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ABSTRACT Pectin has been used in the development of safe and effective drug delivery systems because of its unique physicochemical and biological characteristics. However, it still needs to be modified to overcome some inherent drawbacks. In the present study, pectin was alkylated by bromododecane. The C12-alkylated pectin (PC12) can form strong hydrogels in the presence of Ca2+. Such hydrogels were explored to prepare bovine serum albumin (BSA)-loaded microspheres (PC12-MS). The BSA encapsulation yield of PC12-MS was significantly higher than that of microspheres prepared with the original pectin (PC-MS). Differential scanning calorimetry analysis indicated that interactions existed between BSA and pectin during the preparation of microspheres. Release tests showed that PC12-MS almost avoided BSA release in simulated gastric fluids, which was verified by environmental scanning electron microscopy analysis, and exhibited an effective controlled release throughout the simulated gastrointestinal tract compared to PC-MS. In addition, an MTT assay showed the biocompatibility of C12-alkylated pectin. Thus alkylated pectin may serve as a potential protein drug carrier. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45344. [ABSTRACT FROM AUTHOR]

In recent years, the interest in studying modification of pectin has increased. A number of hydroxyl and carboxyl groups distributed along the backbone as well as a certain amount of neutral sugars presented as side chains make pectin capable of preparing a broad spectrum of derivatives. By forming pectin derivatives, their properties may be modified and some other new functional properties may be created. This article attempts to review the information about various methods used for pectin modification, including substitution (alkylation, amidation, quaternization, thiolation, sulfation, oxidation, etc.), chain elongation (cross-linking and grafting) and depolymerization (chemical, physical, and enzymatic degradation). Characteristics and applications of some pectin derivatives are also presented. In addition, the safety and regulatory status of pectin and its derivatives were reviewed. [ABSTRACT FROM AUTHOR]

The development of effective heavy metal adsorbents has always been the goal of environmentalists. Pectin/activated carbon microspheres (P/ACs) were prepared through simple gelation without chemical crosslinking and utilized for adsorption of Pb2+. Scanning electron microscopy (SEM) revealed that the addition of activated carbon increased the porosity of the microsphere. Texture profile analysis showed good mechanical strength of P/ACs compared with original pectin microspheres. Kinetic studies found that the adsorption process followed a pseudo-second-order model, and the adsorption rate was controlled by film diffusion. Adsorption isotherms were described well by a Langmuir isotherm model, and the maximum adsorption capacity was estimated to be 279.33 mg/g. The P/ACs with the highest activated carbon (P/AC2:3) maintained a removal rate over 95.5% after 10 adsorption/desorption cycles. SEM-energy-dispersive X-ray spectrum and XPS analysis suggested a potential mechanism of adsorption are ion exchange between Pb2+ and Ca2+, electronic adsorption, formation of complexes, and physical adsorption of P/ACs. All the above results indicated the P/ACs may be a good candidate for the adsorption of Pb2+. [ABSTRACT FROM AUTHOR]

We previously reported that dynamic high-pressure microfluidization (DHPM) can degrade pectin in aqueous solution. In this study, we further investigated the effect of DHPM on pectin in water-ethanol systems. In the absence of DHPM treatment, it was found that pectin exhibited increased average particle size and unchanged average molecular weight, but a decline in reducing-sugar-ends content with the increase of ethanol concentrations (0–10% v/v). These results indicated that the addition of ethanol induced aggregation of pectin. During DHPM treatment, pectin underwent disaggregation and degradation under all measured ethanol concentrations. Disaggregation was enhanced but degradation was weakened with the increase of ethanol concentration. FT-IR and UV spectra indicated that demethylation but no β-elimination occurred in the water-ethanol system during DHPM. Finally, the mechanism of DHPM-induced disaggregation and degradation of pectin under a water-ethanol system was updated. This work may help us to find a suitable condition for reducing the degradation of pectin during the process of homogenization. [ABSTRACT FROM AUTHOR]

This work investigated effects of the galacturonic acid content (GA), degree of methoxylation (DM), degree of amidation (DA) and molecular weight (M W ) of pectin on the pasting properties of rice starch (RS). Pectins with varying structures were selected randomly. Different pectins when added to RS showed significant differing ( p < 0.05) influences on pasting properties of RS. Multiple regression analysis was adopted to establish equations between structural characteristics of pectin and pasting properties of RS. The obtained equations had a good fit (all R 2 ≥ 0.936), and relative errors of pasting properties for prediction group were very close to the coefficient of variation (except breakdown). The contribution of the specific pectin structural characteristic on the change of the pasting properties of RS was also evaluated. DM was greatly correlated with peak and trough viscosity. Breakdown was strongly affected by DA and GA. Two primary factors that affected setback were the M W and GA. Furthermore, peak time was mainly influenced by DA. [ABSTRACT FROM AUTHOR]

Recently there has been an increased interest in modification of pectins. Pectins were alkylated with alkyl chain of various lengths (hexyl, dodecyl or octadecyl) at different degrees of substitution (0.69, 2.43 or 3.60) by reaction of TBA-pectin with alkyl bromide in this study. Their structures were characterized by GC, FTIR and 1 H NMR, which confirmed the formation of ester linkages between hydrophobic alkyl segment and carboxyl group of galacturonic acid. Alkylated pectins produced interesting rheology properties. They showed higher apparent viscosities but lower intrinsic viscosities than the original one. The higher apparent viscosities may be due to intermolecular association of hydrophobic segments in the molecule. The lower intrinsic viscosities would be ascribed to more compact conformation. In addition, the modified pectins showed an enhancement of emulsifying properties. These properties were significantly influenced by the degree of substitution and alkyl chain length. Such amphiphilic derivatives open new perspectives for improving or altering viscosity and emulsifying properties of pectin. [ABSTRACT FROM AUTHOR]

Abstract: Pectic-oligosaccharides (POSs) were prepared from apple pectin by dynamic high-pressure microfluidization (DHPM). Operating under selected conditions (pectin concentration 1.84%, solution temperature 63°C, DHPM pressure 155MPa and number of cycles 6 passes), 32.92% of the pectin was converted into POS. The resulting POS contains 29.56% galacturonic acid and 58.53% neutral sugars. The prebiotic properties of POS were then evaluated using a fecal batch culture fermentation. The POS increased the number of Bifidobacteria and Lactobacilli, and produced a higher concentration of acetic, lactic, and propionic acid than their parent pectin. Furthermore, POS decreased the number of Bacteroides and Clostridia while their parent pectin increased them. Moreover, the effects of POS on the growth of these bacteria and production of short-chain fatty acids are comparable to those of the most studied prebiotic, fructooligosaccharide. These results indicated that the POS prepared by DHPM has a potential to be an effective prebiotic. [Copyright &y& Elsevier]

Abstract: High-methoxyl pectin was degraded by dynamic high pressure microfluidization (DHPM). It was found that apparent viscosity, average molecular weight and particle size of pectin decreased, whereas the amount of reducing sugars increased with increasing DHPM pressure. At the same time, the surface topography of pectin was changed from large flake-like structure to smaller porous chips. The mechanism of DHPM-induced degradation of pectin was also investigated. Fourier transform infrared spectra showed DHPM had no effect on the primary structure of pectin. On the other hand, reducing sugars content increased linearly with decreasing average molecular weight, suggesting the degradation may derive from the rupture of glycosidic bond. The breakdown of glycosidic bond may not only result from intensive mechanical forces but also from acid hydrolysis, which was evidenced in the reduction of degradation when the concentration of H+ was lowered. In addition, neither β-elimination nor demethoxylation occurred with DHPM. Based on these results, a model was proposed to illustrate the degradation of pectin induced by DHPM. [Copyright &y& Elsevier]

Poly(m-phenylenediamine) assembled on pectin microsphere for Pb2+ adsorption and their adsorption mechanisms [Display omitted] • Novel pectin/poly(m-phenylenediamine) (P/PmPDA) microsphere was prepared. • The amount of PmPDA assembled on pectin microsphere could be controlled. • P/PmPDA microsphere showed high efficiency of Pb2+ removal. • The potential adsorption mechanisms were ion exchange and chelation. Novel pectin/poly(m-phenylenediamine) (P/PmPDA) microspheres with different content of PmPDA were prepared by assembling PmPDA on the surface of pectin microsphere. The successful preparation was confirmed by the results of Fourier Transform Infrared spectra (FTIR), scanning electron microscopy (SEM) and elemental analysis. Compared with pectin microsphere, the Pb2+ adsorption performance of P/PmPDA microspheres was significantly improved. The results of batch adsorption experiments were in good agreement with the Langmuir isotherm model for Pb2+ adsorption, indicating the adsorption was monolayer. The maximum adsorption capacity of Pb2+ was found to be 390.9 mg/g. The kinetic adsorption process was well described by the pseudo-second-order model and chemical adsorption dominated the adsorption process. The potential mechanisms of Pb2+ adsorption were speculated as ion exchange and chelation, which were supported by X-ray photoelectron spectroscopy (XPS). The P/PmPDA microspheres showed good recyclability after five adsorption/desorption cycles. All these results indicated the potential of P/PmPDA microspheres for removing Pb2+. [ABSTRACT FROM AUTHOR]

Pb2+ adsorption by ethylenediamine-modified pectins and their adsorption mechanisms. • Ethylenediamine-modified pectins (EPs) with different DA were synthesized. • The EP 48 showed high efficiency of Pb2+ removal at low Pb2+ concentration. • The amide groups on pectin behaved as effective sites for Pb2+ capture. • The adsorption mechanisms were due to ion exchange and chelation. Ethylenediamine-modified pectins (EPs) with different degrees of amidation (DA) were prepared and characterized by Fourier Transform Infrared spectra (FTIR), elemental analysis, X-ray photoelectron spectroscopy (XPS). The prepared EPs were then used to remove Pb2+ from the aqueous solution. It was found that EPs with the highest DA (EP 48) exhibited great removal efficiency of Pb2+ (≥94 %) at low concentrations of 40−80 mg/L. The zeta potential analysis showed that EP 48 had the fastest increase in zeta potential when Pb2+ was continuously added and was the first to be electroneutralized. Particle size analysis further confirmed that EP 48 was the first precipitated and formed a larger EP 48 -Pb2+ complex. The FTIR and XPS analyses indicated that Pb2+ was adsorbed via the ion exchange of carboxylic groups and chelation with acylamino and amino groups. These results suggested that the EP 48 might be a promising adsorbent for the removal of low concentrations of Pb2+ in contaminated water. [ABSTRACT FROM AUTHOR]