Transient infrared spectroscopy for detection of toxigenic funs in corn: Potential for on-line evaluation

An urgent need for rapid sensors to detect contamination of food grains by toxigenic fungi such as Aspergillus flavus prompted research and developmen t of Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) as a highly sensitive probe for fungi growing on the surfaces of individual corn kernels. However, the photoacoustic technique has limited potential for sc reening bulk corn because currently available photoacoustic detectors can a ccommodate only a single intact kernel at a time. Transient infrared spectr oscopy (TIRS), on the other hand, is a promising new technique that can acq uire analytically useful infrared spectra from a moving mass of solid mater ials. Therefore, the potential of TIRS for on-line, noncontact detection of A. flavus contamination in a moving bed of corn kernels was explored. Earl y test results based on visual inspection of TIRS spectral differences pred ict an 85% or 95% success rate in distinguishing healthy corn from grain in fected with A. flavus. Four unique infrared spectral features which identif ied infected corn in FTIR-PAS were also found to be diagnostic in TIRS. Alt hough the technology is still in its infancy, the preliminary results indic ate that TIRS is a potentially effective screening method for bulk quantiti es of corn grain.