Abstract body - Pickering emulsions (PEs) stabilized by biopolymer-based microgels, particularly protein-polysaccharide complexes, have emerged as highly promising, surfactant-free alternatives to conventionally stabilized emulsions. Their particle-laden interfaces and percolated network microstructures enable effective fat mimicry, making them ideal candidates for clean-label fat replacement in structured foods such as mousses, spreads, and dairy desserts. In this study, whey protein isolate (WPI)-pectin microgels were fabricated via heat-induced complex coacervation under controlled pH and ionic strength, followed by high-shear homogenization to yield sub-micron interfacial particles. These microgels were subsequently employed as Pickering stabilizers to formulate oil-in-water (O/W) emulsions, which were then incorporated into mango mousse systems as fat replacers. The primary objective was to systematically evaluate the influence of pectin type (citrus pectin [CP], apple pectin [AP]) and concentration (0.5-1.0% w/w, relative to total emulsion) on PEs microstructure, emulsion property, physical stability, and the resulting mousse’s visual appearance, texture, microstructure and color attribute.

Compared with CP, AP had a higher molecular weight, a greater degree of esterification and a more pronounced abundance of “hairy” regions. Zeta potential analysis confirmed that pectin incorporation significantly increased the net negative surface charge of WPI aggregates. The particle size decreased after pectin addition, indicating that pectin inhibited aggregation of protein particles. The intermoleular electrostatic repulsion plays a critical role in it. Fourier-transform infrared spectroscopy showed that predominant interactions between WPI and pectin were hydrogen bonding. The inclusion of pectin at all concentration reduced the content of α -helix and increased β-sheet and β-turn, indicating partial unfolding and interfacial rigidification, which could promote the formation of compact, surface-active protein-pectin complexes and facilitate stronger adsorption at the oil-water interface. Confocal laser scanning microscopy visualized that pectin decreased the oil droplet sizes, and the emulsion droplets became more concentrated and smaller in size as the concentration of pectin increases. In AP emulsion, the droplets maintained smaller and more homogeneous size compared to CP emulsion at the same concentration. Furthermore, the PEs with pectin, especially AP, showed higher emulsifying activity index, better long-term storage stability, salt ion stability compared to pure WPI-PEs.

To evaluate application potential, Pickering emulsions with 0.5% pectin were used as fat replacer in mango mousse and mousse samples with different fat replacement rates