Advancing sustainable protein enrichment: Insights and pathways from integrated milling and tribo-electrostatic separation of yellow pea

Traditional wet-fractionation methods produce plant protein isolates (>90 %) but may compromise the protein's bio-functional properties. Tribo-electrostatic separation (TES) is a promising dry and waste-free approach to producing native protein concentrates from legumes. This study investigated the effects of milling type (Ferkar and Pin) and milling intensity (fine and coarse), airflow rate (7–14 LPM), and plate voltage (±3 to ±12 kV) on protein enrichment from yellow pea flour via TES. Compositional analysis under optimal conditions showed protein enrichment in the negatively charged plate (NCP), starch in both the positively charged plate (PCP) and chamber bottom (CB), and dietary fiber mainly in the loss fraction. The General Linear Models identified the significant main effects and two-way interactions of processing parameters on fractions' yield, protein content, and separation efficiency. The airflow rate primarily influenced protein enrichment/depletion of fractions. The maximum separation efficiency of the protein-rich fraction was achieved at laminar flow on the NCP. Plate voltage did not influence NCP's protein enhancement but improved its separation efficiency. The interaction between plate voltage and milling intensity influenced protein enrichment in the bottom half of the NCP fraction. Low plate voltage with a fine milling intensity or high plate voltage with a coarse milling intensity elevated protein enrichment in this fraction. These results underscore the flexibility of this waste-free TES approach for protein enrichment from starch-rich legumes. It offers promising avenues for piloted and large-scale applications and could eventually result in optimizing the capital cost investment in the milling-TES process as a future step.