Galacturonic Acid Content Research Articles

Sequential extraction of phenolics and pectin from mango peel assisted by ultrasound

The present work evaluated the use of ultrasound to extract sequentially phenolics and pectin from mango peel. Initially, the influence of ethanol and ultrasound on the phenolics extraction was investigated. The results showed that the ultrasound did not affect the extraction yield of these compounds. The best total phenolics yield (67%) was obtained with an extraction solution consisting of 50% of ethanol in water (v/v) and without ultrasound application, according to the experimental design. As an innovative extraction methodology, the residue of this extraction was then used to extract pectin assisted by ultrasound. The use of ultrasound increased over than 50% of the pectin extraction yield and did not affect its quality, measured by the galacturonic acid content and the degree of esterification. The sequential extraction of phenolics and pectin shows to be an alternative to use the whole residue from mango peel.

Effect of enzyme-assisted extraction on the physicochemical properties of mucilage from the fronds of Asplenium australasicum (J. Sm.) Hook

Enzyme-assisted extraction (EAE) possesses the advantages of being environmentally friendly and easily operated owing to relatively mild reaction conditions. Thus, mucilage from Asplenium australasicum was extracted with xylanase, glucanase and simultaneous application of both enzymatic preparations then investigated for their physicochemical properties. It was observed that compared to the control, the yield of mucilage increased significantly by EAE (from 3.64% to 6.04–6.86%), while the average molecular weight also increased slightly. SEM results showed that enzymes can erode the raw material which contributed to the higher extraction efficiency of polysaccharide. Furthermore, EAE modified the monosaccharide composition profile of A. australasicum mucilage considerably, especially there was a significant increase in glucose and galacturonic acid content. Although the FT-IR fingerprint did not change pronouncedly due to the action of the enzymes, but the degree of polysaccharide branching seemed to be more complicated, thus significantly reducing the intrinsic viscosity and water holding capacity of mucilage.

Microwave heating extraction of pectin from lime peel: Characterization and properties compared with the conventional heating method.

Microwave and conventional heating methods were used to extract pectin from lime peel waste using different acid extractants (hydrochloric or citric acid) and peel-to-extractant ratios (1:20 or 1:40). Hydrochloric acid as the extractant resulted in a higher yield of pectin with both methods. The methoxyl content and galacturonic acid content of lime peel pectin were in the range 8.74-10.51% and 79.29-95.93%, respectively. The intense band around 1730 cm-1 corresponded to methyl esterified uronic carboxyl groups and confirmed the higher equivalent weight and degree of esterification for the microwave-extracted pectin than that from conventional extraction. Lime peel pectin could be classified as high methoxyl pectin having a rapid-set gel formation. The viscosity and viscoelastic properties of the pectin solution from both heating methods enhanced with increasing solid concentration. Hence, microwave heating can be a short processing time for pectin extraction from lime peel waste with suitable pectin properties.

Complete Utilization of Waste Pomegranate Peels To Produce a Hydrocolloid, Punicalagin Rich Phenolics, and a Hard Carbon Electrode

This work demonstrates the complete utilization of waste pomegranate peels (WPP) to produce pectin, punicalagin rich phenolics, and a hard carbon electrode. The high yields of pectin (24.8%) and phenolics (11.9%) were obtained at optimal ultrasound (20 min ultrasound time, 15 mL g–1 liquid:solid ratio) and cellulase treatment (55 U g–1 cellulase dosage, 4 h treatment time) of WPP. The IR, 1H NMR, and TGA analysis showed that the recovered pectin was similar to commercial pectin. The recovered pectin had a 68.5% degree of esterification, 146.5 kDa molecular weight, and 72% galacturonic acid content. A high content of valuable punicalagin (71.2% of total phenolics) occurred in the recovered phenolics. The WPP leftover (after pectin and phenolics recovery) was carbonized via pyrolysis and then impregnated with potassium hydroxide and heated in an inert atmosphere to obtain hard carbon (HC) to be employed as an electrode in electrochemical cells. The Raman spectroscopy, X-ray crystallography, and CHN analysis...

Pectin from Black Tomato Pomace: Characterization, Interaction with Gallotannin, and Emulsifying Stability Properties

Hydrochloric acid and ammonium oxalate are used to refine pectin from black tomato pomace. The characterization of pectin‐yield, galacturonic acid (GalA) content, degree of methoxylation, neutral sugar composition and molecular weight, interaction with gallotannin as well as emulsion stability are investigated. Hydrochloric acid‐extracted pectin (HEP) and chelating agent‐extracted pectin (ChEP) satisfy the commercial pectin requirements (GalA% > 65%) and are smooth pectin with high homogalacturonan segments (70.6 and 65.4%, respectively). As the structure results suggest, HEP has fewer and shorter branches compared with ChEP. As titration results suggest, gallotannin is bound by pectin and forms insoluble gallotannin–pectin complexes, the maximum combination gallotannin to pectin mass ratios are 0.28 and 0.47 for HEP and ChEP, respectively. Yet as distribution of volume‐weighted diameter, micrographs and values of surface‐weighted diameter suggest, the emulsions stabilized by HEP show better stability than ChEP. The study shows that ChEP is a better additive in beverages containing gallotannin, while HEP has better emulsifying stability.

Production of Pectinolytic Enzymes by Two Bacillus spp. Strains and Their Application in Flax Degumming

This study demonstrated that Bacillus licheniformis HDYM-03 and Bacillus megaterium HDYM-09, isolated from a liquid sample of flax retting pool, were able to produce pectinolytic enzymes using polysaccharides as substrates. Bacillus megaterium HDYM-09 produced pectin lyase that exhibited the highest activity of 2116.71 ± 11.55 U/mL. Bacillus licheniformis HDYM-03 produced pectate lyase that exhibited the highest activity of 611.21 ± 14.54 U/mL. Based on these findings, we constructed four retting systems to degrade the pectin substance. The results showed that the content of galacturonic acid in the mixed system was 529.21 μg/mL, the content of reducing sugar was 98.14 mg/mL, and the weight loss ratio of cells reached 19.49%, which were significantly higher than those in other systems. The mixed system has more advantages, and the utilization rate of degumming was higher, which further ensured that the degumming can be carried out efficiently and quickly. The mixed system exhibits feasible applications in the fiber and textile industry.

Characterization of the structural and emulsifying properties of sugar beet pectins obtained by sequential extraction

In this study, we examine how the extractant type used and extraction steps effect the structural and emulsifying properties of the resulting sugar beet pectins (SBPs). Using ammonium oxalate and sulfuric acid as the extractants, two oxalate-extracted pectins (denoted OEP1 and OEP2) and four acid-solubilized pectins (denoted AEP1, AEP2, AEP3 and AEP4) were sequentially extracted and characterized regarding their structures and emulsifying properties. All six pectins shared common features such as having a high galacturonic acid content and a low methylation degree, however, OEP1 and OEP2 not only had lower amounts of ferulic acid (FA) and protein but their molecular sizes were also smaller in comparison to the remainder. Moreover, the oxalate-extracted sample series was significantly different from the acid-extracted sample series in regards to amino acid compositions. Due probably to the hydrophobicity of the proteinaceous components and the lower contents of FA and protein, OEP1 failed to stabilize oil-in-water emulsions containing 15% middle chain triglyceride (MCT). In contrast, AEP1-4 were shown to have better emulsifying activities, producing fine emulsions under favorable conditions (e.g. pectin concentration 1.5%). The d43 values of the emulsions prepared at a 1.5% concentration of AEP2, AEP3, or AEP4 did not markedly change throughout the period of storage (28 days) at 30 °C, whereas the AEP1 emulsion was relatively less stable. The correlation between emulsifying properties and the structures among the acid-extracted pectins highlights that the extraction sequence plays an important role in the resulting compositional and emulsifying properties of SBP.

Upgrading Pectin Production from Apple Pomace by Acetic Acid Extraction.

Pectin, as one of the most widely used functional polysaccharide, can be abundantly extracted from apple pomace which is the main by-product of apple juice industry. In the case of 110min, 10% (w/w) acetic acid (AA), and 100°C, extraction yield of pectin reached 19.6%. Compared with mineral acid-extracted pectin, the yield, molecular weight, galacturonic acid content, and DE of the AA-extracted pectin were higher while neutral sugars were lower. Furthermore, the AA-extracted pectin solution demonstrated a higher viscosity during the shear rate increased, and a higher G″ modulus than pectin extracted with mineral acid and commercial pectin possibly because of stronger polymer chain interaction, which was reflected in gel textural properties. The green approach for the pectin production, in terms of pectin components was developed from apple pomace using AA that was highly competitive and environmentally friendly process.

Effects of Extraction Methods on Physicochemical Properties and Viscosity of Polysaccharides from Orange Peel

In order to take full advantage of the orange peel resource, polysaccharides were extracted from orange peel by hot buffer, chelating agent, dilute alkaline, concentrated alkaline, acid and enzyme extraction, respectively. The physicochemical properties and viscosity of the six polysaccharides were determined. The results showed that the six polysaccharides were mainly consisted of rhamnose, arabinose, galactose and glucose and traces of other monosaccharide. The six polysaccharides exhibited high total carbohydrate (89.74–98.08%), galacturonic acid content (GalA, 8.95–33.16%) and little proteins (<2%). Degree of methoxylation in polysaccharide obtained from orange peel by enzyme extraction and orange peel by acid extraction was higher than the others. They all showed good thermal stability under 84.5°C and non-Newtonian flow behaviors. Polysaccharide obtained from orange peel by hot buffer extraction has higher viscosity than the others at the 0.5% concentration. Polysaccharide obtained from orange peel by dilute alkali extraction appeared the highest viscosity with the increase of concentration, which may be due to the smallest hydrodynamic diameter and the highest rhamnose content.

Relationship between texture and cell-wall components of safou (<i>Dacryodes edulis</i> (G. Don) H.J. Lam) fruits at different storage conditions

Objective: The objective of this study was to determine the relationship between texture and cell wall component of safou (Dacryodes edulis (G Don) HJ Lam) at different storage conditions during the safou softening.Methodology and results: Using a General Linear Model (GLM), statgraphic software plus v. 5. 0 and XLstat 2007software, the relationship between texture and cell wall component of safou at different storage conditions was evaluated. At different stages of ripeness, safou were picked and stored in different conditions including: cultivar, picking mode, packaging mode and temperature. For each condition, texture, water loss, alcoholinsoluble CDTA- soluble pectins and neutral sugar level and methoxylation degree were measured.The results showed that the temperature and method of storage and theirs interaction influenced significantly the texture of the safou during storage. Softening and dehydration through transpiration are the two processes that changed the safou texture at high temperature (28°C and 36°C). The cultivar and the maturity stage also influenced significantly the texture. The correlation between texture and cell-wall component including alcohol insoluble solids, CDTA soluble pectin extracts, rhamnose and arabinose were very high. MIA (Materiel Insoluble in Alcohol) content increased and galacturonic acid content of CDTA Soluble Pectin extracts decreased, depending on the maturity level of safou: the degradation of homogalacturonans of pectins during the safou softening.Conclusion and application of results: the degradation of homogalacturonans of safou pectins had an impact on their texture. Therefore, for their postharvest shelf life, safou must be stored at low temperature (18°C) with or without packing.Keywords: Safou, texture, pectins, softening, Dacryodes edulis

Characterization of polysaccharides from Prunus amygdalus peels: Antioxidant and antiproliferative activities

Prunus amygdalus is used in the folk medicine that proved the interest of this plant which cures many diseases. Many researchers are interested to valorize almond waste (hull and shell) and to evaluate their biological and pharmacological activities. In this work, polysaccharides from Prunus amygdalus shell were extracted sequentially by water, ammonium oxalate and hydrochloric acid. The monosaccharide composition of polysaccharides fractions was performed by GC–MS. Water-soluble polysaccharide was found to be the most effective extracting agent with an extracted yield of 9%. The acid Soluble Polysaccharides (ASP) exhibited the highest galacturonic acid content (31.95%), the highest polysaccharides extractability (88.57%) and the lowest degree of esterification (31.76%). The different polysaccharides fractions were characterized by FTIR, 1H NMR and SEC/MALS/VD/DRI. The antioxidant tests (DPPH, ABTS and FRAP) indicated that ASP showed even better antioxidant activities. Moreover, the result of the antiproliferative activity against Caco-2 and B-16 cells showed that ASP exhibited strong cytotoxicity ability which confirmed that the Prunus amygdalus peels may comprise the natural raw materials for new drug and functional food.

Modification of pectin distribution in sunflower (Helianthus annuus L.) roots in response to lead exposure

The pectic component is an integral part of the plant cell wall and plays an important role in plant growth. The structure and composition of the cell wall depends on the type of cell in particular organs and can be modified by environmental factors. Due to the interaction between the roots and rhizosphere, the cell wall components, including pectin, are the first constituents which react to a toxic rhizosphere ingredient - lead. The aim of this study was to evaluate the effect of lead treatment on pectic polysaccharide occurrence in roots, especially on the distribution of homogalacturonan with low vs. high levels of methyl-esterification in the cells of the root cap, quiescent center, and elongation zone. Moreover, a quantitative analysis of the galacturonic acid content and the amount of ruthenium red binding were performed. The obtained results indicate the effect of lead on arrangement of pectin in roots growing at different toxic ion concentrations. We found a correlation between the increasing lead concentration and the distribution of specific epitopes of methylated (JIM7) and un-esterified (JIM5) homogalacturonan. Overall, the toxic lead ion concentration exerted an impact on the content of homogalacturonan with low and high levels of esterification in all investigated root zones.

Distribution of arabinogalactan proteins and pectins in the cells of apple (Malus × domestica) fruit during post-harvest storage.

Changes in the arrangement of cell wall components determine cell wall properties (integrity, stiffness), thereby affecting the macro-scale properties of fruits, which are important for consumers and industry. Arabinogalactan proteins (AGPs) are ubiquitous components of the plant cell, in which they have various functions. Currently, AGPs are considered to be one of the less well-known, enigmatic proteoglycans, a consequence of their heterogeneous structure and unclear mechanism of activity. An immunocytochemical study was conducted to elucidate the distribution of AGPs and pectic polysaccharides contained in apple (Malus × domestica) fruit during senescence. De-esterified homogalacturonan (LM19), methyl-esterified homogalacturonan (LM20), processed arabinan (LM16) and three AGP epitopes (JIM13, JIM15, MAC207) were identified in the fruit at three stages: fresh fruit, and fruit at 1 and 3 months of post-harvest storage. Microscopy revealed spatio-temporal changes in the localization of all examined epitopes. Changes of fruit cell wall assembly and its degradation were confirmed by determination of the galacturonic acid content in the WSP (water soluble pectins), CSP (chelator soluble pectins) and DASP (dilute alkali soluble pectins) fractions. The results revealed dependencies between AGPs, arabinan and homogalacturonan distribution in apple fruit, which are correlated with changes in microstructure during senescence. We propose that AGPs are involved in establishment of the cell wall - plasma membrane continuum.

Rheological behaviour of acetylated pectins from cactus pear fruits (Opuntia albicarpa and O. matudae)

Acetylated-low methoxyl pectins were isolated from sweet prickly-pear (Opuntia albicarpa) and ‘xoconostle’ or acidic prickly-pear (O. matudae), by sequential extraction with water in presence of ethylenediaminetetraacetic acid as sequestering agent. The extraction protocol resulted in the isolation of pectins of good enough purity as evidenced by their high galacturonic acid contents (65.23 and 75.72% w/w, for sweet prickly-pear pectin (PP) and xoconostle pectin (XP), respectively). Both pectins had an important protein content (10.82 and 2.58% for PP and XP, respectively) and they can be described as acetylated-low methoxyl pectins. Degree of methoxylation (DM) and degree of acetylation (DA) values for PP were 26.83 and 21.83%, respectively. XP showed DM and DA values of 45.62% and 4.94%, respectively. Weight-average molecular weight (Mw) values of 204.08 and 161.73 kDa were determined for PP and XP, respectively. Pectin aqueous dispersions showed a non-Newtonian rheological behaviour which had good fitting to the Cross equation. The viscoelastic behaviour of 1%-pectin-calcium systems exhibited a predominantly solid-like character, the presence of 1 mM CaCl2 was enough to the formation of soft gels, the further increase of Ca2+ ions (3 and 5 mM) yielded the formation of soft and elastic gels. The viscoelastic solid behaviour of PP gels was more dominant than that of XP gels. The high content of acetyl groups did not have negative effect on the gel formation ability of both, PP and XP.

An integrated green biorefinery approach towards simultaneous recovery of pectin and polyphenols coupled with bioethanol production from waste pomegranate peels

An integrated biorefinery, incorporating hydrothermal processing of waste pomegranate peels (WPP), was proposed for the acid and organic solvent-free simultaneous recovery of pectin and phenolics with bioethanol production. The hydrothermal treatment (HT) was optimized using Box-Behnken design and the maximum recovery of pectin (18.8–20.9%) and phenolics (10.6–11.8%) were obtained by hydrothermal treatment at 115 °C for 40 min with a liquid-solid ratio of 10. The WPP pectin was characterized by IR, 1H NMR, and TGA which showed close similarity to commercial pectin. Depending on WPP cultivar type the degree of esterification, galacturonic acid content and molecular weight of pectin were in the range of 68–74%, 71–72%, and 131,137–141,538 Da, respectively. The recovered phenolics contained 57–60% punicalagin. Enzyme digestibility of WPP improved using HT with 177 g glucose produced per kg dry mass which was fermented to obtain 80 g ethanol with 88% of theoretical yield.

Structural and technological characterization of pectin extracted with sodium citrate and nitric acid from sunflower heads.

An optimization of temperature, time, and extracting agent concentration of pectin extraction from sunflower heads using sodium citrate and nitric acid (SP-SC and SP-NA) was carried out. At optimal conditions, the yield of extraction with nitric acid (SPO-NA) was twofold greater than the corresponding with sodium citrate (SPO-SC) (14.3 versus 7.7%, respectively). Regarding pectin structure, the galacturonic acid (GalA) content in both, SPO-SC and SPO-NA, was similar (∼85%). However, SPO-NA showed lower molecular weight (Mw) (88.9 kDa) and neutral sugar content (4%) than SPO-SC (464 kDa, 9%), indicating that nitric acid deeply degraded pectin structure. These differences derived into dissimilar behavior in their technological functionality. SPO-SC showed higher viscosity and better emulsifying capacity than SPO-NA, although any of them were able to stabilize the oil/water emulsion. Both sunflower pectins formed gels with Ca2+ (75 mg/g of pectin) at pH 3.0. However, when sucrose was added, the gels formed by SP-SC and 20% sucrose presented the same hardness as those of SP-NA with 40% sucrose. These results suggest that the pectin extracted with sodium citrate, an eco-friendly agent, could be a promising ingredient, with good thickening and gelling properties.

Extraction of pectin from ponkan (Citrus reticulata Blanco cv. Ponkan) peel: Optimization and structural characterization

A central composite experimental design was used to evaluate the influence of pH, extraction time and liquid:solid ratio on the yield and uronic acid content of the pectin from ponkan peel. The response surface methodology showed that the yield is positively influenced by lower pHs, longer extraction times and higher liquid:solid ratio, whereas the uronic acid content decreases with increasing extraction time. The conditions that resulted in the highest yield and highest uronic acid content were defined as pH 1.6, extraction time of 100 min and liquid:solid ratio of 36 mL/g. The pectin obtained under these conditions (PPOP) had an experimental yield of 25.6%, below the predicted theoretical value despite the good fit of the model (R2 = 0.96) and the galacturonic acid content was 84.5%, in close agreement with the predicted theoretical value. PPOP was composed mainly of a homogalacturonan with degree of methyl esterification of 85.7% and a rhamnogalacturonan I region mainly branched by galactans. In addition, PPOP had a very low degree of acetylation (0.1%) and average molar mass of 80,650 g/mol, determined by light scattering. The results showed that ponkan peel may be used as a source of citrus pectin in the regions where this species is cultivated.

Differential contribution of the two major polygalacturonases from Penicillium digitatum to virulence towards citrus fruit

The fungus Penicillium digitatum is the causal agent of the citrus green mould, the major postharvest diseases of citrus fruit. Lesions on the surface of infected fruits first appear as soft areas around the inoculation site, due to maceration of fruit. The macerating activity has been associated with pectinases secreted by the fungus during infection. In order to evaluate the contribution to virulence and macerating activity of the two major polygalacturonases (PGs) secreted by P. digitatum, we have obtained and characterized mutants lacking either pg1 or pg2, the genes encoding PG1 and PG2, respectively. Disease incidence of deletants in either gene was not different from that of the parental strain or ectopic transformants. However, disease progressed more slowly in deletants, especially in those lacking the pg2 gene. The lesions originated by the Δpg2 deletants were not as soft and the pH was not as acid as those originated by either the wild type strain or the ectopic transformants. Total PG activity in the macerated tissue was also lower in fruits infected with the Δpg2 deletants. Interestingly, the macerated tissue of oranges infected with Δpg2 deletants showed around 50% reduction in galacturonic acid content with respect to lesions caused by any other strain.

Effects of high hydrostatic pressure and high pressure homogenization processing on characteristics of potato peel waste pectin

To better understand the effects of high pressure processing on potato peel waste pectins, the structural characteristics, physicochemical properties, and morphological features of the pectin treated with high hydrostatic pressure (HHP) and high pressure homogenization (HPH) at 200 MPa for 5 min were studied. The potato peel waste pectins subjected to high pressure treatments exhibited increased galacturonic acid contents as well as decreased esterification degree, (Gal + Ara)/Rha ratio, and molecular weight. Furthermore, the potato peel waste pectins treated with high pressure had an increased viscosity and improved emulsifying properties. The morphological features, determined by atomic force microscopy, shown the degradation of side chains of the pectin induced by high pressure treatments. The results suggest that high pressure processing is an efficient technique to modify pectin from potato peel waste to a thickener or stabilizer agent, but high pressure homogenization shows a better effect.

Effect of the degree of esterification and blockiness on the complex coacervation of pea protein isolate and commercial pectic polysaccharides

The complex coacervation of pea protein isolate (PPI) with commercial pectic polysaccharides [high methoxy citrus pectin (P90, 90 representing DE), apple pectin (P78) sugar beet pectin (P62), low methoxy citrus pectin (P29)] of different degrees of esterification (DE) [and galacturonic acid content (GalA)] and blockiness (DB), was investigated. The maximum amount of coacervates formed at a biopolymer weight mixing ratio of 4:1 for all PPI-pectin mixtures, with the exception of PPI-P29 where maximum coacervation occurred at the 10:1 mixing ratio. The pH at which maximum interactions occurred was pH 3.4–3.5 (PPI: P90/P78) and 3.7–3.8 (PPI: P62/P29). PPI complexed with pectins with high levels of DE (low levels of GalA) and DB displayed greater interactions at optimal mixing conditions compared to pectin having lower levels of esterification and blockiness. The addition of P78 to PPI greatly increased protein solubility at pH 4.5.