It causes swelling, makes you fat, triggers allergies. The allegations to the yeast, in recent times, they are no longer counted. So much so that, according to data from the Imagine GS1-Nielsen Observatory, 18,6% of the villagers buy bakery products that do not have them, even if only 4,6% say they have a recognized intolerance.
But why all these allegations toingredient that gives life and flavor to bread, one of the most important products of our table and of the healthy Mediterranean diet? "Food fads often generate hoaxes and false myths," he replies Piero Pasturenzi, president of the Assitol sugar yeast group, which with the project aims to combat disinformation on the issue.
"In reality, contrary to what one thinks, yeast facilitates digestion, because fermentation breaks the sugar and protein chains of the flour and releases precious micronutrients. Plus, it has very little fat and it is rich in proteins, vitamins and minerals. And since it is the base of probiotics, it could even be considered a superfoods". So let's try to unmask lies and false beliefs.
1. The leavened products continue to ferment in the belly
"It's impossible: yeasts are living organisms that develop around 30-40 ° C and die when they exceed 50. If the pizza cooks at more than 200 ° C, the yeasts can no longer ferment or act in any way" , explains Livia Galletti, biologist nutritionist in Bologna. The only ailment of this type could be the yeast only if it is ingested alive by people who already suffer from intestinal problems ».
2. Yeast is a chemical, so it's bad for you
Everything is chemical, even an apple and water (emblems of health at the table) are made up of chemical elements. «The distinction to be made, if anything, is between natural and artificial yeasts», Specifies the expert. «The natural ones, that is the brewer's yeast and sourdough, are formed by microorganisms that digest the molecules contained in the dough and release carbon dioxide as a waste product. This gas tends to disperse and remains trapped in the dough, creating those “holes” called alveoli. THE artificial yeasts, for example those instant powders that are added at the end, just before putting the dough in the oven, are not actually yeasts ». Pasturenzi adds: «In fact, they do not produce fermentation but only gas as a result of a chemical reaction triggered by heat. So they don't bring any advantage ».
3. Swelling after eating pizza is a symptom of an allergy or intolerance
Indeed documented cases of yeast allergy are rare and in any case they manifest themselves above all with skin reactions such as the classic urticaria, not with belly swellings. While theyeast intolerance it is not really recognized by the scientific world, so much so that this food is not included in the list of substances that must be marked in bold on the labels because they are potential allergens. «The difficulty of digestion that many people complain about after having been in a pizzeria, in reality, is linked to the pizza itself, which is a very heavy and abundant food and contains many ingredients », says Dr. Galletti. However, it is true that naturally leavened pizzas with sourdough are usually easier to digest: «This is because the microorganisms have already carried out a first digestion of the flour molecules during the leavening».
4. Mother yeast is better than brewer's yeast
The only difference is that mother yeast contains more microorganisms than that of beer and therefore can digest a greater variety of flour molecules than the second: for this reason the final product is lighter. "The variety of microorganisms also gives more flavor and aroma, especially if you use wholemeal flours that contain more fiber than refined ones," adds the nutritionist biologist. «The more fiber is digested by the microorganisms, in fact, the more different molecules are obtained and the more fragrances there will be in the finished product». Even the flavor changes, because among the microorganisms present in the mother yeast there are also the bacteria, which are different depending on the place where it is born and grows, the hands of those who touch it, the containers in which it is stored.
5. Slow leavening is always to be preferred
This type of fermentation is really necessary only if you use sourdough, to give time to its many and different microorganisms to "eat" and digest the fibers of the dough and produce the gas that will create the alveoli. "For the brewer's yeastinstead, a medium-slow leavening is recommended, because its microorganisms are all the same, so they will all ferment at the same time »explains Dr. Galletti. «Leaving it to rise for many hours will simply result in a dough that“ implodes ”, since all the yeasts, once their function is over, go to die».
EYE TO THE SALT!
The salt kills both brewer's yeast and sourdough microorganisms. So it should always be added to the dough as a last ingredient, after everything is well blended. In this way, in fact, it will be dispersed and will no longer be present in toxic quantities for the microorganisms, which will thus be able to continue their precious fermentation work undisturbed.
