Extraction temperature is a decisive factor for the properties of pectin

Investigation of noncovalent interaction between chelate-soluble pectin from muskmelon and selected volatile during thermal processing using multiple spectroscopy and molecular dynamics

The effect of thermal processing on the binding between methional and chelated-soluble pectin obtained from muskmelon was investigated. Particle size measurements demonstrated that the formed complex between methional and chelated-soluble pectin exhibited small sizes after thermal processing. Pyrene fluorescence analysis showed that the interaction between methional and pectin occurred in the hydrophilic region. Fourier transform infrared and nuclear magnetic resonance analysis revealed that the interaction between chelated-soluble pectin and methional was driven by hydrogen bonding, which was mainly present between carboxyl groups of pectin and the aldehyde groups of methional using the molecular dynamics simulation. Thermal processing can increase the binding rate of methional to pectin to 16 %, affecting its release. This work provided new insight into controlling the volatile release from thermally processed food during thermal processing.

Glycan degradation in Polygonati Rhizoma: Effects of traditional 'nine steaming and nine basking' on low molecular weight Fructans and polysaccharides

The traditional "nine steaming and nine basking" method for processing Polygonati Rhizoma has been practiced in China for over two millennia. However, research on its impact on glycans, particularly low molecular weight fructans, is limited. Therefore, dynamic changes in glycans were analyzed based on the two common species, Polygonatum filipes and Polygonatum cyrtonema. Results revealed the significant degradation of low molecular weight fructans within the first three processing cycles, with complete degradation by the seventh cycle, suggesting that the traditional technique may be excessive. Molecular weight analysis indicated the aggregation, degradation, and reaggregation of polysaccharides, with a notable decrease in fructose and an increase in galactose. This suggested that fructans were the primary constituents before processing, while galactans prevailed afterward. No significant differences in carbohydrate changes were found between the two species. This study enhances our understanding of the traditional processing mechanisms and promotes the efficient utilization of Polygonati Rhizoma.

Optimizing the microwave-assisted hydrothermal extraction of pectin from tangerine by-product and its physicochemical, structural, and functional properties

Microwave-assisted hydrothermal extraction (MAHE) was optimized using a Box-Behnken design (BBD) of the response surface methodology (RSM) for optimal recovery of pectin from tangerine peel (TPP). The effects of three factors (pH, irradiation time and temperature) on extraction yield (EY), galacturonic acid content (GAC) and degree of esterification (DE) of pectin were investigated. The optimal extraction conditions were as follows: pH 1.7, irradiation time 12 min and temperature 109 °C. Under these conditions, the EY, GAC and DE were 30.4, 72.3 and 45.2%, respectively. The low methoxyl content of MHAE (45.2%) compared to CE is confirmed by the 1H NMR and FTIR spectra, and the emulsifying activity is 57.65% and 50.56% for CE and MHAE, respectively. The total phenolic content (TPC) of pectin produced using MAHE is 41.2 mg GAE/g, thus indicating higher antioxidant properties compared to pectin produced with CE, which had a TPC of 38.4 mg GAE/g. In addition, the X-ray diffraction (XRD) and surface morphological analysis (SEM) results showed that TPP had a rough surface and crystalline structure. Overall, our findings show that TTP from MAHE can be used as a natural antioxidant ingredient in the functional food and pharmaceutical industries.

Polysaccharides in fruits: Biological activities, structures, and structure-activity relationships and influencing factors-A review

Fruits are a rich source of polysaccharides, and an increasing number of studies have shown that polysaccharides from fruits have a wide range of biological functions. Here, we thoroughly review recent advances in the study of the bioactivities, structures, and structure-activity relationships of fruit polysaccharides, especially highlighting the structure-activity influencing factors such as extraction methods and chemical modifications. Different extraction methods cause differences in the primary structures of polysaccharides, which in turn lead to different polysaccharide biological activities. Differences in the degree of modification, molecular weight, substitution position, and chain conformation caused by chemical modification can all affect the biological activities of fruit polysaccharides. Furthermore, we summarize the applications of fruit polysaccharides in the fields of pharmacy and medicine, foods, cosmetics, and materials. The challenges and perspectives for fruit polysaccharide research are also discussed.

Optimizing the Extraction of Bioactive Compounds from Porphyra linearis (Rhodophyta): Evaluating Alkaline and Enzymatic Hydrolysis for Nutraceutical Applications

Porphyra sensu lato is one of the most economically significant and widely cultured and consumed algae in the world. Porphyra species present excellent nutraceutic properties due to their bioactive compounds (BACs). This research aimed to find the most efficient aqueous extraction method for BACs by examining alkaline and enzymatic hydrolysis. Alkaline hydrolysis with 2.5% sodium carbonate (SC) and at 80 °C proved optimal for extracting all BACs (phycobiliproteins, soluble proteins, polyphenols, and carbohydrates) except mycosporine-like amino acids (MAAs), which were best extracted with water only, and at 80 °C. Enzymatic hydrolysis, particularly with the 'Miura' enzymatic cocktail (cellulase, xylanase, glycoside hydrolase, and β-glucanase), showed superior results in extracting phycoerythrin (PE), phycocyanin (PC), soluble proteins, and carbohydrates, with increases of approximately 195%, 510%, 890%, and 65%, respectively, compared to the best alkaline hydrolysis extraction (2.5% SC and 80 °C). Phenolic content analysis showed no significant difference between the 'Miura' cocktail and 2.5% SC treatments. Antioxidant activity was higher in samples from alkaline hydrolysis, while extraction of MAAs showed no significant difference between water-only and 'Miura' treatments. The study concludes that enzymatic hydrolysis improves the efficiency of BACs extraction in P. linearis, highlighting its potential for the nutraceutical industry, and especially with respect to MAAs for topical and oral UV-photoprotectors.

Structural characterization, antioxidant and antibacterial activity of three pectin polysaccharides from blueberry

In this study, three pectin polysaccharides BP1, BP2 and BP3, were purified from blueberries. The weight-average molecular weight (Mw) of BP1, BP2, and BP3 were detected to be 9.027 × 104, 9.313 × 104, and 1.223 × 106 Da, respectively. The structures of the three pectin polysaccharides were characterized and compared based on the results of molecular weight, monosaccharide composition, GC-MS and NMR analysis. Structural characterization revealed that BP1, BP2, and BP3 all contain homogalacturonan (HG) and rhamnogalacturonan I (RG-I) domains, and the rhamnose residues in RG-I domains are substituted at C-4 with side chains such as araban and galactosan. BP2 had the highest degree of esterification and HG domain ratio, followed by BP3 and BP1. In addition, BP1, BP2 and BP3 showed great antioxidant and antibacterial activities, and could destroy the cell membrane of Staphylococcus aureus and Escherichia coli. Moreover, the better DPPH and ABTS free radical scavenging and antibacterial activities of BP1 and BP2 than BP3 might be related to their lower molecular weight. The results of this study will provide essential information for the structure-activity relationship of pectin polysaccharides and research basis for development and application of blueberry pectin polysaccharides.

Pectin-rich dragon fruit peel extracts: An environmentally friendly emulsifier of natural origin

Pectin extraction is generally an energy-intensive industrial process, while on the other hand their extraction methods vary from different sources. Starting with that perspective, pectin (WSP) containing ultra-low degree of methylation (31.08 ± 1.27%) from dragon fruit peel (DFP) was extracted by using pure water at room temperature. WSP, dominant in DFP (17.13 ± 1.01%), showed both a high molecular weight and a wide molecular weight distribution, while the yield of the rest acid-soluble pectin (HAP) from DFP residue was only 5.22 ± 0.76%. Furthermore, WSP can stabilize emulsions over a wide range of concentrations and oil phases, especially HIPE. Therefore, the hypothesis was verified that the pectin-rich extract from dragon fruit peel with excellent emulsifying properties could be simply extracted by pure water. This environmentally-friendly and energy-saving extraction method provides a new insight to increase the additional value of dragon fruit peel produced in food processing.

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.

Exploring the effect of utilising organic acid solutions in ultrasound-assisted extraction of pectin from apple pomace, and its potential for biomedical purposes

Biomass resulting from food production represents valuable material to recover different biomolecules. In our study, we used apple pomace to obtain pectin, which is traditionally extracted using mineral acids. Our hypothesis consisted of carrying out extractions with organic acids, assisted by ultrasound, by varying processing parameters including time, temperature, and type of acid. The analytical determinations of galacturonic acid content, methoxylation and esterification degree, ζ-potential and extraction yield were used as pectin quality indicators. Pectins extracted using treatment conditions with better performance were assessed biologically in vitro for their potential to be used in biomedical applications. Overall, the extracted pectin presented a galacturonic acid content, methoxylation and esterification degree ranged from 19.7 to 67%, 26.8-41.4% and 58-65.2% respectively, and were negatively charged (-24.1 to -13.2 mV). It was found that factors of time and temperature greatly influenced the response variables excepting the esterification degree, while the acid type influenced the ζ-potential, methoxylation and esterification degrees. Additionally, it was seen that the longer extraction time (50 min) and higher temperature (50 °C) exhibited the better extraction yield (∼10.9%). Finally, the selected pectin showed high cytocompatibility up to 500 μg/mL of concentration when seeded with Neonatal Normal Human Dermal Fibroblasts.

Characterize the physicochemical properties and microstructure of pectin from high-pressure and thermal processed cloudy hawthorn (Crataegus pinnatifida) juice based on acid heating extraction

Physicochemical properties and morphological features of pectin in high-pressure-processing (JHPP) and thermal-processing (JTP) treated cloudy hawthorn juice were investigated based on acid heating extraction. Pectin from hawthorn juice was identified as low methoxy pectin (41.77%), which was significantly reduced to 34.56%-39.51% from JHPP, while pectin esterification degree (DE) from JTP increased to 45.58%, which can also be confirmed by Fourier transform infrared spectroscopy. In comparison to control, pectin linearity of JHPP and JTP significantly decreased with more highly branched-chains. However, no significate difference was observed in thermostability, crystallinity and main functional groups. Interestingly, a large number of aggregations was observed in JHPP pectin, and the intermodular distance of JTP pectin was enhanced, which was consistent with the results of viscosity, molecular weight and DE. These findings provided insights into utilization of hawthorn pectin and application of high-pressure processing (HPP) for improving quality property of fruit products by pectin modification.

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.

Physicochemical and functional properties of RG-I enriched pectin extracted from thinned-young apples

The demand for obtaining pectin from new sources has been continuously increasing. The abundant but underutilized thinned-young apple is a potential source of pectin. In this study, an organic acid (i.e., citric acid) and two inorganic acids (i.e., hydrochloric acid and nitric acid) commonly used in commercial pectin production were applied to extract pectin from three varieties of thinned-young apples. The physicochemical and functional properties of the thinned-young apple pectin were comprehensively characterized. The highest pectin yield (8.88 %) was obtained from Fuji apple using citric acid extraction. All pectin was high methoxy pectin (HMP) and rich in RG-I regions (>56 %). The citric acid extracted pectin had the highest molecular weight (Mw) and lowest degree of esterification (DE) values, and exhibited great thermal stability and shear-thinning property. Furthermore, Fuji-apple pectin possessed significantly better emulsifying properties compared to pectin obtained from the other two varieties of apples. Thus, pectin extracted with citric acid from Fuji thinned-young apples has great potential to be applied in the food industry as a natural thickener and emulsifier.

Roles of physical fields in the extraction of pectin from plant food wastes and byproducts: A systematic review

Pectin is a naturally occurring hydrocolloid found in the cell wall and middle lamella of many plants and has numerous functional applications in food and other related industries. The type of extraction methods used in production has a strong influence on the structural or physicochemical properties of the resultant pectin and the potential application or market value of the produced pectin. Many conventional extraction methods are well-established and commercially well adopted. However, the increased demand for pectin due to limitations of the existing methods in terms of efficiency and influence on end product quality has been renewed in developing novel techniques or procedures that help to alleviate these problems. In this review paper, a series of strategies involving the application of physical fields, such as acoustic, electromagnetic, electric and mechanical one, are reviewed for potential opportunities to improve the yield and quality attributes of pectin extracted from plant food wastes and byproducts. The extraction mechanism, processing equipment, key operating parameters as well as advantages and disadvantages of each method are systematically reviewed, and findings and conclusions on the potential applications of each method are described. Moreover, the challenges and future directions of physical field assisted extraction (PFAE) of pectin are also discussed to facilitate a better understanding of the complex mechanism in PFAE and optimizing operational parameters. This review may also provide specific theoretical information and practical applications to improve the design and scale up PFAE of pectin.

Structural diversity and physicochemical properties of polysaccharides isolated from pumpkin (Cucurbita moschata) by different methods

Natural polysaccharides were isolated and purified from Cucurbita moschata by hot water extraction and mild acid-base sequential extraction. Chemical and instrumental studies revealed that hot water-extracted and mild acid-extracted polysaccharides with molecular masses of 48 kDa and 85 kDa were both pectic polysaccharides with homogalacturonan (HG) and rhamnogalacturonan-I (RG-I) domains, while mild acid-extracted polysaccharide was more dominated by branched RG-I with higher contents of galactose (10.59 %) and arabinose (8.08 %). Furthermore, mild acid-extracted polysaccharide exhibited better thickening and emulsifying properties, likely due to its larger molecular mass and higher branching degree. Mild base-extracted polysaccharide with a molecular mass of 18 kDa was a glucan-like polysaccharide. It showed the strongest thermostability and gel behavior among these pumpkin polysaccharides, likely attributed to its unique network structure stabilized by substantial intra/intermolecular hydrogen bonds. This study aimed to establish the structure-property relationships between these structurally diverse pumpkin polysaccharides from different extraction methods and provided theoretical foundations for their targeted application in foods.

Jabuticaba (Plinia sp.) Peel as a Source of Pectin: Characterization and Effect of Different Extraction Methods

The peel of jabuticaba, a small fruit native to Brazil, has been shown to be a potential source of antioxidants and soluble dietary fibers. In this study, flours prepared from these peels were evaluated as a source of pectin. Different extraction methods were employed: ultrasound (US) extraction followed by low temperature heating (40 °C); in a microwave (MW) without (method 1) or with cellulase (method 2) or hemicellulase (method 3); or in a water bath (method 4). Pectin yields ranged from approximately 18% for methods 1 and 4 up to 22% for enzyme-assisted extractions (methods 2 and 3). Methods that did not employ enzymes resulted in low amounts of methoxyl pectins, as opposed to high amounts of methoxyl pectins obtained after enzyme treatment. Cyanidin-3-O-glucoside (C3G) and ellagic acid were the main phenolic compounds found in jabuticaba peel pectins, with higher C3G levels obtained with enzyme-free extraction (methods 1 and 4). All pectins from jabuticaba peel presented a reddish tone, good emulsifying properties and high swelling capacity. The pectin extracted using US+MW+cellulase (method 2) presented better emulsifying performance (higher values of emulsifying activity and emulsion stability), more effective than commercially available citrus pectin.

Biological investigation of a novel nanocomposite based on functionalized graphene oxide nanosheets with pectin, silk fibroin and zinc chromite nanoparticles

For biotechnology applications, a novel nanobiocomposite was synthesized based on modification of graphene oxide (GO) by extracted silk fibroin (SF), natural polymer pectin (Pec) and zinc chromite (ZnCr₂O₄) nanoparticles (NPs). The structure and properties of hybrid nanobiocomposite GO-Pec/SF/ZnCr₂O₄ such as thermal stability, less toxicity, biocompatibility, antibacterial, and biodegradable were proved by using field emission scanning electron microscope (FE-SEM), Fourier-transformed infrared (FT-IR), Energy dispersive X-ray spectroscopy (EDS), thermal gravimetric analysis (TGA), and X-Ray diffraction (XRD). According to the biological features of substances, the GO-Pec/SF/ZnCr₂O₄ nanobiocomposite shows perfect results in MTT (83.71 %) and Hemolysis (16.52 %) assays. accordingly, mentioned properties of this nanobiocomposite can be used as a scaffold for medical applications.

Effects of white ginseng on quality characteristics and volatile flavor compounds of roast chickens

The purpose of this study was to investigate the effects of white ginseng addition (1%, 1.5%, 2%, 2.5% and 3% of meat weight) on the physical and chemical properties of roast chickens. The parameters studied were basic characteristics (salting absorptivity, texture, shear force, pH and sensory evaluation), lipid and protein oxidation, volatile compounds and ginsenoside content. Headspace solid phase micro-extraction and gas chromatography-mass spectrometry (GC-MS) were used to identify the flavor compounds of samples. The changes in physical and chemical properties showed that white ginseng had a positive effect on the quality of roast chickens. The oxidation rate of lipid and protein decreased with the increase of white ginseng addition. In addition, the contents of Ginsenoside Rg1 (Rg1), Ginsenoside Re (Re) and Ginsenoside Rb1 (Rb1) in samples were 5.763 μg/g, 6.047 μg/g and 8.447 μg/g, respectively. Obtained data evidenced the possibility of improvement of the quality characteristics and enrichment of the flavor of roast chickens by adding white ginseng.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05394-4.

Physicochemical, structural, and functional properties of wampee (Clausena lansium (Lour.) Skeels) fruit peel pectin extracted with different organic acids

Effects of different extraction acids on physicochemical, structural, and functional properties of wampee fruit peel pectin (WFPP) were comparatively investigated. The hydrochloric acid extracted WFPP (HEP) exhibited the highest degrees of methylation (67.79%) and acetylation (86.29%) coupling with abundant monosaccharides and rhamnogalacturonan branches, but lowest molecular weight (5.58 × 10⁵ Da). The results of SEM, X-ray diffraction, and Fourier transform infrared spectroscopy analyses showed that acid types had little effect on the surface morphology of WFPP. However, compared to commercial citrus pectin (CCP), several specific absorbance peaks (1539, 1019, 920 cm^-1) were found in WFPPs, which corresponds to aromatic skeletal stretching, pyranose, and d-glucopyranosyl, respectively. Moreover, the rheological behavior revealed that WFPP solution was pseudoplastic fluid and affected by acid types. And the WFPPs exhibited higher emulsifying activity and emulsion stability than CCP. All these WFPPs presented well antioxidant activity and promoting probiotics ability, especially for HEP.

Enzyme-extracted raspberry pectin exhibits a high-branched structure and enhanced anti-inflammatory properties than hot acid-extracted pectin

To characterize the structure of purified raspberry pectin and discuss the impact of different extraction methods on the pectin structure, raspberry pectin was extracted by hot-acid and enzyme method and purified by stepwise ethanol precipitation and ion-exchange chromatography isolation. Enzyme-extracted raspberry pectin (RPE50%-3) presented relatively intact structure with molecular weight of 5 × 10⁴ g/mol and the degree of methylation was 39%. The 1D/2D NMR analysis demonstrated RPE50%-3 was a high-branched pectin mainly containing 50% homogalacturonan, 16% branched α-1,5-arabinan and α-1,3-arabinan, 18% β-1,4-galactan and β-1,6-galactan. Acid-extracted raspberry pectin (RPA50%-3) contained less arabinan than RPE50%-3. Moreover, RPE50%-3 inhibited the nitric oxide (NO), TNF-α, IL-6 production of lipopolysaccharide-induced macrophages by 67%, 22% and 46% at the dosage of 200 ug/mL, while the inhibitory rate of RPA50%-3 were 33%, 9%, and 1%, respectively. These results suggested that enzyme-extracted raspberry pectin contained more arabinan sidechains and exhibited better immunomodulatory effect.

Review of phytochemical and nutritional characteristics and food applications of Citrus L. fruits

Since the dietary regimen rich in fruits is being widely recognized and encouraged, Citrus L. fruits have been growing in popularity worldwide due to their high amounts of health-promoting phytonutrients and bioactive compounds, such as flavonoids, phenolic acids, vitamins, carotenoids, pectins, and fatty acids. The diverse physicochemical properties and multiple utilization of citrus fruits in food industry are associated with their unique chemical compositions. Throughout the world, citrus has been used for producing various value-added and nutritionally enhanced products, including juices, wines, jams, canned citrus, and dried citrus. However, the current studies regarding the phytochemical and nutritional characteristics and food applications of citrus are scattered. This review systematically summarizes the existing bibliography on the chemical characteristics, functional and nutraceutical benefits, processing, and potential applications of citrus. A thorough understanding of this information may provide scientific guidance for better utilizing citrus as a functional fruit and benefit the extension of citrus value chain.

New valorization approach of Algerian dates (Phoenix dactylifera L.) by ultrasound pectin extraction: Physicochemical, techno-functional, antioxidant and antidiabetic properties

To exploit the great fortune of date fruits, the current study aimed to valorize an Algerian common variety by extracting pectins. Response surface methodology (RSM) was applied as process optimization tool to achieve the highest yield using ultrasound-assisted extraction (UAE) as compared to conventional acid extraction (CAE). The experimental yield value (6.7%) was well matched with the predicted one (6.6%) at the optimum conditions (60 °C, 90 min, pH 1.5), confirming the validity of the model. The evaluation of the monomeric composition showed higher content of galacturonic acid and lower of neutral sugars in UAE pectin, as compared to CAE pectin. Conventional treatments decreased the molecular weight (Mw) of the extracted pectins (539 kDa) in a higher extent than ultrasound treatment (800 kDa). Fourier-Transform Infrared Spectroscopy (FT-IR) spectral analysis showed that both samples were low-methoxyl pectins. CAE gave rise to pectins with slightly upper technological samples in terms of water and oil holding capacity (5.2 and 3.8 g/g, respectively), and emulsifying activity (38.5 m²/g). Moreover, date pectins obtained by UAE presented enhanced antioxidant activity (24.3 and 61.0 mg/g DW for DPPH and FRAP assays, respectively), and in vitro antidiabetic properties, showing higher glucose adsorption capacity (4 mmol g^-1 at 200 min), as well as α-amylase inhibition (73.7%) and potential capacity to decrease glucose diffusion (1.4 mmol mM g^-1 at 150 min), which could improve the ability to retard starch digestion (0.1 mmol mM g-1 at 150 min), providing potential health-promoting properties.

A Comparative Assessment on the Recovery of Pectin and Phenolic Fractions from Aqueous and DES Extracts Obtained from Melon Peels

This work evaluates the purification of melon peel extracts obtained by two eco-friendly methods: autohydrolysis and sodium acetate/urea/water extraction (1:3:1.6), an alkaline deep eutectic solvent (DES). For that, sequential ethanol precipitation and resin adsorption/desorption stages were proposed for the separate recovery of the pectic and phenolic fractions. In order to screen the optimal purification conditions, in a first step, the effect of ethanol concentrations (from 70 to 85%) on the precipitation of pectic oligosaccharides was assayed. Subsequently, the influence of the selected resin (Amberlite XAD4, XAD16HP and XAD7HP), liquid/resin ratios, and desorption sequences (varying ethanol concentrations and pH) on the phenolic compounds was also studied. The highest pectin yields were achieved with 85% ethanol: 16.11 and 18.05 g pectin/100 g water-insoluble solids (WIS) for autohydrolysis and DES extracts, respectively. All pectins presented a galacturonic acid content of about 45%, while autohydrolysis pectin presented a higher amount of neutral sugar side chains. The presence of low methoxyl GalA and both linear and branched OGalA with DP from 2 to 20 was also confirmed by FTIR and HPAEC-PAD analysis, respectively. Concerning the phenolic fraction, the resin adsorption and desorption steps at the selected conditions (XAD4 resin, liquid/resin ratio of 2 mL/g, eluted with 50% ethanol thrice) resulted in 79.55 and 4.08 mg GAE/g non-volatile content (NVC) for autohydrolysis and DES extracts, respectively, with improved antioxidant capacity. Moreover, some phenolic acids (protocatechuic and ferulic acids) and flavonoids (orientin, vitexin and naringenin) were quantified in the extracts by HPLC–PDA-MS/MS.

The effect of sonication-synergistic natural deep eutectic solvents on extraction yield, structural and physicochemical properties of pectins extracted from mango peels

In this study, eco-friendly deep eutectic solvents (DESs) were used as extracting agents for the first time in the extraction of pectins from mango peel. Two novel green solvents including betaine-citric acid (Bet-CA) and choline chloride-malic acid (ChCl-MaA) were screened, and the extraction conditions were further optimized by full factor design experimental along with RSM. In addition, ultrasound treatment also had an influence on extraction yield, structural and physicochemical properties of extracted pectins. Two DES-extracted pectins had significantly higher yield, larger molecular weight and particles size than HCl-extracted pectin. High intensity ultrasound power enhanced the yield of low-ester pectins, but decreased the molecular weight and particles size of the pectins extracted. Monosaccharide compositions analysis showed that higher content of galacturonic acid (GalA) and larger HG region were observed in two DESs-extracted pectins. Fourier transform infrared spectra (FT-IR) of all pectins extracted were similar, with slight differences. Two DESs-extracted pectins exhibited higher DE values than HCl-extracted pectin. Thermal analysis and zeta potential results showed that HCl-extracted pectin had better stability than ChCl-MaA-extracted pectin. Additionally, HCl-extracted pectin had higher viscosity properties than two DESs-extracted pectins or commercial pectin (CP). Moreover, it was found that HCl-extracted pectin was in a colloid state, while two DESs-extracted pectins or CP were in a flow state. Ultrasound treatment significantly improved the yields of pectin/low-ester pectin. Additionally, ultrasound treatment remarkably decreased the viscosity and viscoelastic properties of the pectins extracted. The results were conducive to our understanding of the relationship between extraction conditions and physicochemical properties of the pectins extracted, which provides theoretical basis for the functional application of mango peel pectins in the food and pharmaceutical industry.

The Influence of Extraction Conditions on the Yield and Physico-Chemical Parameters of Pectin from Grape Pomace

Grape pomace is one of the most abundant by-products generated from the wine industry. This by-product is a complex substrate consisted of polysaccharides, proanthocyanidins, acid pectic substances, structural proteins, lignin, and polyphenols. In an effort to valorize this material, the present study focused on the influence of extraction conditions on the yield and physico-chemical parameters of pectin. The following conditions, such as grape pomace variety (Fetească Neagră and Rară Neagră), acid type (citric, sulfuric, and nitric), particle size intervals (<125 µm, ≥125−<200 µm and ≥200−<300 µm), temperature (70, 80 and 90 °C), pH (1, 2 and 3), and extraction time (1, 2, and 3 h) were established in order to optimize the extraction of pectin. The results showed that acid type, particle size intervals, temperature, time, and pH had a significant influence on the yield and physico-chemical parameters of pectin extracted from grape pomace. According to the obtained results, the highest yield, galacturonic acid content, degree of esterification, methoxyl content, molecular, and equivalent weight of pectin were acquired for the extraction with citric acid at pH 2, particle size interval of ≥125−<200 µm, and temperature of 90 °C for 3 h. FT-IR analysis confirmed the presence of functional groups in the fingerprint region of identification for polysaccharide in the extracted pectin.

The Complex Biological Effects of Pectin: Galectin-3 Targeting as Potential Human Health Improvement?

Galectin-3 is the only chimeric representative of the galectin family. Although galectin-3 has ubiquitous regulatory and physiological effects, there is a great number of pathological environments where galectin-3 cooperatively participates. Pectin is composed of different chemical structures, such as homogalacturonans, rhamnogalacturonans, and side chains. The study of pectin's major structural aspects is fundamental to predicting the impact of pectin on human health, especially regarding distinct molecular modulation. One of the explored pectin's biological activities is the possible galectin-3 protein regulation. The present review focuses on revealing the structure/function relationship of pectins, their fragments, and their biological effects. The discussion highlighted by this review shows different effects described within in vitro and in vivo experimental models, with interesting and sometimes contradictory results, especially regarding galectin-3 interaction. The review demonstrates that pectins are promissory food-derived molecules for different bioactive functions. However, galectin-3 inhibition by pectin had been stated in literature before, although it is not a fully understood, experimentally convincing, and commonly agreed issue. It is demonstrated that more studies focusing on structural analysis and its relation to the observed beneficial effects, as well as substantial propositions of cause and effect alongside robust data, are needed for different pectin molecules' interactions with galectin-3.

A biorefinery approach for pectin extraction and second-generation bioethanol production from cocoa pod husk

A biorefinery approach was applied for pectin extraction, xylooligosaccharides' (XOs) and bioethanol production from cocoa pod husk (CPH) using citric acid-assisted hydrothermal pretreatment. Under optimal conditions at 120° C, 10 min and 2% w.v^-1 of citric acid a high pectin recovery (19.5%) with high content of uronic acids (41.9%) was obtained. In addition, the liquid fraction presented a XOs concentration of 50.4 mg.g^-1 and 69.7 mg.g^-1 of fermentable sugars. Enzymatic hydrolysis of solid fraction showed glucan conversion of 60%. Finally, the hydrothermal and enzymatic hydrolysates of CPH were used in bioethanol production by Candida tropicalis and Saccharomyces cerevisiae, reaching 30.9 g and 45.2 g of bioethanol per kg of CPH, respectively. An environmentally friendly and rapid pretreatment method was development for pectin extraction, XOS and second-generation bioethanol production from CPH with great perspectives for the application of these biomolecules in food and bioenergy industry.

Extraction, characterization and spontaneous gelation mechanism of pectin from Nicandra physaloides (Linn.) Gaertn seeds

Nicandra physaloides (Linn.) Gaertn seeds (NPGS) could be manually scrubbed to obtain water-soluble pectin, which forms gel at room temperature without additives. The extraction, characterization and spontaneous gelation (SG) mechanism of the pectin were studied. The results showed that the pectin was located on the surface of NPGS and easily to be dissolved. Chemically, the pectin was low methoxy pectin with esterification degree of 46.93%, Gal-A content of 65.80%, and average molar weight of 631.15 kDa. The SG occurred at the pectin concentration of 1.5%, it can be destroyed by urea and SDS, however, EDTA cannot. In addition, KCl and NaCl induced the gelation of 1.0% pectin solution and the ions of K, Mg, Ca and Na were detected in the pectin. Hydrogen bonding, electrostatic and hydrophobic interaction contributed to the SG. This study could promote the commercial applications of the pectin in the field of edible colloids and cosmetics.

Added-value biomolecules' production from cocoa pod husks: A review

Cocoa beans are produced through on-farm processing where residual biomass is discarded, including cocoa pod husks (CPH), cocoa bean shells and cocoa sweatings. CPH represents about 80% of these residues that are generated during the initial cocoa bean processing steps and their disposal occupies large areas, causing social and environmental concerns. In the last decades, the lignocellulosic composition of CPH has attracted the attention of the scientific and productive sector. Recently, some studies have reported the use of CPH in the production of medium to high value-added molecules, with potential applications in food and feed, agriculture, bioenergy, and other segments. This review presents biotechnological approaches and processes for the exploitation of CPH, including pre-treatment methods for the production of different biomolecules. Great perspectives and innovations were found concerning CPH exploitation and valorisation, but still more efforts are needed to valorise this potential feedstock and give support to producers in-development countries.

Citric acid assisted hydrothermal pretreatment for the extraction of pectin and xylooligosaccharides production from cocoa pod husks

The main purpose of this work was the development of a new citric acid assisted hydrothermal pretreatment of cocoa pod husks (CPH), which has not yet been exploited for pectin recovery. CPH́s pectin recovery was improved with concomitant production of xylooligosaccharides (XOS) through efficient enzymatic hydrolysis of the solid fraction. A central composite experimental design was planned to analyze the effect of pretreatment conditions. Under optimal conditions at 120 °C, 10 min and 2% w.v^-1, the recovery of pectin accounted for 19.3% of the biomass submitted to pretreatment with 52.2% of methyl esterification degree. Additionally, 51.9 mg.g^-1 of XOS were also produced. The enzymatic conversion efficiency of the cellulosic fraction was 58.9%, leading to a production of 92.4 kg of glucose per ton of CPH. Great perspectives were observed in the implementation of CPH hydrothermal pretreatment for the production of value-added biomolecules under a biorefinery concept.

Bioactive pectic polysaccharides from bay tree pruning waste: Sequential subcritical water extraction and application in active food packaging

The potential isolation of bio-active polysaccharides from bay tree pruning waste was studied using sequential subcritical water extraction using different time-temperature combinations. The extracted polysaccharides were highly enriched in pectins while preserving their high molecular mass (10-100 kDa), presenting ideal properties for its application as additive in food packaging. Pectin-enriched chitosan films were prepared, improving the optical properties (≥95% UV-light barrier capacity), antioxidant capacity (˃95% radical scavenging activity) and water vapor permeability (≤14 g·Pa-1·s-1·m-1·10-7) in comparison with neat chitosan-based films. Furthermore, the antimicrobial activity of chitosan was maintained in the hybrid films. Addition of 10% of pectins improved mechanical properties, increasing the Young's modulus 12%, and the stress resistance in 51%. The application of pectin-rich fractions from bay tree pruning waste as an additive in active food packaging applications, with triple action as antioxidant, barrier, and antimicrobial has been demonstrated.

Nutrients and bioactives in citrus fruits: Different citrus varieties, fruit parts, and growth stages

Citrus fruits are consumed in large quantities worldwide due to their attractive aromas and taste, as well as their high nutritional values and various health-promoting effects, which are due to their abundance of nutrients and bioactives. In addition to water, carbohydrates, vitamins, minerals, and dietary fibers are important nutrients in citrus, providing them with high nutritional values. Citrus fruits are also rich in various bioactives such as flavonoids, essential oils, carotenoids, limonoids, and synephrines, which protect from various ailments, including cancer and inflammatory, digestive, and cardiovascular diseases. The composition and content of nutrients and bioactives differ significantly among citrus varieties, fruit parts, and growth stages. To better understand the nutrient and bioactive profiles of citrus fruits and provide guidance for the utilization of high-value citrus resources, this review systematically summarizes the nutrients and bioactives in citrus fruit, including their contents, structural characteristics, and potential health benefits. We also explore the composition variation in different citrus varieties, fruits parts, and growth stages, as well as their health-promoting effects and applications.

Kinetic, Thermodynamic, Physicochemical, and Economical Characterization of Pectin from Mangifera indica L. cv. Haden Residues

The effect of temperature (60, 70, 80, and 90 °C) and time (30, 45, 60, 75, and 90 min) on citric acid extraction of Haden mango (Mangifera indica L. cv. Haden) peel pectin was evaluated in the present study. In order to obtain a better understanding of both the extraction process and the characteristics of the pectin (obtained from an agro-industrial waste) for a future scaling process, the following characterizations were performed: (1) Kinetic, with the maximum extraction times and yields at all evaluated temperatures; (2) thermodynamic, obtaining activation energies, enthalpies, entropies, and Gibbs free energies for each stage of the process; (3) physicochemical (chemical analysis, monosaccharide composition, degree of esterification, galacturonic acid content, free acidity, Fourier-transform infrared spectroscopy, thermogravimetric and derivative thermogravimetric analyses); and (4) economical, of the pectin with the highest yield. The Haden mango peel pectin was found to be characterized by a high-esterified degree (81.81 ± 0.00%), regular galacturonic acid content (71.57 ± 1.26%), low protein (0.83 ± 0.05%) and high ash (3.53 ± 0.02%) content, low mean viscometric molecular weight (55.91 kDa), and high equivalent weight (3657.55 ± 8.41), which makes it potentially useful for food applications.

Effect of ultrasonic pretreatment monitored by real-time online technologies on dried preparation time and yield during extraction process of okra pectin

BACKGROUND

Ultrasonic pretreatment is a novel physical method that can be used in the extraction process of okra pectin. Real-time online monitoring technologies were introduced in time and frequency domains when okra was pretreated. Preparation time of dried okra and yield of okra pectin were studied; and physicochemical properties of okra pectin were analyzed at the optimum ultrasonic parameter.

RESULTS

Results showed that ultrasonic intensity of sweeping-frequency ultrasonic (SFU) pretreatment was stronger than that of fixed-frequency ultrasonic pretreatment (FFU). SFU pretreatment (60 ± 1 kHz) at 30 min had a strong ultrasonic voltage peak of 0.05387 V and signal power peak of -6.62 dBm. The preparation time of dried okra was 160 ± 14.14 min in the pretreated group, 44.83% lower than control without SFU pretreatment. The intercellular space was 56.03% higher than control. Water diffusion coefficient increased from 1.41 × 10^-9 to 2.14 × 10^-9  m²  s^-1 . Monobasic quadratic equations were developed for the monitored ultrasonic intensity and pectin yield. Compared to control, extraction yield (16.70%), pectin content (0.564 mg mg^-1 ), solubility (0.8187 g g^-1 ) and gel strength (30.91 g) were improved in the pretreated group. Viscosity decreased, and values of G' and G″ crossing at 63 rad s^-1 revealed the viscoelastic behavior and the beginning of viscous behavior with a sol state.

CONCLUSION

Decrement of dried preparation time and increment of yield were achieved by ultrasonic pretreatment during the extraction process of okra pectin, and the relationship of ultrasonic intensity monitored by real-time online technologies and yield was given. © 2021 Society of Chemical Industry.

Synergistic gelling mechanism of RG-I rich citrus pectic polysaccharide at different esterification degree in calcium-induced gelation

RG-I rich pectic polysaccharide is common in fruit and vegetable and possesses health benefits. However, it is removed during commercial pectin production because of poor gelling properties. Synergistic gelation can improve rheological properties of RG-I pectic polysaccharide and expand its application in functional food hydrocolloids. In the study, RG-I rich pectic polysaccharides at different degree of esterification was extracted from citrus membrane by sequential mild acidic (0.4% HCl, 28 °C) and alkaline (0.6% NaOH, 32 °C) treatment. The pectic polysaccharide from acid water (PA) composes of 41% RG-I and 44% HG with DM of 45%, while the pectic polysaccharide from basic water (PB) composed of 63% RG-I and 19% HG with DM of 15%. PA/PB blend gel under CaCO₃-glucono-δ-lactone system showed improved rheological properties compared with pure gels. Ca-bridges connected pectin aggregates and promoted the three-dimensional structure of PA/PB blend gels, while neutral sugar side-chains prompted hydrogen bonds and strengthened gel network.

Highly Branched RG-I Domain Enrichment Is Indispensable for Pectin Mitigating against High-Fat Diet-Induced Obesity

Obesity is associated with gut microbiome dysbiosis. Our previous research has shown that highly branched rhamnogalacturonan type I (RG-I)-enriched pectin (WRP, 531.5 kDa, 70.44% RG-I, Rha/(Gal + Ara) = 20) and its oligosaccharide with less branched RG-I [DWRP, 12.1 kDa, 50.29% RG-I, Rha/(Gal + Ara) = 6] are potential prebiotics. The present study is conducted to uncover the impact of the content, molecular size, and branch degrees of RG-I on the inhibiting effect of high-fat diet (HFD)-induced obesity. The commercial pectin (CP, 496.2 kDa, 35.77% RG-I, Rha/(Gal + Ara) = 6), WRP, and DWRP were orally administered to HFD-fed C57BL/6J mice (100 mg kg^-1 d^-1) to determine their individual effects on obesity. WRP significantly prevented bodyweight gain, insulin resistance, and inflammatory responses in HFD-fed mice. No obvious anti-obesity effect was observed in either CP or DWRP supplementation. A mechanistic study revealed that CP and DWRP could not enhance the diversity of gut microbiota, while WRP treatment positively modulated the gut microbiota of obese mice by increasing the abundance of Butyrivibrio, Roseburia, Barnesiella, Flavonifractor, Acetivibrio, and Clostridium cluster IV. Furthermore, WRP significantly promoted browning of white adipose tissues in HFD-fed mice, while CP and DWRP did not. WRP can attenuate the HFD-induced obesity by modulation of gut microbiota and lipid metabolism. Highly branched RG-I domain enrichment is essential for pectin mitigating against the HFD-induced obesity.