Effect of assembly sequence on characteristics, antimicrobial activity, and release properties of lactoferrin-almond gum-ferulic acid self-assembled complexes

Abstract

The purpose of this research is to produce and characterize the self-assembled composite particles of lactoferrin (LF), almond gum (AG) and ferulic acid (FA), representing a novel delivery system tailored for food preservation and health promotion. Three different formulations (coded as A, B, and C) were prepared based on the order of mixing the components. The lowest minimum inhibitory concentration against Staphylococcus aureus and the lowest minimum bactericidal concentration against all investigated microorganisms, Escherichia coli, Shigella flexneri, Staphylococcus aureus, and Listeria monocytogenes, were obtained by complex C (adding LF to a pre-mixed AG and FA solution, selected as the optimal one for further characterization). This can be explained by its smaller particle size and greater penetration into the microorganism membrane. According to the SEM images, the resulting complex had a flaky structure with irregular size and shape. The red shift in the FTIR OH stretching peak confirms hydrogen bonding between the components, which weakens the OH bond and lowers the vibrational frequency. The (dis)appearance and displacement of peaks in the XRD graph of the complex compared to the components provide another evidence of their interactions. The absolute value of zeta potential >30 for all complexes indicates their stability. In release modeling, the Kopcha model demonstrated the optimal fit to the experimental release data across both simulated gastric and intestinal fluids. The substantial release of FA in simulated gastric conditions, combined with the anti-ulcer activity of all three components, renders this formulation promising for gastroprotective applications alongside natural food preservation.