Rheological synergy in aqueous mixtures of pectin and mucin

The interaction between pectin and mucin was investigated by comparing the viscoelastic properties of mucin–pectin mixtures, using a small-strain oscillatory rheology, against those of the pure components. All pectins showed rheological synergism when mixed with mucin, as evidenced by an increase in dynamic moduli and a decrease in loss tangent. The interaction between pectin and mucin related to the physical entanglement of gel network and depended on pectin type, pectin concentration, mucin concentration and dispersion medium. Pectin with higher degree of esterification (DE) showed a greater interaction than that with lower DE. Amidated low DE pectin in deionized water showed the strongest interaction with mucin due to the presence of amide and carboxylic acid groups in its structure facilitating H-bond with mucin. Increasing of mucin concentration affected the mucoadhesive interaction of pectin. The results suggested that the study of rheological synergy can be used to indicate the mucoadhesive interaction of the materials to be used in mucoadhesive drug delivery systems.