All the samples: adulterated juices (the different mixtures), the
authentic orange and grapefruit juices as well as laboratory-pressed juices were all analysed by 3D-front- face fluorescence
(3D-FFF) spectroscopy in the same conditions. Two different prep-arations were performed for each sample.
Fluorescence landscapes (3D spectra) were measured directly
on the samples without prior preparation, using a Xenius spectro-fluorometer (SAFAS, Monaco) equipped with a xenon lamp source,
excitation and emission monochromators and a front-face sample-cell holder. Measurements were carried out using acryl cuvettes.
The instrumental settings were: bandwidths 10 nm, excitation
wavelengths 270–600 nm (every 4 nm) and emission wavelengths
290–700 nm (every 4 nm). A photomultiplier (PM) voltage of 470 V
was used to avoid detector saturation. The ‘‘Forcing’’ option was
also used in order to limit the emission range so that data acquisi-tion started 25 nm beyond the excitation wavelength, thus avoid-ing interference from Rayleigh scattering. The data consisting of