Formation of bigels as solid fat replacers: Impact of oleogel/hydrogel ratio and cassava starch content on the structure and physicochemical properties

This study constructed a bigel system based on cassava starch/sodium alginate hydrogel and sunflower seed oil/beeswax oleogel and evaluated its potential as a solid fat substitute. By adjusting the oleogel/hydrogel ratios (2:8, 5:5, 8:2) and starch content (10%, 20%), the intrinsic relationship between the structural and physicochemical properties was investigated. The results showed that as the proportion of oleogel increased, the microstructure of the bigel transitioned successively from an O/W type to a bicontinuous type and finally to a W/O type. FTIR and XRD analyses confirmed that the bigel formed through physical interactions without covalent crosslinking and showed the highest crystallinity at a 5:5 oleogel/hydrogel ratio. Increasing the cassava starch content significantly enhanced the hardness, chewiness, freeze-thaw stability, and crystallite size of the bigel. Correlation analysis showed that crystallite size was positively associated with cohesiveness, gumminess, chewiness, and gelatinization enthalpy. The hardness and springiness of the O/W type bigel were significantly superior to those of the W/O type bigel, also demonstrating the better rheological properties and oxidation stability. This study provides a new strategy and technological pathway for the application of bigel in fat replacement functions. • Changes in the ratio of oleogel/hydrogel give the bigel a different structure. • Increasing the hydrogel content improved hardness, springiness, and storage modulus. • Bigels with high starch content showed excellent freeze-thaw and oxidative stability. • 2:8-20% has great potential as a sustainable replacement for solid fats.