Effect of Microfluidization on Functional Properties and Digestibility of Flaxseed Protein Isolates

Abstract

Extracting proteins from flaxseed meal can add value to this by-product while increasing the availability of plant-based protein. However, the pressing processes, as well as the alkaline protein extraction process, can affect protein functionality. Dynamic high-pressure microfluidization (DHPM) is a potential physical technique capable of improving protein functionality. This study aimed to investigate the impact of DHPM on the technological properties and digestibility of flaxseed protein isolates (FPI) obtained by alkaline extraction. Following protein extraction, the samples were treated in a microfluidizer at 137 MPa for five passes. The treated samples were then evaluated for their functional properties (solubility, emulsification, foaming, and gelation) and in vitro digestibility, assessed through protein digestibility (IVPD), degree of hydrolysis (DH), and SDS-PAGE analysis. DHPM treatment significantly increased solubility from 66.71% ± 2.42% to 92.18% ± 0.91% (p < 0.05). While no change was observed in the emulsion activity index (EAI), the emulsion stability index (ESI) improved from 118.28 ± 14.83 to 216.08 ± 16.86 min (p < 0.05). Emulsions prepared with treated samples also exhibited smaller increases in droplet size and polydispersity over 7 days. Gels formed with treated samples were more homogeneous, with no visible pores. However, foaming properties were not improved. No significant differences were observed between the control and DHPM-treated samples in IVPD or DH after in vitro digestion (p > 0.05). These findings demonstrate that DHPM can improve the functional properties of FPI without compromising its in vitro digestibility, highlighting its potential for applications in diverse food systems.