Absorption and phase contrast images of transverse cut of the raw
and cooked beef sample are presented in Fig. 1. The grayscale images
are reconstructed from a single slice of the data sets. The dark ring surrounding
the samples is the sample tube. The absorption images
(Fig. 1A+B) appear noisy and hardly any contrast between the muscle
components is seen. In the absorption image of the raw meat (Fig. 1A)
only the intra muscular fat can be separated from the muscle structure.
In the cooked meat (Fig. 1B) the structure of the muscle fibers and connective
tissue is faintly observed. In comparison, superior contrast is
provided in the phase contrast images (Fig. 1C+D), where muscle
fibers, connective tissue, intra muscular fat and the surrounding water
phase appear clearly separated. In the phase contrast images intensity
differences reflect differences in electron density of the structural components
where the light intensity increases with increasing densities.
In the raw meat (Fig. 1C) the muscle fiber part of the muscle is represented
by the gray areas, whereas the connective tissue, mainly the
perimysium, is thewhite areas. The small black spots are intramuscular
fat. Towards the edge of the samples darker gray areas are seen
representing a water phase. Due to changes in electron density of the
muscle components as a consequence of heating an intensity shift is
seen in the image of the cooked sample (Fig. 1, D) compared to the
raw sample. In the cooked sample muscle fibers have contracted and
thus increased in density,which is seen as thewhite areas: The connective
tissue has decreased in density due to absorption of water and appears
as light gray. The most remarkable changes in the structure are
the shrinkage of both the total sample volume and the individual fiber
bundles. In the cooked sample the fiber bundles appear clearly separated
by the surrounding perimysium. The shrinkage of the myofibrils has
forcedwater to be expelled,which can be observed as an increase in the
area of the water phase surrounding the meat. The area of the perimysium
is increased indicating partly solubilization.