Conjugation of aminated sugar beet pectin–tannic acid nanoparticles with cinnamaldehyde at the oil–water interface to stabilize a 3D printable high-internal phase emulsion

In this work, we demonstrated the use of aminated sugar beet pectin (SBP–NH2)–tannic acid (TA) nanoparticles (NPs) conjugated with cinnamaldehyde (CA) to form 3D printable high-internal phase emulsions (HIPEs). Unlike the absorption of common stabilizers, the interfacial conjugation of SBP-NH2/TA NPs with CA formed ultra-absorbed NPs at the oil–water interface through electrostatic bonding, hydrogen bonding, hydrophobic interactions, and Schiff base reaction. The addition of CA (2.5 wt%) to the oil phase significantly reduced the mean droplet size of SBP-NH2/TA NPs stabilized HIPE (75 vol% oil; SBP-NH2/TA mass ratios of 1:0.5) from 23.03 to 18.33 μm and greatly improved the stability of HIPEs during a 90-day storage period at 25 °C. Concomitantly, rheological studies indicate that HIPEs with CA had high viscoelasticity up to 3 orders of magnitude, providing HIPE-based inks with exceptional support performance and smooth extrusion features. In particular, TA and CA act as the components of a stabilizer and adsorb onto the oil–water interface, imparting combined antioxidant and antimicrobial dual capabilities to HIPEs. In the SBP-NH2/TA NPs stabilized HIPEs, the addition of CA resulted in 0.34-fold lower amounts of primary and secondary lipid oxidation products and 0.4–0.5-fold higher antimicrobial properties against either E. coli or S. aureus. This work established that the interfacial conjugation of the SBP-NH2/TA NPs with CA advanced the antioxidant and antimicrobial properties, stability, water-holding capacity, and viscoelastic properties of HIPEs. Furthermore, the three-dimensional (3D) printed structure with notable mechanical strength was achieved.