Oleogel fabrication from Lactobacillus-stabilized emulsion templates: The role of bacterial surface properties in...

Lactobacillus cells, owing to their combined interfacial stabilizing and potentially postbiotic functionalities, have emerged as promising natural Pickering stabilizers. However, the relationship between bacterial surface properties, emulsion-template stability, and oleogel formation remains poorly understood. In this study, eight Lactobacillus strains with distinct surface properties were employed to subsequently construct Pickering emulsion templates and oleogels. Principal component analysis revealed distinct relationships among bacterial surface properties and emulsion-template characteristics, enabling the selection of representative strains for oleogel fabrication. Significant differences (p < 0.05) in emulsion and oleogel properties were observed among the strains. The most hydrophobic strain, L. delbrueckii subsp. bulgaricus NM134-4 (water contact angle ∼86°), produced highly stable emulsions with dense interfacial bacterial coverage and generated oleogels exhibiting the highest hardness (130.98 g) and oil-binding capacity (93.92%). In contrast, hydrophilic and electroneutral strains, L. helveticus AG10-1, formed unstable emulsion templates and defective oleogel networks with low hardness (40.81 g) and oil-binding capacity (73.33%). L. acidophilus ATCC4356, possessing moderate hydrophobicity and highly-negative surface charge, yielded oleogels with comparable mechanical properties through interfacial adsorption and droplet anchoring by bacterial aggregates in the continuous phase. Mechanistically, bacterial hydrophobicity governed interfacial adsorption and emulsion-template stability, whereas surface charge regulated bacterial distribution and oleogel network architecture. These findings establish a structure-function relationship linking bacterial surface properties to oleogel performance, providing a basis for the rational design of potentially postbiotic-based oleogels and the development of clean-label structured lipid systems for fat substitutes, bakery products, and functional food delivery applications.