Sustainable modification of starch color via dual cold plasma and electron beam irradiation

Cold plasma and electron beam irradiation are increasingly recognized as green, energy-efficient, and solvent-free techniques in biopolymer modification. In this study, starch was subjected to single and sequential treatments, varying in irradiation dose (up to 20 kGy) and sequences of fixed plasma conditions. Structural and optical changes were evaluated using dynamic light scattering and spectrophotocolorimetric measurements in both CIELAB and CIELCH color spaces. All treatments significantly influenced particle size distribution and color parameters depending on treatment type and sequence. Cold plasma treatment reduced the Z-average value by ∼10 % without significantly affecting polydispersity, while irradiation induced a dose-dependent decrease in Z-average (∼77 % at 20 kGy) and enhanced size uniformity. Sequential treatments of cold plasma followed by irradiation produced the most pronounced reductions in both Z-average and polydispersity, indicating synergistic effects between surface changes and granule disruption. Colorimetric analysis revealed clearly perceptible changes in all treated samples, with irradiation alone and dual treatments enhancing all colorimetric parameters except hue angle, which decreased, consistent with likely formation of radiation-induced chromophores. Strong inverse correlations were observed between Z-average and color attributes (e.g., r = −0.977 for Z-average vs. C∗ ), highlighting the relationship between structural disruption and optical response. Hierarchical cluster analysis differentiated treatment groups, revealing four distinct clusters based on the extent of modification. These findings demonstrate that the combined application of cold plasma and electron beam irradiation represents an effective and eco-friendly strategy for tailoring the structural and visual properties of starch without chemical additives, offering potential for use in advanced applications. • Sequential cold plasma and electron beam modified starch without chemicals. • Dual treatments significantly reduced particle size and polydispersity. • Color changes correlated with structural degradation and size reduction. • Cold plasma pre-treatment led to the most pronounced starch modifications. • Sustainable process yields tailored starch for clean-label applications.