Gamma irradiation-induced modulation of physicochemical and techno-functional properties of quinoa protein isolates

Gamma irradiation is an emerging technique to modify the structure and functional properties of food proteins. This study investigated the effects of irradiation at 2.5, 5, 7.5, and 10 kGy (S1-S4) on the physicochemical and techno-functional characteristics of quinoa protein isolates (QPIs). Irradiation induced structural changes in QPIs, resulting in dose-dependent alterations in functionality. The highest water absorption and water solubility were observed at 2.5 kGy, whereas the highest water-holding capacity and surface hydrophobicity occurred at 10 kGy. Foaming capacity decreased while foaming stability increased with increasing irradiation dose, with S4 showing the lowest capacity (31.67 ± 0.08%) and highest stability (26.08 ± 0.01%). Thermal and pasting analyses indicated that S4 had reduced gelatinization enthalpy (78.01 ± 0.05 J/g) and increased setback viscosity (33.02 ± 2.07 cP), reflecting protein rearrangements and enhanced hydrophobic interactions that facilitated starch retrogradation. Functional group analysis revealed no new groups formed, while confocal microscopy showed aggregation in samples exposed to doses above 5 kGy. These results demonstrate that gamma-irradiation can tailor QPI structure and techno-functional properties, with low doses enhancing solubility and high doses improving foam stability, water-holding capacity, and thermal behavior. The findings highlight the potential application of irradiation treatment for optimizing QPIs in diverse food formulations.