Joint International Conference on Long-term Experiments ...

BREAD PROPERTIES AND CRUMB STRUCTURE
Ruska L.*, Chereji Rodica**, Purcărea Cornelia**, Timar A.**
* Bakery Bicaciu
** University of Oradea, Faculty of Environmental Protection
ABSTRACT
The relationship between bread-crumb cellular structure and many aspects of quality in a
loaf of white bread justifies investigations of how the structure arises during processing of
the dough. Following a brief overview of the development of bread cellular structure in the
dough, three parts of the literature pertaining to crumb appearance (visual texture) and
bread quality are reviewed, with emphasis on the mechanical properties (physical texture)
of the crumb. The importance of an objective segmentation of the two macroscopic phases
(crumb cells and cell walls solids) is emphasised in digital image analysis studies of breadcrumb
structure. A review of studies where mechanical properties have been measured in
fundamental units has sections on the mechanical properties of the composite structure and
on recent analyses of the mechanical properties of the solid phase. Finally, models which
have been used to relate structure to mechanical properties. Compared with the rule of
mixtures, these bounds represent a good (52%) improvement in the ability to predict values
for bread crumb moduli (crumb firmness).
Keywords: Bread;Crumb; Mechanical properties; Structure; Processing. 1
INTRODUCTION
The relationship between crumb structure and crumb appearance may be self-evident, but
this same crumb structure is also a determinant of loaf volume (Zghal, Scanlon, &
Sapirstein, 1999), the resilience of the loaf [the typical consumer purchasing decision
assessment test (Ponte & Ovadia, 1996)], the texture during eating and even the taste
(Baker, 1939). Therefore, some knowledge of the structure that defines crumb appearance
will permit us to predict many of the quality attributes of bread from knowledge of the
ingredients and how they are processed into the cellular structure on which bread quality is
established. The review addresses three parts of the literature pertaining to crumb
appearance, bread crumb physical texture and bread quality.
MATERIALS AND METHODS
1. Formation of the bread crumb
Bread: Bread as a solid is ‘‘soft’’ (Scanlon, Sapirstein, & Fahloul, 2000), and, like many
other foodstuffs (Campbell & Mougeot, 1999), is comprised, at a macroscopic level, of two
phases- a fluid (air) and a solid (cell wall material). When viewing a cross-section of bread
crumb (Fig.1), it is apparent that the solid phase is entirely connected (Torquato, 2000);
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