Broccoli byproducts protein concentrate: Microwave treatment effect on functional, thermal, and structural properties

Inspired by the exploration of underutilized byproducts to address food security concerns, broccoli byproduct protein concentrate (BBPPC) was subjected to microwave treatment to enhance its properties for broader food applications. The study examined the effects of varying power levels (270, 450, and 630 W) and a fixed processing time of 90 s on the conformation, physicochemical attributes, and functional properties of BBPPC. The findings revealed that microwave treatment led to modifications in the spatial structure of BBPPC, significantly enhancing its functional properties. SDS-PAGE showed the presence of RuBisCO (Small and large subunit), prolamin and glutelin, whereas amino acid profiling indicated transient exposure and subsequent burial of buried residues. Secondary structure analysis showed an initial decrease then increase in β-sheet content, with random coil content rising then falling, reflecting initial protein unfolding followed by refolding. Intense heating cleaved disulfide bonds into free sulfhydryl groups, which later reformed, facilitating intermolecular aggregation of BBPPC. Notably, the average particle size reduced from 647.7 nm to 336.5 nm at a power of 450 W for the specified duration. The functional properties improved significantly (p < 0.05), with a maximum water absorption capacity of 2.89 g/g, oil absorption capacity of 3.72 g/g, foaming capacity of 89.36%, foam stability reaching 58.49%, and emulsification activity index and stability index at 6.56 m²/g and 64.4 min, respectively. These results provide a theoretical foundation for the utilization of BBPPC and illustrate the effectiveness of microwave treatment in modifying plant proteins.