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A gelling strategy for HP was proposed in this study, ammonium sulfate (AS) as a co-solute could induce the gelling of HP in acidic environment. The solubility and Zeta potential of HP dramatically decreased in AS solution, which indicated AS could promote the aggregation of HP. The rheological results confirmed the gelling of HP (G' > G″) with AS: 25-30 wt% and pH ≤ 3.0, and the gel strength is mainly depended on HP rather than AS concentration. Smaller AS crystals (SEM) and reduced T 2 values (LF-NMR) were observed in HP gels, suggested the gel network of HP could limit the migration of AS and water. Finally, it was found that the release process of NH 4 + in HP + AS gel was lagged behind that of pure AS, which verified the potential of HP + AS gel in the field of sustained-release fertilizers., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Moderate alkali de-esterification can change the physicochemical characteristics and thus the functional properties of high methoxyl pectin (HMP). The results revealed that de-esterification could increase negative charges (Zeta potential from -21 to -31 mV), decrease molecular weight (from 448 to 136 kDa) and apparent viscosity of HMP. Homogalacturonan (HG) content decreased (from 62% to 49%) while rhamnogalacturonan Ⅰ (RG-Ⅰ) content increased (from 32% to 46%) after de-esterification. The group characteristics of HMP with different degree of esterification (DE) were similar and no obvious impact was made on degree of crystallinity by alkali de-esterification. A conformation transition of HMP molecule implied by Congo red test were occurred as the DE decreased. With the decrease of DE, the molecular structure of HMP became shorter and smaller, and the entanglement was weaker. The de-esterification caused slight decrease of thermal stability. Alkali de-esterification would weaken the gel property and the emulsifying ability of HMP., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Bismuth-contained therapies are effective in treating gastric ulcer and eliminating Helicobacter pylori (Hp). Anion polysaccharides ligand could reduce the intake of bismuth, and enhance drug efficacy of bismuth compounds. In this study, pectin-bismuth (PB) was prepared and the changes of PB structure in acidic environment were reported for the first time. The structure of PB was characterized by FT-IR, XRD, and TGA, which suggested that combined with bismuth could alter the crystal structure of pectin. XPS confirmed the ionic binding of Bi 3+ with carboxyl groups of pectin. The aggregating of PB with different pH level were also investigated, and the influence of pH on PB structure were observed by SEM. Results showed that PB has much larger volume of flocculation in acidic environment compared with bismuth nitrate. Additionally, apparent shear stress (τ a ) of PB suspension was evaluated. These results revealed the structural characteristics and acid-induced aggregation of pectin-bismuth, and bismuth could aggregate in acidic solution with the gelation of pectin., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Summary: The acid heating extraction process is commonly employed to extract pectin from citrus peels, which results in the leaching of bioactive constituents into solvents. However, the discharge of these solvents represents a significant loss of valuable resources. To address this issue, this study aims to identify the composition and concentration of the bioactive constituents that escape into the solvents and propose an extraction process based on an ethanol‐salt aqueous two‐phase system (ATPS). The well‐designed ATPS enables the enrichment and recovery of the bioactive constituents, and the findings demonstrate that the ethanol/sodium citrate‐based ATPS can recover up to 80.61% of limonoids, 84.11% of flavonoids, and 88.09% of polyphenols that escape at an enrichment efficiency of 50.00%. Moreover, HPLC‐DAD and UPLC‐HRMS analysis of the ATPS extracts revealed the presence of nine bioactive constituents, including flavonoids, phenolic acids, and limonoids. Remarkably, in vitro antioxidant capacity studies indicate that the ATPS extracts exhibit superior antioxidant activity compared to the vacuum‐concentrated solution. Thus, these results suggest that the application of ATPS extraction is a feasible and promising strategy for the recovery of bioactive constituents. [ABSTRACT FROM AUTHOR]

In this study, pectin polysaccharide (SDPP) was obtained from soybean dreg (26.2% yield), and characteristics of SDPP were compared with those of soybean soluble polysaccharides (SSPS) and citrus pectin (HMP). The galacturonic acid and molecular weight of SSPS, SDPP or HMP were 11.8%, 40.6% or 70.2% and 112, 446, or 440 kDa. SDPP had similar viscosity and protein content to SSPS, and functional groups and linear structure to HMP. SSPS, SDPP or HMP differed in particle size of 260, 467 or 1195 nm and ζ–potential of −5.8, −14.6 or −23.5 mV at pH 4.0. The precipitation of acidified milk drink (AMD) was 6.31% without stabiliser or below 1.75% with 0.4% SDPP at pH 3.6–4.6. These results suggested that SDPP combines the structure and characteristic of HMP and SSPS, and AMD with SDPP had great stabilising behaviour at wider pH range (pH 3.6–4.6). [ABSTRACT FROM AUTHOR]

Summary: The objective of this work was to extract high methoxyl (HM) pectin with oxalic acid, characterise its physicochemical properties and evaluate its dispersion stability in acidified milk drink (AMD). HPSEC–MALLS analysis revealed that the obtained HM pectin was high in molecular weight (522.4 kDa). The ζ‐potential of the obtained HM pectin in aqueous solution at pH 4.0 was −31.5 mV. The AFM images proved that the obtained HM pectin contained several long linear molecules. The apparent diameter of AMD stabilised by the obtained HM pectin was 636 nm at the concentration of 3.0‰. The stability analysis of AMD and the microscopic observation with confocal laser scanning microscopy (CLSM) proved that the obtained HM pectin was a prominent stabiliser in AMD. [ABSTRACT FROM AUTHOR]

In 25% (v/v) ethanol system, an acid induced pectin gelling mechanism was proposed in this study, which could be used to construct emulsion gel system. FT-IR, GPC, and monosaccharides analysis were used to investigated the structure of pectins. HMP and LMP are different in molecular wight and chain structure, and HMP shows excellent gelling property. Intermolecular interaction of acid/ethanol induced HMP gel was investigated with SDS, Urea, and shifted pH. Those results indicated HMP has larger molecular wight, more neutral sugar side chain, and lower zeta potential than LMP, which facilitates the construction of compact gel network. LMP and HMP emulsions with 25% (v/v) ethanol were prepared and HMP emulsions with different oil volume fractions (Φ 0.2–0.75) exhibit gelling properties. Furthermore, the compact structure of HMP gel is stable during the freeze-thaw cycle which improved the freeze-thaw stability of pectin emulsions. The purposed mechanism for acid/ethanol induced HMP emulsion gel and its freezing-thawing stability. [Display omitted] • In 25% (v/v) ethanol, acid could induced high methoxyl pectin (HMP) gelling. • HMP have better gel properties than low methoxyl pectin in acid/ethanol system. • Gelling of HMP in acid/ethanol system was dominated by hydrogen bonds. • Acid/ethanol induced HMP emulsion gel remained stable over 3 × freeze-thaw cycles. [ABSTRACT FROM AUTHOR]

The purposed mechanism for the effects of ethanol on the chain conformation and the emulsifying properties of high methoxyl pectin. • The pectin chain conformation is compressed in a binary solvent of water/ethanol. • Ethanol reduces the electrostatic repulsion and promotes pectin aggregation. • Condensation of pectin chain is beneficial to its adsorption at the O/W interface. • The pectin in binary solvent has better emulsion stability. Pectin is widely distributed in plant cell wall, most of which have limited emulsifying properties. Ethanol could alter the solubility of pectin, and affect its emulsifying properties. No creaming and breaking of emulsion appeared in 21% (v/v) ethanol contained emulsion. This project investigated the influence of ethanol (0%–35%, v/v) on conformation and emulsifying properties of pectin. Results shown that ethanol could reduce the helix conformation and zeta potential of pectin chain, which leading to compact conformation and enhanced interaction among pectin molecules. Although emulsion droplet diameter increased with ethanol content, the most stable emulsion was found in 21% (v/v) ethanol. CLSM also indicated over-aggregated pectin have a poor adsorption capacity on the interface of O/W. All results manifested the emulsifying properties of pectin can be improved by 21% (v/v) ethanol. This study provides a new strategy to improve the emulsifying property of pectin by changing its conformation. [ABSTRACT FROM AUTHOR]

Pectin-rich dietary fibers were prepared from citrus peel through alkaline hydrogen peroxide treatment (AHP-CF) or homogenization treatment (H-CF). Structural and physicochemical properties of the citrus fibers were evaluated and compared with a commercial one (Fiberstar). Results showed that pectin content of citrus fibers (CF) increased from 15.23% to 21.52% and 26.79% after AHP and homogenization treatment. AHP-CF had the highest water-holding capacity (WHC) (21.32 g/g), water-swelling capacity (WSC) (32.70 mL/g) and cation exchange capacity (CEC) (1.02 Meq/g) among the fibers. SEM results showed porous or wrinkled surface of the treated CFs. XRD and TG analysis indicated that AHP treatment increased the crystallinity and thermal stability of CF while homogenization treatment was the opposite. Besides, H-CF had similar chemical component, oil-holding capacity and CEC with Fiberstar but higher WHC, WSC and thermal stability. These results suggested that AHP-CF and H-CF might be suitable to be an additive used in functional food. Image 1 • The content of pectin has important effects on the properties of dietary fiber. • Pectin-rich dietary fiber was obtained through chemical or homogenization treatment. • The obtained pectin-rich fiber has superior hydratability and large surface area. • Well properties might be due to further interaction between pectin and cellulose. [ABSTRACT FROM AUTHOR]