Real-time monitoring of interactions between dietary fibers and lipid layer and their impact on the lipolysis process

As a functional ingredient, dietary fibers can be neither degraded by digestive enzymes in the human gastrointestinal tract nor absorbed by individuals. However, they play a significant role in controlling healthy lipid digestion and bioavailability. The real-time impact of dietary fibers on lipid digestion cannot be tracked in situ. The optical interference lipid layer was prepared by loading triolein into an ordered porous layer composed of a silica colloidal crystal (SCC) array. Ordered porous layer interferometry (OPLI) system was constructed for real-time tracking the adsorption of water-soluble dietary fibers such as pectin and polydextrose, insoluble dietary fiber (ethylcellulose, EC), and modified dietary fiber (nanocrystalline cellulose, CNC) at the aqueous/lipid interface, respectively. The process of mass change of the lipid layer caused by the lipase degradation of triolein was transformed into real-time monitoring optical thickness change (ΔOT). The effect of dietary fibers as a functional component on the release and degradation of the lipid layer was analyzed by studying digestion rate, digestion time, and real-time OT curve. Different molecular structures, solubility, and chemically modified dietary fibers had different retardation on lipid digestion. The real-time investigation of the reaction at the interface deepens the understanding of the interaction between lipids and dietary fibers in complex food matrices. Meanwhile, the method provides a basis for designing functional foods with specific health benefits.