An investigation of pectin and pectic acid in dilute aqueous solution

Abstract

SynopsisLight-scattering measurements have been carried out on carefully clarified aqueous solutions of pectin and pectic acid. The strong dependence of the inverse excess scattering intensity on angle yields pectin chain dimensions that are inconsistent with the complete molecular dispersion of pectin molecules possessing the degrees of polymerization indicated by the measured osmotic molecular weights. Negligible or negative concentration dependences of the inverse scattering intensities coupled with the centrifugation, filtration, and gel permeation chromatography behavior of the samples likewise suggest nonequilibriuni aggregation of the pectin molecules in solution. It is shown that the measured mean polymer chain dimensions can be rationalized in terms of the presence of a very small proportion of aggregated material.

Studies of pectin solution properties by high-performance size exclusion chromatography

“…In contrast, biosynthetically methylated pectin showed only resonances assigned to carbomethoxy linkages. CONCLUSIONS Pectin can undergo changes in /Lin pH 7.3 buffer (this work), in neutral salt (Jordan and Brant, 1978), and also at acid pH (Davis et al, 1980). Since our samples have a fairly narrow range of M"'s, the degree of esterification appears to be the most important parameter governing pectin size in buffered solutions (Figure 4a,b,d).…”

“…Several reports indicate that pectins undergo aggregation in solution (Jordan and Brant, 1978;Sorochan et al, 1971; Davis et al, 1980). A combination of elongated helices at low ionic strength and side by side aggregation with partial overlap of chains could explain the extremely large £g's found for both PG and pectin in distilled water.…”

Structural mechanism of complex assemblies: characterisation of beta-lactoglobulin and pectin interactions

“…This may be due to several reasons: (1) the overall or local charge density of such pectin was not strong enough to initiate the electrostatic interaction with bLgA, since it is known that the interaction between bLgA and polysaccharides is mostly electrostatically driven during the early stage of the titration 14,15 and is entropically disfavoured by analogy with the other pectin complexes formed. (2) The non-methylesterified sites were significantly separated by the methyl-ester groups, hence the potential binding motifs were too small to accommodate the protein molecule; (3) highly methyl-esterified pectin molecules may have a tendency to self-aggregate prior to the titration, 26,49 so that there would be less sites available for protein interactions.…”

Authorised EU health claims on pectins

“…Lower levels of methyl-esterification (25-50% methyl-esterification) increase the likelihood that calcium gels will form (Thakur et al, 1997;Vincken et al, 2003), while pectins with a high degree of methyl-esterification (50-80% methyl-esterification) will form acid gels 8 (Jordan and Brant, 1978;Davis et al, 1980;Walkinshaw and Arnott, 1981;Oakenfull and Scott, 1984;Pilgrim et al, 1991;Thakur et al, 1997). Calcium gels are generally more moisture-and heat-stable than acid gels.…”