Objective: Elucidate properties of raft-forming alginates in vitro with varying composition, a system in which the raft was formed (HCl solution; tomato soup; protein-rich beverage), and pH levels for a more accurate representation of postprandial gastric conditions.
Significance: Knowledge of the impact of the food system and pH on properties of raft-forming alginates may aid in formulation optimization. Recommendations may be made on food that is consumed prior to their consumption to optimize efficacy as a therapeutic agent.
Methods: Dispersions of sodium alginate, calcium carbonate, and sodium bicarbonate were prepared with levels similar to commercial formulations. Rafts were formed in HCl solution, tomato soup, and a protein-rich beverage at pH 1-4 to assess raft properties.
Results: Significant differences (p < 0.05) in raft mass, strength, resilience, and ability to buffer acid were observed depending on the system in which the rafts were formed. The highest mass was obtained in tomato soup (48.5 ± 9.8 g) compared to the protein-rich beverage and HCl solution (32.5 ± 4.5 g and 23.4 ± 4.8 g, respectively) at pH 1. Rafts formed in the protein-rich beverage exhibited the highest strength. Rafts formed in both food systems had a greater ability to buffer added acid compared to rafts formed in HCl solution.
Conclusions: In vitro testing of raft forming alginates in HCl solution at low pH may not be sufficient to describe in vivo events, as a strong matrix effect was observed when rafts were formed in model meal systems at representative postprandial pH levels.
Keywords: Raft-forming alginates; alginate-food interactions; gastric digestion; gastroesophageal reflux disease; in vitro; intragastric gelation; raft properties.