Validation of the enhanced physicochemical and bioactive properties of Lessonia trabeculata fucoidan upon transfer to the fluid interface via upper gastrointestinal model in vitro

The prominent bioactivities of fucoidan have attracted increasing attention from food scientists. Recent studies have highlighted the potential structural damages triggered by gastrointestinal digestion, which reduces the bioactive performance of fucoidan. Here, we aimed to preserve the bioactivities of fucoidan in a digestive environment by incorporating fucoidan at the interface of an oil/water emulsion. The effects of the digestive progression on fucoidan structures and bioactivities were traced by the dynamic changes in reducing sugar content and radical scavenging activities of digesta collected from different simulated digestion timepoints. Notably, there was a 71 % increase in the DPPH radical scavenging rate after fucoidan (0.25 %; w/w) was incorporated into an emulsion. Besides, the formulated emulsion showed remarkable storage stability at 4 °C with no cream layer formation for seven days. Although the acidified emulsion showed a 15.63 % creaming index, there was still a significant reduction in reducing sugar content after 2-h small intestinal digestion from 2.76 mg/mL for fucoidan digesta in a free form to 2.63 mg/mL for interfacial fucoidan digesta. Here, we highlighted that the fucoidan-stabilized emulsion retained superior antioxidant potential throughout the simulated gastrointestinal tract, which is possibly due to improved structural integrity. These data provide comprehensive information on the enhancement in physiochemical properties and bioactivities of fucoidan after transferring from a continuous phase to an interface, which suggests the potential application of fucoidan in functional fortified beverages and presents a novel supplementation approach to enhance its bioavailability in the health products.