Mucin immobilization in calcium alginate: A possible mucus mimetic tool for evaluating mucoadhesion and retention of flavour

To reduce animal testing, there is a need to develop novel in-vitro models for evaluating the retention of bioactive compounds in food and pharmaceutical products. Here, a mucus-mimetic platform was developed through a one-step approach based on encapsulating mucin within alginate gel beads. We found that mucins form micron sized aggregates distributed across the surface of the calcium-alginate bead, as shown by environmental scanning electron microscopy (ESEM). Retention of bioactive compounds on the mucin-functionalised surface was tested using a commercial orange drink formulation. To aid flavour retention, different mucoadhesive polymers with varying charge, including anionic, neutral and strongly cationic, were tested for their ability to interact with mucin and aid retaining flavour compounds within the mucin-alginate bead. The alginate-mucin mucus mimic was validated using an ex-vivo bovine tongue, with the flavour retention results showing qualitative agreement. The developed method proved to be a convenient, efficient tool for providing information on the effectiveness of mucoadhesive polymers without variability, safety and sustainability issues associated with an ex-vivo or in-vivo system. We propose that by encapsulating other relevant oral proteins, alongside mucins, current gaps between in-vitro and the ex-vivo systems may be narrowed.