Bread on trial
Today we are going to put bread dough on trial; in fact we are going to discuss about various processes which happen during the preparation of dough and are extremely important for the final success of bread.
Bread, as we have largely pointed out since the beginning of our talk about it, is a unique and constant mixture of four main ingredients in different percentages of: flour, water, yeast and salt to which other ingredients can be added in small quantities; but it is always these four ingredients that give shape to bread. Yet we Italians know all too well that four ingredients give rise to various products with shapes but above all tastes, scents and fragrances completely different from each other.
The processes we are talking about in this post contribute to generate that surplus of taste, scent and fragrance. There are four types of these very important processes involved in the kneading stage. Let's see them together.
PHYSICAL-MECHANICAL PROCESSES: when we make bread, the first stage of preparation is the dough formation phase, consisting of mixing the ingredients. This operation, whether manual or using machines, must result in a smooth, homogeneous, soft and elastic dough. The kneading phase plays a very important role in the quality of the finished product, because the very characteristics of the dough and how it will develop during fermentation first and then baking depend on it.
The physical-mechanical processes require careful mixing of the ingredients because, by kneading them, the chemical components of the flour are united at a molecular level with the rest of the ingredients...an aspect that should not be underestimated. In the kneading phase, the main reaction is the formation of the glutinic mesh (I remember the union of gliadins and glutenins to form a spongy mass capable of incorporating liquids and gases); always in this phase there is a certain incorporation of air that allows a decrease in density and an increase in the softness of the dough. The oxygenation of the dough, you would not say, but it has a fundamental importance, that's why the professional machines (diving or spiral mixers) are designed to be able to "aerate" the dough. It promotes fermentation processes because the oxygenation of the dough strongly stimulates the activity of yeasts. As described in the post about yeasts, I remember that in the presence of oxygen (aerobiosis) they reproduce and produce ethyl alcohol. In addition, oxygen reinforces the glutinous mesh.
I have mentioned that the mechanical action of the kneading machine is of fundamental importance in activating the physical-mechanical processes. The effort that the kneading machine opposes to the dough is not always constant and changes according to the characteristics of the dough itself. The kneading phase takes place in three periods:
- The FIRST PERIOD is the one that starts from the first mixing of the ingredients up to the formation of the glutinous mesh, which progressively increases the effort of the kneading machine up to a maximum that then remains almost constant;
- The SECOND PERIOD the effort of the kneading machine brings the dough to assume optimal characteristics: smooth and extensible appearance. The glutinic mesh becomes softer and softer and the dough decreases its resistance due to proteolytic reactions. At this stage the dough is ready to be removed from the mixer;
- THIRD PERIOD prolonging the kneading beyond the second period, the effort of the mixer will begin to decrease because the dough will become softer and softer due to its excessive overheating that causes the breakdown of the gluten mesh.
From what has been said so far, therefore, it is clear that the kneading time plays a key role in the success of the dough.
For each dough, the time needed to reach the optimal characteristics of the second period depends on three factors:
- The STRENGTH OF THE FLOUR the kneading time of a weak flour will logically be less than that required for a strong flour, because the resistance of its gluten mesh is lower;
- FROM THE TYPE OF Dough if dry, soft or soft. Dry doughs should generally be kneaded less than soft doughs because they need to be quite "cold" after kneading because they need to be cylindered (we'll look at cylindering in the next post); soft doughs, on the other hand, need to be kneaded longer to reach their maximum consistency;
- FROM TYPE OF KNEADING MACHINE kneading by hand imparts minimal effort and is very slow. A spiral kneading machine allows for faster kneading because it applies more friction to the dough than it does.
COLLOIDAL PROCESSES: when flour is mixed with water, a very hydrated colloidal mass is formed. Gliadins and glutenins absorb 2-3 times more water than their weight. As mentioned above, by absorbing water the gluten proteins swell, stretch and bind to form gluten. Gluten, in turn, continues to absorb water, liquids and gases which then cause the dough to swell. The dough is, in food technology, a complex system made up of three phases: a solid phase, a liquid phase and a gas phase.
- Solid phase is represented by the gluten proteins, the starch granules and the portion of bran still present in a more or less high quantity according to the type of flour used. Starch is also able to absorb liquids, in smaller quantity than gluten, but since its quantity is considerable in the flour, in the end the water it is able to trap is similar to that of gluten. The bran, finally, is the solid part with the highest absorbing capacity (800% of its weight) and this explains why whole-wheat doughs are very absorbent.
- Liquid phase, in addition to water, all the soluble substances that make up the ingredients make up this phase, namely: soluble proteins, mineral salts and sugars.
- GASSIAN PHASE given by the air incorporated during the mixing process and by the carbon dioxide generated by the yeasts during their anaerobic/fermentative phase.
BIOCHEMICAL PROCESSES: these are activated by the enzymes in the flour and yeast that act, modifying them, on the fats, carbohydrates and proteins in the flour and other ingredients, also leading to the formation of the homogeneous mass that we call dough. The proteases in the flour, activated by the water, break down the proteins making the dough softer and more plastic. The amylases hydrolyze the starch as soon as kneading begins, but it peaks during fermentation, providing sugars, nutrients for the yeasts. The biochemical process of starch hydrolysis also leads to a liquefaction of the dough. The lipases which break down the fats facilitate the extensibility and malleability of the dough.
Microbiological processes: these concern the microflora of the dough, i.e. the development and multiplication of yeast cells and lactic acid bacteria with relative alcoholic and lactic fermentation. During the kneading phase, as seen above, the large quantity of oxygen assists the multiplication of saccharomyces which then begin to ferment during the first phase of working the dough, known as punching.
In these lines we were able to understand, probably a little more, how many causalities intervene within that mass of only four ingredients. What does it take to make bread... just a lot of knowledge, experience and passion. Hats off to our talented bakers.
Blog edited by Enrico Gumirato pastry chef and trainer.
