Utilisation of model pectins reveals the effect of demethylated block size frequency on calcium gel formation

Calcium-mediated gelation of LMP is thought to arise from formation of a dense network of Ca2+-cross-linked DMB meeting a required minimum average length along pectin chains. The use of MP containing specific average DMB size ( B S ¯ ) types, in the range of 3–100 and in varying proportion (0–100%), has afforded further insights into the gelling behaviour of pectins with a certain DM in the presence of Ca2+ ions. It clearly appeared that a required minimum B S ¯ and a required minimum average frequency ( B S F ¯ ) of the required minimum B S ¯ are conditions that must be satisfied by a pectin for formation of a highly dense Ca2+-cross-linked DMB network equaling an elastically stable, strong, and cohesive gel. Furthermore, there is a clear contribution of the pectin branched domains to gelation and formation of a firmer and more cohesive gel. The results suggest that this pectin portion may function, not only as a “maintainer” of the pectin molecular weight to a sufficiently high level which fosters good gelation regarding the gelling rate and the strength and nature of the gel formed, but also as junction-zone-terminating structural elements that limit the appearance of undesirable phenomena, notably turbidity, syneresis, and precipitation.