| dc.description.abstract | Micronizing is accomplished by heating the grain with infra-red burners and crushing the heated kernels between corrugated steel rollers. This study examined for the first time the chemical, physical, and structural changes that occur in the sorghum kernel during the micronizing process and related this information to the performance of the micronized sorghum grain in a food system.
A laboratory model Pierce micronizer was used to process three sorghum varieties with different endosperm characteristics: waxy, heterowaxy, and nonwaxy. A subsample of the nonwaxy variety was pearled prior to micronizing to remove the pericarp.
The waxy grain had the greatest expansion followed by the heterowaxy, and nonwaxy varieties; the pearled nonwaxy grain was more expanded than the unpearled grain. Changes in structure of the grain were observed with light and scanning microscopy. The greatest alterationin endosperm structure was seen in the waxy sorghum variety.
The extent of gelatinization, measured by los s of birefringence, enzyme susceptibility, and viscosity values, occurred in the following decreasing order: waxy, heterowaxy, pearled nonwaxy and unpearled nonwaxy sorghum variety.
The chemical composition of the grain; including available lysine content, was unaffected by micronization.
The highly expanded waxy flake would be desirable as a ready-to-eat breakfast cereal, whereas the dense nonwaxy flake would be well suited for a cookie, pie or granola bar formulation. The pearled nonwaxy flake, white and bland in flavor, would perform well in a cooked cereal. | en |
