Abstract
Sea buckthorn (Hippophae rhamnoides L.) puree is exceptionally rich in lipophilic bioactive compounds, particularly functional carotenoids, but is highly sensitive to thermal and oxidative degradation during traditional powder processing. In this study, a novel supercritical carbon dioxide (scCO2) assisted foam mat drying technique was developed and evaluated for sea buckthorn puree. Puree formulations containing soy protein isolate (1.5% w/w) and carboxymethyl cellulose (0.5% w/w) were saturated with scCO2 at pressures of 8–12 MPa and temperatures of 35–45 °C before rapid depressurization to generate stable micro-foams, followed by thin-layer drying at 50, 60, and 70 °C. The drying kinetics were successfully fitted to empirical thin-layer models, with the Midilli et al. model demonstrating the highest predictive performance (R² > 0.994, RMSE < 0.012). The scCO2-assisted foaming treatment reduced effective drying time by up to 38% compared to conventional foam mat drying. Total carotenoid retention reached 88.4% under optimal conditions (scCO2 treatment at 10 MPa/35 °C with drying at 50 °C), significantly outperforming hot-air controls (54.2%). Reconstitution properties of the resulting powder revealed high water solubility (84.6%), rapid wettability (14.2 s), and low bulk density, supported by scanning electron microscopy that revealed a highly porous honeycomb microarchitecture. This green drying technology offers an efficient pathway for producing bioactive-rich fruit powders with superior instant properties.
