One-step fabrication of microfluidic W/O/W droplets as fat-reduced high internal phase emulsions: Microstructure, stability and 3D printing performance

High internal phase emulsions (HIPEs) have been served as effective fat replacements, but they still remain calorie-dense. Herein, we described microfluidic fabrication of W/O/W mononuclear high internal phase double emulsions (MHIPDEs) with a reduced oil fraction ranging from 38 vol% to 53 vol%. These emulsions were composed of oil drops (∼170 μm) that contained smaller water droplets (117.22–136.33 μm). The incorporation of gellan gum in the internal water droplets and palm oil in the oil phase facilitated the stabilization of MHIPDEs. All the emulsions demonstrated favorable stability during storage at both 4 °C and 25 °C, maintaining their intact structure for a duration of 90 days. This feature enabled the emulsions to effectively protect lipids from oxidation, resulting in a notable two-thirds reduction in the production of MDA during stored at 4 °C. All of these emulsions maintained a uniform appearance after undergoing freeze-thaw processing eight times, and MHIPDEs with the highest oil content (62 vol%) remained structurally intact. Additionally, the apparent viscosity and elastic modulus of MHIPDEs increased with higher oil content, suggesting the formation of a stiffer lipid crystal shell surrounding the water droplet. MHIPDEs with a moderate oil fraction (54 vol%) possessed optimal 3D printing performance due to their appropriate viscoelasticity and high yield stress (6.3%). These findings propose a fresh perspective on the design and manufacturing of fat-reduced high internal phase emulsions with desirable physicochemical properties.