Mapping gamma irradiation-induced changes in dried figs: from molecules to microstructure

This study characterizes the effects of γ-irradiation (0, 1, 1.5, and 2 kGy) on the bioactive compounds and microstructural properties of dried figs ( Ficus carica L.). Using high-performance liquid chromatography (HPLC), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), dose-dependent changes in phenolic compounds and microstructure were assessed. The results revealed progressive degradation of radiation-sensitive phenolics (e.g., ferulic acid and furanocoumarins) alongside elevated concentrations of others (e.g., luteolin-7-O-glucoside and isorhamnetin-3-O-galactoside). Restricting interpretation to strong correlations (|r| > 0.5), pronounced negative associations were identified between irradiation dose and radiation-sensitive compounds, while positive correlations indicated stimulation of flavonol biosynthetic pathways. FTIR analysis revealed dose-dependent molecular alterations in protein, dietary fiber, and lipid functional groups, with a pronounced decrease in spectral intensity at 1.5 kGy and partial recovery at 2 kGy. SEM imaging revealed progressive microstructural degradation at doses ≥1.5 kGy, including cell wall rupture and starch granule disruption, whereas 1 kGy largely preserved structural integrity. These findings indicate that 1 kGy represents the optimal balance between effective insect disinfestation and preservation of microstructural integrity and bioactive compound content, providing a mechanistic framework for evidence-based irradiation strategies in the dried fig industry. • Gamma irradiation (at doses of 1–2 kGy) effectively controls pests and preserves dried fig quality. • Phenolic compounds respond dose-dependently, showing an irregular pattern of decrease and increase. • FTIR and SEM reveal minor structural changes at 1 kGy and clear ultrastructural alterations at higher doses. • Gamma irradiation induces microstructural changes in fig pericarp and potentially reduces hygroscopicity. • This study supports irradiation as a viable, chemical-free alternative for extending dried fig shelf life.