Peanut oil body as a food-grade ink for 3D printing: Preparation, characterization and performance

Peanut oil body (POB) refers to intact micron-sized organelles in plants that store lipids, functioning as natural oil-in-water emulsion systems. This characteristic has garnered significant interest in the food industry due to the excellent emulsifying properties and safety of POB. In this study, POB was utilized as the ink for direct 3D printing of soft food products without the addition of any cross-linking agent, and the underlying mechanisms were investigated. First, POB-based inks with favorable rheological and self-supporting properties were prepared from two types of peanuts with varying oleic acid contents, exhibiting behavior akin to high internal phase emulsions. Second, direct 3D printing of POB was achieved for the first time by modulating the interfacial properties of POB through pH adjustment, which influenced the composition and molecular interactions of the ink phase components. Notably, the ink derived from high oleic acid peanuts demonstrated superior printability under elevated pH conditions. Third, a novel mechanism for the direct 3D printability of POB is proposed. This mechanism involves the elution of interfacial proteins, decreased hydration and alterations in the phase composition of the ink system, thereby enhancing printing performance. Additionally, changes in interfacial properties improved hydrophobic interactions and electrostatic forces, leading to the formation of network structures with elastoplastic rheological properties that enhanced self-supporting capabilities. In summary, this study successfully achieved direct 3D printing of POB ink for the first time, elucidated the mechanisms underlying the printability of POB, and proposed a novel strategy for the 3D printing of high-oil food-grade inks. These findings offer valuable insights for the future development of 3D printing applications of POB in the food industry.