Effects of Calcium, pH, and Blockiness on Kinetic Rheological Behavior and Microstructure of HM Pectin Gels

Abstract

The kinetic behavior during gel formation and the microstructure of 0.75% high methoxyl (HM) pectin gels in 60% sucrose have been investigated by oscillatory measurements and transmission electron microscopy for three comparable citrus pectin samples differing in their degree of blockiness (DB). Ca2+ addition at pH 3.0 resulted in faster gel formation and a lower storage modulus after 3 h for gels of the blockwise pectin A. For gels of the randomly esterified pectin B, the Ca2+ addition resulted in faster gel formation and a higher storage modulus at pH 3.0. At pH 3.5, both pectins A and B were reinforced by the addition of Ca2+. In the absence of Ca2+, the shortest gelation time was obtained for the sample with the highest DB. Microstructural characterization of the gel network, 4 and 20 h after gel preparation, showed no visible changes on a nanometer scale. The microstructure of pectins A and B without Ca2+ was similar, whereas the presence of Ca2+ in pectin A resulted in an inhomogeneous structure.

Advances in biomedical applications of pectin gels

“…Other parameters, such as temperature, pH, presence of cosolutes or cations, need to be further considered for pectin gel fabrication [70]. Furthermore, the esterification patterns of pectin chains vary according to the chemical or physical agents used during the extraction: acidic de-esterification causes random distribution, whereas pectinesterase enzymatic degradation results in blockwise distribution of the methyl ester groups [70].…”

Pectin homogalacturonans: Nanostructural characterization of methylesterified domains

“…Analyses were performed in triplicate. Degree of blockiness (DB) for the base saponified HG was calculated by measuring the amount of GalA 1 e GalA 3 released divided by the amount of non methylesterified GalA present in the sample (Daas et al, 1999;Daas, Voragen, & Schols, 2000;Lofgren, Guillotin, Evenbratt, Schols, & Hermansson, 2005), while absolute degree of blockiness (DB abs ) is the amount of released oligomers expressed as a percentage of total GalA Str€ om et al, 2007). The DB and DB abs were calculated as follows:…”

Influence of Pectins on Preparation Characteristics of Lactoferrin Bioadhesive Tablets

“…1, LM pectins readily form gels in aqueous solution by cross-linking with free Ca 2ϩ . [15][16][17][18] In this study, we attempted to investigate the influence of the degree of esterification and the molecular weight of pectins on the characteristics of B-LF bioadhesive tablets, because preparation characteristics such as bioadhesive force and B-LF release properties may influence the ulcer healing effect. Pectins of various degrees of esterification and LM pectins cross-linked with Ca 2ϩ were used to prepare B-LF bioadhesive tablets, and the usefulness of the pectins as a bioadhesive polymer were evaluated.…”