68 Infrared microscopy for grain processing.

D. L. WETZEL.

Infrared spectroscopy performed through a microscope equipped with Schwartzschild mirror-lens objective and condenser makes possible highly localized chemical analysis. The molecular information includes the quantity and type of lipids, carbohydrates, proteins, and presence of other select substances. The spatial resolution of the instrument combined with concentration of a particular chemical in nature to a select botanical part of the seed makes the technique particularly powerful. Substances below detection limits in the bulk may thus be detectable. Spectrochemical analysis in situ of different botanical parts of a section of a wheat kernel is done to catalog the contents without homogenization or extraction. Material found in any fraction of product or byproducts resulting from a processing step (e.g. milling) can be examined. In a homogeneous mixture, individual particles can be analyzed and traced back to the point of origin in the seed. Chemical imaging with a 4.5 ĉm pixel size covering the range of 4000–7000 cm(^–1) provides functional group molecular maps. Infrared sensitive HgCdTe or InSb focal plane array (cameras) detectors (recently adapted from defense use) coupled with a step scan FT-IR spectrometer opens the way to such chemical imaging in 5–10 minutes of data collection time. Commitment to plant material imaging by this technique has recently been made by two major industrial organizations involved in agriculture and grain breeding.