Improvement of 3D printing performance of pea protein isolate Pickering emulsion gels by regulating electrostatic interaction between protein and polysaccharide

3D food printing had attracted wide attention for its multiple advantages such as being able to customize food according to individual needs. In this study, plant-based edible inks suitable for 3D food printing applications were formulated using Pickering emulsion gels containing pea protein isolate (PPI) and flaxseed gum (FG). The effect of different electrostatic interaction between PPI and FG on the 3D printing performance, rheology properties and microstructure of emulsion gel inks were investigated in acidic (pH 3) and neutral (pH 7) environments, respectively. At pH 3, the inks showed good printing performance with the addition of FG at 0.5%, 0.7% and 0.9%, respectively. At pH 7, the inks at 0.5% had the best 3D printing performance. They demonstrated printing performance with precise shape, smooth surface and clear texture. The inks produced were soft matter solids with a storage modulus (G′) greater than the loss modulus (G″). According to Lissajous plots analysis, the addition of FG significantly improved the viscoelasticity, which was beneficial to improve the 3D printing performance of inks. These inks also exhibited good thermal stability. In addition, Cryo-SEM analysis showed that the inks had a striated structure at pH 3 but a honeycomb structure at pH 7 due to the difference in electrostatic interaction. And the honeycomb structure is more stable compared to the striated structure. This study showed that edible inks can be formulated from plant-derived ingredients, which may increase their application in the development of plant-based foods with improved properties using additive manufacturing processes.