550 Produce Degradation: Reaction Pathways and their Prevention
relatively minor wrinkling, more debris was found on the surfaces (Figure 18.14e),
and at high magnifications the wax seems to have dissolved and redeposited in an
irregular fashion (Figure 18.14f).
FIGURE 18.13Scanning electron micrographs of ‘Forcelle’ pear cross sections. (a) Fresh
surface and underlying tissues of the mesocarp showing fresh fracture plane where breaks
occur through cells. (b) Aged surface and underlying tissues where the fracture occurs between
cells, indicating that the middle lamella has failed. (c) Aged sample of mesocarp cells showing
nonturgid cells; most breaks have occurred between cells, intercellular gaps and extensive
tissue disruption toward the top of the micrograph. (d) Aged sample at the periphery showing
the epidermis, exocarp, crushed peripheral mesocarp, and underlying mesocarp tissues; note
the intercellular gap in the mesocarp. (e) Fresh inner mesocarp showing fully hydrated cell
walls. (f) Aged inner mesocarp showing dehydrated cell walls and possible cell wall thick-
ening. Magnification bars: a, b, 500 μm; c, 200 μm; d, 50 μm; e, f, 25 μm.