All-natural gel-in-gel water-in-oil high internal phase emulsions featuring biphasic network stabilization and application of 3D printing

Abstract

Water-in-oil high internal phase emulsions (W/O-HIPEs) are promising for 3D printing to design healthy foods with novel shapes and low calories/fats. Oleogel-based W/O-HIPE (O-HIPE) was formed by soybean phosphatidylethanolamine (SP) and beeswax. Based on stable O-HIPE, a gel-in-gel W/O-HIPE was prepared with potato starch hydrogel containing 80% internal phase volume, in which the fat volume was decreased to 20% to reduce the fat/calorie contents. Results showed that besides decreasing interfacial tension, SP could change crystal habit of beeswax to obtain denser (crystal size reducing from 4.09 Å to 3.85 Å) and stickier beeswax-based oleogel to restrict droplet movement and coalescence, leading to the formation of O-HIPE with smaller droplet size. With the addition of starch hydrogel, droplet size of gel-in-gel W/O-HIPE was further decreased to 3.23 µm in gel-in-gel W/O-HIPE. The viscoelasticity (higher storage modulus), deformation resistance (higher critical stress), and recovery (82.3%) were also improved. The enhanced rheological properties facilitated the printability of gel-in-gel W/O-HIPE, allowing the patterns to be printed with more delicate details and without collapse. Gel-in-gel W/O-HIPE has potential to broaden 3D printing applications.