Microscopic evidence for Ca(2+) mediated pectin-pectin interactions in carrot-based suspensions

Unveiling the structural properties of three pectin fractions variation affecting pulp browning during peach processing

Peach ripening accompanying by processing browning exacerbated has not been clarified in perspective of pectin fractions structural variation. This study investigated pectin fractions of water-soluble (WSP), trans-cyclohexane-1,2-diaminetetraacetic acid-soluble (CSP) and sodium carbonate-soluble (NSP) pectin in peach with different ripening times (24, 48, 72 h) and pretreatments (cold shock, CaCl2, the combination) effect on pulp browning in processing. Results showed that extended ripening time increases browning index and rate, along with increased reactive oxygen species levels, polyphenol oxidase and pectinase activities, and the structural of the pectin fractions. Thereinto, weight-average (Mw) and number-average (Mn) molecular weight of WSP increased, its linearity and branching degree decreased, while CSP and NSP showed decreases in Mw, Mn, and branching degree, but increases in linearity, rhamnogalacturonan structure proportion, and bending degree. Browning was correlated positively with Mn, Mw, rhamnogalacturonan proportion of WSP and CSP, linearity and bending degree of NSP, while negatively correlated with Mw of CSP and NSP and esterification degree and branching of all fractions. Thus, maintaining pectin polydispersity and rhamnogalacturonan branching helps protect the system from being quickly browning by compartmentalization effect of hindering the polyphenol substrates and enzymes possibly effective. This study offers insights into controlling browning through pectin fractions modulation.

Water-soluble biopolymers from heat-treated and high pressure homogenized vegetable purées: investigating their emulsion forming and stabilizing capacities

The emulsion forming and stabilizing capacities of water-soluble biopolymers originating from the aqueous (serum) phase of heat-treated and high pressure homogenized purées were investigated. The serum biopolymers were characterized and then utilized as emulsifier/stabilizer in simple oil-in-water emulsions. The resulting emulsions were stored at 4 °C and monitored for 2 weeks. Results revealed that carrot and tomato sera contained higher amounts of pectin and lower protein compared to broccoli. The serum pectic biopolymers exhibited distinct molecular structures, depending on the vegetable origin. Given these natural biopolymer composition and characteristics, emulsions with small droplet sizes were observed at pH 3.5. However, emulsions at pH 6.0 showed large mean droplet sizes, except for the emulsion formulated with carrot serum. Regardless of the pH, emulsions containing carrot serum biopolymers exhibited high capacity to form fine emulsions that were stable during the 2-week storage period at low temperature. This study clearly shows the capacity of natural water-soluble biopolymers isolated from the serum phase of vegetable purées to form fine emulsion droplets and maintain its stability during storage, especially in the case of carrot serum biopolymers.

VvPL15 Is the Core Member of the Pectate Lyase Gene Family Involved in Grape Berries Ripening and Softening

The process of ripening and softening in grape begins at veraison and is closely related to the depolymerization of pectin components. A variety of enzymes are involved in pectin metabolism and one class of enzyme, pectin lyases (PLs), have been reported to play an important role in softening in many fruits; however, little information is available on the VvPL gene family in grape. In this study, 16 VvPL genes were identified in the grape genome using bioinformatics methods. Among them, VvPL5, VvPL9, and VvPL15 had the highest expression levels during grape ripening, which suggests that these genes are involved in grape ripening and softening. Furthermore, overexpression of VvPL15 affects the contents of water-soluble pectin (WSP) and acid-soluble pectin (ASP) in the leaves of Arabidopsis and significantly changes the growth of Arabidopsis plants. The relationship between VvPL15 and pectin content was further determined by antisense expression of VvPL15. In addition, we also studied the effect of VvPL15 on fruit in transgenic tomato plants, which showed that VvPL15 accelerated fruit ripening and softening. Our results indicate that VvPL15 plays an important role in grape berry softening during ripening by depolymerizing pectin.

Acetic Acid Immersion Alleviates the Softening of Cooked Sagittaria sagittifolia L. Slices by Affecting Cell Wall Polysaccharides

This study investigated the mechanism for acetic acid pretreatment to improve cell wall integrity and thereby enhance the hardness of cooked Sagittaria sagittifolia L. slices by affecting polysaccharides in the cell wall. Distilled water immersion and 0.6% acetic acid immersion (the solid/liquid ratio is 1:10) for 15 h at room temperature could result in the conversion of pectin through different reactions during thermal processing. Combined in situ and in vitro analysis demonstrated that acetic acid pretreatment could promote the interaction of cellulose microfiber or hemicellulose with RG-Ⅰ side chains during thermal processing of S. sagittifolia L. slices, promote the entanglement between linear pectin molecules and make hemicellulose show a lower molecular weight under cooking, making it easy to firmly bind to pectin, which resulted in texture changes. The findings may help improve the texture of thermally processed vegetables and fruits and deep processing of starchy vegetables.

Hawthorn Juice Simulation System for Pectin and Polyphenol Adsorption Behavior: Kinetic Modeling Properties and Identification of the Interaction Mechanism

The interaction between polyphenols and polysaccharides plays an important role in increasing the turbidity stability of fruit juice and improving unpleasant sensory experiences. The binding adsorption behavior between hawthorn pectin (HP) and polyphenols (epicatechin and chlorogenic acid) accorded with the monolayer adsorption behavior driven by chemical action and were better fitted by pseudo-second order dynamic equation and Langmuir model. The HP binding sites (Qm) and adsorption capacity (Qe) to epicatechin were estimated at 75.188 and 293.627 μg/mg HP, respectively, which was about nine and twelve times higher than that of chlorogenic acid. The interaction between HP and polyphenols exhibited higher turbidity characteristics, particle size and lower zeta potential than epicatechin and chlorogenic acid alone. Meanwhile, according to Fourier Transform Infrared Spectroscopy (FT-IR) analysis, it could be speculated that the interaction between HP and polyphenols resulted in chemical combination. Moreover, ΔH < 0 and TΔS < 0, which indicated that the interaction between HP and polyphenols was mainly driven by hydrogen bonds and van der Waals forces.

Modified Rhamnogalacturonan-Rich Apple Pectin-Derived Structures: The Relation between Their Structural Characteristics and Emulsifying and Emulsion-Stabilizing Properties

In the context of the increasing interest in natural food ingredients, the emulsifying and emulsion-stabilizing properties of three rhamnogalacturonan-rich apple pectin-derived samples were assessed by evaluating a range of physicochemical properties. An apple pectin (AP74) was structurally modified by a β-eliminative reaction to obtain a RG-I-rich pectin sample (AP-RG). Subsequent acid hydrolysis of AP-RG led to the generation of pectin material with partially removed side chains (in particular arabinose depleted) (AP-RG-hydrolyzed), thus exhibiting differences in rhamnose, arabinose, and galactose in comparison to AP-RG. All samples exhibited surface activity to some extent, especially under acidic conditions (pH 2.5). Furthermore, the viscosity of the samples was assessed in relation to their emulsion-stabilizing properties. In a stability study, it was observed that the non-degraded AP74 sample at pH 2.5 exhibited the best performance among all the apple pectin-derived samples evaluated. This emulsion presented relatively small oil droplets upon emulsion production and was less prone to creaming than the emulsions stabilized by the (lower molecular weight) RG-I-rich materials. The AP-RG and AP-RG-hydrolyzed samples presented a slightly better emulsion stability at pH 6.0 than at pH 2.5. Yet, neither pectin sample was considered having good emulsifying and emulsion-stabilizing properties, indicated by the presence of coalesced and flocculated oil droplets.

Multi-scale pectin/polyphenol beads for non-fouling fluorescence tracking on soft matter under water

The smart polyphenol material could be designed to form two competitive interactions related to same one polyphenol molecule with different objects that could easily adhere to one surface through the weak interaction, and also could be entirely removed from the same surface by the strong interaction. In this study, the multi-scale pectin beads were fabricated by crosslinking with ions that could be acted as polyphenol loading agent through electrostatic force between the ions loading on the surface of pectin beads and polyphenol. The two effects on the size and appearance of pectin beads were detected. Because of the hydrogen bond between polyphenols loading on the beads and the surface of target, fluorescence-functionalized beads could easily adhere on target surfaces. Meanwhile, attributing to stronger electrostatic force between surface ions on beads and polyphenol, the thin membrane made of the beads can be entirely removed from the target surface to avoid the pollution of fluorescence probes.

Physico-Chemical Changes of Composite Whey Protein Hydrogels in Simulated Gastric Fluid Conditions

Polysaccharide blended whey protein isolate (WPI) hydrogels were developed for the delivery of black carrot ( Daucus carota) concentrate as bioactive agent in simulated gastric fluid (SGF). Pectin (PC), gum tragacanth (GT), and xanthan gum (XG) were blended as additional polymers to modulate the release characteristics of the WPI hydrogels. Experiments showed that sole whey protein (C), XG, and GT blended hydrogels possessed restricted release profiles 67%, 61%, and 67%, respectively, whereas PC samples attained higher release rates (83%) ( p < 0.05). Interactions between polymers and aqueous medium were analyzed by nuclear magnetic resonance relaxometry. C (82 ms) and GT (84 ms) hydrogels attained higher T₂ values than PC (74 ms) and XG (73 ms) samples in SGF. Hardness of only XG hydrogels increased from 1.9 to 4.1 N after gastric treatment. Physicochemical changes within hydrogels during release were also investigated, and hydrogels were proved to be appropriate for desired delivery purposes.

Comparison of selected clean and green extraction technologies for biomolecules from apple pomace

Apple pomace has been considered as a sustainable source for antioxidant phenolic compounds. Previous reports show extraction of total phenolic contents (TPC) by following various conventional and non-conventional techniques; however, a comparative study has not been reported. In the present work, conventional extraction was compared with several non-conventional extraction methods including ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), high-speed homogenization (HH). Moreover, efficacy of combined treatments, including high-speed homogenization coupled with MAE and ultrasound-assisted enzymatic extraction (UAEE) was evaluated for the recovery of TPC. The results revealed that UAEE results in the highest TPC (4.62 mg GAE/g), moreover, it simultaneously enabled the recovery of low methoxy pectins with the degree of methylation ranging from 14.03- 28.85%. The LC-Q-Tof analysis revealed the presence of various phenolic acids and flavonoids. The DPPH radical scavenging assay showed that the phenolic rich extracts had IC50 values ranging from 27.1 to 54.6, depending on the extraction parameters. This article is protected by copyright. All rights reserved.