Comparative evaluation of radiofrequency-treated and naturally aged rice (Var. Jhelum): Physicochemical, rheological, thermal, microstructural and glycemic characteristics

This study investigated radiofrequency (RF) heating as a rapid method to simulate natural rice ageing by comparing the physicochemical, thermal, rheological, microstructural, and starch digestibility properties of freshly harvested rice (FHR), naturally aged rice (NAR), and RF-treated rice and paddy (RFR, RFP) of the Jhelum cultivar. RF treatment induced ageing-like structural and functional changes. Scanning electron microscopy showed starch granule surface disruption and aggregation in RFR, closely resembling NAR. These microstructural changes increased resistant starch content (4.18 ± 0.47%) and reduced the glycaemic index from 70.34 ± 3.39 (FHR) to 61.17 ± 2.18 in RF-treated rice. RF ageing also enhanced milling quality, increasing head rice yield to 61.81 ± 3.57% in RFP, and shifted grain physical properties towards those of NAR. Higher gelatinization temperatures, reduced enthalpy, increased pasting viscosity, and improved gel consistency indicated enhanced starch stability and cooking quality. Overall, RF heating effectively induces ageing-like structural, functional, and nutritional changes in rice within minutes, offering a rapid alternative to conventional ageing.