Production of pectic-oligosaccharides from pomelo peel pectin by oxidative degradation with hydrogen peroxide

Innovative Applications of Pectin in Lipid Management: Mechanisms, Modifications, Synergies, Nanocarrier Systems, and Safety Considerations

Pectin, a natural polysaccharide predominantly sourced from the cell walls of terrestrial plants, is widely regarded for its gelling, thickening, and stabilizing properties, which have extensive applications in the food, pharmaceutical, and biotechnological industries. This review discusses the mechanistic pathways by which pectin mediates its lipid-lowering properties, such as pectin's antioxidant activity, the modulation of gut microbiota, its anti-inflammatory properties, its capacity to bind bile acids and cholesterol, and its impact on the expression of genes associated with lipid metabolism. To enhance its hypolipidemic properties, chemical, physical, and enzymatic modification techniques are explored. Additionally, the synergistic effects of pectin in combination with other bioactive compounds such as phytosterols and polyphenols, as well as its potential in nanocarrier-mediated delivery systems for lipid-lowering agents, are highlighted. The review also conducts a critical analysis of the safety and regulatory considerations associated with pectin use, emphasizing the necessity for comprehensive toxicological evaluations and adherence to regulatory standards. This paper underscores the growing potential of pectin not only as a dietary fiber but also as a multifaceted agent for ameliorating hyperlipidemia, catalyzing a shift toward more targeted and efficacious lipid-lowering strategies.

Biochemical characterization of a novel acid-active endopolygalacturonase for pectin depolymerization, pectic-oligomer production, and fruit juice clarification

Endopolygalacturonases are crucial pectinases known for their efficient and sustainable pectin depolymerization activities. The present study identified a novel gene encoding endopolygalacturonase from an acidic mine tailing metagenome. The putative gene showed a maximum identity of 67.55 % with an uncharacterized peptide sequence from Flavobacterium fluvii. The gene was cloned and expressed in a heterologous host, E. coli. Biochemical characterization of the novel endopolygalacturonase enzyme variant (EPHM) showed maximum activity at 60 °C and at 5.0 pH, while retaining 50 % activity under the temperature and pH range of 20 °C to 70 °C for 6 h, and 3.0 to 10.0 for 3 h, respectively. The enzyme exhibited tolerance to different metal ions. EPHM was characterized for the depolymerization of methylated pectin into pectic oligosaccharides. Further, its utility was established for fruit juice clarification, as endorsed by high transmittance, significant viscosity reduction, and release of reducing sugars in the treated fruit juice samples.

Degradation Mechanisms of Six Typical Glucosidic Bonds of Disaccharides Induced by Free Radicals

Increasing hydrogen peroxide (H2O2)-based systems have been developed to degrade various polysaccharides due to the presence of highly reactive free radicals, but published degradation mechanisms are still limited. Therefore, this study aimed to clarify the degradation mechanism of six typical glucosidic bonds from different disaccharides in an ultraviolet (UV)/H2O2 system. The results showed that the H2O2 concentration, disaccharide concentration, and radiation intensity were important factors affecting pseudo-first-order kinetic constants. Hydroxyl radical, superoxide radical, and UV alone contributed 58.37, 18.52, and 19.17% to degradation, respectively. The apparent degradation rates ranked in the order of cellobiose ≈ lactose > trehalose ≈ isomaltose > turanose > sucrose ≈ maltose. The reaction pathways were then deduced after identifying their degradation products. According to quantum chemical calculations, the cleavage of α-glycosidic bonds was more kinetically unfavorable than that of β-glycosidic bonds. Additionally, the order of apparent degradation rates depended on the energy barriers for the formation of disaccharide-based alkoxyl radicals. Moreover, energy barriers for homolytic scissions of glucosidic C1-O or C7-O sites of these alkoxyl radicals ranked in the sequence: α-(1 → 2) ≈ α-(1 → 3) < α-(1 → 4) < β-(1 → 4) < α-(1 → 6) < α-(1 → 1) glucosidic bonds. This study helps to explain the mechanisms of carbohydrate degradation by free radicals.

Innovative biocatalyst synthesis of pectinolytic enzymes by cross-linking strategy: Potentially immobilised pectinases for the production of pectic-oligosaccharides from pectin

Pectinases are outstanding multienzymes, which have the potential to produce new emerging pectic-oligosaccharides (POS) via enzymatic hydrolysis of pectin. However, free pectinase is unable to undergo repeated reaction for the production of POS. This study proposed a sustainable biocatalyst of pectinases known as cross-linked pectinase aggregates (CLPA). Pectinase from Aspergillus aculeatus was successfully precipitated using 2 mg/mL pectinase and 60 % acetone for 20 min at 20 °C, which remained 36.3 % of its initial activity. The prepared CLPA showed the highest activity recovery (85.0 %), under the optimised conditions (0.3 % (v/v) starch and glutaraldehyde mixture (St/Ga), 1.5: 1 of St/Ga, 25 °C, 1.5 h). Furthermore, pectin-degrading enzymes from various sources were used to produce different CLPA. The alteration of pectinase secondary structure gave high stability in acidic condition (pH 4), thermostability, deactivation energy and half-life, and improved storage stability at 4 °C for 30 days. Similarly to their free counterpart, the CLPA exhibited comparable enzymatic reaction kinetics and could be reused eight times with approximately 20 % of its initial activity. The developed CLPA does not only efficaciously produced POS from pectin as their free form, but also exhibited better operational stability and reusability, making it more suitable for POS production.

Dietary pectin attenuates Salmonella typhimurium-induced colitis by modulating the TLR2-NF-κB pathway and intestinal microbiota in mice

The role of dietary pectin on microbial-induced colitis, oxidative status, barrier function, and microbial composition, as well as the underlying mechanisms, is scarce. In this study, we aimed to investigate whether dietary pectin alleviates Salmonella typhimurium-induced colitis in mice. Male C57BL/6J mice fed an isocaloric and isofibrous diet with 7% pectin or cellulose were administered sterile water or Salmonella typhimurium to induce colitis, which is equal to a human food dose of 0.57% (5.68 g/kg). Dietary pectin alleviated Salmonella typhimurium-induced colitis and oxidative stress as shown by the reduced disease activity index score, decreased colon shortening and histological damage score, colonic hydrogen peroxide, malondialdehyde concentrations, and relative mRNA expressions of coenzyme Q-binding protein COQ10 homologue B (Coq10b), Ccl-2, Ccl-3, Ccl-8, Tnf-α, Il-1β, Ifn-γ, Ifn-β, and serum TNF-α protein level. Moreover, pectin administration ameliorated the downregulated colonic abundances of occludin, zonula occludens-1, zonula occludens-2, and the upregulated abundances of TLR2 and p-NF-κB in Salmonella-infected mice. Additionally, 16S rRNA analysis demonstrated that pectin altered the microbial beta-diversity and reduced Salmonella levels. Collectively, pectin ameliorated Salmonella typhimurium-induced colitis, oxidative stress, and tight junction, which may be related to the inactivation of TLR2-NF-κB signalling and reduced abundance of Salmonella.

Pectin from Fruit- and Berry-Juice Production by-Products: Determination of Physicochemical, Antioxidant and Rheological Properties

Plums (Prunus domestica); red currants (Ribes rubrum); black currants (Ribes nigrum); gooseberries (Ribes uva-crispa); sour cherries (Prunus cerasus); pumpkins (Cuccurbita spp.) are sources for valuable fruit- and berry-juice and cider production. This process leaves a large number of by-products (BP) in the form of pomace, which accounts for up to 80% of the raw material. This by-product represents a rich source of biologically active compounds, especially in the form of different pectic polysaccharides. The pectin extracted from commercial fruits such as citric fruits and apples has high medicinal properties, can be used as edible films and coatings, and is also useful in texture improvement and gel production in the food industry. However, many under-utilized fruits have received little attention regarding the extraction and characterization of their high/value pectin from their by-products. Moreover, the commercial extraction process involving strong acids and high temperature to obtain high-purity pectin leads to the loss of many bioactive components, and these lost components are often compensated for by the addition of synthetic antioxidants and colorants. The aim of the research is to extract pectin from juice production by-products with hot-water extraction using weak organic (0.1 N) citric acid, thus minimizing the impact on the environment. The yield of pectin (PY = 4.47-17.8% DM), galacturonic acid content (47.22-83.57 g 100^-1), ash content (1.42-2.88 g 100 g^-1), degree of esterification (DE = 45.16-64.06%), methoxyl content (ME = 4.27-8.13%), the total content of phenolic compounds (TPC = 2.076-4.668 µg mg^-1, GAE) and the antiradical scavenging activity of the pectin samples (DPPH method (0.56-37.29%)) were determined. Free and total phenolic acids were quantified by saponification using high-pressure liquid chromatography (HPLC). The pectin contained phenolic acids-benzoic (0.25-0.92 µg mg^-1), gallic (0.14-0.57 µg mg^-1), coumaric (0.04 µg mg^-1), and caffeic (0.03 µg mg^-1). The pectin extracts from by-products showed glucose and galactose (3.89-21.72 g 100 g^-1) as the main neutral sugar monosaccharides. Pectin analysis was performed using FT-IR, and the rheological properties of the pectin gels were determined. The quality of the obtained pectin from the fruit and berry by-products in terms of their high biological activity and high content of glucuronic acids indicated that the products have the potential to be used as natural ingredients in various food products and in pharmaceutical products.

Development of soy protein isolate/sodium carboxymethyl cellulose synbiotic microgels by double crosslinking with transglutaminase and aluminum chloride for delivery system of Lactobacillus acidophilus

This study was carried out to develop soy protein isolate (SPI)/sodium carboxymethyl cellulose (NaCMC) synbiotic microgels by applying a double-crosslinking technique using transglutaminase and different concentrations of AlCl₃ (0, 6, 7, 8 %) and also by adding Lactobacillus acidophilus (L. acidophilus) and pectic oligosaccharide. Synbiotic microgels crosslinked using 8 % AlCl₃ (SPI/NaCMC-Al³⁺₈ microgels) showed the highest encapsulation efficiency (92 %). The double-crosslinked microgels exhibited a smooth surface as proved by SEM. FT-IR, XRD, and DSC analyses showed the possible interaction within matrices and demonstrated the higher thermal stability of synbiotic microgels prepared using a higher concentration of AlCl₃. All in all, after exposure to simulated digestion fluid, heat treatment (72 °C, 15 s), and refrigerated storage, more cells in double-crosslinked microgels survived compared to single-crosslinked microgels. In particular, probiotic viability was highest in SPI/NaCMC-Al³⁺₈ microgels. These results indicate that the SPI/NaCMC-Al³⁺₈ microgels developed in this study can effectively protect L. acidophilus against the external environment.

Rheological and gelling properties of Nicandra physalodes (Linn.) Gaertn. pectin in acidic media

Nicandra physalodes (Linn.) Gaertn. polysaccharide (NPGP) was previously recognized as a pectic polysaccharide, with a high galacturonic acid content (87.8%) and a low methoxylation degree (28%). In the present study, it was found that NPGP can form self-supporting gels when cooling its heated solutions (2.0%, w/v) acidified by citric acid. It was demonstrated that the decrease in pH led to the suppression in electrostatic repulsions between the pectin chains, thereby promoting pectin chain-chain association mainly through hydrogen bonding. As the pH decreased from 3.2 to 2.4, the gel strength and gel thermal stability were continuously increased. Moreover, it was shown that sucrose addition slightly promoted the gelation and gel thermal stability of NPGP, but the effect of monovalent ions (Na⁺) and divalent ions (Ca²⁺) was not significant. Conclusively, our results indicate that NPGP is a new gelling polysaccharide that shows great potential in formulation of acidic gel foods.

Trends in "green" and novel methods of pectin modification - A review

Modification of hydrocolloids to alter their functional properties using chemical methods is well documented in the literature. There has been a recent trend of adopting eco-friendly and "green" methods for modification. Pectin, being a very important hydrocolloid finds its use in various food applications due to its gelling, emulsifying, and stabilizing properties. The adoption of various "green" methods can alter the properties of pectin and make it more suitable for incorporation in food products. The novel approaches such as microwave and pulsed electric field can also be utilized for solvent-free modification, making it desirable from the perspective of sustainability, as it reduces the consumption of organic chemicals. Pectic oligosaccharides (POSs) produced via novel approaches are being explored for their biological properties and incorporation in various functional foods. The review can help to set the perspective of potential scale-up and adoption by the food industry for modification of pectin.

Preventive Effect of Pectic Oligosaccharides on Acute Colitis Model Mice: Modulating Epithelial Barrier, Gut Microbiota and Treg/Th17 Balance

Pectin as dietary fiber supplements has shown emerging potential in clinical ulcerative colitis (UC) adjuvant therapy. In this study, the preventive and prebiotic effect of enzymatic-degraded pectic oligosaccharides (POS) was...

Enzymatic extraction of pectic oligosaccharides from finger citron (Citrus medica L. var. sarcodactylis Swingle) pomace with antioxidant potential

Finger citron pomace is a cheap and renewable by-product of the citrus processing industry, representing up to 60% of the fruit biomass. In this study, a pectinase-based and ultrasonic-assisted method was firstly used to extract pectic oligosaccharides (POS) from finger citron pomace. Using the orthogonal experiment design (OED), the maximum conversion rate of up to 64.5% from pomace to POS was obtained under the extraction conditions of 0.25 mg mL^-1 pectinase and 50 mg mL^-1 pectin at 45 °C and pH 4.5 for 2 h. The extracted POS was then fractionated and purified to homogeneous oligosaccharides (FCPOS-1) with a molecular weight of 2.15 kDa, and the analyses of monosaccharide composition, FTIR, NMR and ESI-MS indicated that FCPOS-1 consisted of GalA and a small amount of mannose, galactose and arabinose. Multiple antioxidant activity assays in vitro revealed that FCPOS-1 possessed remarkable antioxidant properties, especially scavenging activity against DPPH radicals up to 94.07%. FCPOS-1 has the potential to be an effective natural antioxidant for applications in the food and pharmaceutical industries.