(703c) Simultaneous Separation of Protein and Starch Particles in Oat Flour Via Dry Fractionation Approaches

Concurrent classification of cereal grains into their major constituents of protein and starch through dry fractionation technologies is a promising approach towards sustainable food industry. Conventional wet technologies that are commonly used for plant protein separations are water-, chemical- and energy-intensive processes thus reducing the nutritional quality and bio-functionality of the extracted proteins. We have developed a novel dry fractionation approach by combining dry sieving and electrostatic separation techniques to effectively enrich oat (Avena sativa) flour with proteins. Milled oat flour with ~14% protein was initially passed through a sieving system where the starch-rich fraction with ~10% protein and the bran-rich fraction with ~17% protein were obtained. The starch-rich fraction was then enriched through novel electrostatic separation approach utilizing a lab-scale pneumatic tribo-electrostatic separator consisted of a fluidized bed, tribo-charging tube, and a fractionation chamber with two oppositely charged electrodes and a high voltage supply. In this approach, oat flour was suspended in the air stream inside the fluidized bed and then pneumatically passed through a tribo-charger tube where protein particles and starch granules were selectively charged to different levels and separated based on their acquired charges in the fractionation chamber under the influence of an electric field. We have systematically studied the chargeability of protein and starch particles in the air stream and their separation behavior as a function of air flow rate and electric field strength. Optimum sieving and electrostatic separation conditions resulted in the production of protein-rich fraction with ~20% protein accounting for ~35% of the total protein of the starch-rich fraction. This novel sustainable technique not only resulted in rapid simultaneous separation of protein and starch particles, but also produced protein-enriched fractions with preserved native bio-functionality.