Technology of Baked Goods - Sourdough Biotechnology - page 55

of proteins and humidity of the flour. The hydration capacity of the flour is usually
calculated based on the farinographic absorption index (see Sect. 3.5.1.1 ). Although it
is very practical for routine applications, this approach does not describe the distribution
of water within the components and the competition among the hydrophilic com-
pounds. The dough is a highly complex system where numerous aqueous stages coexist
and each one is variously rich in chemical components [ 30 ]. The dough is a sophisti-
cated metastable dispersed system, where water moves from one phase to another and
where thermodynamic incompatibility among different polymers occurs [ 31 ] . The
time needed to obtain homogeneous and uniform hydration of the flour particles is
strictly related to the dimension of the particles, their hardness and vitreosity, the pres-
ence of non-starch polysaccharides and intensity of mixing.
Water is not only necessary for the formation of gluten, but it also performs a
solvent action for the other ingredients present in the formula (e.g. salt and sugars)
and it allows the enzymatic activities to take place. Another function played indi-
rectly by water is the control of the dough temperature. After mixing, ca. 45% of the
total water in dough is associated with starch, 30% with proteins and 25% with non
starch polysaccharides (pentosans) [ 32 ]. Water allows the swelling of the starch
granules during baking and their gelatinization, a key phenomenon for the physical
and nutritional properties of baked goods [ 33 ] .

3.3.2 Other Ingredients: Salt, Sugar and Fats

Flour, water and leavening agents are the indispensable ingredients for making baked
goods. Often the formula requires the addition of salt, which influences the sensory
and rheological properties of the dough, and additives or improvers. The use of salt
in leavened baked products generally refers to sodium chloride. Salt is an ingredient
that is almost always present in the formulation of bread and other bakery products.
The role of salt is related to its ability to enhance the aroma of the product and to
mask off-flavours such as a bitter and metallic taste, but salt addition also strengthens
the structure of the dough. This effect on dough structure is caused by the positive
effects on both hydrogen bonds and hydrophobic interactions between protein mac-
romolecules. Salt optimizes the mixing time and the kneading, and controls the speed
of yeast fermentation [ 34 ]. In dough without salt, the high speed of CO 2 production
may be responsible for the deterioration in the product structure. On the contrary,
NaCl allows the leavening step to be controlled and optimized by slowing the rate of
gas production [ 35 ]. However, this positive effect is strongly influenced by the
amount of salt added [ 36 ]. In particular, a great increase in volume was observed in
bread prepared by adding 1.5-2% of NaCl, while quantities exceeding this threshold
were associated with a strong decrease in the volume of the product.
Other ingredients such as sugar or fats are optional. The addition of sugar or fat
over a certain value markedly changes the rheological properties of the dough. The
presence of sugars influences each stage of processing: it gives more consistency to
the dough, in some cases promotes the fermentation, facilitates the browning of the