Physicochemical properties of chitosan-coated nanoliposome loaded with orange seed protein hydrolysate

In the present study the enzymatic production of orange seed protein hydrolysate (OSPH) from orange (Siavaraze, Citrus sinensis) seed protein using alcalase and pepsin enzymes under optimal conditions was evaluated. Then, the effect of OSPH type and chitosan concentration (0, 0.1, 0.2, and 0.4% w/v) on physicochemical characteristics, release rate, stability, antioxidant activity, and morphology of the loaded nanoliposomes was assessed. The results revealed that the particle size, polydispersity index (PDI), and encapsulation efficiency (EE) were influenced by the type of loaded OSPH and chitosan concentration. The zeta potential value in the nanoliposomes after loading with OSPH obtained from alcalase and pepsin changed from -8.87 mV to -9.45 mV and +4.41 mV, respectively. In addition, this index shifted toward positive values after coating with chitosan. The freeze-thaw stress and storing at 4 degrees C (for 4 weeks) led to the highest (about 10-fold) and lowest (about 2-fold) changes in the nanoparticles size, respectively. Among different treatments, the nanoliposome coated by 0.2% W/V chitosan showed decreased peptide release rate, retention of EE, and physical stability under different conditions. Evaluation of the chemical structure using FTIR indicated the positioning of the peptides inside the polar regions, bilayer-membrane, and their ionic complexation with liposome phosphate groups. Moreover, the evaluation of the nanoparticles' morphology indicated spherical particles with smooth surfaces, confirming the dynamic light scattering (DLS) results. The results of this study indicate the efficacy of coated liposomes in protection, control of release and maintaining the antioxidant activity of peptides.