In the present study, the potential of cold atmospheric-pressure plasma (CAPP) for fabrication of Grass pea protein isolate nanoparticles (GPPINPs) was investigated. The size of nanoparticles decreased and their morphology became more non-uniform when higher voltage and longer processing time were applied. The lowest z-average was observed for GPPINP fabricated at 18.6 kVpp after 600s of plasma treatment. The FTIR spectra for amid I and amid II bands were changed after the plasma treatment. The content of carbonyl groups and dityrosine crosslinks in GPPINPs were higher, while the content of free SH groups was lower than the native GPPI. The main subunits of 7S and 11S retained in GPPINPs after plasma treatment. GPPINPs fabricated at 9.4 kVpp had more ordered secondary structure while partial unfolding was observed for the GPPINPs fabricated at 18.6 kVpp. Except for GPPINPs fabricated at 18.6 kVpp for 600s, 3rd structures of nanoparticles were more compact. With increasing the treatment time and voltage, the surface hydrophobicity of GPPINPs increased while their solubility decreased. The hydrophobic interactions in GPPINPs increased and the hydrogen bonding decreased as the plasma treatment time and voltage increased. However, GPPINPs were much more efficient in achieving an absorption equilibrium at oil-water interface, indicating the great potential for application as surface active particles. Protein nanoparticles did not show any cytotoxicity in Human Dermal Fibroblasts (HDF) cells, however, their biological activities depended on the concentration used. Overall, these findings indicate that CAPP can be used for fabrication of protein nanoparticles with new functional property for food and pharmaceutical applications.

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