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A Modified Laboratory Method to Remove Outer Layers from Cereal Grains Using 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

A variety of nutrients and some undesirable components are found and possibly concentrated in outer layers of cereal grains. There is a need to develop simple, efficient, and inexpensive laboratory methods in decorticating cereal grains for physicochemical and nutritional characterization and end-use exploration. This study focused on using a Strong-Scott barley pearler (BP) to abrade barleys and investigated factors that could affect kernel breakage, uniformity of abrading, repeatability, and quality of resulting fractions. Results show that the smaller the sample size, the higher the rate of surface removal. The difference in % removal among pearling times decreased as sample charge size increased. Screens with smaller holes (larger number of mesh per inch) decreased abrading efficiency but reduced kernel breakage significantly. The successive pearling mode (several pearling 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 as compared with the continuous pearling mode (only one pearling cycle per sample). As pearling progressed, the surface color of both outer layer and abraded kernel fractions became whiter. Subsequent trials with several other cereal grains (wheat, rice, sorghum, and oats) confirmed these findings. In conclusion, when modifications of equipment and procedures are made, the BP can be used as an efficient and inexpensive alternative for abrading various species of cereal grains.