Low-esterified Pectin Research Articles

Availabilities of calcium, iron, and zinc from dairy infant formulas is affected by soluble dietary fibers and modified starch fractions

Objective Insoluble dietary fiber is a known inhibitor of mineral absorption, whereas the effects of soluble dietary fibers (including prebiotics) are less known. The aim was to study calcium, iron, and zinc availabilities from dairy infant formulas supplemented with soluble dietary fibers and modified starches in vitro. Methods Dairy infant formulas were supplemented with soluble dietary fibers (3%, dry wt) and modified starches (16% pregelatinized rice starch and 1.9% maltodextrin, dry wt) and kept in a well-controlled and defined environment in vitro. Pooled mature human milk was used as the reference standard. Results Calcium availability from standard formula was elevated by 30% after inulin supplementation (17.2%), whereas locust bean gum (11.9%) and high esterified pectin (11.7%) reduced availability by approximately 10%. Iron availability from standard formula was increased by pregelatinized rice starch (3.8%), whereas availability was reduced in the following order: high esterified pectin (2.3%), oligofructose (2.2%), and low esterified pectin (2.1%). Zinc availability was highest after the addition of pregelatinized rice starch (13.5%) but lowest with the addition of locust bean gum (6.8%) and maltodextrin (5.4%). Conclusions This study showed that addition of soluble dietary fiber affects calcium, iron, and zinc availabilities in positive (inulin) and negative ways, depending on the type of the dietary fiber used.

Unsaturated oligogalacturonic acids are generated by in vitro treatment of pectin with human faecal flora

Pectins with a degree of esterification (DE) of 95, 66, 34 and 0%, respectively, were incubated in vitro with human faecal flora (pH 7.8). The concentration and composition of oligogalacturonic acids (oligoGalA) generated were determined using high-performance thin-layer chromatography (HPTLC) with UV and colorimetric detection. In the first period of the anaerobic degradation, the pectin macromolecules were fragmented into unsaturated oligoGalA as intermediate products by the action of bacterial pectate lyases. Depending on the incubation time and the DE of pectin, the amount of unsaturated oligoGalA having different degrees of polymerization changed continuously. These oligoGalA were present in the cultures for some hours. Mixtures of unsaturated di-, tri- and tetraGalA were the end products of a pectate lyase action. Later, the oligoGalA disappear as a result of their further fermentation by the gastrointestinal microflora under formation of short-chain fatty acids (SCFA). Low-esterified pectins were depolymerized and fermented faster than the highly esterified by the human faecal flora in vitro. Furthermore, a mixture of unsaturated oligoGalA prepared from pectic acid by the action of pectate lyase from Erwinia carotovora was completely fermented by human faecal flora.

DNA adducts in tissues of germ-free and conventional rats fed high- and low-esterified pectins.

Tissue samples from germ-free and conventional rats fed pectins with different degrees of esterification (DE) were tested for containing indigenous DNA adducts (I-compounds). For 21 days groups of six germ-free and 10 conventional rats each were fed either pectin-free or with diets containing 7.5% of three differently esterified pectin preparations (Pectin A, DE 92.6%; Pectin B, DE 70.8%; Pectin C, DE 34.5%). DNA was isolated from colonic mucosa, liver, lung, kidney and analysed for DNA adducts by the 32P-postlabelling assay. The experiments showed a tendency to a higher number and intensity of DNA-adduct-like spots (1) in the colonic mucosa compared with liver, lung, and kidney, (2) in germ-free compared with conventional rats, (3) with pectin-free compared with pectin-containing diets, (4) under the low-esterified compared with the higher-esterified pectins.

On the production of low esterified pectins by acid maceration of pectic raw materials with ultrasound treatment

The effect of temperature, time and nitric acid concentration on the yield and quality of low esterified pectins obtained from apple pressings by preliminary acid maceration of the raw materials was studied. Regression equations describing the changes in the degree of esterification, the yield, the polyuronide content and the characteristic viscosity of the pectins obtained depending on the temperature and time of maceration of apple pressings at various nitric acid concentrations were derived. The opportunity of intensifying the process of pectin deesterification by combining the acid maceration of raw materials with ultrasound treatment was investigated. An additional decrease in the degree of esterification of pectin (about 6%) and an important increase in the yield of pectin (about 18%), as compared to the reference sample, were established. The optimum ultrasound treatment proved to be within 24–30 min. A more prolonged ultrasound treatment resulted in obtaining pectins of lower gel strength.

Production of extracellular pectinase enzymes by a mutant (Pol6) of Penicillium occitanis

Penicillium occitanis strain Pol6, a mutant developed for hyperproduction of cellulase and pectinase enzymes was used for the study of extracellular pectinase production when pectins from different sources (apple and citrus) and with varying degree of esterification (DE) were used as inducers. Highly esterified citrus pectins were found to be suitable substrates for polygalacturonase, pectinase and pectin methyl esterase production, while low esterified citrus pectin favoured pectin lyase (PL) production. Apple pectins induced other hydrolytic enzymes (e.g., β-1,3-glucanase, β-glucosidase, β-galactosidase), in addition to pectolytic enzymes. Moreover, the combination of high and low esterified citrus pectins induced the production of a complete pectinase complex. The extent of degradation of the substrate and the affinity for PL decreased with decreasing DE irrespective of the source. There was no evidence of PL activity in this strain. No significant effect of cations (Ca++, Mn++, Na+) on PL activity was observed. However, EDTA (100 mm) inhibited 50% of the activity, when tested on highly esterified (rapid set citrus) pectin.

Zur Charakterisierung der Pectinase von Coniophora cerebella Duby

1. 6 investigated strains of Coniophora cerebella proved to be very uniform in growth and rate of enzyme synthesis. 2. Coniophora cerebella secretes a pectinase in high activity into the culture fluid when galacturonic acid, pectic acid or pectin are present. 3. The activity of the extracellular enzyme is higher than of the intracellular one. No differences of the properties could be found. 4. Pectin-methylesterase (pectase) activity is negligible or absent. 5. The activity of the pectinase is dependent on the methoxy-content of the pectin and of its origin. Low esterified pectin is faster attacked than high esterified pectin. Therefore the enzyme ist to be classified as an Endo-polygalacturonase. 6. The optimal pH-value for pectinase and pectase is 5.0. At 51° C the pectinase is inactivated for 50% after 5 min incubation. 7. Whether an Exo-Polygalacturonase (saccharifying enzyme) is produced, could not be established.