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Relationships Between Simple Grain Quality Parameters for the Estimation of Sorghum and Maize Hardness in Commercial Hybrid Cultivars

¹Department of Food Science, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa. ²Agricultural Research Council–Grain Crops Institute, Potchefstroom, 2520, South Africa. ³Cereal Quality Laboratory, Department of Soil and Crop Sciences, Texas A&M University, College Station, TX 77843. ⁴Extraordinary professor, Department of Food Science, University of Pretoria. ⁵Corresponding author. Phone: +27 124204296. E-mail: john.taylor@up.ac.za

Grain hardness affects sorghum and maize processing properties especially for dry milling. A variety of simple grain quality parameters were assessed on 17 sorghum and 35 white maize hybrid cultivars grown in six and four locations, respectively, in South Africa. The purpose was to determine tests that can be used to distinguish hardness in commercial sorghum and maize. The grains were characterized by test weight (TW), thousand kernel weight (TKW), decortication with the tangential abrasive dehulling device (TADD), and kernel size. Maize was also characterized for susceptibility to breakage, stress cracking, and near-infrared transmittance (NIT) milling index. Principal component analysis showed that, in nontannin and tannin sorghums, TADD hardness and TW were closely correlated (P < 0.001). In maize, TADD hardness was closely correlated (P < 0.001) with NIT milling index and TW. Hence, TADD hardness and NIT milling index or TADD hardness and TW would be suitable for maize hardness evaluation. A combination of TADD hardness, TW, TKW, and kernel size >3.35 mm can be used together to select sorghum grain for hardness. It thus appears that TADD hardness is an excellent method of estimating both sorghum and maize hardness that can be applied for routine batch analysis and cultivar evaluation.