Antimicrobial activity of complexes formed from pea (Pisum sativum L.) proteins and red beet (Beta vulgaris L.) extract – effect of foam fractionation

• Complexes were formed from Pea Protein Glour (PPF) and Red Beet Extract (RBE). • Charge neutralization and increased particle size occurred with PPF-RBE interaction. • RBE control and complexes (foamed and non-foamed) exhibited antimicrobial activity. • Foam-fractionated complex had better antimicrobial activity than the RBE control. A novel protein system based on foam-fractionated pea ( Pisum sativum L.) protein was developed to enhance the antimicrobial potential of red beet ( Beta vulgaris L.) extract. The strategy involved the complexation of red beet extract (RBE) with foam-fractionated pea protein flour (PPF) to form a foam-fractionated PPF-RBE complex; complexation with non-foamed PPF was also studied for comparison. The non-foamed PPF-RBE exhibited a zeta-potential (ξ-potential) decrease from +19.467 ± 0.723 mV to +16.333 ± 0.493 mV, while the foam-fractionated PPF-RBE complexes demonstrated a similar reduction, transitioning from +21.633 ± 0.451 mV to +16.233 ± 0.321 mV. This suggests that the formation of the complexes involves a charge neutralizing effect. Both the non-foamed PPF-RBE and foam-fractionated PPF-RBE complexes showed increased particle size as a result of interactions between the PPF and RBE, as demonstrated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Antimicrobial activity was exhibited by the RBE control and both PPF-RBE complexes (foamed and non-foamed). Specifically, foam-fractionated PPF-RBE was more effective in inhibiting and killing gram-negative bacteria. These foam-fractionated complexes lowered the minimum bactericidal concentration (MBC) of Escherichia coli ( E. coli ) by twofold in comparison to the RBE control. This investigation offers valuable insights into the potential of red beet extract as an antimicrobial agent and the enhanced functionality of foam-fractionated pea protein as a natural preservation ingredient for the food industry.