Inactivation of lipase and lipoxygenase in whole wheat flour using atmospheric cold plasma and steam treatments: Kinetics, mechanism, and impact on its compositional properties

This study aims to utilize two separate techniques, viz., atmospheric cold plasma (voltage: 5–25 kV; time: 1–10 min) and steam treatments (at 100 °C for 1–4 min), to inactivate lipase and lipoxygenase in whole wheat flour (WWF) and assess the impact on its compositional properties. The cold plasma exposure of WWF at 25 kV/6 min resulted in 97.5% and 100% inactivation in lipase and lipoxygenase activity, respectively, whereas corresponding inactivation values after the steam treatment (100 °C/4 min) were 90.6% and 99.7%. The inactivation order (n) of lipase and lipoxygenase during cold plasma treatment was 1.2 and 1.0, respectively. In the optical emission spectra of cold plasma-induced air, the band heads within 328–426 nm confirmed the transition between various reactive nitrogen species (second positive, first negative, second positive, and mono-positive systems). The band-head for OH radicals was recorded at 314 nm. The oxygen molecular band at 739 nm and singlet oxygen transition line at 778 nm were also observed. The cold plasma and steam treatments resulted in a more random coil in lipase's secondary structure. The cold plasma treatment at 25 kV/6 min didn't impact the particle size, density, color profile, and proximate composition of the flour.