The dry and chemical-free tribo-electrostatic separation (TES) process fractionates food particles while maintaining their functionality. Its mechanism relies on the pneumatic transfer of particles within a tribo-charger tube, wherein inter-particle and particle-wall collisions induce distinct charges on particles before being exposed to an external electric field for electrostatic separation. This study assessed the relative chargeability of protein and starch single components of yellow pea and wheat using various conductor and insulator tribo-charger tubes via online charge analysis while investigating the simultaneous impacts of particle dosing rates (g/h) and airflow rates. Accordingly, the triboelectric series was determined as (+) nylon >
yellow pea protein >
wheat gluten >
polyvinylchloride (PVC) >
wheat starch >
yellow pea starch >
polytetrafluoroethylene (PTFE) >
copper alloy (-). The PTFE tribo-charger tube was quickly saturated with charged particles through their repetitive continuous collisions, thereby limiting effective charge transfer over time, making the impacts of tube length and airflow rate negligible on particles' chargeability across all particle dosing rates. However, for the PVC, copper alloy, and nylon tribo-chargers, the use of longer tubes and turbulent airflow at low particle dosing rates (<
200 g/h for starch and <
500 g/h for protein) maximized specific charge (nC/g) acquisition for all protein and starch particles. All protein and starch particles charged with PVC, copper alloy, and nylon exhibited significantly higher specific charges (nC/g) at lower dosing rates compared to higher particle dosing rates, regardless of the airflow rate. This suggests that particle-particle collisions play a more significant role in charge acquisition than particle-wall collisions in concentrated particle flow. Yellow pea and wheat protein particles achieved higher specific charges with increasing airflow rate (7-14 LPM) than tube length (50-150 cm), a pattern not seen with starch particles. These fundamental findings regarding the charging behavior of protein and starch components at different airflow and particle dosing rates can help researchers gain a better understanding of the separation behavior of milled legumes and cereals, as well as protein-starch binary mixtures during TES.