Search

RG-I rich pectic polysaccharide is common in fruit and vegetable and possesses health benefits. However, it is removed during commercial pectin production because of poor gelling properties. Synergistic gelation can improve rheological properties of RG-I pectic polysaccharide and expand its application in functional food hydrocolloids. In the study, RG-I rich pectic polysaccharides at different degree of esterification was extracted from citrus membrane by sequential mild acidic (0.4% HCl, 28 °C) and alkaline (0.6% NaOH, 32 °C) treatment. The pectic polysaccharide from acid water (PA) composes of 41% RG-I and 44% HG with DM of 45%, while the pectic polysaccharide from basic water (PB) composed of 63% RG-I and 19% HG with DM of 15%. PA/PB blend gel under CaCO 3 -glucono-δ-lactone system showed improved rheological properties compared with pure gels. Ca-bridges connected pectin aggregates and promoted the three-dimensional structure of PA/PB blend gels, while neutral sugar side-chains prompted hydrogen bonds and strengthened gel network., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Rhamnogalacturonan I (RG-I) pectin are regarded as strong galectin-3 (Gal-3) antagonist because of galactan sidechains. The present study focused on discussing the effects of more structural regions in pectin on the anti-Gal-3 activity. The water-soluble pectin (WSP) recovered from citrus canning processing water was categorized as RG-I pectin. The controlled enzymatic hydrolysis was employed to sequentially remove the α-1,5-arabinan, homogalaturonan and β-1,4-galactan in WSP. The Gal-3-binding affinity KD (kd/ka) of WSP and debranched pectins were calculated to be 0.32 μM, 0.48 μM, 0.56 μM and 1.93 μM. Moreover, based on the more sensitive cell line (MCF-7) model, the IC 30 value of WSP was lower than these of modified pectins, indicating decreased anti-Gal-3 activity. Our results suggested that the total amount of neutral sugar sidechains, the length of arabinan and cooperation between HG and RG-I played important roles in the anti-Gal-3 activity of WSP, not the Gal/Ara ratio or RG-I/HG ratio. These results provided a new insight into structure-activity relationship of citrus segment membrane RG-I as a galectin-3 antagonist and a new functional food., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2020. Published by Elsevier Ltd.)

To better understanding the potential of manosonication to accelerate the extraction of RG-I pectic polysaccharides from citrus wastes, alkaline-mediated manosonication extraction (MSE) was optimized using a Box-Behnken design, and the extraction kinetics model was analyzed. The single-factor method revealed that NaOH significantly impacted on the yield and RG-I characterizations (Rha mol% and (Gal+Ara)/Rha ratio), whereas other factors were focused on influences of yields. In the developed quadratic polynomial model, the maximum extraction yield of 25.51 ± 0.81 % was obtained with sonication at 42 ℃, 40 % amplitude, and 250 kPa for 20 min. The kinetics study demonstrated that MSE facilitated the extractability, dissolution and degradation of pectin, resulting in the highest extractability of 27.83 % compared with ultrasonic extraction (22.86 %) and alkaline extraction at high (24.71 %) and low temperature (20.21 %). Rheology and thermal analyses verified the change in polymerization by MSE and the potential functional applications of the RG-I pectic polysaccharides., Competing Interests: Declaration of Competing Interest There is no conflicting interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Rhamnogalacturonan I (RG-I) pectin is composed of backbone of repeating disaccharide units →2)-α-L-Rhap-(1→4)-α-D-GalpA-(1→ and neutral sugar side-chains mainly consisting of arabinose and galactose having variable types of linkages. However, since traditional pectin extraction methods damages the RG-I structure, the characteristics and health effects of RG-I remains unclear. Recently, many studies have focused on RG-I, which is often more active than the homogalacturonan (HG) portion of pectic polysaccharides. In food products, RG-I is common to fruits and vegetables and possesses many health benefits. This timely and comprehensive review describes the many different facets of RG-I, including its dietary sources, history, metabolism and potential functionalities, all of which have been compiled to establish a platform for taking full advantage of the functional value of RG-I pectin.

Rhamnogalacturonan-I (RG-I) was considered to be incompatible with gel formation. Due to its important health benefits, our previous study reported synergistic gelation of RG-I enriched pectin from citrus membranes with sequential acidic and alkaline treatment. In the present study, we further fabricated RG-I enriched pectin-based emulsion gels with the synergistic gelation for hydrophobic bioactive encapsulation. The effect of oil fraction and interfacial compositions including pectin itself and Tween 20 on the physical properties and delivery characteristics of emulsion gels was investigated. As to interfacial compositions, pectin reduced syneresis and swelling ratio and increased water holding capacity. Oil fraction had no marked influence on syneresis and swelling ratio, but significantly increased water holding capacity. Particularly, all the emulsion gels showed an elastic behavior and a full structure recovery after shearing. Increase in pectin instead of Tween 20 onto the surface of oil droplets and oil fraction markedly improved their gel strength. Curcumin was encapsulated within the oil phase of emulsion gels. Improvement in gel strength provided enhanced protection of curcumin against heat-induced degradation. In vitro digestion revealed that interfacial compositions decelerated curcumin release by increasing the proportion of pectin onto the surface, but didn't change its bioaccessibility eventually. Increase in oil fraction accelerated curcumin release, but reduced its bioaccessibility. Overall, fabrication of RG-I enriched pectin-based emulsion gel with pectin itself as interfacial composition and low oil fraction would contribute to improving curcumin bioavailability for its sustained release, which should be further validated in vivo. [Display omitted] • Rhamnogalacturonan-I enriched pectin-based emulsion gels were fabricated. • Interfacial compositions influenced strength of the emulsion gels. • Increase in oil fraction improved strength of the emulsion gels. • Curcumin was encapsulated within oil phase of the emulsion gels. • Protection and sustained release of curcumin were achieved. [ABSTRACT FROM AUTHOR]

RG-I enriched pectin is present in fruit and vegetable containing products. However, it is removed by the hot acid treatment during commercial pectin production to improve gelling properties and to afford a more uniform pectin quality. Recently, an awareness of the health benefits of RG-I enriched pectin has caused technologists to rethink its utilization by the food industry, especially as a novel healthy gelling agent. Unique RG-I enriched pectin with abundant arabinan side-chains was extracted from citrus membrane by sequential mild acidic and alkaline treatment. Arabinose was then removed by enzymatic treatment to investigate the impact of arabinose side-chains on gelation. The properties of RG-I enriched pectin gels, prepared using cations or acid, showed it could form gels under conditions required for both low and high methoxyl pectin as a result of its highly branched structure. In cation-induced gelation, the HG region forms egg-box junction zones with divalent cations and the side-chains of the RG-I region stabilizes the network structure through entanglements. In acid-induced gelation, low pH promotes formation of hydrogen bonding and hydrophobic interactions within the HG region and the side-chains create a tighter conformation, eventually allowing for stronger interactions between the pectin chains. Image 1 • RG-I enriched pectin extracted from citrus membrane by sequential mild treatment contains abundant arabinan side-chains. • RG-I enriched pectin forms gel under both cation and acid conditions and its side-chains improve network formation. • Arabinan side-chains stabilize junction zones in cation-induced gel through entanglements. • Arabinan side-chains form dense network in acid-induced gel through hydrogen bonds. [ABSTRACT FROM AUTHOR]

• Ultrasonically accelerated NaHCO 3 -H 2 O 2 system was optimized. • Highly active O 2 − generated from HCO 4 - plays the key role in HG domain degradation. • Ultrasound promoted degradation by chemical and mechanical effects. • Degradation fragments have lower degree of methylation (DM) and higher galactose content and anti-cancer activity. The modified pectin (MP) showed the improved functional properties than the native one. The aim of present study was to develop the ultrasonic accelerated bicarbonate-hydrogen peroxide system for pectin modification to generate short fragments with advanced bioactive properties. The depolymerization effects of this system on the physicochemical properties, structural features, and bioactivity of the degraded fragments were studied systematically. The results indicated that the molecular weight of pectin was reduced drastically from 1088 kDa to 33 kDa within 50 min under an optimized condition (M H2O2 -M NaHCO3 = 1:2.5, 50 °C, and ultrasound intensity = 11.4 W/cm3). The resulting fragments also showed lower degree of methoxylation and rheological viscosity. The investigation on the sample structures and active oxygen species demonstrated that the highly active O 2 − species generated from HCO 4 - of NaHCO 3 -H 2 O 2 acted preferentially on the GalA backbone in the HG region, while the RG-I region was maintained; and ultrasound enhanced the degradation efficiency via both chemical effects (increasing the transformation of free radicals) and mechanical effects (disaggregating polysaccharide clusters). The atomic force microscope (AFM) imaging directly verified the branched-chain morphology of pectin and the small-strand degradation fragments. Moreover, ultrasound and NaHCO 3 -H 2 O 2 treatment induced high galactose content in the degraded products, contributing to an improved inhibitory activity against A549 lung cancer cells, as shown by MTT assay. [ABSTRACT FROM AUTHOR]