Joint International Conference on Long-term Experiments ...

those portions that are not, are not bread crumb, but merely bread crumbs. In Fig. 1 it can be
seen that the air cells are isolated. However, in three dimensions, at least a portion (and
perhaps most) of the cells are connected. The volume fraction of the phases and the nature
of their connectivity (Warren & Kraynik, 1997) determines the structure, and consequently
the mechanical properties of the bread.
Fig. 1. Digital image of bread crumb.
Breadmaking: The mix ingredients that are used to create a basic formula dough are flour,
water, leavening agent (yeast or chemicals) and sodium chloride. In order to convert these
mix ingredients into the structure shown in Fig. 1 a number of processing operations are
performed. The operations are carried out in such a way that the dough can possess the
appropriate mechanical properties which will permit it to retain gas and thus produce a wellexpanded
loaf of bread with an even crumb structure. Three objectives are sought in the
processing operations :
1. mixing and development of the dough (mixing and fermenting);
2. formation of a foam structure in the dough (moulding, proofing and baking);
3. stabilization of a porous structure by altering the molecular configuration of the
polymeric components in the cell walls through the application of heat (baking).
2. Evaluating bread crumb cellular structure
Crumb cellular structure (or its grain) is an important quality criterion used in commercial
baking and research laboratories to judge bread quality alongside taste, crumb colour and
crumb physical texture. Bread crumb visual texture accounts for approximately 20% of the
weighting used in judging bread quality. Regardless of the weight assigned to it, crumb
grain is believed to have considerable importance in defining bread quality since the
accuracy in scoring other quality attributes in bread (e.g. loaf volume, loaf symmetry)
depends on the underlying crumb grain characteristics. In bread crumb scoring, the
examined parameters are crumb fineness (open versus closed cells), uniformity, cell shape,
and cell wall thickness (Pyler, 1988).
Image acquisition: In examining the visual texture of bread, particularly if one is trying to
obtain quantitative information on its structural organisation to determine the influence of
formula or processing conditions, the goal is to enhance the contrast between the two phases
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