Abstract
Seven improved sorghum hybrids and two commercial hybrids were tempered and steam flaked. The flakes were evaluated for hardness, bulk density, flake durability, in vitro digestibilities, starch properties, and other physical/chemical properties. The flakes from the waxy grain were large, more resistant to breakage, and attractive in appearance. The waxy flakes also had the most unique starch pasting properties. Overall, the waxy flakes had the highest quality. The white food type sorghums produced flakes with superior appearance to commercial red and white sorghums. The floury sorghum produced inferior flakes high in fragility and low in test weight. The hard food type sorghum produced small, uniform flakes that were very hard. Tempering of sorghum reduced the amount of energy used, improved flake strength, reduced dust, improved the appearance of the flakes significantly, and increased the bulk density of flakes for all non waxy sorghums. However, the waxy sorghum flake bulk density decreased slightly with increased tempering moisture. Addition of a selected grain conditioner (< 15x normal rate) during tempering did not effect pericarp structure and/or increase water absorption by the kernel when viewed with the ESEM. Sulfurous acid and 2-mercaptoethanol caused significant disruption of the sorghum pericarp and endosperm when viewed with the ESEM. The use of these chemicals could enhance efficiency of the sorghum processing. The in vitro digestibility and enzyme susceptible starch values had a great deal of variability and there were no significant differences found between flakes prepared from the varieties. The pasting properties of the different sorghum flakes were significantly affected by tempering and endosperm type. This suggests that it may be possible to utilize starch viscosity changes to monitor steam flaking. The flake breakage and durability tests appeared to be good quality control tests for steam flaking. However, there are many aspects of steam flaking that are not well understood. Further research is needed to evaluate endosperm differences among sorghum hybrids and lines and their effects on digestibility and processing.
Anderson, Brian J. (1994). The effects of tempering and steam flaking on sorghum. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1994 -THESIS -A5453.