Effects of short-term and long-term cold plasma treatment on the color, structure, and Pickering foaming properties of Grass pea protein particles

Abstract

In this study, the effects of short-term (30 and 60 seconds) and long-term (300 and 600 seconds) cold plasma treatments at two voltages (9.4 and 18.6 kVpp) on the color, structure, and foaming properties of Grass pea protein isolate (GPPI) were investigated. The b* value of the protein particles (yellow color) increased with increasing treatment time and applied voltage. FTIR spectroscopy revealed a decrease in intramolecular aggregates of GPPI after short-term cold plasma treatment (S-CPT), which was accompanied by an increase in the α-helix to β-sheet transition with increasing treatment time and applied voltage. Long-term cold plasma treatment (L-CPT) increased the intermolecular aggregates, α-helix and β-sheet structures, with the exception of L-GPPIPT/60018.6 particles. The pH of the protein dispersion decreased as treatment time and applied voltage increased, with the exception of L-GPPIPT/60018.6 dispersion. Changes in the free amino groups and particle size distribution demonstrated that the S-CPT fabricated smaller particles with flexible conformations, whereas the L-CPT produced particles of different sizes with compact conformations due to protein aggregations and intermolecular interactions. S-CPT increased particle water binding capacity and the absorption rate of particles at the water-air interface, whereas L-CPT decreased these properties. The best foamability and foam stability were obtained with S-GPPIPT/6018.6 and L-GPPIPT/6009.4 particles, respectively. Microscopic observation indicated that cold plasma treatment altered the morphological properties of the protein-stabilized foam. Results of this study indicate that S-CPT is an effective solution for improving GPPI's foamability, while L-CPT has the potential to enhance protein foam stability through the Pickering mechanism.