Effect of oil-soluble emulsifiers on the self-assembly behaviors of citric acid esters in bulk and emulsified systems.

Fat replacement in pastries is a long-standing challenge, as roll-in fats constitute over 30 % (by weight) of laminated dough formulations and are predominantly composed of high-melting-point triglycerides. Citric acid esters of mono- and diglycerides (CITREM) was recently demonstrated to stabilize bulk oil through self-assembly and thereby reduce saturated fat. In this study, CITREM was used as a structuring agent to investigate the effects of oil-soluble emulsifiers on its self-assembly in bulk and emulsified systems. In oleogels, amphiphilic molecules influenced the CITREM crystal growth rate and morphology. Moreover, the effects of emulsifier type and water content on the mechanical performance of CITREM-based emulsion gels were investigated in detail. At 18 wt% water, the hardness of gels ranged from 24.69 to 139.14 g. Interestingly, the aqueous phase in polyglycerol polyricinoleate (PGPR), propylene glycol fatty acid esters, or phospholipase-stabilized emulsion gels functioned as an active filler, enhancing gel strength and significantly increasing hardness and elastic modulus. And PGPR-stabilized emulsion gels with 28 wt% water exhibited a superior structural integrity compared to roll-in butter under large amplitude oscillatory shear, including enhanced shear resistance and greater viscous energy dissipation. However, excessive water (38 wt%) compromised the crosslinking density of the crystal network, leading to structural collapse during storage. The water content and emulsifier type modulated hydrogen bonding and van der Waals interactions, thereby influencing polymorphic transitions, nanocrystal packing and thermal properties of the CITREM-based emulsion gels. Molecular dynamics simulations further revealed that PGPR promoted the CITREM molecules to form an interconnected, stable three-dimensional networks. This study demonstrates the potential of W/O emulsion gels as alternatives to traditional roll-in fats, and provide a new perspective for the design of innovative food structures by regulating active fillers.