Micro- and ultrafiltration of pea proteins from a water-only extraction process

• MF and UF were applied without compromising wet extraction side product quality. • The flux of pea protein filtration was dominated by cake layer formation. • Increasing operating conditions in MF/UF of pea extract had minimal impact on flux. • Pea protein particles, much smaller than the pore size of MF/UF, are retained. • Concentration performance of MF was higher than UF and fine-tunes their difference. For smoother protein transition, mild alternative processes like membrane processing are required. In this study, a novel processing route is investigated using pilot-scale membrane processing of pea proteins for sustainable protein extraction by using only water throughout the extraction process. The protein-rich supernatant from the water-only extraction was processed using MF and UF. The effects of transmembrane pressure (TMP), crossflow velocity, and temperature were studied to optimize permeation flux and composition of the outlet streams. Despite the subtle effects observed during MF, neither membrane showed a significant rise in flux with increasing TMP and crossflow velocity. Increasing temperature did not improve the flux in both MF and UF, even though, decreasing in feed viscosity with increasing temperature. During UF, 90 % of the solutes with molecular weight ≥ 4 kDa are retained by the membrane, while the same retention is achieved during MF for solutes ≥ 50 kDa, which highlights that both MF and UF retain solutes much smaller than their pore size due to cake formation. During concentration mode experiments, MF achieved a 33 % higher volume reduction factor (VRF) than UF at a given operating time, with a slightly higher protein purity, making MF more effective. The outcomes of the study, therefore, provide insights into the pilot-scale recovery and fractionation of proteins from the water-only fractionation of yellow peas using MF and UF by identifying the key challenges for scaling the processes to an industrial level.