Why are fermented foods good for you?

Cooks are a little like scientists, but instead of tiny test tubes they use bowls and spoons for their experiments: they experiment, they mix, they measure out ingredients to bring extraordinary creations to life. And that is exactly what we are going to talk about today — a chemical process behind the making of some of our favourite foods: pizza, bread, brioche and other leavened products, both sweet and savoury.

In cooking, fermentation is a biological process by which microorganisms — such as bacteria, yeasts and moulds — turn the sugars and starches in food into alcohol, carbon dioxide and organic acids. This process lies at the heart of many leavened products, both sweet and savoury: bread, pizza, brioche, panettone and colomba. 
But what are the benefits of fermentation? What secrets lie hidden behind this process? Let's begin exploring the world of fermentation right now! 

Types of fermentation

Not only does fermentation ensure good preservation of food by preventing the growth of harmful microorganisms, but it also makes food more digestible and enriches the intestinal flora with beneficial microorganisms, contributing to the wellbeing of the immune system. 

During fermentation, the gluten proteins (gliadins and glutenins) keep swelling as they absorb the CO2 produced by the saccharomyces, which stretch and bond together, making the dough spongy. Throughout this process, the proteolytic enzymes help to make the dough more pliable. Another important effect of fermentation is the rise in the temperature of the dough, caused by the breakdown of the sugars by the yeast: this reaction is known as an exothermic reaction, that is, one that generates heat. The exothermic reaction takes place towards the end of fermentation, when the dough loses 2–3% of its weight through the conversion of the sugars into volatile substances (carbon dioxide and ethyl alcohol) and the evaporation of water.

In making leavened products, fermentation plays a crucial role. The yeast — which may be baker's yeast or natural yeast (such as sourdough starter) — acts on the sugars present in the dough, producing carbon dioxide and alcohol.

To achieve good fermentation, you need to create an environment favourable only to the desired microorganisms, which tend to be more active in foods rich in sugars. You can also use bacterial cultures, starters or mothers that can be bought online or at the pharmacy, to ensure more consistent results.

The benefits of fermentation

Not only does fermentation improve the organoleptic characteristics of food, it also makes it more digestible and enriches its nutritional value; what is more:

1. It improves digestion. Fermentation pre-digests food, making it more easily absorbed by the body.
2. It strengthens the immune system. Fermented foods are rich in probiotics that help reinforce the body's natural defences.
3. Absorption of nutrients. Fermentation helps the body absorb vitamins better, especially vitamin B, which is essential for various bodily processes such as digestion and liver and brain function.

8. Removal of harmful bacteria. The fermentation process can eliminate any harmful bacteria and toxic substances present in food.
9. Food preservation. Fermentation is a natural method of preservation that inhibits the growth of pathogenic microorganisms.
10. Development of new flavours. Fermentation can enhance the organoleptic character of food, creating new and pleasant flavours.

As a process, fermentation not only extends the shelf life of food, but also brings significant health benefits: it improves digestibility and the nutritional profile and contributes to the wellbeing of the immune and digestive systems.

Alcoholic fermentation

In leavened products, alcoholic fermentation is a fundamental biological process that takes place through the action of microorganisms such as yeasts, in particular Saccharomyces cerevisiae, which turn the sugars in the dough into ethyl alcohol (ethanol) and carbon dioxide (CO2). 

This process takes place in the absence of oxygen (anaerobiosis) and unfolds in two main phases:

1. Splitting of the sugars. The complex sugars in the dough, such as sucrose, are split into simpler sugars (glucose and fructose) by the enzyme invertase.
2. Conversion into ethanol and CO2. The glucose and fructose are then transformed into ethanol and CO2 through a series of biochemical reactions. This process is called glycolysis and takes place in the cytoplasm of the yeast cells. Glycolysis produces pyruvic acid, which is subsequently converted into ethanol and CO2 by other specific enzymes.

As for leavened products, the CO2 produced during alcoholic fermentation is particularly important because it is responsible for the rising of the dough. The carbon dioxide is released as a gas inside the dough, creating bubbles that make it softer and lighter. This is why bread, pizza and other baked goods have a honeycomb crumb structure and a soft texture.

Alcoholic fermentation: some facts

Here are a few interesting — but above all useful — facts and little tricks to use while you ferment your doughs.

• Yeast cells multiply more actively when their initial quantity is small. Some laboratory tests have shown that if the flour in the dough contains 0.5% yeast, the increase in cell mass will be as much as 88%, whereas with 2% the growth drops to just 29%. 
• The cell multiplication of yeasts is stimulated by the presence of certain important substances needed for their metabolism: vitamins and mineral salts occur naturally in stone-ground flours, while in highly refined flours they are found in small amounts, so it may be necessary to add them to encourage the multiplication of the yeast and its subsequent fermentation.
• The ideal temperature for the multiplication of yeasts is 25–30 °C, while their maximum fermentation activity is reached at 35 °C. 
• The humidity yeasts need is around 80%. A home method for reaching the required humidity level is to create a proofing chamber in the oven (set to minimum) by placing a bowl of lukewarm water on the bottom, or by covering the bread with cling film and putting it in the oven at minimum, so that it generates its own humidity as it rises.

All in all, fermentation is one of the oldest and most fascinating culinary techniques in the history of cooking, still able to amaze us with its power to turn simple ingredients into foods rich in flavour, nourishment and health benefits. But it does not end here! This is only one part of this vast world: we invite you to carry on discovering this fascinating world in the second part, where we will delve into techniques, recipes and secrets for successfully experimenting with this age-old practice in your own kitchen. 

Blog by Enrico Gumirato, pastry chef and trainer.