Pectic Fractions Research Articles

Pectin obtention from agroindustrial wastes of Malus domestica using green solvents (citric acid and natural deep eutectic solvents). Chemical, thermal, and rheological characterization.

The use of green solvents, citric acid (CA), and natural deep eutectic solvents (NADES) for the obtention of pectin from wastes (pulp and peel) of Malus domestica was studied. The NADES used comprised citric acid-glucose-water (N1) or lactic acid-glucose-water (N2). The fractions rich in pectin obtained after exposure to NADES showed lower yield (≈4 g/100g CA vs. ≈ 11g/100g CA), equal to or lower degree of methoxylation (53-71mol/100mol CA vs. 73mol/100mol CA), equal to or greater content of uronic acid (50-63 g/100g CA vs. 51g/100g CA) than those isolated with CA, and the ones obtained from peel were the most thermally stable. These pectins showed greater linearity, shorter branch lengths, and lower arabinose content than those obtained with CA. The neutral sugars present in the highest concentration in all the isolated fractions were arabinose, xylose, galactose, and rhamnose. Glucose was also detected, probably due to contamination with starch. Their aqueous solutions showed pseudoplastic behavior. The effect of ultrasound assistance was preliminarily evaluated in the production of pectic fractions using N2, observing higher yields (13-18g/100g), in general, a higher concentration of uronic acid and a higher degree of methoxylation when compared with the extraction without US. They also showed greater arabinose content (less degradative treatment), lower glucose content (increased purity), and higher rhamnogalacturonan I (RG-I) content. It is known that RG-I is linked to pectin bioactivity and rheological behavior. The green solvent techniques assayed allowed obtaining fractions rich in uronic acid with different chemical, thermochemical, and rheological characteristics. In the case of isolation with NADES, the yield was low, but preliminary tests with ultrasound assistance showed that it is possible to overcome this limitation.

Valorisation of Blackcurrant Pomace by Extraction of Pectin-Rich Fractions: Structural Characterization and Evaluation as Multifunctional Cosmetic Ingredient

Blackcurrant pomace is a widely available waste stream derived from the industrial production of juice rich in pectin and unextracted polyphenols. Since pectin, an emerging class of gastrointestinal prebiotics, is also a common cosmetic ingredient, the aim of this work was to evaluate blackcurrant pomace as a source of pectin-rich fractions suitable for application in prebiotic cosmetics. Hereby, this raw material was valorised by sequential extraction of acid-soluble (by citric acid, CAP) and Ca-bound (by ammonium oxalate, AOPP) pectic polysaccharides. Both fractions had favourable physicochemical features and a similar degree of methyl-esterification between low- and high-methoxyl pectin (approx. 50%), but CAP had significantly higher galacturonic acid content (72.3%), branching, and purity. Regardless of that, both had very high oil (18.96 mL/g for CAP and 19.32 mL/g for AOPP) and water (9.97 mL/g for CAP and 7.32 mL/g for AOPP)-holding capacities and excellent emulsifying properties, making them promising cosmetic ingredients. The polyphenol content was 10 times higher in CAP, while corresponding antioxidant activity was 3-fold higher. Finally, the influence of varying CAP and AOPP concentrations on common skin pathogen, Staphylococcus aureus, and beneficial skin bacteria, Staphylococcus epidermidis, was examined. The results show significant prebiotic potential of two pectic fractions since they were capable of selectively stimulating S. epidermidis, while S. aureus growth was inhibited, whereas CAP demonstrated a particularly high capacity of up to 2.2, even with methicillin-resistant S. aureus.

Pectin-like heteroxylans in the early-diverging charophyte Klebsormidium fluitans.

The cell walls of charophytic algae both resemble and differ from those of land plants. Cell walls in early-diverging charophytes (e.g. Klebsormidiophyceae) are particularly distinctive, in ways that may enable survival in environments that are incompatible with land-plant polymers. This study therefore investigates the structure of Klebsormidium polysaccharides. The 'pectin' fraction (defined by extractability) of Klebsormidium fluitans, solubilised by various buffers from alcohol-insoluble residues (AIRs), was digested with several treatments that (partially) hydrolyse land-plant cell-wall polysaccharides. Products were analysed by gel-permeation and thin-layer chromatography. The Klebsormidium pectic fraction made up ~30-50% of its AIR, was optimally solubilised at pH 3-4 at 100°C, and contained residues of xylose ≈ galactose > rhamnose > arabinose, fucose, mannose, glucose. Uronic acids were undetectable and the pectic fraction was more readily solubilised by formate than by oxalate, suggesting a lack of chelation. Some land-plant-targeting hydrolases degraded the Klebsormidium pectic fraction: digestion by α-l-arabinanase, endo-β-(1⟶4)-d-xylanase, and α-d-galactosidase suggests the presence of β-(1⟶4)-xylan with terminal α-l-arabinose, α-d-galactose and (unexpectedly) rhamnose. 'Driselase' released oligosaccharides of xylose and rhamnose (~1:1) and graded acid hydrolysis of these oligosaccharides indicated a 'rhamnoxylan' with rhamnose side-chains. Partial acid hydrolysis of Klebsormidium pectic fraction released rhamnose plus numerous oligosaccharides, one of which comprised xylose and galactose (~1:2 Gal/Xyl), suggesting a galactoxylan. Lichenase was ineffective, as were endo-β-(1⟶4)-d-galactanase, endo-β-(1⟶4)-d-mannanase, β-d-xylosidase and β-d-galactosidase. Klebsormidium pectic fraction possesses many land-plant-like linkages but is unusual in lacking uronic acid residues and in containing rhamnoxylan and galactoxylan domains. Uronic acids allow land-plant and late-diverging charophyte pectins to form Ca2+-bridges, facilitating cell-wall polymer association; their absence from Klebsormidium suggests that neutral heteroxylans rely on alternative cross-linking mechanisms. This lack of dependency on Ca2+-bridges may confer Klebsormidium's ability to grow in the acidic, metal-rich environments which it tolerates.

Valorization of pectins from coffee wastes for the development of pectin-chitosan films

Coffee wastes are underused materials, largely available in coffee producing regions, which can be used to obtain pectins for the development of films for packaging. Coffee residual water (CRW) provided a phenolic and protein rich-pectic fraction (CRWP), which has 49 % uronic acid. This pectic fraction was used for the development of films with chitosan (Chit). Additionally, pectins extracted from coffee pulp with acid, Coffea arabica pectin (CAP), hot water-soluble pectic fraction (HWSP), and chelating agent-soluble pectic fraction (CSP), were used to develop pectin-chitosan films. Flow and viscoelastic properties of film forming solutions were assessed, showing better characteristics for the pectins from the pulp over those from the residual water. The different composition of the pectin fractions allowed to relate film properties with their structural features and Fourier transform infrared (FTIR) spectroscopy showed interactions between pectin and chitosan in the films. Results showed that CAP-Chit and CSP-Chit films were transparent, hydrophobic, and had the best mechanical properties. These results demonstrate that coffee residual wastes have the potential to provide pectins that can be used for the development of films.

Fractionation and characterization of cell wall polysaccharides from coffee (Coffea arabica L.) pulp

Cell wall polysaccharides were isolated by sequential extractions from coffee pulp, the main solid waste from coffee processing. Extractions were conducted with distilled water at room and boiling temperatures, 0.5 % ammonium oxalate and 0.05 M Na2CO3 to obtain pectic fractions. Hemicelluloses were extracted by using 2 M and 4 M NaOH. The composition of the hemicellulose fractions suggested the presence of xyloglucans, galactomannans and arabinogalactan-proteins (AGPs). The main part of the cell wall polysaccharides recovered from coffee pulp were pectins branched with arabinogalactans. Coffee pulp pectic fractions were low-methoxylated with various amounts of protein (0.5–8.4 %) and phenolics (0.7–8.5 %). Detection at 280 nm in the HPSEC analyses and radial gel diffusion assay using Yariv reagent indicated the presence of AGPs in most of these fractions. NMR analyses of chelating agent (CSP) and dialyzed water (WSPD) extracted pectins were carried out. The results demonstrated that CSP contains only AG I. On the other hand, AG I and AG II are present in WSPD, probably covalently linked to the pectic portion. Comparison with the literature indicated similarities between the cell wall polysaccharides from coffee pulp and green coffee beans.

Changes in the physicochemical characteristics and biological activities of polysaccharides from Panax ginseng during defense against red-skin disease

Red-skin roots are a common disease symptom in cultivation of Panax ginseng, which strongly affects its quality and production. Differences in polysaccharides between red-skin and healthy ginseng were examined for the first time to elucidate their function as resistance to disease and explore their potential as active ingredients. Fluorol Yellow 088 and ruthenium red staining revealed changes in the distribution and composition of ginseng polysaccharides during defense against red-skin disease. Acid pectin content was observed to increase significantly in cell walls of the diseased epidermal tissue. Furthermore, targeted extraction approaches were used to obtain water-solution polysaccharides (WPS) and pectic polysaccharides (PP) which marked different characteristics with the health group. WPS from red-skin roots exhibited novel pectic characteristics, consisting of 32.25% GalA which is 10 times more than the healthy sample, accompanied by a sharp decrease in starch content (approximately 50%). Another study on the adsorption and gel properties of PP indicated that it played an important role in disease resistance by reducing metal toxicity and increasing the strength of the cell wall. For further analysis of the abnormal pectic composition, DEAE-52 purification was used and various pectic fractions (WPS-1,2,3) consisting of the RG-Ⅰ pectic domain were obtained. The analysis of antioxidant and immunoactivity was performed to explore the effect of characteristic changes on biological activities. Higher radical scavenging ratios of DPPH and ABTS indicated that red-skin fractions had stronger antioxidant activities. Stronger promotion effect on Raw264.7 secretion of TNF-α and IL-1α represented the higher immunological activities. Therefore, the red-skin ginseng polysaccharides could be utilized in the pharmaceutical industry to compensate for the value loss caused by red-skin roots.

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

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

Gastrointestinal Fermentable Polysaccharide Is Beneficial in Alleviating Loperamide-Induced Constipation in Mice.

To investigate the role of gastrointestinal (GI) polysaccharide fermentation in alleviating constipation, two polysaccharide fractions were isolated from a soluble fiber extract with determined anti-constipation activity: a 2.04 kDa neutral fraction (SSP-1) contained 99.29% glucose, and a 41.66 kDa acidic fraction (SSP-2) contained 63.85% uronic acid. After mice were given loperamide for 14 d to induce constipation, the GI transit rate increased significantly in the SSP-1 group (p < 0.05) but not in the SSP-2 group. The stool weight in the SSP-2 group was significantly higher than that in SSP-1 (383.60 mg vs. 226.23 mg) (p < 0.05). Both SSP-1 and SSP-2 groups had significantly increased serum gastrin and motilin levels (p < 0.05) and changes in their fecal short-chain fatty acid (SCFA) profiles, while SSP-1 showed better fermentation properties than SSP-2 in terms of statistically higher fecal contents of acetic acid and total SCFAs (p < 0.05). Bioinformatic analysis indicated that SSP-1 upregulated bacteria such as Oscillibacter to improve SCFA metabolism and stimulate GI hormone secretion, while SSP-2 had less influence on the gut microbiota. These results suggest that the neutral polysaccharide with superior GI fermentation properties exerted beneficial effects on constipation, while the less fermentable pectic fraction might act as a stool-bulking agent.

The cell walls of different Chara species are characterized by branched galactans rich in 3-O-methylgalactose and absence of AGPs.

Streptophyte algae are the closest relatives to land plants; their latest common ancestor performed the most drastic adaptation in plant evolution around 500 million years ago: the conquest of land. Besides other adaptations, this step required changes in cell wall composition. Current knowledge on the cell walls of streptophyte algae and especially on the presence of arabinogalactan-proteins (AGPs), important signalling molecules in all land plants, is limited. To get deeper insights into the cell walls of streptophyte algae, especially in Charophyceae, we performed sequential cell wall extractions of four Chara species. The three species Chara globularis, Chara subspinosa and Chara tomentosa revealed comparable cell wall compositions, with pectins, xylans and xyloglucans, whereas Chara aspera stood out with higher amounts of uronic acids in the pectic fractions and lack of reactivity with antibodies binding to xylan- and xyloglucan epitopes. Search for AGPs in the four Chara species and in Nitellopsis obtusa revealed the presence of galactans with pyranosidic galactose in 1,3-, 1,6- and 1,3,6-linkage, which are typical galactan motifs in land plant AGPs. A unique feature of these branched galactans was high portions of 3-O-methylgalactose. Only Nitellopsis contained substantial amounts of arabinose A bioinformatic search for prolyl-4-hydroxylases, involved in the biosynthesis of AGPs, revealed one possible functional sequence in the genome of Chara braunii, but no hydroxyproline could be detected in the four Chara species or in Nitellopsis obtusa. We conclude that AGPs that is typical for land plants are absent, at least in these members of the Charophyceae.

Extraction, characterization, and antioxidant properties of cell wall polysaccharides from the pericarp of Citrus Reticulata cv. Chachiensis

The pericarp of Citrus reticulata cv. Chachiensis (PCRC) had been used as a traditional herbal medicine in southeast and eastern Asia, and it was also an important source of nutraceuticals and functional food ingredients. In the present study, the cell wall polysaccharides were sequentially extracted from PCRC using different solvents, resulting in five pectic fractions and two hemicellulose fractions, namely water-soluble pectin (WSP), hot water-soluble pectin (HWSP), chelator-soluble pectin (CSP), diluted acid-soluble pectin (HSP), sodium carbonate-soluble pectin (NSP), 1 mol/L KOH soluble hemicellulose (KSH-1) and 4 mol/L KOH soluble hemicellulose (KSH-2). The seven fractions were characterized in terms of composition, structure, thermal, rheological, and antioxidant properties. The pectin fractions were classified as high-methoxy pectin with a degree of methyl esterification (DM) between 56.89% and 62.20%. Ammonium oxalate extraction provided the CSP fraction with the highest content of galacturonic acid (75.18%) and the lowest degree of acetylation (0.03). HWSP was considered to be an aggregative of homogalacturonan (HG) and rhamnogalacturonan I (RG-I) containing side chains of galactans and arabinans. Thermal analysis indicated that HWSP had the highest thermal stability than other fractions. All fractions exhibited the characteristics of non-Newtonian fluids, with NSP showing the highest apparent viscosity. Assays for antioxidant activities suggested WSP had the highest DPPH radical scavenging activity while NSP had the highest hydroxyl radical scavenging activity. The result could be a good basis for the applications of cell wall polysaccharides, especially pectin, of PCRC in the preparation of functional food products.

Sweetpotato chip texture and fat content: Effects of enzymatic modification of cell wall polymers.

Impacts of cell wall polymers on sweetpotato chip texture and fat content were investigated through enzymatic modification. Covington sweetpotato slices were treated with cellulase, hemicellulase, pectinase, pectin methyl esterase, protease, the enzyme blend Viscozyme, or no enzymes (control) at 40-45°C for 0.5-2 h. Treated slices were blanched, dried, and fried in triplicate per experimental condition. Breaking forces of 20 chips per frying replicate were measured followed by chip fat, moisture, sugar, alcohol insoluble solids, glass transition temperature, and color analyses. Untreated slices from each batch (daily check) were fried and analyzed to account for starting material variability. Viscozyme and protease-treated chips had the greatest reduction in breaking force from untreated chips (-30.9% and -23.7%, respectively), while pectin methyl esterase-treated chips had the lowest reduction in breaking force (-9.0%). Chips treated with Viscozyme for 2 h were 6.7-6.3 percentiles lower in fat than the control. Principal component analysis elucidated that chip breaking force was associated with unfried slice puncture force, alcohol insoluble solids, and chip color, and chip fat content was inversely associated with maltose content and glass transition temperature. Breaking down multiple cell wall polysaccharides or structural proteins weakened chip textures, while strengthening the pectic fraction resulted in harder chips. Chip fat reduction also occurred when multiple cell wall polysaccharides were broken down. Therefore, cell wall polymers impact sweetpotato chip texture and fat contents, and their attributes should be considered when selecting cultivars and processes for sweetpotato chips. PRACTICAL APPLICATION: Sweetpotato chips are an increasingly popular snack, but there is little understanding how cell wall polymers impact chip textures and fat contents. Raw sweetpotato slices were enzymatically treated to selectively modify cell wall polymers before frying. Chip breaking forces were lowered by protease or Viscozyme (cell wall enzyme blend) treatments, while breaking forces were increased with pectin methyl esterase. In addition, chip fat contents were reduced by the Viscozyme treatment. Since cell wall modifications could impact chip texture and fat content, cell wall polymer attributes should be considered in selection and processing of sweetpotatoes for chip manufacturing.

Profiling the cell walls of seagrasses from A (Amphibolis) to Z (Zostera)

BackgroundThe polyphyletic group of seagrasses shows an evolutionary history from early monocotyledonous land plants to the marine environment. Seagrasses form important coastal ecosystems worldwide and large amounts of seagrass detritus washed on beaches might also be valuable bioeconomical resources. Despite this importance and potential, little is known about adaptation of these angiosperms to the marine environment and their cell walls.ResultsWe investigated polysaccharide composition of nine seagrass species from the Mediterranean, Red Sea and eastern Indian Ocean. Sequential extraction revealed a similar seagrass cell wall polysaccharide composition to terrestrial angiosperms: arabinogalactans, pectins and different hemicelluloses, especially xylans and/or xyloglucans. However, the pectic fractions were characterized by the monosaccharide apiose, suggesting unusual apiogalacturonans are a common feature of seagrass cell walls. Detailed analyses of four representative species identified differences between organs and species in their constituent monosaccharide composition and lignin content and structure. Rhizomes were richer in glucosyl units compared to leaves and roots. Enhalus had high apiosyl and arabinosyl abundance, while two Australian species of Amphibolis and Posidonia, were characterized by high amounts of xylosyl residues. Interestingly, the latter two species contained appreciable amounts of lignin, especially in roots and rhizomes whereas Zostera and Enhalus were lignin-free. Lignin structure in Amphibolis was characterized by a higher syringyl content compared to that of Posidonia.ConclusionsOur investigations give a first comprehensive overview on cell wall composition across seagrass families, which will help understanding adaptation to a marine environment in the evolutionary context and evaluating the potential of seagrass in biorefinery incentives.

Sequential extraction and analysis of cell wall polysaccharides from Inula viscosa leaves and stems

Inula viscosa (syn Dittrichia viscosa) (sticky fleabane) from the Asteraceae family, is well-known for its pharmacological activities. In this research, anatomical characterization of leaves and stems of Inula viscosa plants revealed a considerable heterogeneity in their cell walls. Cell walls were isolated separately from leaves and stems and subjected to sequential extractions with boiling water, oxalate ammonium, KOH and NaOH solutions. The four polysaccharide fractions obtained were comparatively analysed using gas chromatography-flame ionization detector (GC-FID) and Fourier Transform Infrared–Attenuated Total Reflectance (ATR-FTIR) spectroscopy. The findings showed that the polysaccharides were unevenly distributed in the two organs. ATR-FTIR data reflected a higher proportion of pectins in stems relative to leaves in both fractions. Pectic fractions (hot water soluble and oxalate soluble fractions) seemed to be mainly composed by homogalacturonan and rhamnogalacturonan, with a residual presence of inulin. Hemicellulose (KOH and NaOH) fractions, instead, were rich in xylans, and still contained a low proportion of pectic polysaccharides. ATR-FTIR data pointed to a higher proportion of xylans in stems than in leaves. Finally, attending the molecular mass of cell wall polysaccharides from leaves, pectin fractions showed the presence of populations of polysaccharides with lower molecular masses than those of hemicellulose fractions.

Preparation, characterization, antioxidant and anti-inflammatory activities of acid-soluble pectin from okra (Abelmoschus esculentus L.)

Currently, there are few studies on acid-soluble pectin from okra, especially in biological activity for antioxidant and anti-inflammatory. In this study, the antioxidant properties of acid-soluble okra pectin components and their anti-inflammatory were explored. Firstly, two acid-soluble okra pectic fractions, namely crude acid-soluble okra pectin (CAOP) and acid-soluble okra pectin (AOP), were obtained and exhibited structural and compositional variation. The two pectic fractions contained a low degree of esterification (42.0–46.5%) and a relatively high uronic acid content (31.6–37.3%). AOP was composed of galacturonic acid (79.1 mol/%), galactose (4.3 mol/%), rhamnose (14.5 mol/%) and xylose (2.1 mol/%), and the molecular weight was 92.8 kDa. Morphological and thermal properties of acid-soluble okra pectin components were also investigated. Compared to CAOP, AOP expressed better antioxidant activity, and suppressed the NO production in LPS-induced RAW 264.7 macrophages. All the above results indicated that AOP had the potential to act as a natural antioxidant or a functional anti-inflammatory food, which would broaden the development and utilization of okra resources.

Cell Wall Polysaccharide Composition of Grafted 'Liberty' Watermelon With Reduced Incidence of Hollow Heart Defect.

Grafting watermelon scions to interspecific squash hybrids has been found to increase fruit firmness. Triploid (seedless) watermelon are prone to hollow heart (HH), an internal fruit disorder characterized by a crack in the placental tissue expanding to a cavity. Although watermelon with lower tissue firmness tend to have a higher HH incidence, associated differences in cell wall polysaccharide composition are unknown. Grafting “Liberty” watermelon to “Carnivor” (interspecific hybrid rootstock, C. moschata × C. maxima) reduced HH 39% and increased tissue firmness by 3 N. Fruit with and without severe HH from both grafted and non-grafted plants were analyzed to determine differences in cell wall polysaccharides associated with grafting and HH. Alcohol insoluble residues (AIR) were sequentially extracted from placental tissue to yield water soluble (WSF), carbonate soluble (CSF), alkali soluble (ASF), or unextractable (UNX) pectic fractions. The CSF was lower in fruit with HH (24.5%) compared to those without HH (27.1%). AIRs were also reduced, hydrolyzed, and acetylated for GC-MS analysis of monosaccharide composition, and a portion of each AIR was methylated prior to hydrolysis and acetylation to produce partially methylated alditol acetates for polysaccharide linkage assembly. No differences in degree of methylation or galacturonic and glucuronic acid concentrations were found. Glucose and galactose were in highest abundance at 75.9 and 82.4 μg⋅mg–1 AIR, respectively, followed by xylose and arabinose (29.3 and 22.0 μg⋅mg–1). Mannose was higher in fruit with HH (p < 0.05) and xylose was highest in fruit from grafted plants (p < 0.05). Mannose is primarily found in heteromannan and rhamnogalacturonan I side chains, while xylose is found in xylogalacturonan or heteroxylan. In watermelon, 34 carbohydrate linkages were identified with galactose, glucose, and arabinose linkages in highest abundance. This represents the most comprehensive polysaccharide linkage analysis to date for watermelon, including the identification of several new linkages. However, total pectin and cell wall composition data could not explain the increased tissue firmness observed in fruit from grafted plants. Nonetheless, grafting onto the interspecific hybrid rootstock decreased the incidence of HH and can be a useful method for growers using HH susceptible cultivars.

Characterization of tissue‐specific differences in cell wall pectic polysaccharides of carrot root

This study investigated the physicochemical characteristics of CWPs from epidermis, cortex, and stele of carrot. The CWPs extracted from cortex contained the highest content of galacturonic acid (GalA), as well as the highest degree of methylation. Compared to Na2CO3 extractable fraction (NEF) and water extractable fraction (WEF), chelator extractable fraction (CEF) contained higher GalA content, and it was identified with more linear homogalacturonan (HG). The highest amounts of Gal, Ara, and Rha were obtained in NEF extracted from cortex, suggesting that abundant side chains attached to pectic backbone of NEF and formed “hairy region.” In addition, gentle changes of the molar mass along with tissue zones were observed in different pectic fractions. However, the molar mass of NEF was always higher than WEF regardless of the tissues. According to FTIR, the configurations of all CWPs were similar and exhibited typical structural properties of pectic polymers. Practical applications Cell wall pectic polysaccharides (CWPs) are important macromolecules which highly correlated with food products qualities. The CWPs extracted from epidermis, cortex, and stele of carrot root were prepared and their physicochemical characteristics were evaluated. Detailed characteristics of tissue-specific differences in CWPs of carrot root could provide more fundamental information for carrot-related food processing.

Optimization of acid-extraction of pectic fraction from grape (Vitis vinifera cv. Chardonnay) pomace, a Winery Waste

Chardonnay grape pomace was evaluated as a source of pectin. A central composite design was used in order to determine the effect of pH, extraction time (Et) and liquid: solid ratio (LS) on the yield and uronic acid (UA) content of the pectins extracted using boiling HNO3 solution. The optimized extraction condition to reach the maximum yield and UA was pH = 2.08, Et = 135.23 min and LS = 35.11 ml/g, resulting in theoretical yield of 12.8% and UA of 64.4%. The experimental yield of the pectic fraction obtained under the optimized conditions (GPOP) was 11.1% and the UA was 56.8%. GPOP had ~25% glucose. It was treated with α-amylase and amyloglucosidase, resulting in the fraction α-GPOP. The starch-free pectic fraction was composed of 63.5% UA, 7.8% rhamnose, 6.0% arabinose, 13.6% galactose and minor amounts of other neutral monosaccharides. It contained a low-methoxyl pectin (degree of methyl-esterification 18.1%) and had an average molar mass of 154,100 g/mol. It consisted of 55.7% homogalacturonan and 35.2% rhamnogalacturonan I (RG-I). NMR analyses suggest that RG-I portion of α-GPOP is highly branched by short chains or single residues of arabinose and galactose.

Pectins from food waste: Characterization and functional properties of a pectin extracted from broccoli stalk

Currently about 60–75% of world broccoli production is wasted during harvesting. The aim of the present study was to extract and characterise the pectin present in broccoli stalks and to evaluate its functional properties. The stalks were initially treated with boiling ethanol to remove compounds such as pigments and free sugars and then the pectin (FB) was extracted with 0.1 M nitric acid for 30min. The pectic fraction FB (18% yield) was found to contain 75% galacturonic acid with a degree of methyl-esterification of 56%, and an acetyl content of 1.1%. Rhamnose and galactose were the main neutral sugars present. NMR analyses showed that FB was composed of homogalacturonan and rhamnogalacturonan I substituted with β-1,4-D-galactan. The molar mass of FB was 72.2 × 103 g/mol and the viscosity of a 5% (w/w) solution in 0.1M NaCl at pH 4 showed shear thinning behaviour with a low shear Newtonian plateau of ~100 Pa s at 25 °C. At the same concentration FB showed a weak gel like behaviour. FB (0.5–4%, w/w) was also able to stabilize medium chain triglyceride oil in water emulsions. The results suggest that broccoli stalk could be used as an alternative source of commercial pectins.

Effects of bovine serum albumin on the ethanol precipitation of sugar beet pulp pectins

Bovine serum albumin (BSA) was used as an auxiliary to improve the ethanol precipitation yield of sugar beet pulp pectin (SBPP). The adjunction of BSA reduced the zeta potential of SBPP solution to a certain extent, which indicated that they were related to each other by electrostatic interaction. The hydration radius (Rh) of SBPP molecules decreased with the addition of BSA, reflecting the decrease of hydration degree of SBPP molecules. The effect of BSA on the ethanol precipitation yield of SBPP at different ethanol concentrations and different pH values was studied. The results showed that the presence of BSA could significantly reduce the dependence of SBPP on ethanol during the precipitation process. The effect of BSA on the precipitation behavior of SBPP was also regulated by system pH. The results of pectin structural analysis showed that there was no significant difference between SBPPs precipitated along with BSA and the original pectin samples in terms of galacturonic acid (GalA), neutral sugar (NS) and degree of methylation (DM). The high-performance size-exclusion chromatography (HPSEC) analysis showed that BSA could precipitate together with SBPP, but did not contribute to the precipitation of small-sized pectic fractions in SBPP solution. SBPP-BSA co-precipitation products were used to stabilize oil-in-water emulsions, and the storage stability of the resulting emulsions was significantly higher than that of the SBPP-stabilized emulsions. This method provided a new idea for reducing the consumption of ethanol in pectin precipitation. Meanwhile, the pectin-protein complex product obtained by co-precipitation had a good performance at stabilizing emulsions.

Molecular binding between anthocyanins and pectic polysaccharides – Unveiling the role of pectic polysaccharides structure

The interaction between cyanidin-3-O-glucoside and four citrus pectic fractions was investigated using a combined molecular approach, including isothermal titration calorimetry (ITC), magnetic nuclear resonance (NMR) and UV–Visible spectrophotometry. These pectic fractions differed on their type and degree of esterification (amidated (AHG 30%), low (HG 30%) and high methyl esterified fractions (HG 70%)) and on the pattern of esterification (blockwise (HG-B 70%) vrs random (HG-R 70%)). The binding constant (Ka) and the associated thermodynamic parameters determined showed weak noncovalent interactions, particularly due to electrostatic interactions, hydrogen bonding and hydrophobic effect. The degree and the type of esterification of each pectic fractions had a significant effect on the binding constants determined by ITC and NMR experiments. The binding constants ranged from 102 to 104 M−1, with the highest Ka value observed for the interaction between cy3glc and low methylesterified fraction, followed by the amidated fraction. Pectic fractions with a higher degree of methyl esterification, resulted on lower binding affinities, with these interactions being mostly driven by hydrophobic effect compared to enthalpy. The different binding affinities could be correlated with anthocyanins colour impact, as a higher red colour intensity could be observed for a cy3glc model solution fortified with a low methylated fraction. However, this colour improvement was not observed for amidated fraction, presumably due to charge repulsive forces, lowering the stability of the flavylium cation.