Radio frequency-assisted mitigation of off-flavor formation in pea protein isolate

The efficiency of radio frequency (RF) seed pretreatment to mitigate lipid oxidation-related beany volatile compounds during pea protein isolation via wet fractionation and its underlying mechanism were evaluated. RF treatments above 110 °C for >20 min fully inactivated lipoxygenase (LOX) but caused up to 50% loss in protein yield. By optimizing sample thickness, electrode distance, and heating duration, RF heating achieved >90% LOX inactivation below 100 °C while preserving protein yield, outperforming conventional heating. Moderate RF treatment (∼75 °C) reduced LOX activity by 80% while retaining intrinsic phenolic compounds, which stabilized EPR-detectable free radicals and promoted the accumulation of hydroxyoctadecadienoic acids (HODE-13) rather than volatile off-flavor compounds. In contrast, more intense RF treatments (∼85-95 °C) degraded intrinsic antioxidants and accelerated lipid breakdown to hydroperoxides and volatile off-flavor compounds. Overall, optimized RF pretreatment can effectively limit lipid oxidation and off-flavor formation during pea protein isolation by combining LOX inactivation with phenolic-mediated radical stabilization, without compromising protein yield.