ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The environmental scanning electron microscope (ESEM) has the ability to image both dry and hydrated materials, without the need for a conductive coating, unlike conventional SEM. This presents a unique opportunity to explore the structure and dynamic mechanical characteristics of food systems, including those in a moist state. We have developed a technique in which quantitative stress-strain relationships can be obtained whilst allowing simultaneous imaging, by ESEM, of the mechanical response of a sample. The results of in situ compression tests on dry and hydrated wheat flour breadcrumbs are presented and discussed. It was found that a maximum in the critical fracture stress occurred at intermediate moisture content (∼16%). ESEM micrographs demonstrate the differences in mechanical behaviour at three different moisture contents (nominally dry, 16% and 30%). Our findings suggest that 'voids' in cell walls, along with discontinuities between starch granules and gluten in the crumb, play an important role in fracture initiation. Further evidence shows that voids may be bridged by 'struts' and 'strings' of matrix material, which may be factors in the control of fracture propagation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1004720209547
Permalink