Submitted to: National Fusarium Head Blight Forum Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 10/28/2008
Publication Date: N/A
Technical Abstract: We have developed rapid near infra red (NIR) techniques for nondestructive automatic sorting of Fusarium damaged wheat kernels and for estimation of deoxynivalenol (DON) levels in single wheat kernels. We studied NIR optical characteristics of DON to identify NIR absorption bands and to assess the applicability of NIR technique for direct measurement of DON in order to improve the calibrations. NIR transmission spectra of DON (0.5 - 2000 ppm) dissolved in acetonitrile and that of water (0 - 640 ppm) in acetonitrile were studied to identify NIR absorption bands of DON and water and to see how strong NIR absorption bands of water interact with DON NIR absorption bands. Deoxynevalenol crystals were dissolved in acetonitrile to prepare a 2000 ppm stock solution. It was thereafter serially diluted to prepare a series of DON solutions up to 0.5 ppm. The solutions in IR quartz (10 mm path length) cuvettes were scanned using an ASD spectrometer. Solutions were scanned three times to collect three different spectra per each DON concentration. Likewise, water was added to acetonitrile and spectra were recorded. The collected DON spectra were used to develop a calibration to predict DON levels in acetonitrile solution. Two spectra from each concentration were used for developing the calibration by PLS regression method and the other spectra used to validate the calibration. The optical density spectra of DON and water in various concentrations were used to study DON and water absorption peaks. Difference spectra and second derivative spectra of DON and water were used to identify and resolve absorption peaks. In the 950 - 2200 nm range two DON absorption bands were identified at 1390 -1440 nm and 1880-1950 nm having peaks at 1410 and 1905 nm respectively. The absorbance at 1905 nm is approximately one magnitude stronger than the absorbance at 1410 nm. Water absorption bands were found around 970 and 1420 nm in increasing intensity. The water absorption bands above 1850nm were much stronger being unable to measure even at 40 ppm using 10 mm path length. The calibration developed for DON in acetonitrile (R2=0.995 SECV=38.8 with 6 PLS factors) predicted DON levels in acetonitrile with a R2=0.998. This shows that NIR absorbance can be used to accurately estimate DON levels in acitonitrile. However, when it comes to predicting DON in cereal grains such an accuracy is difficult to achieve due to interference with stronger water absorption bands that overlap DON absorption bands. Our present SKNIR technique for scab sorting and DON estimation use 950-1650 nm waveband. Based on the observations of this study it may be possible to further improve calibrations by extending NIR scanning range above 1950 nm to include the stronger DON absorption band at 1905 nm. Acknowledgement: This material is based upon work supported by the U.S. Department of Agriculture. This is a cooperative project with the U.S. Wheat & Barley Scab Initiative. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.