Dispersive Raman spectroscopy at 1064 nm for rapid screening of deoxynivalenol in wheat bran: preliminary results.

Deoxynivalenol (DON) is a Fusarium toxin which frequently occurs in grains. Because of the toxic effects induced by DON, many regulations worldwide have established safety levels in food and feed. For instance, the EC maximum limit for DON in unprocessed wheat bran has been set at 750 ?g/kg. New devices are envisaged for the rapid detection of DON in grain stocks in order to verify the compliance with EU regulation and to perform a quick assessment of contamination without using chemicals and bench analytical instruments. Optical spectroscopy is currently emerging as a modern and "green" analytical technique for intact food analyses, thanks to the non-destructive nature of light measurements which enable rapid checks without making use of reagents or chemical treatments, thus avoiding the problem of waste disposal. The objective of this study was to assess the use of Raman spectroscopy, excited at 1064 nm by using a dispersive detection scheme, for rapid screening of DON in wheat bran. Twelve wheat bran samples contaminated with DON in the range <=100-1600 ?g/kg were considered. Four replica measurements were carried out for each sample, thus taking into account unavoidable inhomogeneity of contamination. Raman spectra were processed using Standard Normal Variate (SNV) and Orthogonal Signal Correction (OSC) for compensation of scattering influence, and removal of DON-independent effects. Then, Partial Least Square regression was applied as a predictive model for DON quantification. A coefficient of determination R2=0.72 was obtained, together with a root means square error of calibration RMSEC=313 ?g/kg, thus indicating that Raman spectroscopy has good potential as a rapid tool for DON detection.