Tailoring the Properties and Oxidative Stability of Idesia polycarpa Crude Oil-Based HIPEs via Xanthan Gum and Ovalbumin: Implementation in Biscuit Processing

This study aims to improve the utilization of Idesia polycarpa crude oil (IPCO) in the food industry by developing high-internal-phase emulsions (HIPEs) stabilized through ternary complexes (ovalbumin (OVA), xanthan gum (XG), and tannic acid (TA)). IPCO is highly prone to oxidation due to its polyunsaturated fatty acid (PUFA) content. Optimal formulations were obtained by varying the component concentrations and assessing the structure, stability, and fat-substitution potential. Under conditions of 0.6% w/v XG and 2.5% w/v OVA-TA, HIPEs exhibited a smaller particle size (3.31 μm), high centrifugal oil retention (99.29%), strong emulsifying activity (49.91 m2/g), and excellent stability (99.69%). Additionally, a formulation with 1.5% w/v OVA-TA and 0.8% w/v XG showed good wettability, particle size, and stability, possibly due to excessive self-aggregation of XG, which caused a decrease in emulsion stability and wettability. Structural analysis (FTIR, XRD, SEM, CLSM) revealed that the stability of the emulsions was mainly attributed to strong non-covalent interactions and a dense interfacial adsorption layer. In cookie applications, substituting 25% w/w butter or 50% w/w shortening with HIPEs resulted in comparable texture to the control group. GC–MS analysis of relative fatty acid composition showed that partial replacement with IPCO-based HIPEs shifted the final biscuits toward a lower relative proportion of palmitic acid (C16:0) and a higher relative proportion of linoleic acid (C18:2n6c). Overall, OVA–TA–XG-stabilized HIPEs effectively delayed the oxidation of IPCO and enabled partial replacement of conventional solid fats in biscuits, thereby shifting the relative fatty acid composition of the final products toward a higher proportion of unsaturated fatty acids.