Cereals processing technology

222 Cereals processing technology
Rounding and first moulding
After dividing the individual dough pieces are commonly worked in some way
to change their shape before first or intermediate proof. The most common
shaping is by rounding, an action which mimics that carried out by hand in the
craft bakery. The action of mechanical first moulding places the dough under
stress and strain which may lead to damage to the existing gas bubble structure
in the dough. Some breadmaking processes require the rounder to have a
degassing effect, however, if the dough comes from a breadmaking process
which leaves little gas in the dough at the end of mixing (e.g. the CBP) then this
requirement is unnecessary. A key function of rounding is to generate a uniform,
largely spherical dough piece which makes it suitable for handling in pockettype
provers, rolling down chutes, conveying without concern for orientation
and delivering a uniform dough piece to the final moulder.
During rounding the dough piece is rotated on its axis between the two inner
surfaces of a V- or U-shaped trough, where one side is driven and the other fixed
or moving at a lower speed. The dough piece quickly forms the shape of the
trough as it moves under the force of the driven side. The differential in speed
between the two surfaces is the same but the angular diameter of the dough piece
reduces as the two surfaces converge, so that the top of the dough piece is
rotated faster than the bottom effectively attempting to twist it about its axis.
However, because the dough piece slips on one of the surfaces the action
becomes one of spiralling or rolling.
There is a wide variety of rounders available where rotational speed, angle of
cone, angle and shape of track, inclination of track and different surface finishes
all modify rounder action on the dough. The most common type of rounder
consists of a cone which is rotated about a vertical axis with the track of the
fixed moulding surface located in a spiral pattern about the outside of it. Some
conical rounders have an inverted cone with the rounding track on the inside and
others use a track around a cylindrical drum. Shaping belts provide an
alternative to rounders.
Intermediate or first proving
In most modern dough make-up processes intermediate, or first proof is used as
a period of rest between the work carried out by dividing and rounding and
before final shaping. The length of time chosen for this process is related to the
dough rheology required for final moulding. Changes occur in dough rheology
as it rests, the longer that it rests the greater will be the changes. In no-time
doughmaking processes (e.g. the CBP) the changes in dough rheology which
may occur in first proof can have a considerable effect on final bread quality and
its elimination can lead to a reduction of loaf volume and an increase in damage
to the bubble structure in the dough. This is especially the case when ascorbic
acid is the only oxidant in the recipe.
The pocket-type prover is the most common form. The pockets are held in
frames fixed between two chains carrying swings. The latter move around the
proving cabinet from charging to discharging stations and incorporate turn-over