Physical and bloom stability of low-saturation chocolates with oleogels based on different gelation mechanisms

Oleogels are being increasingly used as solid fat alternatives in food . Low-saturation chocolates (referring to chocolates with low content of saturated fat) were prepared by replacing 50 g/100 g cocoa butter with three oleogels (monoglyceric stearate, β-sitosterol +  lecithin , and ethyl cellulose oleogel), which were fabricated through different gelation mechanisms (crystalline particles, self-assembly fibers, and polymeric strands, respectively). The physical characteristics and microstructures of oleogel-based chocolates during isothermal (4 and 20 °C) and fluctuating (20 °C for 17 h and 29 °C for 7 h) storage conditions were evaluated for 60 d, including whiteness index, hardness, thermal behavior, and crystal polymorph. We found that oleogel-based chocolates exhibited bloom delaying property through assessing whiteness index and polarized light microscopy images, especially under fluctuating temperatures. Among three oleogel-based chocolates, β-sitosterol + lecithin oleogel-based chocolate maintained the lowest whiteness index. Differential scanning calorimetry and X-ray diffraction revealed that oleogel-based chocolates showed sustained thermal and polymorphic stability throughout the storage period. Crystal morphology of fat phase observed by polarized light microscopy confirmed the existence of stable β crystals in oleogel-based chocolates. Collectively, oleogel-based chocolates not only lower the degree of saturation but also exhibit high physical and bloom stability during isothermal and fluctuating storage.