Elucidate properties of raft-forming alginates in vitro with varying composition, 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.
Knowledge of the impact of 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.
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.
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. 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.
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.