(194e) Development of a Sustainable Tribo-Electrostatic Separation Approach for Dry Fractionation of Legume Flours

Conventional wet fractionation techniques for the production of plant protein powders require the use of solvents, concentrated acids and alkali that result in protein denaturation, thereby reducing the functionality and quality of the protein product. We have explored the potential of a dry or solvent free triboelectrification-based approach for producing protein-rich fractions from legume flours with the advantage of preserving their nutritional value and native functionalities. A vertical bench-scale tribo-electrostatic separator was developed and successfully applied in the classification of navy bean flour as a model system. The approach consisted of a fluidized bed flour reservoir, polytetrafluoroethylene (PTFE) tribo-charging tube, and a plate-type separation chamber. A tribo-electrostatic approach was used to charge proteins and carbohydrates in navy bean flour to different levels before fractionating them based on the magnitude and type of charge inside the separation chamber under the influence of an electric field. Optimization of a single-stage tribo-electrostatic separation of navy bean flour was done by conducting a mixed level full factorial experiment with the aim of investigating the influence of various process variables including air flow rate, tribo-charger length, plate voltage, and plate angle on the protein enrichment and fractionation efficiency. A multiple linear regression model was developed and used to analyze the experimental data. Using the optimum operating conditions identified, the protein content of the original navy bean flour was increased from 25.4% to ~38% accounting for 50% of the total protein. This novel solvent-free tribo-electrostatic separation approach has considerable commercial significance as it preserves the bio-functionality of the protein and averts the likelihood of toxic microbial contamination common in currently used wet processes.