Galacturonic Acid Content Research Articles

Isolation and characterisation of pectic substances from murta ( Ugni molinae Turcz) fruits

Cell walls polysaccharides from murta fruit ( Ugni molinae Turcz), an endemic Chilean species with relevant food uses, were fractionated by water, ammonium oxalate, hot diluted HCl and cold diluted NaOH extractions. The polysaccharide fractions were analysed for monosaccharide composition and physicochemical properties. Pectic substances were found in all extracts, but mainly in the oxalate and acid soluble fractions, in which they appear as homogalacturonan polymers. Murta pectin was further extracted by hot diluted acid treatment using industrial conditions, yielding 30% by weight of dry fruit. The polymer showed similar composition and physicochemical properties to those of commercial citrus pectin, presenting a galacturonic acid content of 70.9% (w/w), a molecular weight of 597 kDa, and a methoxylation degree of 57%. The FT-IR spectrum of murta pectin suggests the presence of ferulic acid residues on its structure and the NMR analysis confirmed the structure of this polysaccharide. It is concluded that murta fruit can be considered as a valuable source of high quality pectin.

Pectin Extraction from Lemon By-Product with Acidified Date Juice: Effect of Extraction Conditions on Chemical Composition of Pectins

Mixtures of date and lemon pectins were extracted from lemon by-product with acidified date juice under different conditions of temperature, pH and time. Individual pectins from date and lemon, respectively, were also extracted using the same experimental conditions, then analysed and compared to pectin mixtures. It was found that the use of extreme conditions resulted in higher galacturonic acid content, lower degree of methylation, lower neutral sugar content, lower molecular weight and darker colour pectins. Examination of the individual neutral sugars showed that the main ones were galactose (1.6–5.4%), arabinose (1.6–4.2%) and rhamnose (0.5–0.8%). The Gal A/Rha molar ratios varied from ∼53 to ∼149. Moreover, mixture of pectin extracted at the optimal extraction conditions (84.34 °C, pH 2.8 during 3 h 34 min) had interesting properties, with a high galacturonic acid content (63.4%), low degree of methylation (∼35%) and a mass molecular weight of about 243 kg/mol.

A study of the recovery of the dietary fibres from olive mill wastewater and the gelling ability of the soluble fibre fraction

A novel method of the recovery of a dietary fibre containing material from olive mill wastewater (OMW) was developed. Extraction was based on thermal treatment with mixtures of ethanol and acids, prior to the isolation of the alcohol insoluble residue (AIR). Different mixtures were tested and the extracted residues were characterized. The maximum AIR recovery accounted 64.8 g/100 g OMW dry matter, while the corresponding total fibre content was 5.1 g/100 g of the AIR. Despite the high potassium (8.4 g/100 g) and the low galacturonic acid content (3.3 g/100 g), AIR was able to form gels after a simple isolation and concentration of the soluble fraction. The soluble fibres were exclusively composed of pectin (93.9 and 6.1 mol/100 mol galacturonic acid and arabinose, respectively) with 59 mol/100 mol GalA degree of methylation. The viscoelastic properties of the gels were evaluated as a function of galacturonic acid content, where the gel rigidity and elasticity was found to increase exponentially with this parameter. A further treatment of the pectin material with citric acid during its concentration, allowed the formation of more rigid, but less elastic gels.

Extraction of pectins with different degrees of esterification from mulberry branch bark

Pectins were extracted from mulberry branch bark, a byproduct of the sericulture industry. A single-factor experiment was used to optimize the production conditions. Under optimal conditions, the galacturonic acid yields from bark with and without epidermis were 61.73 ± 1.39% and 35.12 ± 0.24%, respectively. The extracted pectins mainly consisted of galacturonic acid with a trace amount of neutral sugars, and the total galacturonic acid content in the pectins extracted from the bark without epidermis reached 85.46 ± 2.76%. Pectins extracted from bark without epidermis had a higher degree of esterification (71.13 ± 1.67%) than those extracted from bark with epidermis (24.27 ± 2.89%). Pectin solution from bark without epidermis showed higher apparent viscosity, suggesting its higher gelation ability. Thus, the mulberry branch bark is a potential source of pectin with different degrees of esterification.

Effect of extraction conditions on the quality characteristics of pectin from passion fruit peel ( Passiflora edulis f. flavicarpa L.)

Passion fruit ( Passiflora edulis f. flavicarpa L.) yellow variety is composed of 50–55 g peel per 100 g of fresh fruit which is discarded as waste during processing. Utilization of passion fruit peel for pectin extraction was studied. Passion fruit peel obtained after juice extraction was blanched in boiling water for 5 min, dehydrated in a cross flow hot air drier at 60 ± 1 °C to a moisture content of 4 g/100 g of dried peel. The dehydrated passion fruit peel was used for extraction experiments of pectin. The effect of pH, peel to extractant ratio, and number of extractions, extraction time and temperature on the yield and quality characteristics of pectin were investigated. The optimized conditions for extraction of pectin from passion fruit peel yielded 14.8 g/100 g of dried peel. Pectin extracted from the dried peels had a methoxyl content of 9.6 g/100 g, galacturonic acid content of 88.2 g/100 g and jelly grade of 200. Extraction of pectin from dried peels of passion fruit may be considered for effective utilization of passion fruit processing waste.

Apple Pectin Behavior Separated by Ultrafiltration

Separation conditions of ultrafiltration for apple pectin, and relations between apple pectin with different relative molecular weights and their structures and properties are studied. Five kinds of ultrafiltration membranes with different molecular weight cut-offs are used to separate apple pectin. FT-IR and HPGC are used individually to determine the structures and monosaccharide composition of apple pectin with different relative molecular weights. In the case of transmembrane pressure difference of 0.08 MPa, material concentration of 1 g L −1, and temperature of 50°C, 6 kinds of apple pectins with different molecular weights have been obtained. Molecular weight of apple pectin is correspondingly related to its physicochemical properties. The galacturonic acid contents and esterification and gelatination degrees increase relatively with an increase in molecular weight, and the monosaccharide composition relatively increase much more. And at the same time, the ultrafiltration has a better role to play in decoloring apple pectin solution. Accordingly, this research can be used as a new method for in-depth exploration of apple pectin.

Lemon juice improves the extractability and quality characteristics of pectin from yellow passion fruit by-product as compared with commercial citric acid extractant

An environment-friendly procedure, allowing the extraction of safe pectin products with good functional properties from yellow passion fruit by-product, was developed using two natural acid extractants, namely, pure lemon juice and citric acid solvent. The results show that both of them solubilise, from cell wall material, pectins characterised by high galacturonic acid content (64–78% w/w), degree of esterification (52–73), viscosity-average molecular weight (70–95 kDa) and capable of forming gels in the presence of high soluble solids (sucrose) content and acid. However, compared to pure citric acid solvents, lemon natural juice and its concentrate isolate, under similar extraction conditions, pectins of superior quality characteristics, i.e., higher galacturonic acid content, degree of esterification, viscosity-average molecular weight and gelling power.

Optimasi Kondisi Depolimerisasi Pulp Biji Kakao

Pulp breaking on cocoa processing could be conducted with depolymerization of cocoa pulp by enzyme polygalacturonase (PG) endogenous. This research was aimed to determination the optimum condition of depolymerization of cocoa pulp by enzyme polygalacturonase endogenous during incubation. This research was carried out by incubating cocoa pulp for 6 days on various of optimum condition of PG endogenous treatments, that is: temperature were 32.5o C, 37.5o C, 42.5o C, 47.5o C, 52.5o C and initial pH of pulp were 4.1; 4.6; 5.1, respectively. Optimum condition of depolymerization of cocoa pulp was determination by effectiveness test. Effectiveness test result, based on the highest effectiveness index, showed that the optimum condition of depolymerization of cocoa pulp was 47.5o C incubation temperature and 4,6 initial pH of pulp. Those treatment produced 18.29% of pulp liquid wieght total during 5 days incubation with average per day for pectin content, galacturonic acid content, acid total content, and the change of pH were 1.12%, 8.36%, 0.209 meq NaOH/g and 0,19 in cocoa pulp extract was incubated for 6 days, respectively.

Pectin from low quality ‘Golden Delicious’ apples: Composition and gelling capability

Pectin was acid-extracted from low quality ‘Golden Delicious’ apple fruit, yielding 16% (w pectin/w apple fruit). Composition and some of its physicochemical and functional properties were assessed. The pectin fraction presented a galacturonic acid content of 65% (w/w), an esterification degree of 57%, an intrinsic viscosity, [η], of 307 ml/g and a molecular weight (Mw) of 112 kDa. Pectin gels were obtained in 60% (w/v) fructose and pH 2.7. Pectin gels at 2.0% and 3.0% (w/v) presented hardness values of 10.2 and 20.4 g after 12 h at 4 °C. The gel hardness was greatly affected by aging (20% and 25% decrease in 48 h for gels at 2% and 3%, respectively). The results attained suggest the use of this gum as a potential texturing agent for the food industry.

Polyuronide content and correlation to optical properties measured by time-resolved reflectance spectroscopy in ‘Jonagored’ apples stored in normal and controlled atmosphere

Abstract Time-resolved reflectance spectroscopy (TRS) studies on fruit have shown that the absorption coefficient (μa) at 670 nm is a good maturity index and that the scattering coefficient ( μ s ′ ) at 780 nm allows an insight into the textural properties of apples. This work aimed at studying the relationship between the polyuronide pattern, firmness and TRS optical properties (μa and μ s ′ ) at 630, 670, 750 and 780 nm measured in ‘Jonagored’ apples at harvest, after 6 months’ storage in normal (NA) and controlled atmosphere (CA), and after 7 days of post-storage shelf life at 20 °C. Results showed that fruit of different TRS maturity class had a different polyuronide content, even if their firmness was not different: ‘less mature’ (high μa630) fruit compared to ‘more mature’ (low μa630) ones showed at harvest higher total galacturonic acid (GA) content, residue insoluble pectin (RIP) and protopectin index (PI), and lower GA content in oxalate-soluble pectin (OSP) fraction, indicating a less advanced breakdown of insoluble protopectins to soluble pectins. The μa630 and μa670 were correlated to alcohol-insoluble substances (AIS) and GA content in RIP measured after storage: as maturity increased, GA decreased in RIP, showing pectin solubilisation. AIS, water-soluble pectin (WSP), RIP and PI measured after storage were highly correlated to scattering coefficients measured after storage. Generally, with increasing μ s ′ , AIS and GA in WSP increased while firmness, RIP and PI decreased. CA apples were characterised by lower μ s ′ values than NA ones, along with lower WSP and OSP and higher total GA, RIP and PI.

Effect of extraction techniques and conditions on the physicochemical properties of the water soluble polysaccharides from gold kiwifruit (Actinidia chinensis)

SummaryThe extraction of nonstarch polysaccharides from fruits and vegetables has received much attention recently in terms of their utilisation in functional food systems. In New Zealand kiwifruit production is one of the major fruit growing exploits. This paper explores the potential extraction techniques which may be employed to extract water soluble polysaccharides from kiwifruit material, in an attempt to utilise this commodity as an added value food ingredient. Crude water soluble polysaccharides of fresh gold kiwifruit were extracted under different extraction techniques (acid, hot water and enzyme) and conditions (time, temperature and concentration). The recovery of water soluble polysaccharide fraction (WSP), chemical composition, and their rheological behaviour were examined. The extraction technique had a significant effect on the WSP yield, galacturonic acid content, as well as the viscosity. Enzymatic extraction method yielded higher WSP and galacturonic acid than water and acid extraction, but this fraction exhibited lower viscosity. Acid extracted WSP yield decreased with increasing temperature and time. In contrast, water extracted WSP yield increased with increasing temperature and time. The selected extraction parameters for acid extraction were temperature 50 °C, extraction time 60 min, and 1:6 kiwifruit puree to acid solution ratio. The water extraction optimum parameters were 25 °C, 30 min and 1:4 puree to water ratio and 25 °C, 30 min with medium concentration for enzymatic extraction. The WSP viscosity and galacturonic acid content was maximum under these extraction conditions.

Yield and Quality of Pectins Extractable from the Peels of Thai Mango Cultivars Depending on Fruit Ripeness

Pectins, recovered from the peels of four mango ( Mangifera indica L.) cultivars by mimicking industrial techniques, were evaluated in terms of yield, composition, macromolecular properties, and technofunctional quality. Freeze-dried peels of mature-green fruits, after major mesocarp softening, and at full ripeness were extracted using hot acid. The pectins were precipitated in propan-2-ol and their crude yields quantified as alcohol-insoluble substance. Like apple pomace, the dried peels provided hardly acetylated (DAc < 6.3%) rapid-set to ultrarapid-set high-methoxyl pectins at starch-adjusted yields of 11-21 g/100 g. However, despite similar high molecular weight fractions and galacturonic acid/rhamnose ratios, their average molecular weight was markedly reduced by a characteristic, almost monodisperse fraction of 16000-19000. Expanded galactans, indicated by galactose/rhamnose ratios of 15-24 mol/mol, probably represented arabinogalactan side-chain fragments withstanding hot-acid extraction at pH 1.5 and 2.0, as implied by arabinose/galactose ratios of 8-15 and 33-56 mol/100 mol, respectively. Limited galacturonic acid contents made the mango peel pectins less valuable than commercial apple pectins with regard to gelling capacity and thickening properties. Whereas starch and matrix glycan fragments almost completely degraded during ripening, depolymerization of pectins and galactans was insignificant. Technofunctional properties, modulated by extraction at different pH values, were ascribed to structural differences influencing macromolecular entanglements.

A subtilisin‐like serine protease essential for mucilage release from Arabidopsis seed coats

During Arabidopsis seed development large quantities of mucilage, composed of pectins, are deposited into the apoplast underneath the outer wall of the seed coat. Upon imbibition of mature seeds, the stored mucilage expands through hydration and breaks the outer cell wall that encapsulates the whole seed. Mutant seeds carrying loss-of-function alleles of AtSBT1.7 that encodes one of 56 Arabidopsis thaliana subtilisin-like serine proteases (subtilases) do not release mucilage upon hydration. Microscopic analysis of the mutant seed coat revealed no visible structural differences compared with wild-type seeds. Weakening of the outer primary wall using cation chelators triggered mucilage release from the seed coats of mutants. However, in contrast to mature wild-type seeds, the mutant's outer cell walls did not rupture at the radial walls of the seed coat epidermal cells, but instead opened at the chalazal end of the seed, and were released in one piece. In atsbt1.7, the total rhamnose and galacturonic acid contents, representing the backbone of mucilage, remained unchanged compared with wild-type seeds. Thus, extrusion and solubility, but not the initial deposition of mucilage, are affected in atsbt1.7 mutants. AtSBT1.7 is localized in the developing seed coat, indicating a role in testa development or maturation. The altered mode of rupture of the outer seed coat wall and mucilage release indicate that AtSBT1.7 triggers the accumulation, and/or activation, of cell wall modifying enzymes necessary either for the loosening of the outer primary cell wall, or to facilitate swelling of the mucilage, as indicated by elevated pectin methylesterase activity in developing atsbt1.7 mutant seeds.

Combined enzymatic and colorimetric method for determining the uronic acid and methylester content of pectin: Application to tomato products

A simple procedure for determining the galacturonic acid and methanol contents of soluble and insoluble pectins, relying on enzymatic pectin hydrolysis and colorimetric quantification, is described. Pectin samples are incubated with a commercial pectinase preparation, Viscozyme, then the galacturonic acid content of the hydrolyzed pectin is quantified colorimetrically using a modification of the Cu reduction procedure originally described by Avigad and Milner. This modification, substituting the commonly used Folin–Ciocalteau reagent for the arsenic containing Nelson reagent, gives a response that is linear, sensitive, and selective for uronic acids over neutral sugars. This method also avoids the use of concentrated acids needed for the commonly used m-phenylphenol method. Methanol, released by the action of the pectin methylesterase found in the Viscozyme, is quantified using alcohol oxidase and Purpald. This combined enzymatic and colorimetric procedure correctly determined the galacturonic acid and methanol content of purified, soluble citrus pectin. Application of the procedure to water insoluble pectins was evaluated with water insoluble material from apples and oranges. In both cases good agreement was obtained between this method and commonly used methods based on chemical pectin hydrolysis. Good agreement between these procedures was also found in the analysis of both soluble and insoluble pectins from several tomato products.

Structural Characterization and Solution Properties of a Galacturonate Polysaccharide Derived from Aloe vera Capable of in Situ Gelation

A series of highly purified galacturonate polysaccharides have been extracted from the Aloe vera plant and analyzed in terms of chemical composition and molecular weight. This Aloe vera polysaccharide (AvP) has been found to exist as a high molecular weight species and possess a unique chemical composition, including a high galacturonic acid (GalA) content and low degree of methyl ester substitution. These factors facilitate gel formation upon exposure to low concentrations of calcium ions, leading to potential application in formulations designed for in situ nasal or subcutaneous protein delivery. Thorough examination of classic dilute solution properties, the [eta]-M(w), and R(g)-M(w) relationships, persistence length (L(p)), and inherent chain stiffness (B parameter), indicate an expanded random coil in aqueous salt solutions. The critical concentration for transition from dilute to concentrated solution, C(e), was determined by measuring both the zero shear viscosity (eta(o)) and fluorescence emission of the probe molecule 1,8-anilino-1-naphthalene sulfonic acid (1,8-ANS) as a function of polymer concentration. Examination of zeta potential and C(e) as a function of ionic strength indicates that the shift in C(e) from 0.60 to 0.30 wt % is related to an increased occurrence of intermolecular interactions at high salt concentrations. Additionally, dynamic rheology data are presented highlighting the ability of AvP to form gels at low polymer and calcium ion concentrations, exemplifying the technological potential of this polysaccharide for in situ drug delivery.

Effect of variety and harvest date on pectin extracted from chicory roots (Cichorium intybus L.)

The influence of harvest date on pectin quality and yield of five varieties of chicory is investigated in this work. The pectin is extracted from the raw material with an acidic treatment at 85°C for an hour after inulin extraction. Main changes due to harvest date are observed in terms of neutral sugar content, average molecular weight, esterification degree and extraction yield. The galacturonic acid content remains relatively constant throughout the harvest period. While no statistically significant differences (p<0.05) in terms of galacturonic acid content and neutral sugar content are observed between the five cultivars studied, average molecular weight, esterification degree and extraction yield are significantly affected by the cultivar type. Depending on the harvest date, a broad range of pectins can easily be extracted from chicory pulps.

Characterisation of pectins extracted from banana peels (Musa AAA) under different conditions using an experimental design

An experimental design was used to study the influence of pH (1.5 and 2.0), temperature (80 and 90°C) and time (1 and 4h) on extraction of pectin from banana peels (Musa AAA). Yield of extracted pectins, their composition (neutral sugars, galacturonic acid, and degree of esterification) and some macromolecular characteristics (average molecular weight, intrinsic viscosity) were determined. It was found that extraction pH was the most important parameter influencing yield and pectin chemical composition. Lower pH values negatively affected the galacturonic acid content of pectin, but increased the pectin yield. The values of degree of methylation decreased significantly with increasing temperature and time of extraction. The average molecular weight ranged widely from 87 to 248kDa and was mainly influenced by pH and extraction time.

Relationship between texture and pectin composition of two apple cultivars during storage

The texture of two apple cultivars was characterised by sensory and instrumental methods for five different storage periods. The aim of this study was to explain the changes in apple texture during storage by different physical (penetrometry, compression) and chemical measurements (extraction and analysis of pectin composition). The emphasis was on determining the most relevant biochemical markers in relation to different sensory properties of apple texture. Contrary to ‘Fuji’, ‘Golden Delicious’ fruit softened easily during storage, became mealy and had higher neutral sugar concentrations in their alcohol-insoluble residues (AIR) and more galacturonic acid in the water-soluble pectin extracts (WSP). The most relevant biochemical marker linked to texture change was the galacturonic acid content in the water-soluble pectin extracts. High and positive correlation coefficients were observed between sensory mealiness ( R = 0.84) and galacturonic acid content in the WSP while, sensory crunchiness and instrumentally measured firmness were negatively correlated with this component. The total neutral sugar content in the alcohol-insoluble residues and in the water-soluble pectin fractions also changed with apple texture properties.

Dietary fibre components and pectin chemical features of peels during ripening in banana and plantain varieties

The effects of the ripeness stage of banana ( Musa AAA) and plantain ( Musa AAB) peels on neutral detergent fibre, acid detergent fibre, cellulose, hemicelluloses, lignin, pectin contents, and pectin chemical features were studied. Plantain peels contained a higher amount of lignin but had a lower hemicellulose content than banana peels. A sequential extraction of pectins showed that acid extraction was the most efficient to isolate banana peel pectins, whereas an ammonium oxalate extraction was more appropriate for plantain peels. In all the stages of maturation, the pectin content in banana peels was higher compared to plantain peels. Moreover, the galacturonic acid and methoxy group contents in banana peels were higher than in plantain peels. The average molecular weights of the extracted pectins were in the range of 132.6–573.8 kDa and were not dependant on peel variety, while the stage of maturation did not affect the dietary fibre yields and the composition in pectic polysaccharides in a consistent manner. This study has showed that banana peels are a potential source of dietary fibres and pectins.

CHARACTERIZATION OF CLOUD COMPONENTS FROM SELECTED TROPICAL FRUITS

ABSTRACT The composition and characteristics of insoluble fruit matter (IFM) and alcohol insoluble solids (AIS) from banana, mango and orange were evaluated. The galacturonic acid content was significantly higher for mango and orange pectin (6.0%) compared to banana (5%). The degrees of esterification of pectin in AIS were 78 ± 5, 85 ± 6 and 85 ± 2 for mango, orange and banana, respectively. Proteins in the fruit pulps were of low molecular weight (&lt;100,000 Da). The relative proportions of the amino acids in the AIS and IFM were similar, with predominant aspartic acid and low methionine and tyrosine contents. Phenolic compounds were highest in banana pulp (138 ± 2 mg gallic acid equivalent/L = mg GA/L) compared to 102 ± 8 mg GA/L for orange. Phenolic compounds were about 10‐fold less (15 ± 2 mg GA/L) in mango.PRACTICAL APPLICATIONSThis work has applications to the development of natural clouding agents for juices, juice‐added beverages and protein‐fortified beverages. The chemical analysis provides fundamental information on the potential for stable protein interactions from banana and mango, tropical fruits that are desirable in beverages. Further, the research enhances the potential for value‐added processing of these fruits.