Spectroscopic Investigation of Typical Comestible Vegetables for Bioengineering Diagnostics

The absorption and fluorescence spectra of chlorophylls from a large variety of edible plants intended for bioengineering applications were investigated. The plants pigments were extracted in 95% ethanol-based solvents and spectrally analyzed in the VIS-NIR wavelength range. By further dilution steps in the ethanol solvent, an optimized maximum fluorescence was obtained for the plants investigated with a characteristic Chl-a concentration in the range of 0.5-5 g/cm3. A shift of the leading Gaussian fluorescence peak towards 674 nm was observed during dilution for all plants solutions extracts, concomitant with reducing its FWHM optical bandwidth to about 35 nm. This specific behavior in all studied plants can be best explained by self-absorption of Chl-a molecules, capturing the fluorescence energy in the red band and re-emitting it in the NIR region at about 724 nm.