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Laboratory Methods to Remove Surface Layers from Cereal Grains Using a Seed Scarifier and Comparison with a Barley Pearler

¹Grain Chemistry and Utilization Laboratory, National Small Grains and Potato Germplasm Research Unit, USDA-ARS, 1691 S. 2700 West Aberdeen, ID 83201. Phone: 208-397-4162. Fax: 208-397-4165. E-mail: KeshunL@UIdaho.edu

The distribution of nutrients and undesirable components within a cereal seed is heterogeneous, and many of the valuable nutrients are located in the outer layers. Efficient laboratory methods to remove these layers will allow for the experimental production of value-added products. A seed scarifier (SS) was used to abrade barleys, and factors affecting abrading performance and the quality of end fractions including sample charge size, mode of operation, motor speed, and cereal species were investigated. Results showed that the level of surface removal decreased as the sample charge size increased. Compared with a continuous abrading mode (only one abrading cycle per sample), a successive abrading mode (multiple abrading cycles per sample) not only provided a means to collect different fractions of outer layers and remaining kernels, but also minimized kernel breakage and gave more uniform removal of outer layers among seeds. Reduction in motor speeds tended to decrease removal efficiency but significantly prevented kernels from breakage. Subsequent trials with other grain species (wheat, rice, sorghum, and oat) confirmed these findings. Compared with a barley pearler, the SS was easier to operate, produced more repeatable data, and gave more uniform removal from a seed. The SS is an inexpensive and reliable alternative for abrading various species of cereal grains.