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Internal defect in pickling cucumbers can cause bloater damage during brining, which lowers the quality of final pickled
products and results in economic loss for the pickle industry. Hence it is important to have an effective optical inspection
system for detection and segregation of defective pickling cucumbers. This research was intended to measure the spectral
absorption and scattering properties of normal and internally defective pickling cucumbers and whole pickles, using
hyperspectral imaging-based spatially-resolved technique. Spatially-resolved hyperspectral scattering images were
acquired from 50 freshly harvested 'Journey' pickling cucumbers in the summer of 2008. The cucumbers were then
subjected to rolling under mechanical load to induce internal damage. The damaged cucumbers were imaged again one
hour and one day after the mechanical stress treatment. In addition, 20 whole pickles each of normal and defective
(bloated) class were also measured by following the same procedure as that for pickling cucumbers. Spectra of the
absorption and reduced scattering coefficients for pickling cucumbers and whole pickles were extracted from the
spatially-resolved scattering profiles, using an inverse algorithm for a diffusion theory model, for the spectral range of
700-1,000 nm. It was found that within one hour after mechanical damage, changes in the absorption and reduced
scattering coefficients for the cucumbers were minimal. One day after mechanical damage, the absorption coefficient for
the cucumbers increased noticeably for the wavelengths of 700-920 nm, whereas the reduced scattering coefficient
decreased more significantly for the wavelengths of 700-1,000 nm. Overall mechanical damage had greater impact on
the scattering properties than on the absorption properties. After brining, pickles became translucent and scattering was
greatly diminished. Thus the diffusion theory model was no longer valid for determining the optical properties of whole
pickles. This research suggests that effective defect detection may be achieved by enhancing scattering features in the
optical evaluation of cucumbers.
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