High Methoxyl Citrus Pectin Research Articles

Red Orange and Bitter Orange IntegroPectin: Structure and Main Functional Compounds.

DRIFT, HPLC-MS, and SPME-GC/MS analyses were used to unveil the structure and the main functional compounds of red (blood) orange (Citrus sinensis) and bitter orange (Citrus aurantium). The IntegroPectin samples show evidence that these new citrus pectins are comprised of pectin rich in RG-I hairy regions functionalized with citrus biophenols, chiefly flavonoids and volatile molecules, mostly terpenes. Remarkably, IntegroPectin from the peel of fresh bitter oranges is the first high methoxyl citrus pectin extracted via hydrodynamic cavitation, whereas the red orange IntegroPectin is a low methoxyl pectin. C. aurantium IntegroPectin has a uniquely high concentration of adsorbed flavonoids, especially the flavanone glycosides hesperidin, naringin, and eriocitrin.

Structural Heteropolysaccharide Adhesion to the Corneal Glycocalyx

The cornea presents unique challenges to wound care. The cornea is constantly exposed to bacterial colonization, has ongoing risk of wound‐related astigmatism, and is cumbersome for traditional wound dressings. A potential solution to these challenges is provided by the corneal glycocalyx.Recent high pressure rapid freezing fixation techniques suggest that the glycocalyx is much thicker than previously believed. In the case of the cornea, the glycocalyx may provide an opportunity for wound care anchored to the transmembrane carbohydrate surface layer.To probe the surface glycocalyx we used a plant‐derived structural heteropolysaccharide called pectin. Pectin has been shown to mirror the structure of the glycocalyceal surface layer of visceral organs. To test the adhesivity of pectin to the corneal glycocalyx, high methoxyl citrus pectin was molded into tape form. Bovine globes were obtained from a local abattoir and used same day. Experiments were performed with custom fixtures using a materials analyzer (TA‐XT plus, Stable Micro Systems). To assess pectin adhesion to cornea, pectin was compressed onto the corneal surface then withdrawn, recording force and distance. A corneal incision was sealed with pectin and subject to increased pressure, until leak. At least three biologic replicates were analyzed, expressed as mean ± one standard deviation. Significance was assessed by Student’s T‐test. Pectin films on cornea were also fixed with formalin and imaged using a scanning electron microscope (Philips XL30 ESEM).Pectin films were flexible, translucent, thin (80um), and did not distort an Amsler grid. Pectin was significantly more adherent (3.2±0.54 N) to the bovine cornea than control polymers nanocellulose fibers (1.2±0.4 N), sodium hyaluronate (1.7±0.7 N), and carboxymethyl cellulose (1.3±0.1)(p<0.05). The work of adhesion, reflecting the area under the adhesion curve, was also significantly greater (p<0.05, asterisk, Figure 1). The cornea incisions sealed with pectin were resistant to pressure fluctuations ranging from ‐51.3±8.9 mmHg to +214.4±68.0 mmHg, both extremes beyond physiologic human intraocular pressures. Sudden or complete sealant failure was not observed. Consistent with these findings, scanning electron microscopy demonstrated a low‐profile tape densely adherent to the bovine cornea (Figure 2).The tensile and peel adhesive strength of the pectin biopolymer suggests a mechanism of polymer‐polymer entanglement with the corneal glycocalyx. As a therapeutic option for corneal wounds, the entangled pectin provides not only a protective barrier, but also an opportunity for pectin‐embedded drug delivery.

Kinetics of Plant‐derived Heteropolysaccharide Bioabsorption Characterized by Fluorescence‐based Microfluidics System

Plant‐derived structural polymer, pectin, is the “glue” between plant cells, a biomaterial with promising performance as a sealant on visceral organs. However, the nature of bioabsorption and biodurability of pectin remains unclear. Here, we investigate the feasibility of a quantitative microfluidic perfusion assay based on photochemical quenching, to define the kinetics of pectin bioabsorption.We hypothesize that fluorescent tracers embedded into pectin biopolymers will reliably reflect predictable kinetics patterns of bioabsorption including predictable trends when modifying the chemical species used in fluorescence quenching experiments.A fluorescent tracer, Fluorescein Sodium, was embedded into high methoxyl citrus pectin. Dried Fluorescein pectin films were placed into 24‐well plates, to monitor degradation via parallel microfluidics perfusion. This perfusion was performed via micro‐perfused exogenous 0.4% Trypan Blue, an anionic hydrophilic azo dye, which was delivered into porous matrix interfacing on pectin in each well. To assess biodurability, the fluorescence of perfused pectin under quenching by dye was monitored over time using a multi‐well plate fluorescence reader (Cytofluor 4000, PerSeptive Biosystems).Our data show that consistent trends in fluorescence result during quenching experiments. When un‐perfused, Fluorescein‐embedded pectin exhibited statistically insignificant change in quantum yield over 1 week (p=0.457), suggesting that results were not impacted by substantial photobleaching over the course of experimentation. To minimize interfacial flow artifact, 6µm porous matrix provided an effective interface for observable perfusion of azo dye into pectin. During micro‐perfusion, serial measurements of fluorescence in Fluorescein pectin demonstrated exponential decline in fluorescence intensity. This quenching of fluorescent signal from Fluorescein correlated with the progressive bioabsorption of the pectin polymer. Absorption was feasibly modulated by adjusting dye volumes used in perfusion.In this in vitro assay, plant‐derived pectin exhibits predictable decay characteristics and bioabsorption kinetics when incorporated with fluorescent tracers. These tracers not only provide a quantitative measure of biodurability, but also an opportunity for guided biochemical tuning of the complex biomaterial, to improve its performance as a potential therapeutic sealant.

Novel Biocomposite Films Based on High Methoxyl Pectin Reinforced with Zeolite Y for Food Packaging Applications.

Pectin is a natural biopolymer with broad applications in the food industry and it is suitable to prepare edible films to prolong food shelf-life. However, the main limitation of pectin-based films is their poor mechanical and barrier properties. Zeolite Y is a hydrophobic clay that can be used as film reinforcement material to improve its physicochemical and mechanical properties. In this work, the influence of high methoxyl citrus and apple pectin on physicochemical properties of biopolymer films modified with zeolite Y (0.05–0.2 wt%) was investigated. The films were characterized by FTIR, TGA, WAXD, mechanical analysis, and water vapor permeability analysis, and a potential film application is presented. The WAXD and FTIR analysis demonstrated that the strongest interaction between pectin chains and zeolite Y occurred when citrus high methylated pectin was used. Adding 0.2 wt% of zeolite Y into citrus high methylated pectin matrix enhanced the tensile strength by 66%, thermal stability by 13%, and water vapor barrier by 54%. In addition, fruit shelf-life test was performed, where strawberries were sealed in film. It was shown that sealed strawberries maintained a better color and healthy appearance than the control treatment after 7 days at 10 °C. This study enabled the development of biocomposite films with improved properties for potential application in food packaging.

Functional Adhesion of Pectin Biopolymers to the Lung Visceral Pleura.

Pleural injuries and the associated “air leak” are the most common complications after pulmonary surgery. Air leaks are the primary reason for prolonged chest tube use and increased hospital length of stay. Pectin, a plant-derived heteropolysaccharide, has been shown to be an air-tight sealant of pulmonary air leaks. Here, we investigate the morphologic and mechanical properties of pectin adhesion to the visceral pleural surface of the lung. After the application of high-methoxyl citrus pectin films to the murine lung, we used scanning electron microscopy to demonstrate intimate binding to the lung surface. To quantitatively assess pectin adhesion to the pleural surface, we used a custom adhesion test with force, distance, and time recordings. These assays demonstrated that pectin–glycocalyceal tensile adhesive strength was greater than nanocellulose fiber films or pressure-sensitive adhesives (p < 0.001). Simultaneous videomicroscopy recordings demonstrated that pectin–glycocalyceal adhesion was also stronger than the submesothelial connective tissue as avulsed surface remnants were visualized on the separated pectin films. Finally, pleural abrasion and hyaluronidase enzyme digestion confirmed that pectin binding was dependent on the pleural glycocalyx (p < 0.001). The results indicate that high methoxyl citrus pectin is a promising sealant for the treatment of pleural lung injuries.

Biomaterial-Assisted Anastomotic Healing: Serosal Adhesion of Pectin Films.

Anastomotic leakage is a frequent complication of intestinal surgery and a major source of surgical morbidity. The timing of anastomotic failures suggests that leaks are the result of inadequate mechanical support during the vulnerable phase of wound healing. To identify a biomaterial with physical and mechanical properties appropriate for assisted anastomotic healing, we studied the adhesive properties of the plant-derived structural heteropolysaccharide called pectin. Specifically, we examined high methoxyl citrus pectin films at water contents between 17–24% for their adhesivity to ex vivo porcine small bowel serosa. In assays of tensile adhesion strength, pectin demonstrated significantly greater adhesivity to the serosa than either nanocellulose fiber (NCF) films or pressure sensitive adhesives (PSA) (p < 0.001). Similarly, in assays of shear resistance, pectin demonstrated significantly greater adhesivity to the serosa than either NCF films or PSA (p < 0.001). Finally, the pectin films were capable of effectively sealing linear enterotomies in a bowel simulacrum as well as an ex vivo bowel segment. We conclude that pectin is a biomaterial with physical and adhesive properties capable of facilitating anastomotic healing after intestinal surgery.

Small Laccase from Streptomyces coelicolor catalyzed chitosan–pectin blending film for hazardous gas removal

This paper aims to prepare chitosan (CH)/high methoxyl citrus pectin (HMCP) film catalyzed by Streptomyces coelicolor (SLAC) and explore its properties. The properties of the film forming solution (FFS) and the as-prepared film were studied. The results showed that the FFS with 0.8 U 100 mL −1 SLAC catalysis has higher viscosity and larger particle size; texture analysis showed that the film with 0.8 U 100 mL −1 SLAC possessed the best mechanical properties; morphological and crystallinity analyses (SEM, XRD) demonstrated that the internal structure of the film with 0.8 U 100 mL −1 SLAC was the most uniform. After adding SLAC, the film had better CO 2 barrier performance. In conclusion, the properties of CH/HMCP blending film catalyzed by SLAC were improved and displayed promising application in food packaging. • Effects of SLAC concentration towards chitosan/pectin blending film have been studied. • Comprehensive characterizations were performed on the as-prepared biofilm. • CO 2 barrier performance was generally better with biofilm catalyzed by SLAC. • Biofilm with 0.8 U 100mL-1 SLAC showed best mechanical and morphological properties. • SLAC catalyzed CH/HMCP blending film is suitable to be applied as food packaging.

Gelation kinetics and characterization of enzymatically enhanced fish scale gelatin-pectin coacervate.

Protein-polysaccharide complex coacervations have been considered extensively for the development of functional foods. The main problem of the complex coacervates is that they are highly unstable under different conditions and that cross-linking is necessary to stabilize them. In this study, the effects of pectin at different concentrations on the gel and structural properties of fish scale gelatin (FSG)-high methoxyl citrus pectin (HMP) coacervate enhanced by microbial transglutaminase (MTGase) were studied. The gelation rates and gel strength of the MTGase-enhanced FSG-HMP coacervate gels decreased with increasing HMP concentration. However, the enhanced coacervate gels exhibited better thermal behavior and mechanical properties compared with the original gels. Also, TG-P8 exhibited the highest melting point (27.15 ± 0.12 °C), gelation point (15.65 ± 0.01 °C) and stress (15.36 ± 0.48 kPa) as HMP was 8 g kg-1 . Particle size distribution, fluorescence emission and UV absorbance spectra indicated that MTGase and HMP could make FSG form large aggregates. Moreover, confocal laser scanning microscopy of treated coacervate gels showed a continuous protein phase at low HMP concentrations. FSG and HMP could form soluble coacervate, and MTGase could improve the thermal and mechanical properties of coacervate gels. © 2017 Society of Chemical Industry.

Development of double layered emulsion droplets with pectin/β-lactoglobulin complex for bioactive delivery purposes

The objective of the present study was to load piroxicam (PX) into multi-layered oil in water emulsions stabilized by β-lactoglobulin (β-Lg)/pectin complexes. A primary emulsion was produced by homogenizing the sunflower oil contains PX in β-Lg solution (at pH=3.5). Then, the emulsion droplets were stabilized further by coating with pectin as a secondary layer. Four different pectin types including low-methoxyl sunflower pectin (LMSP), high-methoxyl apple pectin (HMAP), high-methoxyl citrus pectin (HMCP), and low-methoxyl citrus pectin (LMCP) were applied for production of double layered emulsion droplets. The entrapping efficiency of PX (%), creaming stability, and mean droplet size (D43) of emulsions were measured. Also, the release trends of PX were determined and fitted with experimental models of zero order, Higuchi, and Pepass. Our results revealed that the emulsions stabilized by β-Lg/high-methoxyl apple and citrus pectins with NaCl had a higher creaming stability and more loading capacity of PX compared to stabilized emulsions by β-Lg/pectin without NaCl. The mean droplet size (D43) of double layered emulsions was increased at higher pectin fraction and were decreased by lower β-lg fraction.

Effect of low and high methoxyl citrus pectin on the properties of polypyrrole based electroactive hydrogels

Electroactive hydrogels were prepared using commercial citric pectin, either raw (PC) or purified through dialysis (dPC), and chemically synthesized polypyrrole (PPy). 1H NMR analyses showed that PC is a low methoxyl pectin (degree of methoxylation, DM=46%) and dPC is a high methoxyl pectin (DM=77%). The pyrrole polymerization was monitored through UV⿿vis spectroscopy and both samples were observed to be good stabilizers for PPy in aqueous medium. The dispersions were used to prepare the hydrogels h-PC-PPy and h-dPC-PPy. The hydrogel h-dPC-PPy has a higher swelling index (SI⿿25%) at pH 1.2 than the hydrogel h-PC-PPy (SI⿿7%). Contrastingly, at pH 6.8 both hydrogels lost their mechanical integrity. Raman spectroscopy revealed that PPy is more oxidized in h-PC-PPy. Nevertheless, both hydrogels are electroactive and therefore can be considered for applications in which the control of the degree of swelling is desired.

Fractionation of citrus pectin on diethylaminoethyl-cellulose columns

A sample of high-methoxyl citrus pectin was separated into its major fractions on diethylaminoethyl-cellulose columns using increasing concentrations of NaH 2PO 4 solution as the eluent. The fraction eluted with the lowest concentration of NaH 2PO 4 had the highest methoxyl content, and latter fractions, obtained with progressively increasing NaH 2PO 4 concentrations, showed progressively lower methoxyl values. The percentage esterification and equivalent weight also decreased in a similar manner. This decrease in methoxyl content from one fraction to the next was accompanied by an increase in setting times and jelly grades. A small decrease in molecular weight from one fraction to the next towards the low-ester range was observed and none of the fractions had a molecular weight as high as the original pectin.

Static light scattering technique applied to pectin in dilute solution. Part II: The effects of clarification

The effects of purification/clarification by ultracentrifugation and/or membrane filtration were studied by light scattering, GPC plus off-line capillary viscometry and GLC sugar analysis using a high-methoxyl citrus pectin as model substance. The emphasis of light scattering measurements was put on analysing the angular dependence of the scattered light. For that reason the interpretation of the measured data involved the use of master curves in addition to Zimm or Guinier plots. The benefits and limitations of this method of data treatment for complex systems are discussed both in theory and practice. Due to the natural heterogeneity of pectins, purification or classification modified the original sample by removing the high molecular weight and dense tail, leaving a physically and chemically heterogeneous polysaccharide.

Static light scattering technique applied to pectin in dilute solution. Part I: Reliability of experiments and model calculations

During static light scattering studies of a commercial high-methoxyl citrus pectin in phosphate buffer, problems arising from sample clarification have been identified. Therefore, the effect of varying the pore size of the membrane filters between 5·0 and 0·2 μm was studied. Also, the effect of repeated filtration was investigated. Data are presented as Zimm and Guinier plots. The lower the pore size of the filter, the lower the average molecular weight, but the higher the negative second virial coefficients found. Results suggest that the negative virial coefficients are due to residual particulate matter. Model calculations suggest that a bimodal system consisting of a molecularly dispersed major component and smaller amounts of a high molecular weight particulate component is an appropriate description of the pectin sample. Dextran sulphate was used to demonstrate the behaviour of a ‘homogeneous’ non-aggregating polysaccharide.

Static light scattering technique applied to pectin in dilute solution. Part III: The tendency for association

The tendency for association was studied by light scattering applied to a series of a high-methoxyl citrus pectin solution in phosphate buffer. To prevent artefacts, the clarified stock solution and buffer were mixed within the measuring cell. The measured data are presented as Zimm and master plots. A reversible increase of the apparent molecular weight with rising polymer concentration and slightly negative second virial coefficients were found in the case of the uncentrifuged, but filtered, solutions, indicating a slight tendency for association. The associates formed remain relatively small. This is independent of the pore size of the filters used for clarification. Prepurification by ultracentrifugation gave solutions which showed two-component behaviour and gave no hint of association.

The determination of the molecular weight distribution of pectins by calibrated GPC Part I. Calibration by light scattering and membrane osmometry

Commercial high methoxyl citrus pectin was fractionated on Sepharose 2 B/Sepharose 4 B. Fractions were used to calibrate GPC by light scattering and membrane osmometry. The angular dependence of light scattering of the fractions was interpreted in terms of a two-component system giving reliable M w/ M n ratios for the major molecularly dispersed component which forms coils of considerable stiffness in solution. A minor particulate spherical component was identified which was rich in neutral sugars. Structural parameters of this component were determined by comparison of the experimental scattering behavior with master curves. β-Elimination of the fully esterified pectin was carried out to reveal the chemical nature of the particulate component.

Studies on the heterogeneity of citrus pectin by gel permeation chromatography on Sepharose 2 B/Sepharose 4 B

Commercial high methoxyl citrus pectin was purified by ultracentrifugation or ion exchange chromatography prior to GPC on Sepharose 2 B/Sepharose 4 B. The molecular weights by light scattering and the intrinsic viscosities of the fractions were determined. The effects of the purification procedures on the heterogeneity in shape are discussed by combining the Mark-Houwink plots with the universal calibration plot and the elution profile, respectively. Pectin fractions prepared by GPC are investigated in the same manner. GPC cannot differentiate between lower molecular weight extended coils and more compact high molecular weight molecules of increased polymer density. They are eluted together within a broad elution volume range.