R. M. Johnson. Copyright 1960 by the American Association of Cereal Chemists, Inc.
Five simple, uniform, and accurate methods for quantitative determination of the total smut contamination in wheat have been developed; namely: light transmittance, sedimentation, catalase activity, light reflectance, and light absorption. These methods were applied to 138 samples of smutty wheat ranging from 0.5 to 3.0% smut and representing three crop years. The results were compared to smut spore counts based on a reference microscopic method. Correlation coefficients for the relation between test values for all five methods and respective spore counts were highly significant. Six factors---namely, simplicity, practicability, rapidity, accuracy, precision, and cost of equipment---were considered in evaluating the methods. The sedimentation method would be preferred where low cost of operation is desired. This method could also be used in areas of low smut incidence, where an occasional test for smut may be required. The sedimentation method was used to differentiate between smut and other forms of mold infection in samples of questionable smutty wheat. However, the light-absorption method measuring smut-spore concentration directly on bulk wheat, which takes only 45 seconds per determination, was selected as the most practical and suitable method for routine testing of smut content in wheat where time is a prime factor.