Development and optimization of a triboelectrification bioseparation process for dry fractionation of legume flours

• A solvent-free electrostatic-based plant protein separation approach was optimized.
• Separator consisted of a fluidized bed, tribocharger and a separating chamber.
• The critical parameters affecting the protein enrichment were investigated.
• Air flow rate, plate voltage and tribo-charger length were found as dominant factors.
• Optimized protein enrichment was achieved at laminar flow using long tribo-charger and high plate voltage.

A novel solvent-free tribo-electrostatic separation technique for the fractionation of legume flour has been explored with the aim of producing protein- and carbohydrate-enriched fractions from navy bean (Phaseolus vulgaris) flour as a model system. The process consisted of a fluidized bed flour reservoir, polytetrafluoroethylene (PTFE) tribo-charging tube, and a plate-type separation chamber. The optimization of the single-stage tribo-electrostatic separation of navy bean flour was successfully carried out by designing a mixed level full factorial (41 × 23) experiment, followed by analyzing the data with a multiple linear regression model. The influence of process parameters on the protein content and protein separation efficiency of the resulting protein-enriched fractions was evaluated. Air flow rate, plate voltage, and tribo-charger tube length were found to have a significant impact on the protein content and separation efficiency. Although plate angle had no significant impact on the protein content, interactions with air flow rate, plate voltage and tribo-charger tube length were found to have a significant influence on the protein separation efficiency. The optimal values of air flow rate, tribo-charger length, plate voltage and plate angle were found to be 7 LPM, 240 cm, −6.5 kV and 20°, respectively. The protein-enriched fraction produced at the optimum conditions had a protein content of 38.1% accounting for 50.4% of the total protein. Good agreement was observed between the experimental and predicted values.