Physicochemical, rheological, and volatile properties of rice paste: Effect of the degree of starch gelatinization

This study systematically investigated the impact of pregelatinization (PG) time on the physicochemical, rheological, and volatile properties of rice paste (RP), a key intermediate in nonfermented rice yogurt production. Rice samples were pregelatinized at 100°C for 0–7 min and immediately homogenized using a high-shear blender before paste formation. Results revealed that increasing PG time significantly reduced whiteness (from 80.43 to 70.63, p < 0.05) and gelatinization enthalpy (from 8.31 to 0.11 J/g), while progressively increasing gelatinization temperatures. Rheological analyses indicated that 4 min of PG yielded optimal paste quality, with a flow behavior index (n) of approximately 0.5 and enhanced system stability. Structural characterization via fourier transform infrared (FTIR) spectroscopy, X-ray diffractometer (XRD), and scanning electron microscopy (SEM) confirmed the disruption of starch crystallinity (relative crystallinity decreased from 23.74% to 5.28%, p < 0.05), loss of A-type starch structure, and formation of a denser more uniform gel network at 3–4 min PG. Volatile profiling by electronic nose and gas chromatography-ion mobility spectroscopy (GC-IMS) demonstrated that PG altered the aroma composition, reducing grassy aldehydes and improving fruity and sweet notes after 4 min. Overall, 4 min PG optimally balances structural integrity, rheological stability, and flavor development, providing a scientific basis for enhancing plant-based dairy alternatives. • The impact of varying PG durations on rice paste characteristics was investigated. • PG treatment enhanced RP viscosity, exerting a positive influence on its texture. • Starch network structure initially forming and subsequently undergoing disruption. • Optimal PG duration enriched the volatile flavor compounds in rice paste.