Pectin Structure Research Articles

Cell wall modifications during storage: Changes in the texture behavior of the canned yellow peach

Textural changes in canned yellow peach (CYP) soaked in a concentrated sucrose syrup that led to softening during storage were always accompanied by the depolymerization of the cell wall, as the result of the cell wall-modifying enzymes. In this study, we evaluated the changes in texture, pectin fractions (namely, WEP, CEP and AEP) and pectinase activities (namely, PME and PG) during storage. Results showed that the undoubted decrease in Gal contents of all pectin fractions (∼44.16%, ∼36.98% and ∼ 66.59% declines in WEP, CPE and AEP, respectively) were observed as well as the reduced texture properties. Specially, the hardness, chewiness and resilience of CYP dramatically decreased at the first 40 days-storage. Upon the storage, PG activities were significantly facilitated, while PME activities were markedly inhibited. Together with the results of molar mass and monosaccharide composition, sucrose syrup could promote the conversion and depolymerization in HG region of AEP fraction. Moreover, sugar ratio analysis and 13C NMR spectroscopy also illustrated the changes in pectin structures, contributing to the texture softening of CYP, which was confirmed by the gradual depolymerization and solubilization in HG regions of all the pectin fractions.

Modification of pectin with high-pressure processing treatment of fresh orange peel before pectin extraction: Part I. The effects on pectin extraction and structural properties

The possibility of utilizing endogenous plant pectin methyl-esterase (PME) to modify pectin in source material prior to pectin extraction is proposed and explored in this study. This is based on the reports about activation of endogenous PME in plant-based foods by high-pressure processing (HPP) treatment. Fresh orange (Hamlin) peel from a local commercial juice plant was pretreated with HPP at different combinations of pressures and durations, followed by pectin extraction with a commercial method. The effects of HPP pretreatments on pectin yield and structural properties of the extracted pectins were determined. HPP pretreatment increased the yield of subsequent pectin extraction by 41.10 %. Crude extracts from HPP-treated peels showed higher PME activities than the untreated peel. Pectins extracted from HPP pretreated peel (Hp) had a lower degree of methyl-esterification (DM), accompanied by an increase in degree of blockiness (DB) of non-esterified galacturonic acid (GalA) than the control (pectin extracted from un-treated peel). GalA content and linearity of pectin (LP) were higher, while neutral sugar content and degree of branching (DBr) were lower in Hp. The reduction in weight average molecular weight of Hp was minor, and it was positively correlated with a reduction in neutral sugars, indicating an effect of pectin debranching without degradation of the pectin main chain. The effects of HPP on the pectin main chain, degree, and distribution of methyl-esterification in this study were similar to the reported effects of orange PME on extracted pectin. The identified pectin structural features were validated by Fourier Transform Infrared Spectroscopy analysis and a newly developed lateral flow assay. The study indicates that HPP modification of pectin structure in fresh orange peel before pectin extraction may be an efficient and economical way to generate pectin with desirable structural features and to increase pectin yield.

Mutation of AtPME2, a pH-Dependent Pectin Methylesterase, Affects Cell Wall Structure andHypocotyl Elongation.

Pectin methylesterases (PMEs) modify homogalacturonan's chemistry and play a key role in regulating primary cell wall mechanical properties. Here, we report on Arabidopsis AtPME2, which we found to be highly expressed during lateral root emergence and dark-grown hypocotyl elongation. We showed that dark-grown hypocotyl elongation was reduced in knock-out mutant lines as compared to the control. The latter was related to the decreased total PME activity as well as increased stiffness of the cell wall in the apical part of the hypocotyl. To relate phenotypic analyses to the biochemical specificity of the enzyme, we produced the mature active enzyme using heterologous expression in Pichia pastoris and characterized it through the use of a generic plant PME antiserum. AtPME2 is more active at neutral compared to acidic pH, on pectins with a degree of 55-70% methylesterification. We further showed that the mode of action of AtPME2 can vary according to pH, from high processivity (at pH8) to low processivity (at pH5), and relate these observations to the differences in electrostatic potential of the protein. Our study brings insights into how the pH-dependent regulation by PME activity could affect the pectin structure and associated cell wall mechanical properties.

Modification of pectin with high-pressure processing treatment of fresh orange peel before pectin extraction: Part II. The effects on gelling capacity and emulsifying properties of pectin

The most important functionalities of pectin are gelling and emulsifying properties, which can be tailored by modifying pectin structure through chemical/enzymatic treatments or physical processes. In a companion article (Zhao et al., 2023), the modification of pectin structure with high-pressure processing (HPP) was reported. In this study, the functionalities of the HPP-modified pectins (Hp) were evaluated and compared with commercial low methoxy (LM) and high methoxy (HM) pectins. The calcium sensitivity of Hp was comparable to that of commercial LM pectin, which was remarkably higher than the control pectin extracted from untreated peel and commercial HM pectin. Hp had a dramatically higher gelling capacity for calcium-mediated gelation than the control and commercial HM pectin. The strength and viscoelastic properties of Hp-calcium gels were comparable to that of commercial LM pectin. Meanwhile, most of the Hp also showed a comparable gelling capacity for sugar-acid-mediated gelation to that of the control and commercial HM pectin. Hp also had higher emulsifying stability than the control and commercial pectins. The increased capacity of Hp for calcium-mediated gelation was attributed to the block-wise distribution of non-esterified galacturonic acid (GalA) introduced by the HPP treatment, and the higher emulsifying stability was mainly attributed to the debranching of pectin. The study further confirmed that pectin functionalities were highly correlated with its structural properties. The data reveal the great potential of producing low-cost, high-quality pectins with increased gelling capacity and a broadened scope of applications, by adding a simple HPP pretreatment of fresh source material for pectin extraction.

Interaction between ultrasound-modified pectin and icaritin.

Pectin can improve the bioaccessibility of icaritin as a nanocarrier, and ultrasound can modify the pectin structure. However, the interaction between ultrasound-modified pectin (UMP) and icaritin remains unclearly. In this work, the effects of UMP on the physiochemical properties of icaritin/pectin micelles (IPMs) were investigated. The IPMs prepared with UMP (UMP-IPMs) showed lower encapsulation efficiencies and loading capacities, comparing with native IPMs. UMP-IPMs had smaller particle sizes (325-399nm) than native IPMs (551nm). The Mw, viscosity, G' and G" of pectin were determined. NMR spectra indicated that the repeating unit in pectins remained consistently before and after ultrasound treatment, and 7-OH of icaritin was involved in hydrogen bond formation with pectin. The larger chemical shift movement of 6-H and 7-OH for U3-IPMs than P0-IPMs suggested that stronger hydrogen bond interaction between icaritin and pectin. UMP-IPMs exhibited stronger anti-proliferation activities against HepG2 cells than native IPMs.

Mechanism for gel formation of pectin from mealy and crisp lotus rhizome induced by Na+ and D-glucono-d-lactone

Lotus rhizome residue, a cell wall material produced during the production of lotus rhizome starch, has long been underutilized. This study aims to extract pectin-rich polysaccharides from the cell wall of lotus rhizome and investigate their gelation mechanism in order to improve their industrial applicability. The results indicated that both CP and MP (pectin extracted from crisp and mealy lotus rhizome) exhibited a highly linear low methoxyl pectin structure, with the primary linkage mode being →4)-GalpA-(1→. The pectin chains in MP were found to be more flexible than those in CP. Then the impact of Na+, D-glucono-d-lactone (GDL), urea, sodium dodecyl sulfate (SDS), either individually or in combination, on the rheological characteristics of gels was evaluated. The results indicated that gels induced by GDL exhibited favorable thermoreversible properties, whereas the thermoreversibility of Na+-induced gels is poor. In addition to hydrogen bonding and ionic interactions, hydrophobic interactions also play a significant role in the formation of pectin gels. This study offers theoretical guidance and methodologies to improve the utilization rate of lotus rhizome starch processing by-products, while also provides novel insights into the correlation between LMP structure and gelation mechanism.

Electron beam irradiation pretreatment for efficient extraction of pectin from spaghetti squash peel: Structural, functional, and biological properties

The effects of electron beam irradiation (EBI) pretreatment on the extraction, structure, functional, and biological properties of pectin from spaghetti squash peel were investigated. The spaghetti squash peel powder was pretreated by EBI with different doses (0, 25, 50, 75, 100, 125, and 150 kGy), and then pectin samples were successfully prepared in combination with acid extraction. At low doses (25 and 50 kGy), EBI had little effect on the basic structure of pectin, which was manifested by the high molecular weight, degree of esterification and viscosity of the extracted pectin. Additionally, pectin obtained at middle doses (75 and 100 kGy) exhibited high homogalacturonan (HG) domain and excellent thermal stability, while pectin extracted at high doses (125 and 150 kGy) manifested high rhamnogalacturonan Ⅰ (RG-Ⅰ) content, low molecular weight, and superior antioxidant and probiotic properties in vitro. Reasonable modulation of irradiation doses could obtain the desired pectins with different structures and properties. These findings provides valuable insights regarding the role of EBI pretreatment in the extraction and quality improvement of pectin and further promotes the appropriate application of EBI in the food industry.

New insight into pectic fractions of cell wall: Impact of extraction on pectin structure and in vitro gut fermentation

Pectic polysaccharides modulate gut fermentation ability, which is determined by structural characteristics. In this work, apple pectins were extracted by HCl (HAEP), NaOH (AEP), cellulase (EAEP), and in parallel cell wall pectic fractions were sequentially extracted by water (WEP), chelator (CEP) and NaOH (NEP). The aim is to comprehensively compare the impact of extraction on pectin structure and gut fermentation behavior. Results showed that high content of galacturonic acid (90.65 mol%) and large molecular weight (675 kg/mol) were detected in the HAEP. Molecular morphology of the HAEP presented high linearity, while AEP, EAEP and WEP exhibited compact filamentous structures with highly branched patterns. The AEP was characterized by high yield (33.1 g/100 g d.b.), moderate molecular weight (304 kg/mol) and large extent of rhamnogalacturonan-I region (24.88 %) with low degree of branching (1.77). After in vitro simulated gut fermentation for 24 h, total content of short-chain fatty acid (SCFA) generated with the AEP supplement increased to 36.8 mmol/L, followed by EAEP, HAEP and WEP (25.2, 24.2 and 20.3 mmol/L, respectively). Meanwhile, WEP simultaneously produced the highest ammonia content (22.4 mmol/L). This investigation suggests that the fermentation of AEP produces more beneficial SCFA and less ammonia, thus indicating a better gut fermentation property.

Valorization of walnut green husk (Juglans regia L.) through sequential electrohydrodynamic extraction of pectin and phenolics: Process optimization and multidimensional analysis

This study aimed to optimize the extraction of pectin and phenolics from walnut green husk using the electrohydrodynamic method (EHD) and assess its impact on the chemical structure and properties of pectin. A comparative analysis was conducted with acidified water as the conventional extraction method. The results revealed significant improvements under the optimal EHD conditions (36.8 min, 17.5 kV, 90 °C), leading to a remarkable increase of over 64 % in pectin yield and >20 % in total phenolic content in half the extraction time. Chemical analysis showed that pectin samples contain 1.4–1.7 % ash, 3.6–4.6 % protein, over 90 % carbohydrates, and a galacturonic acid content ranging from 67.7 to 68.2 g/g. Both extraction methods yielded pectin with a high methoxyl degree, comparable thermal stability, and amorphous structure. EHD treatment resulted in reduced molecular weight, degree of esterification, water-holding capacity, and emulsion stability of pectin while enhancing its solubility and emulsion capacity. In summary, EHD treatment significantly improved extraction yield and changed the functionality of pectin, particularly in terms of emulsion activity. This alteration should be considered when utilizing pectin for specific applications.

Insights into the structure and Ion transport of pectin-[BMIM][PF6] electrolytes.

We investigate the effect of pectin on the structure and ion transport properties of the room-temperature ionic liquid electrolyte 1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) using molecular dynamics simulations. We find that pectin induces intriguing structural changes in the electrolyte that disrupt large ionic aggregates and promote the formation of smaller ionic clusters, which is a promising finding for ionic conductivity. Due to pectin in [BMIM][PF6] electrolytes, the diffusion coefficient of cations and anions is observed to decrease by a factor of four for a loading of 25 wt. % of pectin in [BMIM][PF6] electrolyte. A strong correlation between the ionic diffusivities (D) and ion-pair relaxation timescales (τc) is observed such that D ∼ τc-0.75 for cations and D ∼ τc-0.82 for anions. The relaxation timescale exponents indicate that the ion transport mechanisms in pectin-[BMIM][PF6] electrolytes are slightly distinct from those found in neat [BMIM][PF6] electrolytes (D∼τc-1). Since pectin marginally affects ionic diffusivities at the gain of smaller ionic aggregates and viscosity, our results suggest that pectin-ionic liquid electrolytes offer improved properties for battery applications, including ionic conductivity, mechanical stability, and biodegradability.

Effect of enzyme‐assisted acid extraction on citrus high‐methoxyl pectin riched in RG‐I: preparation, structure characterisation and physico‐chemical properties

SummaryThe properties of pectin extracted by enzyme‐assisted nitric acid (EAE‐N) and pectin extracted by enzyme‐assisted oxalic acid (EAE‐O) were analysed and compared with pectin extracted by nitric acid (AE‐N) and pectin extracted by oxalic acid (AE‐O) systematically. The yield of pectin obtained by the enzyme‐assisted acid method (23.73% ~ 25.60%) was significantly higher than that by acid extraction method (19.75% ~ 20.60%). Monosaccharide analyses demonstrated that the enzyme‐assisted acid method was able to attain more branched rhamnogalacturonan I (RG‐I) regions (36.59% ~ 42.06%) than using acid solely (31.01% ~ 34.58%). Fourier transform infrared spectroscopy (FT–IR) and nuclear magnetic resonance (1H NMR) analyses indicated that there was no obvious difference in the characteristic structure of pectin. The atomic force microscopy (AFM) images revealed that EAE‐N and EAE‐O had more short side chains and cross‐link compared with AE‐N and AE‐O. Thermogravimetric analysis (TGA) shows that EAE‐N and EAE‐O have good thermal stability. All pectin samples showed a shear‐thinning fluid flow behaviour and an elastic gel‐like behaviour. The results suggested that enzyme‐assisted acid provided a viable alternative method for the extraction of pectin.

Pectic polysaccharides of black radish taproots: Extraction, structural characterization

The mixtures of starch and pectin were isolated by sequential extraction of the pulp and peel of black radish taproots Raphanus sativus L. with cold, hot and acidified water, solutions of ammonium oxalate, sodium carbonate and sodium hydroxide. The polysaccharide fractions obtained with ammonium oxalate solutions from the pulp and peel of the taproots gave the highest yields. The pectin was the main polysaccharide component. The yield of pectin (calculated on dry matter) from the pulp was 9.5%, from the peel −10.5%. The polysaccharide fractions obtained from pulp with hot water and ammonium oxalate solutions were subjected to sequential enzymatic degradation by amyloglucosidase and polygalacturonase, followed by fractionation on DEAE-cellulose. NMR spectra showed that rhamnogalacturonan-I (RG-I) and galacturonan (HG) regions are in structure of pectin. RG-I has unbranched structure, since there are no signals of 2,4-rhamnose residues in NMR spectra.

Pectin-interactions and the digestive stability of anthocyanins in thermal and non-thermal processed strawberry pulp.

This study investigated the digestive stability of anthocyanins (ACNs) and their interaction with three pectin fractions-water-soluble pectin (WSP), cyclohexanetrans-1,2-diamine tetra-acetic acid-soluble pectin (CSP), and sodium carbonate-soluble pectin (NSP)-in strawberry pulp processed by pasteurization (PS), ultrasound (US), electron beam (EB) irradiation, and high pressure (HP). Compared with the control group, the ACNs content increased to the highest level (312.89mg/mL), but the retention rate of ACNs in the simulated intestine decreased significantly after US treatment. The monosaccharide compositions indicated that the WSP and CSP possessed more homogalacturonan (HG) domains than the NSP, which contains more rhamngalacturonan-I (RG-I) domains. The microstructure of US-treated pectin was damaged and fragmented. Comprehensive analysis showed that the retention rate of ACNs was closely related to the pectin structure, primarily reflected by the degree of linearity and the integrity of structure. These results revealed the structure-activity relationship between ACNs and pectin during pulp processing.

Dual crosslinking of low-methoxyl pectin by calcium and europium for the simultaneous removal of pharmaceuticals and divalent heavy metals

The contamination of water resources by heavy metals and pharmaceuticals is a significant threat to human health and the environment. Pectin is a promising material for removing heavy metals from water. However, its removal efficacy for other types of pollutants is limited. In this study, we developed a novel approach to enhance the remediation capacity of pectin (with a low degree of methylation) by crosslinking it with different agents: calcium, europium, and their combination. We performed scanning electron microscopy, infrared spectroscopy, and X-ray diffraction experiments to understand the molecular structure of pectin after gelation with the three agents. Our results showed that calcium, europium, and their combination all induce the gelation of pectin. However, the reticulated pectin structures exhibited significant structural differences depending on the type of crosslinking agent used, which affected the adsorption capacity. Specifically, calcium cations partially formed a crystalline “egg-box” structure, whereas europium cations produced a more homogeneous network without crystalline regions. The dual-crosslinking system comprising calcium and europium cations resulted in an intermediate network with both crystalline and amorphous regions. Our findings suggest that dual-cross-linked pectin is a highly effective adsorbent for the simultaneous removal of both heavy metals and pharmaceutical products. This novel approach of crosslinking pectin with multiple agents has the potential to significantly enhance its remediation capacity, offering a promising solution for the simultaneous removal of multiple pollutants from water.

Space exposure enhanced pectin-degrading enzymes expression and activity in Aspergillus costaricaensis.

Aspergillus is a well-studied fungal genus that is widely used in the processing of plant biomass in industries. This study investigated the effects of space exposure on the ability of Aspergillus costaricaensis, a filamentous fungus isolated from rotten orange peel, to degrade pectin. These fungal spores were carried into space by the Long March 5B carrier rocket and exposed to cosmic radiation for 79h. After the flight, these spores were resuscitated, and then the growing strains were screened with pectin as the sole carbon source, and the pectinase activity was evaluated. A mutant with increased biomass accumulation ability and pectin-degrading activity compared to the ground control strain was obtained. Comparative transcriptome analysis revealed that several CAZymes genes were significantly upregulated in the mutant, especially those related to pectin degradation. Among the 44 pectinases identified from the annotated genome, 42 were up-regulated. The activities of these pectinases are able to synergistically break down the structure of pectin. In addition, the expression of some genes involved in metabolism, sugar transport, and stress response was altered. These results imply that space exposure might serve as a potential mutagenesis breeding technique, offering the opportunity to acquire biomass-degrading microbial strains with potential for industrial application.

Towards Valorization of Food-Waste-Derived Pectin: Recent Advances on Their Characterization and Application.

Pectin, a natural biopolymer, can be extracted from food waste biomass, adding value to raw materials. Currently, commercial pectin is mostly extracted from citrus peels (85.5%) and apple pomace (14.0%), with a small segment from sugar beet pulp (0.5%). However, driven by high market demand (expected to reach 2.12 billion by 2030), alternative agro-industrial waste is gaining attention as potential pectin sources. This review summarizes the recent advances in characterizing pectin from both conventional and emerging food waste sources. The focus is the chemical properties that affect their applications, such as the degree of esterification, the neutral sugars' composition, the molecular weight, the galacturonic acid content, and technological-functional properties. The review also highlights recent updates in nutraceutical and food applications, considering the potential use of pectin as an encapsulating agent for intestinal targeting, a sustainable biopolymer for food packaging, and a functional and emulsifying agent in low-calorie products. It is clear from the considered literature that further studies are needed concerning the complexity of the pectin structure extracted from emerging food waste raw materials, in order to elucidate their most suitable commercial application.

Preparation and characterization of self-standing biofilms from compatible pectin/starch blends: Effect of pectin structure

Pectin structure-miscibility-functionality relationships in starch films remain unknown. In this study, five citrus pectins (CPs) with 17 to 63 % of degree of methyl esterification (DM) and sugar beet pectin (SBP, rich in acetyl moieties and rhamnogalacturonan-I domains) were investigated for composition and structure and, further, blended with pea starch (3:1 starch-pectin weight ratio) to fabricate self-standing films. The incorporation of pectin resulted in a two- to three-fold increase in tensile strength and Young's modulus (up to 52.2 and 1837 MPa, respectively, using CP with low DM) without compromising elongation at break. Starch-SBP films presented the lowest strength among pectin films. Lower film moisture and water vapor permeability were attained with CP of high DM, or with SBP, whereas surface wettability was explained by counteracting factors affecting film compositional heterogeneity. Films made with high methoxyl CP, or with SBP, showed lower overall H-bonding (FTIR) and starch crystallinity (XRD). A DM above 57 % negatively affected the mixing and interfacial adhesion of pectin with starch, as shown by Attenuated Total Reflection-FTIR imaging. Pectins with the lowest purity, presumably with the greatest content in xyloglucan, as suggested by HPAEC, presented ~20 % higher elongation at break than the other films.

Valorization of pistachio industrial waste: Simultaneous recovery of pectin and phenolics, and their application in low-phenylalanine cookies for phenylketonuria

This study introduces a sustainable approach to simultaneously produce pectin and phenolic compounds from pistachio industrial waste and applies them in the formulation of low-phenylalanine cookies. The co-optimization process was performed using the microwave-assisted technique and a Box-Behnken design, considering four variables and two responses: pectin yield and total phenolic content (TPC). The co-optimized condition (microwave power of 700 W, irradiation time of 210 s, pH level of 1.02, and LSR of 20 mL/g) resulted in a pectin yield of 15.85 % and a TPC of 10.12 %. The pectin obtained under co-optimized condition was evaluated for its physicochemical, structural, and thermal properties and the phenolic extract for its antiradical activity. Characterization of the pectin sample revealed a high degree of esterification (44.21 %) and a galacturonic acid-rich composition (69.55 %). The average molecular weight of the pectin was determined to be 640.236 kDa. FTIR and 1H NMR spectroscopies confirmed the structure of pectin, with an amorphous nature and high thermal stability observed through XRD and DSC analysis. Additionally, the extract exhibited significant antiradical activity comparable to butylated hydroxyanisole and ascorbic acid. The isolated ingredients were used to formulate low-protein, low-phenylalanine cookies for phenylketonuria patients. The addition of 0.5 % pectin and 1 mL/g extract led to increased moisture content (from 9.05 to 12.89 %) and specific volume (from 7.28 to 9.90 mL/g), decreased hardness (from 19.44 to 10.39 N × 102), and improved antioxidant properties (from 5.15 % to 44.60 % inhibition) of the cookies. Importantly, there was no significant increase observed in the phenylalanine content of the samples with pectin and extract addition. Furthermore, sensory evaluation scores demonstrated significantly higher scores for taste, odor, texture, and overall acceptability in cookies enriched with 0.5 % pectin and 1 mL/g extract, with scores of 4.53, 3.93, 4.40, and 4.60, respectively.

Unveiling Plant-Based Pectins: Exploring the Interplay of Direct Effects, Fermentation, and Technological Applications in Clinical Research with a Focus on the Chemical Structure.

Pectin, a plant-derived polysaccharide, possesses immense technological and biological application value. Several variables influence pectin's physicochemical aspects, resulting in different fermentations, interactions with receptors, and other functional properties. Some of those variables are molecular weight, degree of methylation and blockiness, and monosaccharide composition. Cancer cell cytotoxicity, important fermentation-related byproducts, immunomodulation, and technological application were found in cell culture, animal models, and preclinical and clinical assessments. One of the greater extents of recent pectin technological usage involves nanoencapsulation methods for many different compounds, ranging from chemotherapy and immunotherapy to natural extracts from fruits and other sources. Structural modification (modified pectin) is also utilized to enhance the use of dietary fiber. Although pectin is already recognized as a component of significant importance, there is still a need for a comprehensive review that delves into its intricate relationships with biological effects, which depend on the source and structure of pectin. This review covers all levels of clinical research, including cell culture, animal studies, and clinical trials, to understand how the plant source and pectin structures influence the biological effects in humans and some technological applications of pectin regarding human health.

Study on the relationship between primary structure/ spatial conformation and gel properties of pectins from different varieties

The structural characteristics of pectin vary considerably among varieties, which causes differences in gel properties. In this study, the relationships among the primary structure, spatial conformation, and gel properties of pectins extracted from grapefruit, apple, bigarade, mango, watermelon, and sugar beet were investigated. The six pectins were all high methoxyl pectins, each having a different degree of methyl esterification (DE). The sugar beet pectin with the lowest DE (54.7%) and loosest conformation (maximum Dmax, 63 nm) exhibited poor gelation properties. Apple pectin, which had a higher molecular weight (314 kDa), the highest DE (77.8%), and a compact conformation (Dmax, 40 nm) showed superior gelation. The compact conformation of pectins contributed to the formation of hydrophobic forces and hydrogen bonds within close proximity of molecules, resulting in a stable three-dimensional network. These results demonstrate that the primary structure and spatial conformation together affect the gelation properties of pectins, and provide new insight into the relationship between the chemical structure and gelation properties of pectins from different varieties.