High Internal Phase Emulsion for Food-Grade 3D Printing Materials

Three-dimensional printing (3DP) has attracted significant attention for its use in additive manufacturing techniques because it provides customizability and flexibility for fabricating structures with arbitrary shapes. Certain applications in the food and medicine industries require 3D printable materials that are both biocompatible and biodegradable. Consequently, this study reports 3D printable materials constructed from food-grade high internal phase emulsions (HIPEs). The studied HIPEs (phase ratio 85%) were stabilized by the efficient adsorption behavior of cod proteins (concentration range, 10–50 mg mL^–1) at the oil–water interface. The stability of the oil-in-water HIPEs was improved by the formation of a concentration-dependent percentage of adsorbed proteins and cross-linking networks, and homogeneous and self-supporting structures were generated after 7 days of storage at 4 °C. The gel-like shear thinning rheological behavior induced by the cross-linking networks in the studied HIPEs can be tuned to obtain the desired printability and extrudability during 3DP. In the present study, the HIPEs stabilized with 50 mg mL^–1 of cod proteins exhibited the highest printing resolution, gel strength, hardness, adhesiveness, and chewiness during 3DP. These food-grade HIPE inks have the potential to diversify the applications of 3DP in foods, cosmetics, drug delivery systems, and packaging materials.