Physicochemical properties of modified citrus pectins extracted from orange pomace

The effect of ultrasonic power on the physicochemical properties and antioxidant activities of frosted figs pectin

Ultrasound has been widely used in industry due to its high energy and efficiency. This study optimized the ultrasonic-assisted extraction (UAE) process of frosted figs pectin (FFP) using response surface methodology (RSM), and further investigated the effect of ultrasonic power on the structural characteristics and antioxidant activities of FFPs. The UAE method of FFP through RSM was optimized, and the optimal extraction process conditions, particle size of 100 mesh, pH value of 1.95, liquid-solid ratio of 47:1 (mL/g), extraction temperature of 50 °C and extraction time of 65 min, were obtained. The extraction rate of FFP under this condition was 37.97 ± 2.56 %. Then, the four FFPs modified by ultrasound were obtained by changing the ultrasonic power. Research had found that ultrasonic power had little effect on the monosaccharide composition, Zeta potential, as well as the thermal stability and appearance structure of the four FFPs. However, ultrasonic power had a significant impact on other properties of FFP: as the ultrasonic power increased, the DM% and particle size decreased continuously, while the total carbohydrate content increased. Meanwhile, ultrasonic power also had a significant impact on antioxidant activities of FFPs. From the research results, it could be seen that different ultrasonic power had certain changes in its spatial structure and properties, and the structural changes also affected the biological activity of FFP. The study of the effects of ultrasonic power on the physicochemical properties and biological activity of FFP lays the foundation for the development and application of FFP in food additives and natural drug carriers.

Insights into the impact of modification methods on the structural characteristics and health functions of pectin: A comprehensive review

Pectin is a complex polysaccharide that is widely present in plant cells and has multiple physiological functions. However, most pectin exists in the form of protopectin, which has a large molecular weight and cannot be fully absorbed and utilized in the human gut to exert its effects. The significant differences in the structure of different sources of pectin also limited their application in the food and medical fields. In order to achieve greater development and utilization of pectin functions, this paper reviewed several commonly used methods for pectin modification from physical, chemical, and biological perspectives, and elaborated on the relationship between these modification methods and the structure and functional properties of pectin. At the same time, the functional characteristics of modified pectin and its application in medical health, such as regulating intestinal health, anticancer, anti-inflammatory, and drug transport, were reviewed, so as to provide a theoretical basis for targeted modification of pectin and the development of new modified pectin products.

Influences of Ultrasonic Treatments on the Structure and Antioxidant Properties of Sugar Beet Pectin

The objective of this study was to explore the structural changes and oxidation resistance of ultrasonic degradation products of sugar beet pectin (SBP). The changes in the structures and antioxidant activity between SBP and its degradation products were compared. As the ultrasonic treatment time increased, the content of α-D-1,4-galacturonic acid (GalA) also increased, to 68.28%. In addition, the neutral sugar (NS) content, esterification degree (DE), particle size, intrinsic viscosity and viscosity-average molecular weight (M_V) of the modified SBP decreased. Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) were used to study the degradation of the SBP structure after ultrasonication. After ultrasonic treatment, the DPPH and ABTS free radical scavenging activities of the modified SBP reached 67.84% and 54.67% at the concentration of 4 mg/mL, respectively, and the thermal stability of modified SBP was also improved. All of the results indicate that the ultrasonic technology is an environmentally friendly, simple, and effective strategy to improve the antioxidant capacity of SBP.

Integration of enzymatic modification and ultrafiltration for the production of pectin fractions with highly potent antioxidant capacity as green valorization of sugar beet pulp

Enzymatic hydrolysis of pectin followed by ultrafiltration of hydrolysate was applied with the aim to produce fractions with potent antioxidant capacity. Pectin was isolated from waste sugar beet pulp by acidic extraction, washed by diafiltration and concentrated by ultrafiltration. Enzymatic hydrolysis was performed with endo-polygalacturonase, and hydrolysate was processed by ultrafiltration into four fractions using membranes in series of decreasing cut-offs from 10 to 1 kDa. Hydrolysis with endo-polygalacturonase increased total antioxidant capacity by twofold in comparison to un-hydrolyzed pectin. Antioxidant capacity of all fractions was considerably higher than that of pectin-from 14.7 to 25-fold, for fraction containing fragments 10 kDa > Mw > 5 kDa and Mw < 1 kDa, respectively. Considerable increase of total antioxidant capacity of pectin through the integration of enzymatic modification and ultrafiltration fractionation indicated great potential of applied green protocol for the production of high-value hydrolysates of pectin from waste sugar beet pulp.

Novel Pectic Polysaccharides Isolated from Immature Honey Pomelo Fruit with High Immunomodulatory Activity

A novel pectic polysaccharide (HPP-1) with high immunomodulatory activity was extracted and isolated from the immature honey pomelo fruit (Citrus grandis). Characterization of its chemical structure indicated that HPP-1 had a molecular weight of 59,024 D. In addition, HPP-1 was primarily composed of rhamnose, arabinose, fucose, mannose, and galactose at a molar ratio of 1.00:11.12:2.26:0.56:6.40. Fourier-transform infrared spectroscopy, periodic acid oxidation, and Smith degradation results showed that HPP-1 had α- and β-glycosidic linkages and 1 → 2, 1 → 4, 1 → 6, and 1 → 3 glycosidic bonds. ¹³C NMR and ¹H NMR analyses revealed that the main glycogroups included 1,4-D-GalA, 1,6-β-D-Gal, 1,6-β-D-Man, 1,3-α-L-Ara, and 1,2-α-L-Rha. Immunomodulatory bioactivity analysis using a macrophage RAW264.7 model in vitro revealed that NO, TNF-α, and IL-6 secretions were all considerably increased by HPP-1. Moreover, RT-PCR results showed that HPP-1-induced iNOS, TNF-α, and IL-6 expression was significantly increased in macrophages. HPP-1-mediated activation in macrophages was due to the stimulation of the NF-κB and MAPK signaling pathways based on western blot analyses. HPP-1 extracted from immature honey pomelo fruit has potential applications as an immunomodulatory supplement.

High-Intensity Ultrasound-Assisted Extraction of Pectin from Mango Wastes at Different Maturity

Valorisation of food processing by-products is a welcome and developing area. The mango processing industry produces 40% to 60% of the fruit as solid waste, in which components of industrial interest, such as pectin, are lost. This study reports on energy-efficient high-intensity ultrasound-assisted extraction (HIUAE) to extract pectin from mango peels. The analysis considered the ripening stage of the fruit (0, 2, and 4), HIUAE frequency (37 kHz and 80 kHz), and extraction time (20 min, 25 min, and 30 min). Extractions of pectin from mango peels with HIUAE have been fairly studied. However, this work differs from those studies in including mango maturity grade as a factor. Pectin extraction yields ranged from 13% to 30%, with no influence (p > 0.05) of time, and the highest yields were obtained at the lowest maturity stage (0) and lowest frequency (37 kHz). This latest condition (37 kHz) also yielded pectin with the highest gel strength, purity, and quality. This work demonstrated that the mango maturity stage influenced pectin extraction yield. Ultrasound-assisted extraction of pectin from mango peels could be an efficient approach toward waste valorisation and extraction of pectin with high yield and good quality attributes for the food industry.

The Use of Interactions Between Microorganisms in Strawberry Cultivation (Fragaria x ananassa Duch.)

As the market indicates a growing interest in organically grown fruit, there is a need for biostimulants to counter the adverse effects of pathogenic fungi and fungal-like-pathogens. Four microbial pathogens (Botrytis cinerea, Verticillium sp., Phytophthora sp., and Colletotrichum sp.) which are the most often causes of strawberry diseases were selected. Five kinds of biostimulants (C1, C2, C3, C4, and C5) containing bacterial consortia were developed to combat the pathogens. The antagonistic effect of selected microorganisms against strawberry pathogens was observed. The effectiveness of various beneficial bacteria in combating fungal pathogens of cv. Honeoye strawberries was compared and the impact of their activity on fruit quality was assessed. The most significant effect on the strawberry firmness was found for the C2 consortium, which provided the strawberries infected with the pathogens group (MIX: B. cinerea, Verticillium sp., Phytophthora sp., and Colletotrichum sp.) with a 140% increase in maximum load in a puncture test compared to the positive control (C0). Strawberries contaminated with Phytophthora sp. after the application of Consortium C4 (C4) showed the largest increase (127%) in soluble solid content (SSC) when compared to the C0. Fruit contaminated with Colletotrichum sp. and B. cinerea after the application of C2 and Consortium 5 (C5), respectively, had the highest levels of anthocyanins and total phenolic content, when compared to C0. The largest increase, which reached as high as 25%, in D-galacturonic acid content was observed for the group of pathogens after Consortium 1 (C1) application. The extraction of strawberry pectin allowed for the study of the rheological properties of pectin solutions; on this basis, strawberry pectin from the control (NC) was distinguished as it showed the highest viscosity (0.137-0.415 Pas). Taking into account the individual effects of bacteria on strawberry pathogenic fungi and fungal-like-pathogens, it is possible to reduce the adverse effects of fungal disease and to improve the properties of strawberries by selecting the appropriate bacterial consortium. Interactions between microorganisms are often complex and not fully understood, which suggests the need for further research in this direction.

Delineating the inherent functional descriptors and biofunctionalities of pectic polysaccharides

Pectin is a plant-based heteropolysaccharide macromolecule predominantly found in the cell wall of plants. Pectin is commercially extracted from apple pomace, citrus peels and sugar beet pulp and is widely used in the food industry as a stabilizer, emulsifier, encapsulant, and gelling agent. This review highlights various parameters considered important for describing the inherent properties and biofunctionalities of pectins in food systems. These inherent descriptors include monosaccharide composition, galacturonic acid content, degree of esterification, molecular weight, structural morphology, functional group analysis, and functional properties, such as water and oil holding capacity, emulsification, foaming capacity, foam stability, and viscosity. In this study, we also delineate their potential as a nutraceutical, prebiotic, and carrier for bioactive compounds. The biofunctionalities of pectin as an anticancer, antioxidant, lipid-lowering, and antidiabetic agent are also conceptually elaborated in the current review. The multidimensional characteristics of pectin make it a potential candidate for use in food and biomedical science.

Mucoadhesive Formulation Designs for Oral Controlled Drug Release at the Colon

Mucoadhesive formulations have been demonstrated to result in efficient drug delivery systems with advantages over existing systems such as increased local retention and sustained drug release via adhesiveness to mucosal tissues. The controlled release of colon-targeted, orally administered drugs has recently attracted a number of studies investigating mucoadhesive systems. Consequently, substantial designs, from mucoadhesive cores to shells of particles, have been studied with promising applications. This review will provide an overview of specific strategies for developing mucoadhesive systems for colon-targeted oral delivery with controlled drug release, including mucoadhesive matrices, cross-linked mucoadhesive microparticles, coatings and mucoadhesive nanoparticles. The understanding of the basic principle of these designs and advanced formulations throughout will lead to the development of products with efficient drug delivery at the colon for therapies for different diseases.

A galactose-rich heteropolysaccharide extracted from "jaboticaba" (Plinia cauliflora) peels

The objective of this work was to extract, identify and characterize a galactose-rich heteropolysaccharide (GH) from "jaboticaba" peel. The best conditions to extract the GH according to a 2³ full-factorial experimental design were 90 °C/30 min/pH 1.0, resulting in a 32.32 % yield using lyophilized sample. The chemical structure analyzed by GC/MS and NMR spectra (HSQC/HSQC-TOCSY) showed that the main chain of GH consists of a (1→4) galactoside branched at carbon 3, containing galactose (67.21 %), glucose (15.78 %), arabinose (9.78 %), rhamnose (2.26 %) and traces of esterified and non-esterified uronic acids. Rheological studies revealed that GH suspensions behave as a Newtonian fluid, with calculated molecular mass of 1.48 × 10⁵ Da. The absolute viscosity of 1 % (w/v) aqueous suspension of GH decreased from 25 mPa s to 10 mPa s in NaCl and 7 mPa s in CaCl₂, indicating the polyelectrolyte character of GH.

A New Water-Soluble Bactericidal Agent for the Treatment of Infections Caused by Gram-Positive and Gram-Negative Bacterial Strains

Grapefruit and lemon pectin obtained from the respective waste citrus peels via hydrodynamic cavitation in water only are powerful, broad-scope antimicrobials against Gram-negative and -positive bacteria. Dubbed IntegroPectin, these pectic polymers functionalized with citrus flavonoids and terpenes show superior antimicrobial activity when compared to commercial citrus pectin. Similar to commercial pectin, lemon IntegroPectin determined ca. 3-log reduction in Staphylococcus aureus cells, while an enhanced activity of commercial citrus pectin was detected in the case of Pseudomonas aeruginosa cells with a minimal bactericidal concentration (MBC) of 15 mg mL⁻¹. Although grapefruit and lemon IntegroPectin share equal MBC in the case of P. aeruginosa cells, grapefruit IntegroPectin shows boosted activity upon exposure of S. aureus cells with a 40 mg mL⁻¹ biopolymer concentration affording complete killing of the bacterial cells. Insights into the mechanism of action of these biocompatible antimicrobials and their effect on bacterial cells, at the morphological level, were obtained indirectly through Fourier Transform Infrared spectroscopy and directly through scanning electron microscopy. In the era of antimicrobial resistance, these results are of great societal and sanitary relevance since citrus IntegroPectin biomaterials are also devoid of cytotoxic activity, as already shown for lemon IntegroPectin, opening the route to the development of new medical treatments of polymicrobial infections unlikely to develop drug resistance.

Antioxidant and antimicrobial applications of biopolymers: A review

Biopolymers have generated mounting interest among researchers and industrialists over the recent past. Rising consciousness on the use of eco-friendly materials as green alternatives for fossil-based biopolymers has shifted the research focus towards biopolymers. Advances in technologies have opened up new windows of opportunities to explore the potential of biopolymers. In this context, this review presents a critique on applications of biopolymers in relation to antioxidant and antimicrobial activities. Some biopolymers are reported to contain inherent antioxidant and antimicrobial properties, whereas, some biopolymers, which do not possess such inherent properties, are used as carriers for other biopolymers or additives having these properties. Modifications are often performed in order to improve the properties of biopolymers to suit them for different applications. This review aims at presenting an overview on recent advances in the use of biopolymers with special reference to their antioxidant and antimicrobial applications in various fields.

Screening of pectinase-producing bacteria from farmlands and optimization of enzyme production from selected strain by RSM

Pectinolytic enzymes that catalyze the breakdown of substrates containing pectin are widespread. Pectinases have potential applications in various industries, including food, animal feed, textile, paper, and fuel. In this study, one hundred bacterial isolates were collected from Marand city farmlands (Azarbaijan-E-Sharqi, Iran) and screened by MP medium on the base of pectinase activity considering the significance of pectinases. The results depicted that three isolates showed the most pectinase activity (more massive halo). The biochemical and molecular test results showed that the three screened bacteria were Enterobacter and named Enterobacter sp. MF41, Enterobacter sp. MF84, and Enterobacter sp. MF90. Enterobacter sp. MF84 had the largest halo, so this strain was selected for the study of its produced pectinase. The results exhibited that the produced enzyme has optimum temperature and pH for activity at 30 °C and in 9, respectively. Finally, the enzyme production by Enterobacter sp. MF84 is optimized using response surface methodology (RSM) considering four factors (NH₄Cl, K₂HPO₄, pectin, and incubation time) as variables. The results showed that the optimization procedure increased the enzyme production up to 12 times (from 1.16 to 14.16 U/mg). The Pareto analysis revealed that ammonium chloride has a significant role in decreasing the enzyme production, probably by inducing the nitrification pathway enzymes in the presence of organic nitrogen in Enterobacter sp. MF84.

Pectin Hydrolysates from Different Cultivars of Pink/Red and White Grapefruits (Citrus Paradisi [macf.]) as Culture and Encapsulating Media for Lactobacillus Plantarum

Citrus pectin hydrolysates (Citrus paradisi [Mafc.]) from "Foster," "Red Shambar," "Tangelo Orlando," and "Citrumelo Swingle" cultivars were obtained by partial chemical hydrolysis and their properties as culture media (sole carbon/nutrient source) and encapsulating agents of Lactobacillus plantarum CIDCA 83114 were evaluated. The concentration of neutral sugars was maximal after 2-hour hydrolysis. All hydrolysates were rich in glucose >xylose >galactose >galacturonic acid >mannose >arabinose. "Citrumelo Swingle" cultivar was the one with the highest concentration of xylose. After 24 hr of fermentation with L. plantarum CIDCA 83114, bacterial viability increased from 6.76 ± 0.14 to almost 9 log CFU/mL, and lactic acid concentration, from 2.63 ± 0.41 to 7.82 ± 0.15 mmol/L in all hydrolysates. Afterwards, bacteria were entrapped in pectate-calcium beads by ionotropic gelation. Bacterial viability did not significantly decrease after freeze-drying and storage the beads at 4 °C for 45 days. PRACTICAL APPLICATION: Pectin hydrolysates were adequate culture media for microorganisms, as determined by the viabililty and lactic acid production. Considering that citrus peels are agro-wastes obtained in large quantities, their use as encapsulating materials provides a solution to overcome the environmental problem they entail.

A facile water-induced complexation of lycopene and pectin from pink guava byproduct: Extraction, characterization and kinetic studies

The redfleshed pulp discarded from pink guava puree industry is a rich source of lycopene and pectin. In this study, we developed a facile extraction process employing water as the primary extraction medium to isolate the lycopene and pectin from pink guava decanter. When the decanter was suspended in water, the complexation of lycopene and pectin formed the cloudy solution, where the colloidal complexes were recovered through centrifugation. The presence of lycopene and pectin in the complex was confirmed by the spectroscopic, microscopic and chromatographic analyses. The lycopene fractionated from the complexes had a purity level of 99% and was in all-trans configuration. The colloidal complexes yielding the highest concentration of lycopene was obtained at pH 7, 1% (w/v) solid loading and 25 °C. The experimental data of time-course extraction of lycopene-pectin complex were best fitted with two-site kinetic model, hinting the fast- and slow-release phases in the extraction process.

Optimization of the integral valorization process for orange peel waste using a design of experiments approach: Production of high-quality pectin and activated carbon

The aim of this study was to optimize the integral valorization of orange peel waste by obtaining activated carbon after a process of pectin recovery in recycling of orange peel by transformation to value-added products of pectin extraction and activated carbon preparation. The study was supported by statistical analysis, and the significant factors and optimal conditions were obtained from the statistical analysis. Using a representative sample of orange peel waste, a yield of 29.37% pectin was recovered at the optimal operating conditions (phosphoric acid as the extraction agent, 95 °C as the impregnation temperature and a 2-hour extraction time). Activated carbon (AC) was prepared from the remaining solid residue. The conditions that improve the resulting material quality were H₃PO₄ [0.6 M] used as the activating agent, an impregnation temperature of 95 °C, a carbonization temperature of 400 °C and 1 h of carbonization time. The obtained AC showed a sorption capacity of 2342.91 mg g^-1, a value higher than that reported for commercial activated carbon. Using a model dye chemical, the sorption kinetics and thermodynamics of AC were found to follow a pseudo-second-order rate and the Freundlich models, respectively. Using the process conditions obtained in this study, it was possible to optimize the yield and also obtain good-quality products from valorization of orange peel.

Characterization of Pectins Extracted from Different Varieties of Pink/Red and White Grapefruits [Citrus Paradisi (Macf.)] by Thermal Treatment and Thermosonication

The physical and chemical properties of pectin extracts obtained from different white and pink/red varieties of grapefruit [Citrus paradisi (Macf.)], using both conventional heating (CHE) and thermosonication (TS), were investigated. The content of galacturonic acid (GalA), degree of esterification (%DM), color and antioxidant capacity were analyzed. Fourier-Transform Infrared Spectroscopy (FTIR) associated with multivariate analysis enabled a structural comparison among the pectin extracts, and differential scanning calorimetry (DSC) completed a full landscape of the investigated extracts. Pectin extracts obtained by CHE showed mostly higher GalA than those obtained by TS. All the extracts had a high antioxidant capacity, as determined by 2,2 diphenyl 1-picrylhydrazyl (DPPH^* ) and 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS^* +) assays, and a high correlation with the GalA content. The main differences observed in the FTIR spectra occurred in the 1200 to 900 cm^-1 region (differences in GalA). The glass transition temperatures (Tgs) of all extracts were above 85 °C, making them interesting as stabilizing agents for the food industry.

PRACTICAL APPLICATION

A wide database for the characterization of pectin extracts from grapefruits was obtained. The relationship between the extraction method and the source of pectins, with the physicochemical and antioxidant properties provided great support for their application in the food industry.

Studies of chitosan/pectin complexes exposed to UV radiation

Chitosan and pectin form complexes owing to electrostatic interactions between positively charged amino groups in chitosan and negatively charged carboxylate groups in pectin, which was confirmed by ATR-FTIR spectroscopy and contact angle measurements. Moreover, the formation of these complexes might be associated with the loss of the biopolymers ordering, which resulted in higher surface roughness and lower thermal stability of the complexes in comparison to those of homopolymers. UV rays, used as a sterilizing agent, caused a moderate increase in the surface polarity of the complexes. Roughness parameters of these samples changed irregularly after irradiation, and their thermal stability was slightly affected by UV rays. The results indicated that the complexes studied appeared to present resistance to UV action higher than homopolymers, which is a desirable property in medical or pharmaceutical applications.

The Antioxidant Properties of Pectin Fractions Isolated from Vegetables Using a Simulated Gastric Fluid

The antioxidant properties of vegetable pectin fractions against intraluminal reactive oxygen species were elucidated in vitro in conjunction with their structural features. The pectin fractions were isolated using a simulated gastric fluid (pH 1.5, pepsin 0.5 g/L, 37°C, 4 h) from fresh white cabbage, carrot, onion, and sweet pepper. The fraction from onion was found to inhibit the production of superoxide radicals by inhibiting the xanthine oxidase. The high molecular weight of onion pectin and a large number of galactose residues in its side chains appeared to participate in interaction with xanthine oxidase. All the isolated pectic polysaccharides were found to be associated with protein (2–9%) and phenolics (0.5–0.7%) as contaminants; these contaminants were shown to be responsible for the antioxidant effect of vegetable pectin fractions against the hydroxyl and 1,1-diphenyl-2-picrylhydrazyl radicals.

Pectin as a rheology modifier: Origin, structure, commercial production and rheology

Pectins are a diverse family of biopolymers with an anionic polysaccharide backbone of α-1,4-linked d-galacturonic acids in common. They have been widely used as emulsifiers, gelling agents, glazing agents, stabilizers, and/or thickeners in food, pharmaceutical, personal care and polymer products. Commercial pectin is classified as high methoxy pectin (HMP) with a degree of methylation (DM) >50% and low methoxy pectin (LMP) with a DM <50%. Amidated low methoxy pectins (ALMP) can be obtained through aminolysis of HMP. Gelation of HMP occurs by cross-linking through hydrogen bonds and hydrophobic forces between the methyl groups, assisted by a high co-solute concentration and low pH. In contrast, gelation of LMP occurs by the formation of ionic linkages via calcium bridges between two carboxyl groups from two different chains in close proximity, known as the 'egg-box' model. Pectin gels exhibit Newtonian behaviour at low shear rates and shear-thinning behaviour when the shear rate is increased. An overview of pectin from its origin to its physicochemical properties is presented in this review.