Gamma radiation-induced structural modifications in millet β-glucan: structure-function relationship and rheological behaviour

This study investigated the effects of gamma radiation-induced modifications to the structural, thermal, morphological, and rheological properties of β-glucan, a naturally occurring biopolymer extracted from pearl millet ( Pennisetum glaucum ) and finger millet ( Eleusine coracana ). The extracted β-glucan samples were exposed to gamma radiation at doses of 5, 10, and 15 kGy, and the resulting modifications were characterised using analytical techniques. Gamma radiation induced a reduction in average particle size along with an increase in the magnitude of zeta potential, indicating enhanced dispersion stability. Structural characterisation using FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-ray Diffraction) and NMR (Nuclear Magnetic Resonance) spectroscopy revealed minor alterations in molecular organisation of β-glucan following gamma radiation treatment, while the primary polysaccharide backbone remained largely preserved. Thermal analysis using TGA (Thermogravimetric Analysis) and DSC (Differential Scanning Calorimetry) showed modest shifts in decomposition temperature, reflecting moderate changes in crystallinity. Morphological analysis indicated mild surface roughening and reduced particle aggregation following irradiation. Rheological measurements demonstrated a dose-dependent reduction in viscosity, indicative of controlled chain scission while preserving the primary polysaccharide structure. These findings highlight gamma radiation as an effective tool for tailoring the structure–function relationship of millet β-glucan, thereby expanding their applications in bio-based polymer systems. • Gamma irradiation modified β-glucan from pearl and finger millets in a dose-dependent manner. • FTIR, XRD, and NMR showed minor backbone changes with structural integrity maintained. • Thermal analysis indicated moderate crystallinity changes after irradiation. • Morphological analysis revealed reduced aggregation and mild surface roughening. • Rheology showed reduced viscosity and more fluid-like viscoelastic behaviour.