Fluorescence of Cereal Flours

Front-surface fluorescence spectra of cereal flours are easily measured with a commercial spectrofluorometer and a simple cell. The emission spectra are intense in the range 290−600 nm in which three emission bands are active. The most intense is due to the aromatic amino acid residues present in the proteins of flours. At least two other fluorophores are active in the above spectral range and compete for light with the chromophores present in the flours. Four absorption bands are revealed in the same spectral region by reflectance spectra, the most intense being due to the amino acidic fluorophores. Thus, the measured emission is the result of absorption, scattering, emission, and reabsorption processes. Information on the microenvironment of some fluorophores can be obtained. The possibility to recognize different species of cereals, even of different cultivars, is shown. Keywords: Front-surface spectroscopy; fluorescence; reflectance; cereal flours; species recognition