Abstract: A quantitative infrared chemical imaging method to determine the concentration of a desired high value product in a milling process is used as a basis to optimize the milling process by changing operational parameters, such as sieve size. In a dry milling process, the method can be used to determine the concentration of purified endosperm within heterogeneous solid particulate mixtures containing endosperm and nonendosperm botanical parts. The imaging component accommodates the analysis of particle size statistics for each component of the mixture, based upon the chemical structural characterization. Timely chemical composition and particle size analyses enables informed selection for the optimization of physical separation for the processing of granular solids. The method involves changing sieves within the sifting apparatus based on chemical imaging to provide smaller or larger screen openings to improve separation of endosperm and nonendosperm material from the ground product.