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Effect of Conditioning Agents on the Structure of Tempered and Steam-Flaked Sorghum

¹Assistant research scientist, graduate student, and professor, respectively, Cereal Quality Lab, Soil and Crop Sciences, Texas A&M University, College Station, TX 77843-2474. ²Corresponding author. E-mail: c-mcdonough@tamu.edu ³R&D manager, Conagra, Atchison, KS.

Tempering agents affect the pericarp of steamed grain and the endosperm of steam-flaked sorghum. Examination by environmental scanning electron microscopy (ESEM) clearly showed that β-mercaptoethanol (BME), sulfurous acid (SA), phosphoric acid, and cellulase significantly altered the structure of the pericarp and endosperm during tempering. Lime and protease had a lesser effect on the pericarp structure of the kernels, and had little effect on the endosperm. Steamed flakes from the SA treatment were more translucent and durable than all other treatments. Flakes with BME were translucent and high in quality, but were more fragile than the SA flakes. Nontempered, water only, and commercial conditioner treatments produced flakes with the lowest quality. Peak, final, and breakdown Rapid Visco Analyzer (RVA) viscosities were lowest for the SA flakes due to disruption of the starch chains by the weak acid. BME viscosity values were higher than SA, but lower than the water and commercial tempering treatments. The commercial conditioner (15×normal concentration) did not alter kernel structure and did not cause any changes in the RVA profiles over kernels tempered with water alone. Starch gelatinization, measured by enzyme susceptible starch (ESS), was highest in the SA and BME flakes and lowest in the nontempered flakes. Feedlot operators may be able to save money by avoiding the use of chemical additives that do nothing to the grain. By using chemicals proven to have positive effects on flake quality, operators could save money by reducing the processing time and energy needed to produce good quality flakes.