Low-ester Pectin Research Articles

Extraction and Structural Analysis of Sweet Potato Pectin and Characterization of Its Gel.

Pectin is widely used in the food and pharmaceutical industries. However, data on sweet potato pectin extraction and structural property analyses are lacking. Here, for the high-value utilization of agricultural processing waste, sweet potato residue, a byproduct of sweet potato starch processing, was used as raw material. Ammonium oxalate, trisodium citrate, disodium hydrogen phosphate, hydrochloric acid and citric acid were used as extractants for the pectin constituents, among which ammonium oxalate had a high extraction rate of sweet potato pectin, low ash content and high molecular weight. Structural and gelation analyses were conducted on ammonium oxalate-extracted purified sweet potato pectin (AMOP). Analyses showed that AMOP is a rhamnogalacturonan-I-type pectin, with a molecular weight of 192.5 kg/mol. Chemical titration and infrared spectroscopy analysis confirmed that AMOP is a low-ester pectin, and scanning electron and atomic force microscopy demonstrated its linear molecular structure. Gelation studies have revealed that Ca2+ is the key factor for gel formation, and that sucrose significantly enhanced gel hardness. The highest AMOP gel hardness was observed at pH 4, with a Ca2+ concentration of 30 mg/g, pectin concentration of 2%, and sucrose concentration of 40%, reaching 128.87 g. These results provide a foundation for sweet potato pectin production and applications.

Heat-induced aggregation behavior of wheat gluten after adding citrus pectin with different esterification degree

Wheat gluten aggregation during heat treatment is beneficial to the final quality of gluten-based products. Exogenous pectin can affect gluten aggregation. However, the effect of pectin with different degrees of esterification on the heat-induced aggregation behavior of gluten and its possible mechanism are still unclear. Thus, the heat-induced aggregation behavior of gluten after adding pectin with different esterification degree was studied in this study. When the temperature was raised from 25 °C to 95 °C, pectin affected gluten aggregation and was related to the degree of esterification. Specifically, the results of rheological properties and particle size indicated that low-ester pectin improved the viscoelasticity of gluten and promoted gluten aggregation. Thermal properties revealed that enthalpy of gluten added with low-ester pectin (37%) increased from 92.96 J/g to 95.40 J/g during heating process. Structurally, the fluorescence intensity and surface hydrophobicity of gluten added with low-ester pectin (37%) were lower than those added with high-ester pectin (73%). In addition, low-ester pectin (37%) significantly increased the disulfide bond content (from 15.31 μmol/g to 18.06 μmol/g) and maintained β-sheet content of gluten compared with gluten alone at 95 °C, indicating that low-ester pectin was more likely to induce gluten aggregation. However, scanning electron microscope showed that the gluten added with low-ester pectin (46%) exhibited a denser network structure at 95 °C than that added with low-ester pectin (37%). These results will provide a theoretical base for the regulation of gluten aggregation and the quality of gluten-based products by pectin with different esterification degree.

The interaction between wheat starch and pectin with different esterification degree and its influence on the properties of wheat starch-pectin gel

The interaction between wheat starch and pectin with different esterification degree (37%–73%) and its influence on the properties of wheat starch-pectin composite gel were investigated in the present study. It was found that high-ester pectin increased the swelling power (from 6.59 to 8.13 g/g) and solubility (from 7.12% to 8.83%) of wheat starch. Dynamic rheological results showed that high-ester pectin could maintain the viscoelasticity of composite gels, while low-ester pectin significantly reduced the viscoelasticity of composite gels. In addition, the composite index (CI) of high-ester pectin and wheat starch could reach 47.29%, which was significantly higher than that of low-ester pectin and wheat starch (23.27%). High-ester pectin (DE = 73%) significantly increased enthalpy (ΔH, from 0.72 to 1.09 J/g), relative crystallinity (from 2.03% to 3.41%) and the degree of short-range order (from 0.6441 to 0.8222) and enhanced the inter-strand hydrogen bond and inter-double helices hydrogen bond. These results indicated that high-ester pectin was more likely to interact with wheat starch to make the internal structure of the composite gels more stable and orderly. The results were also confirmed by the more compact and regular wheat starch-pectin (DE = 73%) gel network structure in SEM. Moreover, the results of intermolecular forces suggested that wheat starch and pectin mainly interacted through hydrogen bonds.

Rhamnogalacturonan I-Enriched Pectin, Flavonoids, and Alkaloids from Lotus Leaf Infusion in Regulating Glycolipid Absorption and Metabolism: Isolation, In Vitro Bioactivity Verification, and Structural Characterization.

Lotus leaf is effective in regulating glycolipid absorption and metabolism, but the roles of small-molecule compounds and polysaccharides are unknown. In this study, the small-molecule compounds including flavonoids, alkaloids, and polysaccharides were gradually isolated from lotus leaf infusion by multi-column chromatography and applied to in vitro activity verification and structural characterization. Although flavonoids and alkaloids were effective in inhibiting pancrelipase and α-glucosidase, polysaccharides more effectively bounded bile acids, inhibited cholesterol micelle solubility, and stimulated the growth of Bifidobacterium than lotus leaf infusion. Polysaccharides, presented as spherical conformation in water, were identified as rhamnogalacturonan I-enriched (93%) low-ester pectin with multiple branches mainly composed of arabinan, arabinogalactan-type II, and galactan formed by →3)-Galp-(1→, →5)-Araf-(1→ and →4)-Galp-(1→ residues. Polysaccharides, which were a key constituent of lotus leaf infusion in regulating glycolipid absorption and metabolism, should be paid more attention and developed as a functional food ingredient.

The effect of degree of esterification of pectin on the interaction between pectin and wheat gluten protein

Pectins with different degree of esterification (DE) (37, 46, 58, 63 and 73%) were prepared by alkali method and the effect of the DE on the interaction between pectin and wheat gluten protein was investigated in the present study. The results showed that low-ester pectin increased the water holding capacity (WHC) and viscoelasticity of gluten protein. The low-ester pectin promoted the conversion of sulfhydryl groups (-SH) to disulfide bonds (-S-S-). Compared with control gluten protein, the -S-S- content of gluten protein added with low-ester pectin significantly increased from 18.82 to 21.65 μmol/g, indicating that the gluten network structure was strengthened. Compared with high-ester pectin, low-ester pectin increased β-sheet content by 18.48%, suggesting that the stability of gluten protein was enhanced. In addition, intrinsic fluorescence spectra showed that the maximum intrinsic fluorescence intensity (Imax) of gluten protein added with low-ester pectin decreased from 826.53 to 630.47. Meanwhile, the surface hydrophobicity (H0) of gluten protein added with low-ester pectin decreased from 497.33 to 419.82. These results showed that low-ester pectin interacted more easily with gluten protein than high-ester pectin and formed some aggregates. Moreover, SEM and mercury intrusion results indicated that the low-ester pectin (DE-46%) was beneficial to maintaining the gluten network structure. These results will provide a theoretical basis for the application of pectin in wheat flour products.

Effects of different extraction methods on structural and physicochemical properties of pectins from finger citron pomace

The functionality and property of pectin are correlated with its structure which is affected by the extraction method used. In this study, three different methods of extracting pectin, the microwave-assisted extraction (MAE), the ultrasonic-assisted extraction (UAE) and the conventional heating extraction (CHE), were used at three different temperatures with both an acid and alkali extraction solution. It was found that temperature mainly influenced pectin yield, while pectin structures and physicochemical properties were affected by the pH condition and extraction technology. The alkali-extraction with MAE and UAE at short time promoted the yield of low-ester pectin. Monosaccharide composition analysis showed a high galacturonic acid (GalA) content in the pectin derived from MAE and UAE. The high viscosity and desirable viscoelastic properties of the acid-MAE pectin were due to its large molecular weight and particle size. The results contribute to our understanding of the association among pectin extraction, structure and properties.

An in vitro study of mucoadhesion and biocompatibility of polymer coated liposomes on HT29-MTX mucus-producing cells

Drug delivery to the oral cavity poses a significant challenge due to the short residence time of the formulations at the site of action. From this point of view, nanoparticulate drug delivery systems with ability to adhere to the oral mucosa are advantageous as they could increase the effectiveness of the therapy. Positively, negatively and neutrally charged liposomes were coated with four different types of polymers: alginate, low-ester pectin, chitosan and hydrophobically modified ethyl hydroxyethyl cellulose. The mucoadhesion was studied using a novel in vitro method allowing the liposomes to interact with a mucus-producing confluent HT29-MTX cell-line without applying any external force. MTT viability and paracellular permeability tests were conducted on the same cell-line. The alginate-coated liposomes achieved a high specific (genuine) mucin interaction, with a low potential of cell-irritation. The positively charged uncoated liposomes achieved the highest initial mucoadhesion, but also displayed a higher probability of cell-irritation. The chitosan-coated liposomes displayed the highest potential for long lasting mucoadhesion, but with the drawback of a higher general adhesion (tack) and a higher potential for irritating the cells.

Effects of Low-Ester Pectin on Wheat Dough's Physical Properties Detected by Rheological Method

The study examined the influence of low-ester pectin on the rheological property of wheat dough through capillary rheological method. The experimental results showed that the more the content of low-ester pectin in wheat dough, the less viscosity of the dough, meanwhile, the higher of the dough strength, the weaker the maximum drawing force endured by the dough. Therefore, the content of low-ester pectin had a direct impact on gluten index of the dough, namely, the stability and stirring resistance ability of the flour would be weaker when excessive low- ester pectin was added. Its additive amount had better be no more than 8% when making bread and other wheaten food.

New insights into the mucoadhesion of pectins by AFM roughness parameters in combination with SPR

The object of this study was to assess the mucoadhesion of the three main commercially available types of pectin by atomic force microscopy (AFM) and surface Plasmon resonance (SPR). Polyacrylic acid and polyvinyl pyrrolidone were used as positive and negative control, respectively. Image analysis of the AFM scans revealed a significant change of roughness parameters when low-ester pectin was introduced to mica supported bovine submaxillarymucin, indicating a high mucoadhesion for this type of pectin. Only minor changes were observed with high-ester and amidated pectin. The same ranking order of adhesion affinity was confirmed by SPR. In conclusion, a high specific mucin interaction of pectin with a high charge density was demonstrated directly on a molecular scale without interference from the viscoelastic properties or the intra-molecular interactions between the polymer chains themselves, using two independent methods.

A polyuronan blend giving novel synergistic effects and bake-stable functionality to high soluble solids fruit fillings

The effects of High M alginate, LE pectin and a combination, GRINDSTED ® FB 850 Stabiliser System (FB 850), giving bake-stable functionality in real, high soluble solids (72%) fruit fillings, are studied as a function of pH, fruit type, syneresis, and gel strength above the accepted bake-stable index of 80%. For acceptable bake stability, alginate showed a broad fruit, and thereby calcium tolerance (24.2–34.8 mg Ca/g Alginate), and a narrow pH range (3.8–4.0); contrary pectin showed a narrower calcium tolerance (20.7–29.4 mg Ca/g Pectin) but broader pH range (3.4–4.0) and FB 850 showed a calcium tolerance similar to pectin, (25.1–33.8 mg Ca/g FB 850) in terms of range, and a pH tolerance broader than both alginate and pectin (3.3–4.3). In alginate, syneresis was absent over the narrow pH range (3.8–4.0); pectin showed syneresis at lower pH (3.4–3.7), and in FB 850 syneresis was prevented over the entire pH range (3.3–4.3). FB 850 required lower gel strengths to achieve bake stability compared to pectin and alginate. For FB 850, pectin and alginate, thixotropy decreased (80, 48 and 23%, respectively), whilst the observed increase in elasticity and relative gel strengths, similarly suggested decreasing pumpability over the same given order. Pectin–alginate chain–chain associations cannot readily explain the synergistic effects seen in FB 850 because of high pH, initial presence of calcium and the low ester pectin. We therefore propose the synergy is driven by antagonistic competition between pectin and alginate for the calcium. We describe this as a mixed-independent system.

Factors affecting the production of low-ester pectin gels

Low-ester pectin gels find wide application in food industries especially in low calorie or dietectic foods because of their low sugar content. They are also relatively stable during prolonged storage at room temperature and they retain their shape at higher temperatures. In the present work the factors affecting the production of low-ester pectin gels including pH, pectin, calcium and sugar concentrations were investigated. The purpose of the work was to obtain the optimum conditions for the production of gels of high firmness and strength with a range of elasticity and free from syneresis. Gel firmness and strength were measured over the ranges of pH 3–3.6, 15–100 mg Ca 2+ /g pectin, 0.5–1.2% pectin and 10–50% sucrose. Conditions of pH (3, 3.6), (35, 45) mg Ca 2+ /g pectin, 1% pectin and (20, 30%) sucrose were optimal for gel firmness and strength.

Gelation Characteristics of Acid-Precipitated Pectin From Sunflower Heads

The acid-precipitated low-methoxyl pectin fraction from sunflower heads had a characteristically high galacturonic acid content but showed a negligible level of amidation as compared to a commercial citrus low-ester pectin. In general, sunflower pectin gels with gel powers of nearly 100 could be obtained in formulations containing 30–40% sucrose and calcium levels of 25–30mg/g of pectin in a pH range of 2.5 to 4.5. Optimum gel formation of the sunflower pectin was less dependent on specific conditions of pH, sucrose content and calcium ion concentration than was required for low-methoxyl citrus pectin. Sunflower pectin gels were firm over a wide range of pH while the commercial citrus product was particularly pH-sensitive.