Nutritional and Physical Characterization of Corn-Based Extrudates Enriched with Water Spinach (Ipomoea aquatica) Flour

This study evaluated the partial substitution of corn flour with water spinach (kangkung) flour in extruded snacks to enhance dietary fiber content without compromising quality. A two-factor, full factorial design was employed, testing four levels of water spinach flour (0,15) combined with three feed moisture contents (12-16). A second experiment evaluated three-barrel temperatures (120-150°C) at 14 feed moisture. Results showed that increasing spinach flour levels up to 15 significantly (p < 0.05) enhanced total dietary fiber, while producing a denser pore structure. Increasing barrel temperature to 135-150°C improved expansion by 2.43 and reduced hardness by 5.40 (p < 0.05), offsetting fiber-induced densification. The optimal formulation was obtained with 5 water spinach flour, 14 feed moisture, and a barrel temperature of 150°C. Results demonstrate that elevated barrel temperatures enable production of fiber-enriched extrudates with desirable physical and structural properties. © 2025 Taylor & Francis Group, LLC.