Evaluation of pectin-based raft-forming systems : A dissertation submitted in partial fulfilment of the requirements for the Degree of Master of Science in Food Innovation at Lincoln University

Abstract

Gastroesophageal reflux disease (GERD) is commonly managed using alginate-based raft-forming antacids that generate a buoyant gel barrier on gastric contents. However, reliance on sodium alginate and the formation of relatively rigid gels have motivated interest in alternative food-grade polymers. This study evaluated low-methoxy pectin (LMP) as a potential substitute for sodium alginate for raft formation under simulated gastric conditions (pH 1.2, 37°C) and investigated whether incorporation of calcium caseinate (CaCN) and microcrystalline cellulose (MCC) could enhance raft integrity through combined ionic crosslinking and structural reinforcement. Sodium alginate served as a control, while pectin-based formulations were prepared with LMP alone or in combination with CaCN and/or MCC. Raft formation and stability were assessed over a 3 h incubation period using complementary visual, mechanical, rheological, spectroscopic, and fragmentation analyses. LMP alone formed a thin and unstable raft that rapidly lost integrity under acidic conditions, indicating insufficient network strength in the absence of additional structuring components. Incorporation of CaCN markedly improved raft cohesion and persistence, producing a thick and homogeneous raft that remained stable throughout incubation. MCC alone provided limited reinforcement, whereas the combined CaCN–MCC system yielded the most robust and deformation-tolerant raft. Mechanical and rheological measurements demonstrated that raft firmness alone did not predict long-term stability, with CaCN-containing formulations exhibiting enhanced viscoelastic resilience despite lower initial firmness. Spectroscopic analysis supported the formation of calcium-mediated pectin networks and protein–polysaccharide associations in reinforced systems. Overall, LMP alone was not sufficient to replace alginate for sustained raft formation, but incorporation of calcium caseinate substantially improved raft stability, with additional reinforcement achieved when combined with MCC. These findings support the potential of CaCN–MCC–pectin systems as food-grade alternatives for raft-forming antacid formulations with prolonged gastric retention.