Characterization of raft-forming alginate suspensions formed in HCl or model food systems at varying pH levels to better simulate gastric postprandial conditions

Abstract

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
• gastroesophageal reflux disease
• raft properties
• alginate-food interactions
• in vitro
• gastric digestion
• intragastric gelation

Acknowledgements

The authors would like to acknowledge Sarah Suriano for help in initial experiments on alginate solution characterization. Gaia Mannara acknowledges the Erasmus + programme of the European Union and the University of Salerno (Italy), which co-funded her mobility to the University of California, Davis.

Disclosure statement

No potential conflict of interest was reported by the author(s).