Effect of variable oxygen concentrations on reduction of off-flavor compounds in soybean protein isolate by dielectric barrier discharge cold plasma.

Soybean protein isolate (SPI) applications are often limited by beany and grassy off-flavors. This study proposes a non-contact strategy using Modified Atmosphere Packaging (MAP)-assisted Dielectric Barrier Discharge Cold Plasma (DBD-CP), where MAP serves as a tunable environment to modulate plasma chemistry. The synergistic effects of gas compositions (20%, 30%, 40%, 50%, 60% O2) and DBD-CP on SPI volatiles were decoded via HS-GC-IMS, GC-MS, and E-nose. Increasing O2 triggered targeted degradation of key off-flavor markers (e.g., 3-methyl-1-butanol, 1-octen-3-ol, 2-pentylfuran), with 60% O2 achieving optimal refinement-evidenced by marked shrinkage in E-nose radar plot area. Beyond quantitative reduction, the treatment induced a qualitative shift toward a cleaner aroma through the controlled formation of pleasant ketones and esters, driven by the interaction between reactive oxygen species (ROS) and off-flavor functional groups. This in-situ physical modification strategy eliminates secondary contamination risks, significantly broadening SPI's potential in premium dairy, meat analogues, and functional foods.