Pea protein-rice bran wax bigels stabilized by different polysaccharides: screening, preparation, characterization, and application as a lipid substitute in bok choy filling.

To address the issues of excessive peroxide values (POV) and lipid quality deterioration in frozen vegetable-filled rice and wheat-based products, this study developed a lipid replacement strategy based on a bigel system using bok choy filling as a model. Bigel network stability under freeze-thaw stress was evaluated by oil-holding capacity (OHC), while relative oxidative protective efficacy was assessed by accelerated oxidation at 40 °C as a comparative formulation-screening tool. First, a hydrogel was prepared using pea protein (PP) as the aqueous phase, blended with xanthan gum (XG), flaxseed gum (FG), or curdlan gum (CUR) (0.2%-1.0%). This hydrogel was then combined with a rice bran wax (RBW)-based oleogel gel to form a bigel system. Multiscale characterization indicated that the XG-0.6% formulation formed a stable network structure, exhibiting a high thixotropic recovery rate (85.0%), excellent freeze-thaw stability, and moderate thermal stability, making it the optimal formulation. Subsequently, lard was replaced with the XG-0.6% bigel at equivalent weights ranging from 0% to 100%. The results indicate that this substance significantly inhibits lipid oxidation primarily through physical encapsulation and interfacial stabilization. Under accelerated oxidation conditions (40 °C), the POV of the 100% replacement group remained below 0.05 g/100 g for unsteamed samples and below 0.07 g/100 g for steamed samples over 28 d, and the 2-thiobarbituric acid value (TBA) was significantly lower than that of the control. At the same time, it restructured the moisture distribution in the filling and reduced the perceived greasiness. Based on a comprehensive evaluation, 25% was determined to be the optimal substitution ratio, effectively controlling oxidation while maintaining overall product quality across the evaluated sensory attributes; 50% substitution may serve as an enhanced fat-reduction option. This study provides a new approach for ingredient screening aimed at reducing fat content and enhancing antioxidant properties in vegetable-based filling.