Cereal Chem 68:454-460   |  VIEW ARTICLE

Computer Analysis of Fluorescence for the Measurement of Flour Refinement as Determined by Flour Ash Content, Flour Grade Color, and Tristimulus Color Measurements.

S. J. Symons and J. E. Dexter. Copyright 1991 by the American Association of Cereal Chemists, Inc. 

Millstreams from repeated pilot-scale millings of a commercially grown No. 1 Canada western red spring wheat were used to measure flour refinement when selecting for aleurone and pericarp tissue by fluorescence. Measurements were averaged from 25 full-field fluorescence images using UV excitation for aleurone and blue excitation for pericarp. Pericarp fluorescence was strongly correlated (r2 greater than 0.9) to the tristimulus color coordinate L* (brightness) of the flour, flour ash content, and flour grade color. The regression equations for pericarp fluorescence to all the above refinement indexes were homogeneous for replicate millings performed over a one-year period and were not influenced by flour age. Aleurone fluorescence was also significantly correlated (P less than 0.05) to the same flour refinement indexes. With the aleurone measurement procedure, millstreams were segregated into two groups, which made the estimation of flour refinement using aleurone more complex than for pericarp using our system. Variability in the fluorescence measurements and flour refinement indexes associated with operators, experimental design, equipment, flour moisture, and flour particle size were investigated. Tristimulus a* and b* values were highly sensitive to moisture changes in the flour, and b* values were sensitive to flour particle size. Tristimulus L* values were slightly sensitive to particle size but insensitive to flour moisture, while relative fluorescence measurements were insensitive to both flour moisture and particle size. Instrumental variability was associated with our fluorescence methods.