Profiling Endosperm Purity of Commercial Mill Streams Preceded by Debranning Using Quantitative Chemical Imaging1,2
Vibrational spectroscopic data obtained simultaneously in a rectangular detector array facilitates chemical analysis of the heterogeneous mixture of solids that constitutes wheat flour. Analyses of 81,920 near infrared spectra followed by partial least squares data treatment enables determination of purity with respect to endosperm versus nonendosperm content for each individual pixel in the image. Heterogeneity is revealed by the resulting image, and a mathematical weighted summation provides the composite composition for the field of view. The advantages of the solid-state technology employed in this method include the high sensitivity of individual indium antimonide detector elements and the programmed electronic wavelength switching of the liquid crystal tunable filter, which operates with no moving parts. The organic chemical content of endosperm (primarily starch and protein) is compared to nonendosperm components (cell walls, aleurone, pericarp, etc.) using the vibrational spectroscopic response of different molecules within the solid mixture. This objective quantitative chemical imaging method was applied to determine the endosperm purity profile of 29 flour streams from a commercial flour mill in which the break system is preceded by a debranning operation. A cumulative flour endosperm purity plot reveals distinct changes in purity as successively less pure streams are incorporated to increase the yield. The sensitivity and chemical structure basis of the endosperm purity method described should be useful in assessing the effects of new equipment installation or significant changes in operational settings on the efficiency of a commercial milling process.