Citrus fibers improve rheology of OSA starch-based high internal phase emulsion for 3D printed elderly foods.

3D printing ready-to-eat emulsions using trans-fat-free edible oil, presents a significant challenge due to the complexities involved in achieving the necessary material structure, rheological properties, and stability. This study fabricated High Internal Phase Emulsions (HIPEs) stabilized with citrus fibers and octenyl succinic anhydride (OSA) modified waxy starch, serving as the printable inks for 3D-printable elderly foods. These printable inks exhibited a pseudoplastic gel structure, which provided enhanced extrudability and improved shape retention. The incorporation of citrus fiber, water, OSA starch, sunflower oil at a concentration of 0.3 wt%, 22.7 % wt %, 2 % wt%, 75 wt% in the 3D-printed HIPEs resulted in optimal addition, yielding the highest level of shape accuracy. Compared to the addition of OSA-modified starch, microstructural analysis and rheological testing (using Lissajous-Bowditch plots) indicated that the addition of citrus fiber had a greater impact on the rheological and textural properties of the HIPEs, which improved shape retention and fluidity of the HIPEs, and ensure the stability of continuous extrusion printing. Additionally, bionic tribological properties demonstrated that tribological properties of the prepared HIPEs were very close to the ones of mayonnaise, which indicating that the prepared HIPEs had smooth texture and easy-to-chew properties for the elderly. These findings offered a comprehensive understanding of the structure-function relationship between the molecular structures of HIPEs and their 3D printability, providing technical insights for the development of 3D-printed emulsion-based ready-to-eat elderly food products. This study provided a good industrialized method for HIPEs stabilized with only fruit dietary fiber and modified starch, and facilitated the development of emulsion-based ready-to-eat food products with 3D printability.