Modulation of native structural architecture and hydrodynamic properties of apple seed protein isolates

The study aimed to synthesize apple seed protein nanoparticles (APN) using planetary ball milling (PBM). On ball milling, protein nanoparticles displayed uniform size distribution with a hydrodynamic diameter of 490.21 nm. Electron microscopy showed irregular, disordered, and rough surfaces of nano-protein particles. FTIR analysis reveals increased β-turn and random coil in APN, indicating loss of ordered protein structure. Changes in secondary structure and microenvironment of amino-acid residues were also depicted by fluorescence quenching and circular dichroism. Owing to conformational changes, a notable decrease in thermal characteristics (∆H = 5.86 to 2.92 J/g) and % crystallinity (36.93 to 32.21%) was observed in APN. Moreover, PBM was found effective in improving the hydrodynamic properties of protein isolates. CLSM demonstrated that emulsions prepared with APN showed increased stability. These results suggest that mechanochemical reduction via ball-milling can be a powerful approach for fabricating nanoparticles with excellent structural and functional characteristics for use in various food systems.