Positive Assessment of Mill Stream Endosperm Purity Using Chemical Imaging Direct measurement of wheat endosperm content, the product of flour milling, is now a reality. The cumulative endosperm mass balance calculated from a series of unit processes provides an overall assessment of separation efficiency, which varies with adjustments made to the operational settings of the individual processing steps. A summation of endosperm concentration multiplied by the flow rates of the individual unit processes is used to calculate the endosperm mass balance. Chemical imaging and endosperm yield are included for 15 product output streams from the Hal Ross flour mill (Kansas State University [KSU]). Results, including cumulative endosperm yield obtained using the new quantitative near infrared (NIR) imaging system are stated in the context of cumulative ash and ferulic acid curves that have been reported previously for two experimental wheats. Cumulative millers' curves from previous large-scale (22 bu) millings on a 23 stream KSU pilot mill were applied for the same two experimental wheats. Organic component (ferulic acid) analysis of the cell walls revealed a difference in flour endosperm yield. However, determination of the inorganic mineral (ash) component did not. Advances in analytical method development for assessing intermediate product purity are reviewed, from the traditional ash or color method to cell wall cellulose using an NIR on-line system, HPLC of ferulic acid with UV and fluorescence detection, and digital fluorescence imaging. All of these updated methods can determine the organic component of bran contamination in intermediate products in preference to inorganic ash. In contrast, the NIR spectroscopic imaging method reported here directly measures the endosperm product, which distinguishes it from methods that measure the nonendosperm bran contaminant. |