Complex bio‐nanoparticles assembled by a pH ‐driven method: environmental stress stability and oil–water interfacial behavior

Abstract BACKGROUND Protein‐based nanoparticles have gained considerable interest in recent years due to their biodegradability, biocompatibility, and functional properties. However, nanoparticles formed from hydrophobic proteins are prone to instability under environmental stress, which restricts their potential applications. It is therefore of great importance to develop green approaches for the fabrication of hydrophobic protein‐based nanoparticles and to improve their physicochemical performance. RESULTS Gliadin/shellac complex nanoparticles (168.87 ~ 403.67 nm) with various gliadin/shellac mass ratios (10:0 ~ 5:5) were prepared using a pH‐driven approach. In comparison with gliadin nanoparticles, complex nanoparticles have shown enhanced stability against neutral pH, ions, and boiling. They remained stable under neutral conditions at NaCl concentrations ranging from 0 to 100 mmol L−1 and even when boiled at 100 °C for 90 min. These nanoparticles were capable of effectively reducing oil–water interfacial tension (5 ~ 11 mNm−1) but a higher amount of shellac in the nanoparticles compromised their ability to lower interfacial tension. Moreover, the wettability of the nanoparticles changed as the gliadin/shellac mass ratio changed, leading to a range of three‐phase contact angles from 52.41° to 84.85°. Notably, complex nanoparticles with a gliadin/shellac mass ratio of 8:2 (G/S 8:2) showed a contact angle of 84.85°, which is considered suitable for the Pickering stabilization mechanism. Moreover, these nanoparticles exhibited the highest emulsifying activity of 52.42 m2 g−1 and emulsifying stability of 65.33%. CONCLUSIONS The findings of the study revealed that gliadin/shellac complex nanoparticles exhibited excellent resistance to environmental stress and demonstrated superior oil–water interfacial behavior. They have strong potential for further development as food emulsifiers or as nano‐delivery systems for nutraceuticals. © 2023 Society of Chemical Industry.