industrial yeast?

The reason is purely commercial: saving time, increasing productivity, and making more money.
The faster the fermentation (1–2 hours with yeast vs. 8–10+ hours with natural sourdough), the more batches a baker can make in a day, the more bread they sell, and the more profit they make. And so the world goes on...

Yet today, sourdough is making a comeback. Consumers are tired of yeast-based bread. Less flavour, less variety—the bread has lost its soul, and few bakers truly work with natural sourdough. Some do make their own sourdough and work in a genuinely artisanal and traditional way, using firm or liquid sourdough. Others, however, use "sourdough-yeast" hybrids (lactose-sourdough, etc.), which are mixes of ferments with added aromas and selected bacteria and yeasts to give bread a particular taste and appearance—but not something truly natural.

Most baguettes and bread from modern bakeries don’t stay fresh for more than a few hours and can’t even be reheated or toasted the next day without being completely stale. Some breads contain more than 14 different chemical additives due to "prepared flours," which are mixes of enzymes, amylases, flavour enhancers, natural aromas, bleaching agents, etc.—all used to make the bread lighter, crispier, and faster to produce, at the cost of taste and health.

Even yeast itself is no longer what it was when used by medieval brewing monks. Though today's yeast still belongs to the Saccharomyces cerevisiae species (brewer’s yeast), modern strains have been selected for their resistance to stress (heat, cold) and their ability to reproduce rapidly in the presence of sugar and oxygen.

This is why more and more chefs, pizzerias, caterers, and even home bakers around the world are turning back to natural sourdough. Sourdough is a complex ecosystem: it contains natural wild yeasts (Saccharomyces cerevisiae among them, but not as the dominant strain!) and, thanks to nature’s magic, wonderful colonies of beneficial lactic acid bacteria. These are the same bacteria found in cheese, yogurt, fruits, vegetables, wheat grains, rice, cereals, and grasses—the bacteria present in our environment is part of our gut and our skin. Belongs to our microbiome.

Sourdough and yeast are both connected, yet so different.
Without the alcoholic fermentation created by yeasts (which turn sugar into alcohol), lactic acid bacteria wouldn’t be able to carry out their lactic and acetic fermentation. A yeast-only fermentation is incomplete. Yeast-based bread will never have the same depth of flavour, aroma, or shelf life as sourdough bread. Yeast bread might rise more (thanks to the high concentration of industrially selected yeasts in just one packet!), but it won’t have the softness, nutritional benefits, or gut health advantages of natural sourdough bread.

Sourdough has many advantages over baker’s yeast:

• It requires up to 60 times less water to produce!
• It doesn’t require sugar like yeast production does (yeast is made from beet and cane sugar, leading to soil erosion, pesticides, and pollution).
• Sourdough transforms gluten into peptides that are easier for the body to digest.
• It provides enzymes that increase the bioavailability of nutrients.
• Sourdough bread lasts longer.
• Sourdough can be stored in the fridge for years (often a lifetime).
• Sourdough makes bread that is healthy, rich in fibre and protein—natural prebiotics that support gut health and strengthen the immune system.
• Finally, sourdough creates unmatched flavour. Real bread, like in the old days.