Germinated Red Lentil Protein Concentrate: Effect of Microwave Pretreatment on Physicochemical, Functional, Thermal, and Structural Properties

Abstract

This study examines the effect of microwave treatment on the properties of protein concentrate derived from germinated red lentil ( Lens culinaris ) flour. Germinated red lentil flour was subjected to microwave (MW) treatment at two power intensities (540 and 720 W) for varying durations (2, 4, and 6 min), following which protein was extracted. The extracted protein was subsequently analyzed to determine modifications in proximate composition, water and oil absorption capacities, foaming and emulsifying properties, as well as structural attributes, employing SEM, FTIR, DSC, and XRD techniques. MW treatment at 540 W for 4 min exhibited significant improvement in the functional properties of the protein concentrate, notably enhancing water and oil absorption capacities. Foaming capacity increased from 125.24% to 175.35% for 540 W at 2 and 4 min, respectively, but declined with prolonged exposure, suggesting protein aggregation and diminished surface activity. Thermal analysis by DSC revealed a disappearance of denaturation peaks in treated samples, indicating pre‐existing conformational changes induced by microwave energy. XRD and FTIR results confirmed disruption of semi‐crystalline regions and secondary structure, with SEM imaging highlighting microstructural loosening and porosity. The findings underscore the potential of microwave processing to tailor protein functionality through targeted structural modification, offering promising applications in the formulation of novel plant‐based foods. However, excessive treatment may compromise thermal stability and emulsifying ability, underscoring the need to optimize microwave parameters to strike a balance between structural integrity and functional enhancement.