Biomedical Engineering Reference
In-Depth Information
where just one refreshment is needed to mix the liquid full sour with the other
ingredients of the recipe. The quite soft dough (DY 175) ferments in two separate
steps: the first at room temperature (ca. 25-26°C) for 25-30 min and the second at
35°C for ca. 75-100 min. Before baking, the dough shows values of pH of 4.3-4.4
and values of TTA of 9-11 ml NaOH 0.1 N/20 g of dough. Overall, the liquid starter
(full sour) represents 37% of the final dough but different percentages can be used,
which depend on the recipe and industrial or artisan levels. In the last case, a lower
quantity of starter is used, which requires a longer fermentation period and different
working schedule. Because of the high acidity of the sourdough starter, a short mix-
ing time is required due to the increased solubility of the gluten proteins, which
decreases the time for development of the gluten network.
4.4.5
Panettone Cake
Panettone is a traditional Italian cake consumed over Christmas and famous through-
out the world. Panettone has a soft structure, with regular holes, and characteristic
flavour, which is derived from dough ingredients (water, flour, butter, sugar, eggs,
salt, and others) and processing. Both at artisan and industrial levels, the sourdough
biotechnology is traditionally based on many refreshments (e.g. type I sourdough)
and an increased concentration of sugar is added during the last steps (
9,
12
) .
Comparable to most other type I sourdoughs, sourdough microbiota are predomi-
nantly composed of
L. sanfranciscensis
. During traditional manufacture, a sour-
dough with a low fermentation quotient (FQ, see Sect.
4.6.3
) is used and time and
temperature of fermentation are strictly controlled. In particular, the dough tem-
perature does not exceed 30°C and the temperature of water and other ingredients
has to be not lower than 20-22°C. Various studies have attributed the prolonged
softness and shelf life of Panettone cake (it is manufactured several months before
consumption) to the presence of dextran producing
Leuconostoc mesenteroides
in
the sourdough, which uses sucrose as an exo-polysaccharide (EPS) precursor (
12
) .
On the basis of such a finding a new protocol relying on type III sourdough has
recently been proposed as an alternative to the traditional manufacture (see Sect.
4.8
).
A sourdough containing 25% (on dry matter) of dextran, which is stabilized by
refrigeration, pasteurization or drying, has been used to shorten the time to obtain-
ing a product with similar characteristics to the traditional Panettone cake (
18
) .
4.4.6
San Francisco Bread
San Francisco bread is traditionally manufactured using the very famous San
Francisco sourdough, which possesses a typical microbial community, mainly
consisting of
L. sanfranciscensis
and
S. exiguus
(renamed to
K. exigua
). Traditional
bread making relies on the type I sourdough. Various refreshments and long
