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 Ca(2+)-cross-linked DMB meeting a required minimum average length along pectin chains. The use of MP containing specific average DMB size (BS) 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 Ca(2+) ions. It clearly appeared that a required minimum BS and a required minimum average frequency (BSF) of the required minimum BS are conditions that must be satisfied by a pectin for formation of a highly dense Ca(2+)-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.

Extraction and Characterization of Highly Gelling Low Methoxy Pectin from Cashew Apple Pomace.

Investigation on the pectic substances of cashew (Anacardium occidentale L.) apple under different acid-extraction conditions (pH 1.0, 1.5, and 2.0) showed that more than 10%-25% of A. occidentale pectins (AOP) could be extracted, depending on the extractant strength. The extracted AOP contained high amounts of galacturonic acid (GalA: 69.9%-84.5%) with some neutral sugars of which rhamnose (Rha: 1.3%-2.5%), arabinose (Ara: 2.6%-5.4%), and galactose (Gal: 4.7%-8.6%) were the main constituents. The degree of methoxylation (DM) was in the range of 28%-46% and was only slightly affected by the extractant strength, thereby indicating isolation of naturally low methoxy pectins (LMP). In terms of gelling capability, AOP yielded firmer Ca2+-mediated LMP gels than commercial citrus LMP with comparable DM. Cashew apple pomace, therefore, appears to be a potentially viable source for possible production of "non-chemically or enzymatically-tailored" LMP.

Dietary fiber components in yellow passion fruit rind--a potential fiber source.

Within the framework for searching for new dietary fiber (DF) sources to remedy the increasing shortage of currently available sources, connected to an upsurge of diabetes, colon cancer, and other diverticular diseases in certain Ivorian areas, yellow passion fruit (Passiflora edulis f. flavicarpa) rind, a byproduct from the juice industry that is available in large quantities, was investigated. The results showed that, as determined by the AOAC enzymatic-gravimetric method, the total dietary fiber (TDF) in alcohol-insoluble material (AIM) from yellow passion fruit (YPF) rind was >73% dry matter of which insoluble dietary fiber accounted for >60% (w/w). The determination of DF using the Saeman hydrolysis method revealed that nonstarchy polysaccharides were the predominant components (approximately 70%, w/w), of which cellulose appeared to be the main fraction. The water holding and oil holding capacities of the fiber-rich material were >3 g of water/g of fiber and >4 g of oil/g of fiber, respectively. All these results lead to the conclusion that DF from YPF rind, prepared as AIM, may be suitable to protect against diverticular diseases.