The magic dust – Part 2

Friends of Erre4m, good morning and welcome to this new post, where we carry on talking about THE FLOUR. In the previous post we looked at where flour is obtained from, what its milling categories are and, lastly, we went in depth into that essential part concerning the strength of the flour according to its gluten content and its W scale value. In this second part we will talk about the fermentation characteristics of the flour, that is, its capacity to produce gas in the form of carbon dioxide. These fermentation characteristics depend on the flour’s ability to form sugars, that is, on how much the starch it contains can be broken down until it becomes glucose thanks to the activity of the enzymes present in the flour itself. The speed at which sugars form is directly proportional to the amount of enzymes and to the degree of starch breakdown.

The most important of these chemical processes is THE CARAMELIZATION OF THE SUGARS in the surface layer, on which aromatic substances and brown-coloured substances form, produced by the union of the sugars with amino acids deriving from the complete hydrolysis of the proteins during baking (this process goes by the name of the MAILLARD REACTION). To produce a good colouring of the crust, the amount of sugars present in the dough at the moment it goes into the oven is generally 2–3%.

We have seen that the sugars-carbohydrates present in the flour, partly responsible for its fermentation activities, are 80% made up of starch. This sugar, besides having a significant presence within the flour itself, has a series of decisive functions:

1. IT ABSORBS THE LIQUIDS DURING MIXING

2. IT SACCHARIFIES DURING RISING. The saccharification of starch is the chemical reaction that transforms starch, which is a polysaccharide, into simpler sugars thanks to the demolishing action of the enzymes alpha and beta amylase. Saccharification proceeds by first splitting the starch into DEXTRINS (4 molecules of glucose), which are then split in half into MALTOSE (2 molecules of glucose), split into a single molecule of GLUCOSE. The glucose obtained from the saccharification of the starch is the nourishment for the yeasts.

3. IT GELATINIZES DURING BAKING; that is, in the oven, when it reaches a temperature of 56–60°C, the starch becomes a gel capable of absorbing water, helping to form the crumb.

4. IT PLAYS A PART IN THE PRESERVATION OF THE BREAD. After baking, as time passes, the starch loses the water absorbed during the gelatinization process, producing moisture and playing a part in the ageing of the bread. This process goes by the name of RETROGRADATION: the amylose molecules draw closer together, forming a rigid structure; part of the water passes to the gluten and part migrates outwards, contributing to the hardening of the bread.

We wrap up this journey into the knowledge of flour by analysing in a little more detail the function of the enzymes, which we have already often talked about in previous posts. Enzymes are substances of a protein nature with a catalysing function. By catalysts we mean those substances that have the ability to promote reactions while not taking part directly in the reactions that occur during the bread-making process, but that help to speed up the reactions themselves. Several types of enzymes are present in flour; let us look at them:

1. ALPHA and BETA AMYLASE = they intervene in the process of saccharification of the starch. The ALPHA-AMYLASES break down the internal bonds of the starch molecule, forming the dextrins. When the alpha-amylases are too active, almost the entire starch molecule is broken down, generating many dextrins which, being water-soluble, increase the liquid part of the dough, leading it to liquefaction and lowering its ability to absorb and retain liquids. For this reason the alpha-amylases are also called liquefying enzymes. The BETA-AMYLASES attack the external bonds of the starch molecule and of the dextrins, demolishing everything little by little into maltose. The beta-amylases act more slowly than the alpha-amylases and do not destroy the entire starch molecule. That is why they are called saccharifying enzymes.

2. PROTEASES = they promote the process of breaking down the proteins present in the flour, called proteolysis. The function of the proteases is to reduce the strength of the flour and the resistance of the dough, making it more extensible and malleable; the dough tends to increase in softness and volume because the gluten network, losing rigidity, stretches out more, facilitating the development of the product (see the post on autolysis)