Cereals processing technology

206 Cereals processing technology
the ingredients to experience the transformation in the mixture which occurs.
Best results, in terms of improved bread volume and crumb softness, will be
achieved with vigorous and prolonged hand mixing and kneading. During the
process of kneading the dough, and more probably you, will become warmer as
energy is generated by the mixing process.
However, there is more to dough development than a simple kneading
process. The process of developing a bread dough brings about changes in the
physical properties of the dough and in particular improvement in its ability to
retain the carbon dioxide gas which will later be generated by yeast
fermentation. This improvement in gas retention ability is particularly important
when the dough pieces reach the oven. In the early stages of baking before the
dough has set yeast activity is at its greatest and large quantities of carbon
dioxide gas are being generated and released from solution in the aqueous phase
of the dough. If the dough pieces are to continue to expand at this time then the
dough must be able to retain a large quantity of that gas being generated and it
can only do this if we have created a gluten structure with the correct physical
properties.
It is important to distinguish between gas production and gas retention in
fermented doughs. Gas production refers to the generation of carbon dioxide gas
as a natural consequence of yeast fermentation. Provided the yeast cells in the
dough remain viable (alive) and sufficient substrate (food) for the yeast is
available, then gas production will continue but expansion of the dough can only
occur if that carbon dioxide gas is retained in the dough. Not all of the gas
generated during the processing, proof and baking will be retained within the
dough before it finally sets in the oven. The proportion that will be retained
depends on the development of a suitable gluten matrix within which the
expanding gas can be held. Gas retention in doughs is therefore closely linked
with the degree of dough development which occurs and as such will be affected
by a large number of ingredients and processing parameters which are not
necessarily independent of one another.
10.3 Breadmaking processes
Most of the desirable changes resulting from ‘optimum’ dough development,
whatever the bread making process, are related to the ability of the dough to
retain gas bubbles (air) and permit the uniform expansion of the dough piece
under the influence of carbon dioxide gas from yeast fermentation during proof
and baking. The creation of dough with a more extensible character is especially
important for improved gas retention while reductions in dough resistance and
elasticity play a major role in the modification of bubble structures during
processing. Until about 40 years ago the necessary changes were achieved by
mixing the dough and allowing it to rest for a defined period of time (several
hours) as a large mass before dividing the bulk dough and processing the unit
pieces.