Development and characterization of food-grade oleogel-in-hydrogel bigels as an animal fat substitute

In response to growing consumer demand for healthier and more sustainable fat alternatives, this study developed and characterized food-grade oleogel-in-hydrogel bigels as potential substitutes for animal fat. The biphasic bigels were formulated by dispersing ethyl cellulose (EC)-based medium-chain triglyceride (MCT) oleogels into a konjac glucomannan-xanthan gum (KGM-XG) hydrogel matrix at varying hydrogel-to-oleogel ratios (9:1 to 6:4). Microstructural analysis revealed that higher hydrogel content promoted finer, more uniform oleogel droplet dispersion, enhancing overall structural stability. All bigels exhibited high liquid binding capacity (>99.8 %) and self-supporting behavior without phase separation. Fourier Transform Infrared (FT-IR) spectroscopy confirmed the coexistence of the two phases without formation of new chemical bonds. Rheological assessments, including frequency sweep and three-interval thixotropy tests, demonstrated solid-like gel characteristics with excellent recovery properties, particularly at higher hydrogel contents. Temperature sweep analysis indicated that the bigels exhibited thermo-responsive viscoelasticity comparable to porcine back fat, especially near 62.8 °C, the USDA's minimum temperature for consumable meat. Texture profile analysis further showed springiness values similar to those of animal fat. These findings underscore the potential of EC-based oleogel-in-KGM-XG hydrogel bigels as structurally stable, thermo-responsive fat replacers for processed food applications.