Capillary force-driven formation of native starch granule oleogels for 3D printing

Abstract

3D printing has extremely high requirements for the design of food matrices with suitable rheological properties. Starch exhibits considerable potential as a material for 3D printing. However, there is limited research available on the direct fabrication of oleogels using starch granules as building blocks. In this study, we developed a simple approach to fabricate plant-based oleogels as edible 3D printable materials by exploiting capillary forces between starch granules. When a small amount of water (less than 5 wt%) was added to starch granules dispersed in an oil phase, a pendular bridging network was formed between the starch granules. The rheological properties of the starch-oil suspension were significantly changed, transitioning it from a fluid-like to a gel-like state. The rheological properties of the oleogel could be altered by varying the starch granule volume fraction, the amount of water added, the structure of starch granules, and the oil-water interfacial tension. Confocal laser microscopy imaging demonstrated that starch granule oleogels exhibit three distinct structural states: pendular state, pendular bridge network, and capillary aggregation. Furthermore, the presence of water was identified as a liquid bridge between starch granules. Additionally, starch granule oleogels exhibited excellent thermal stability and freeze-thaw stability. Overall, this approach enhances the feasibility of preparing starch oleogels and provides valuable insights for the personalized 3D printing of oleogels.