Friends of Erre4m good morning and welcome to our blog. In previous posts, we have seen how many reactions there can be within a bread dough. Although the ingredients are very few: flour, water, yeast, salt, lard or extra virgin olive oil, their mixing, but also the sequence in which they are introduced, play a crucial role in the success of the finished product as we will see below...let's begin!
The formation of the dough is perhaps the most important phase, not only because of the easy mistakes that can be made, but above all because the ingredients that compose it come into contact with each other, modifying their structure.
The most important phenomena that begin and take place during kneading can be generically specified in:
formation of the glutinic mesh,
absorption of water by all the components of the flour itself and therefore not only the proteins but also the starch granules,
the activation of enzymes,
even distribution in the dough of the yeast with consequent development and reproduction of its cells,
incorporation of air and the beginning of the transformation of starch into simple sugars.
But let us proceed in order. It is no coincidence that the formation of the gluten mesh was mentioned first.
Its creation is precisely the factor to which special attention must be paid, especially if there are ingredients in the dough that enrich and weigh it down, such as sultanas, walnuts, olives, chocolate chips, etc. These ingredients must always be added at the end of the kneading process to avoid problems related to the breaking of the gluten link, which slows down its formation, prolongs the kneading time, or causes the dough to stick to the bowl of the mixer.
To better understand these concepts related to the formation and maintenance of the gluten mesh of a dough, we must focus on the ingredient that contains the gluten proteins, i.e. flour.
From a strictly protein point of view, flour is made up of 10-15% water-soluble proteins such as globulins and albumin, and 85-90% insoluble proteins, i.e. the ones already mentioned in previous posts, gliadin and glutenin.
Gliadins and glutenins are proteins with different characteristics. The former are globular proteins with a spherical structure while the latter are fibrous proteins with an elongated structure. It is precisely the interaction between their different structures that allows the formation of the complex lattice responsible for the bread-making characteristics, i.e. the gluten or glutenin mesh. For this to form, however, two fundamental and indispensable conditions must occur:
- The addition of water is necessary to ensure the hydration of all the proteins in the flour; furthermore, the presence of water causes a movement of the proteins such that the soluble ones go to position themselves on the outside of the dough, while the non-soluble ones will be protected on the inside, creating an optimal condition for their interaction, which ultimately results in the gluten.
- The mechanical action of the kneading machine is essential to evenly distribute the water between the flour particles and to allow the protein chains to come closer together, gradually creating a homogenous mass. At a macroscopic level, this is easily noticeable as the dough passes from an initial stickiness to a velvety, smooth dough, without tears or cracks, soft and deformable at the end of the kneading phase.
Gluten is therefore a visco-elastic mass that is formed when gliadins and glutenins interact with each other by absorbing water; this structure is insoluble in water and capable of retaining the air that is incorporated during kneading and the carbon dioxide that develops during the metabolic processes of fermentation.
Secondly, starch granules damaged or broken during the milling process play an important role. Excessive crushing can cause them to break down too quickly, resulting in an increased rate of water absorption, and this leads to defects in the finished product. It is precisely at the moment when the damaged starch granules absorb water that all those chemical and biochemical reactions are triggered that are at the basis of the transformation of a piece of dough into bread. Earlier I mentioned the incorporation of air during kneading. This plays a very important role...the chemical composition of air is, roughly speaking, 20% carbon dioxide, 79% nitrogen and 1% oxygen.
At the end of kneading, the oxygen is used by the yeast to carry out the process of respiration, so the only gas present in a detectable percentage is nitrogen, which is finely distributed in the dough and creates small holes and alveoli; the alveoli will then be the basis for the subsequent structure of the crumb.
During further processing, nitrogen and carbon dioxide escape from the dough, but while the lost carbon dioxide is replaced by that produced mainly by alcoholic fermentation, the nitrogen is totally eliminated. The carbon dioxide infiltrates the holes left free by the nitrogen and tends to enlarge them more or less depending on the structure of the dough, the action of the yeast, fermentation, temperature, the timing of the punching, etc.
In this complex of synergies, the active role of gluten does not begin and end with its ability to form the dough, but goes far beyond this by creating a structure that prevents the escape of gas during fermentation and plays a key role during baking.
In the next post we will continue analysing the phenomena that occur during kneading.
KEEP FOLLOWING US!
Blog by Enrico Gumirato pastry chef
