Development of the first “encapsulated oleogel-in-oleogel” system with tailorable lipid digestion

Abstract

Despite containing a higher proportion of unsaturated fatty acids than traditional solid and semi-solid fats, the calorie-dense nature of oleogels presents a challenge when incorporating them into foods. The next generation of oleogels should feature a customizable lipid digestion profile while having minimal impact on other properties of the food products. To achieve this goal, we developed the first-of-its-kind “encapsulated oleogel-in-oleogel” system with tailorable digestibility. To obtain such a system, a Pickering emulsion containing wax-based oleogel stabilized using crystalline nanocellulose was spray dried using a soluble dietary fibre as wall material (the inner oleogel). Following, the resulting encapsulated oleogel was added to a molten monoglyceride-based oleogel and cooled to set the outer oleogel. The morphological properties of the encapsulated oleogel-in-oleogel system were studied by cryo- and FE-SEM and polarized and fluorescence microscopy. The results of DSC and synchrotron XRD showed that waxes crystallized inside the inner oleogel droplets, confirming also that the entire preparation of the encapsulated oleogel-in-oleogel system did not alter the nanostructure of waxes and monoglyceride crystals. The results of in vitro digestion revealed that both Pickering emulsion and the resulting spray dried encapsulated oleogel were partially indigestible, leading to a lower and tailorable lipid digestion in the encapsulated oleogel-in-oleogel system compared to that of the oil and conventional oleogels. We demonstrated that the digestibility of the encapsulated oleogel-in-oleogel system can be conveniently modulated by varying the ratio between the encapsulated oleogel and outer oleogel, showing promise for developing a new generation of oleogels with tailored digestibility, lower calories, and high dietary fibre content.