Hot Acid Extraction Research Articles

Differences in physicochemical properties of pectin extracted from pomelo peel with different extraction techniques

In order to obtain high yield pomelo peel pectin with better physicochemical properties, four pectin extraction methods, including hot acid extraction (HAE), microwave-assisted extraction (MAE), ultrasound-assisted extraction, and enzymatic assisted extraction (EAE) were compared. MAE led to the highest pectin yield (20.43%), and the lowest pectin recovery was found for EAE (11.94%). The physicochemical properties of pomelo peel pectin obtained by different methods were also significantly different. Pectin samples obtained by MAE had the highest methoxyl content (8.35%), galacturonic acid content (71.36%), and showed a higher apparent viscosity, thermal and emulsion stability. The pectin extracted by EAE showed the highest total phenolic content (12.86%) and lowest particle size (843.69 nm), showing higher DPPH and ABTS scavenging activities than other extract methods. The pectin extracted by HAE had the highest particle size (966.12 nm) and degree of esterification (55.67%). However, Fourier-transform infrared spectroscopy showed that no significant difference occurred among the different methods in the chemical structure of the extracted pectin. This study provides a theoretical basis for the industrial production of pomelo peel pectin.

High-intensity pulsed electric field-assisted acidic extraction of pectin from citrus peel: Physicochemical characteristics and emulsifying properties

Sustainable innovation seeks more energy-efficient processes for producing highly demanded products from industrial by-products. This study follows this endeavor. Comparisons were made on two processes for producing pectins from citrus peel as well as the two derived pectin products: a high-intensity pulsed electric field (HIPEF) pretreatment of citrus peel powder followed by a milder acidic extraction (pH 2, heating at 70 °C for 1 h; pectin termed HIPEF-CP), and a conventional direct hot-acid extraction (pH 2, heating at 90 °C for 2 h; pectin termed CP). HIPEF-assisted extraction significantly improved pectin yield (by 8.48%) and production efficiency (by 100.23%) while reducing energy consumption. Both were low-methoxyl pectins with similar branching degrees and contents of rhamnogalacturonan-I (RG-I), protein, phenolic compounds, total alkaloids and vitamin C. Compared with CP, HIPEF-CP contained higher homogalacturonan content, higher galactose content, higher galacturonic acid content, lower arabinose content, lower xylose content, slightly lower degree of methyl esterification, higher linearity, lower side chain size, higher molecular weight, and wider molecular weight distribution. The antioxidant, emulsifying and emulsion-stabilizing abilities of HIPEF-CP were superior to those of CP, though both pectins were satisfactory emulsifiers, exhibiting good antioxidant activities and emulsifying capacities at pectin concentrations not lower than 1.0%. The HIPEF pretreatment of citrus peel made the subsequent acidic pectin extraction feasible under milder conditions, to produce pectin with desired antioxidant and emulsifying capacities.

Comparisons of pulsed ultrasound-assisted and hot-acid extraction methods for pectin extraction under dual acid mixtures from onion (Allium cepa L.) waste.

The aim of this study is to compare the physicochemical properties and yields of pectins extracted from onion waste under hot acid (HAE) and pulsed ultrasound-assisted extraction (PUAE) methods using different organic-inorganic acids, their mixtures, and pure water. The extraction temperature for experiments carried out under HAE was kept at 90°C for 90 min, whereas PUAE experiments were accomplished at RT in 15 min. In general, HAE gave better pectin yields compared with PUAE due to the significance of the increasing extraction temperature for the release of pectin from the plant matrix. While the maximum pectin yield from onion waste was 16.22% for HAE, the highest yield for PUAE was 9.83%. PUAE provides less time- and energy-consuming extraction of pectin within 15 min and thus seems to be more economic compared with the HAE. According to the physicochemical properties (equivalent weight (EW), degree of esterification (DE), methoxyl (MeO), and galacturonic acid (Gal-A) contents) of obtained pectins, extracted pectins were mostly high methoxy pectin. While the DE and MeO values of pectins extracted in organic acid conditions under HAE were higher, these values were found to be higher for pectins extracted in inorganic acids under PUAE. For acid mixtures, the DE and MeO values of pectins under HAE were mostly found to be lower than those under PUAE. Sequential PUAE and HAE methods for the extraction of pectin from onion waste were also found to be useful in terms of obtaining higher yields and better physicochemical properties. The highest pectin yield was 20.32% for the sequential PUAE and HAE methods. FT-IR analyses of the extracted pectins by both HAE and PUAE methods showed similar vibration bands compared with those of commercial citrus pectin.

Extraterrestrial amino acids and amines identified in asteroid Ryugu samples returned by the Hayabusa2 mission

The hot water and acid extracts of two different Ryugu samples collected by the Hayabusa2 mission were analyzed for the presence of aliphatic amines and amino acids. The abundances and relative distributions of both classes of molecules were determined, as well as the enantiomeric compositions of the chiral amino acids. The Ryugu samples studied here were recovered from sample chambers A and C, which were composed of surface material, and a combination of surface and possible subsurface material, respectively. A total of thirteen amino acids were detected and quantitated in these samples, with an additional five amino acids that were tentatively identified but not quantitated. The abundances of four aliphatic amines identified in the Ryugu samples were also determined in the current work. Amino acids were observed in the acid hydrolyzed and unhydrolyzed hot water extracts of asteroid Ryugu regolith using liquid chromatography with UV fluorescence detection and high-resolution mass spectrometry. Conversely, aliphatic amines were only analyzed in the unhydrolyzed hot water Ryugu extracts. Two- to six-carbon (C2-C6) amino acids with individual abundances ranging from 0.02 to 15.8 nmol g−1, and one- to three-carbon (C1-C3) aliphatic amines with individual abundances from 0.05 to 34.14 nmol g−1, were found in the hot water extracts. Several non-protein amino acids that are rare in biology, including β-amino-n-butyric acid (β-ABA) and β-aminoisobuytric acid (β-AIB), were racemic or very nearly racemic, thus indicating their likely abiotic origins. Trace amounts of select protein amino acids that were enriched in the l-enantiomer may indicate low levels of terrestrial amino acid contamination in the samples. However, the presence of elevated abundances of free and racemic alanine, a common protein amino acid in terrestrial biology, and elevated abundances of the predominately free and racemic non-protein amino acids, β-ABA and β-AIB, indicate that many of the amino acids detected in the Ryugu water extracts were indigenous to the samples. Although the Ryugu samples have been found to be chemically similar to CI type carbonaceous chondrites, the measured concentrations and relative distributions of amino acids and aliphatic amines in Ryugu samples were notably different from those previously observed for the CI1.1 carbonaceous chondrite, Orgueil. This discrepancy could be the result of differences in the original chemical compositions of the parent bodies and/or alteration conditions, such as space weathering. In addition to α-amino acids that could have been formed by Strecker cyanohydrin synthesis during a low temperature aqueous alteration phase, β-, γ-, and δ-amino acids, including C3 – C5 straight-chain n-ω-amino acids that are not formed by Strecker synthesis, were also observed in the Ryugu extracts. The suite of amino acids measured in the Ryugu samples indicates that multiple amino acid formation mechanisms were active on the Ryugu parent body. The analytical techniques used here are well-suited to search for similar analytes in asteroid Bennu material collected by the NASA OSIRIS-REx mission scheduled for Earth return in September 2023.

Production and Characterisation of Pectin from Cocoa Bean Shells

Cocoa bean shells constitute the major waste generated from the industrial processing of cocoa beans. The shells contain about 9% of pectin and extracting it would be of economic and ecological importance. However, limited knowledge on the characteristics of the pectin from cocoa bean shells and the extraction conditions, which would yield pectin of good quality and sufficient quantity, restrict the possible use of the shells as a source of commercial pectin. The objective of this study was to extract and characterise pectin from cocoa bean shells, with focus on finding the optimum extraction conditions. The conventional hot dilute acid extraction method was used. 12 M hydrochloric acid was used to acidify water to pH 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0. Extractions were carried out at temperatures of 60, 70, and 80 °C, for different times of 0.5, 1, and 2 h. The effects of each of the conditions on yield and other properties of pectin were evaluated. Depending on the conditions under which cocoa bean shells were treated, both high methoxyl and low methoxyl pectins were extracted. At the optimum conditions of pH 3.5, extraction time of 2 h and 80 °C extraction temperature, high methoxyl pectin was obtained. The yield was 4.7%, the degree of esterification was 68.9% and the anhydrouronic acid content was 71.2%. While the methoxyl content was 8.6%, the equivalent mass was found to be 805.8 g/eq. Moisture and ash contents were 6.7 and 10.3%, respectively, and the pH of the pectin hydrocolloid was 3.7. Fourier Transform Infrared (FT-IR) spectra confirmed the presence of functional groups found in the pectin structure. The intrinsic viscosity varied between 0.075–0.088 m3/kg and the molecular mass ranged from 23,470 - 42,384 g/mol. The results revealed that the shells are a viable source for commercial pectin, while necessary investigations focusing on the gelling, thickening, emulsifying, texturing, and stabilising potentials of the pectin from cocoa bean shells would inform of the areas of application

Natural polysaccharides from Glycyrrhiza uralensis residues with typical glucan structure showing inhibition on α-glucosidase activities

Two neutral Glycyrrhiza polysaccharide (GP), named GP-LA and GP-HA, with molecular weights of 3.023 × 105 and 1.291 × 105, respectively, were extracted from Glycyrrhiza residues by hot acid extraction (HA) and low-temperature acid extraction (LA) and purified by column chromatography. Comprehensive analysis showed that the backbone of GP was composed of →4)-β-D-Glcp-(1→. For GP-LA, the side chain probably composed of β-L-Araf-(1→, →5)-β-L-Araf-(1→, →4)-β-D-Xylp-(1→, β-D-Glcp-(1→, →3,4)-α-D-Glcp-(1→, →4,6)-α- D-Glcp-(1→, and for GP-LA, the side chain probably composed of→6)-β-D-Galp-(1→, -α-D-Glcp-(1→, →3,4)-α-D-Glcp-(1→, →2,4)-α-D-Glcp-(1→, →4,6)- D-Glcp-(1→. The GP had a triple helix conformation and numerous irregular spherical particles with smooth surfaces. Atomic force microscopy (AFM) confirmed that GP-HA possessed single-branched structures and GP-LA possessed cross-linked network structures. X-ray diffraction (XRD) analysis revealed that GP-LA had both crystalline and amorphous structures, but GP-HA had no crystal structure. Furthermore, the results indicated that GP-LA and GP-HA exhibited certain inhibition activity on α-glucosidase. CD spectra and fluorescence intensity measurements confirmed that the secondary structure of α-glucosidase changed with the addition of GP.

The Effects of Different Processing Methods on the Levels of Biogenic Amines in Zijuan Tea.

This study aimed to evaluate the effects of processing methods on the content of biogenic amines in Zijuan tea by using derivatization and hot trichloroacetic acid extraction with HPLC-UV. The results showed that the most abundant biogenic amine in the original leaves was butylamine, followed by ethylamine, methylamine, 1,7-diaminoheptane, histamine, tyramine, and 2-phenethylamine. However, during the process of producing green tea, white tea, and black tea, the content of ethylamine increased sharply, which directly led to their total contents of biogenic amines increasing by 184.4%, 169.3%, and 178.7% compared with that of the original leaves, respectively. Unexpectedly, the contents of methylamine, ethylamine, butylamine, and tyramine in dark tea were significantly reduced compared with those of the original leaves. Accordingly, the total content of biogenic amines in dark tea was only 161.19 μg/g, a reduction of 47.2% compared with that of the original leaves, indicating that the pile-fermentation process could significantly degrade the biogenic amines present in dark tea.

Increasing RG-I content and lipase inhibitory activity of pectic polysaccharides extracted from goji berry and raspberry by high-pressure processing

The impact of high-pressure processing (HPP) extraction on the structural, rheological, and functional properties of goji berry and raspberry pectic polysaccharides were investigated under acidic and alkaline conditions. These properties were compared with those of pectic polysaccharides extracted by conventional hot-acid and cold-alkali methods. Extraction yield, molecular weight, rheological behavior, and antioxidant activity of pectic extracts depended on the source materials of extraction. The solvent pH was the driving factor for the degree of esterification, as revealed by NMR and FTIR analysis. Monosaccharide composition was the primary variable between the extracts. The hot-acid extraction led to the highest galacturonic acid (GalA) contents, 46.9% for goji berry and 65.2% for raspberry, indicating the prevalence of homogalacturonans (HG) regions. HPP-assisted acidic/alkaline extractions gave rise to higher rhamnogalacturonan-I (RG-I) regions, pointing to the prevalence of hairy regions. The antioxidant activity of raspberry extracts was significantly (P ≤ 0.05) higher than goji berry extracts. The higher amount of RG-I may determine the higher antioxidant activity of raspberry pectic polysaccharides. The correlation between structural parameters and the lipase inhibitory activity also revealed that the higher lipase inhibitory activity of pectic polysaccharides is mostly correlated with the higher content of RG-I (r = 0.9259, P = 0.00033). Thus, HPP-assisted extraction may intensify the lipase inhibitory activity of pectic polysaccharides by increasing their RG-I content.

In vitro biological activities and in vivo hepatoprotective role of brown algae-isolated fucoidans.

Brown seaweeds are rich in polysaccharides, such as fucoidan (FUC) which has shown beneficial effects in several medical conditions. The aim of the present study was to assess the antioxidant, anti-inflammatory, and hepatoprotective properties of Colpomenia sinuosa- and Sargassum prismaticum-isolated FUC in vitro and in vivo. The hot acid extraction method was used to isolate FUC from C. sinuosa (FCS) and S. prismaticum (FSP) species. The antioxidant, anticancer, as well as the effect on neurotransmitter-degrading enzyme and disaccharidase activities were measured using standard protocols. Moreover, the hepatoprotective effect of two FCS doses (100 and 200 mg/kg) on paracetamol-administered rats (one dose of 1 g/kg) were evaluated by measuring blood liver function markers, hepatic pro-oxidants as malondialdehyde (MDA) and nitric oxide (NO), antioxidants as glutathione (GSH) and glutathione peroxidase (GPx), proinflammatory markers as inducible nitric oxide synthase (iNOS), interleukin 1β (IL-1β), tumor necrosis factor-α (TNF-α), and liver histology. The crude fucoidan yield was 15.6% and 14.8% of C. sinuosa and S. prismaticum dry weights, respectively. The antioxidant effects and cytotoxic activity on hepatic cancer cell were higher for FCS than FSP. Moreover, in vivo data showed that FCS administration at both doses significantly improved liver functions and alleviated histological alterations, hepatic inflammation, and oxidative stress following paracetamol intake. In conclusion, fucoidan exerts anti-inflammatory, antidigestive enzyme activity, antioxidant, anticancer, and hepatoprotective effects.

Extraction and isolation of pectin rich in homogalacturonan domains from two cultivars of hawthorn berry (Crataegus pinnatifida)

Hawthorn berries present high pectin content with good ability to form and stabilize oil-in-water emulsions. However, successful applications are determinant of high yield and purity as well as good surfactant properties based on their molecular structure. In this work, pectins from one of the most common Crataegus pinnatifida cultivars (Dajinxing, DA), and from a less known cultivar gaining popularity (Mianqiu, MI), were extracted and isolated. They were comparatively investigated with two commercial pectins from citrus peel [> 67.9% degree of methyl-esterification (DM) and >78% galacturonic acid (GalA)] and analyzed for their yield, molecular weight (HPSEC-MALS-RI), monomer composition and glycosyl linkage analysis (GC-MS), DM (titration, FTIR and 1H NMR), and emulsifying performance. MI showed a 2-fold greater pectin yield (in terms of GalA) than DA (61.2% vs. 38.3%). Thus, hot acid extraction had to be followed by an enzymatic step to remove starch molecules and obtain purified DA and MI pectins (>86% GalA), which also resulted in pectin demethoxylation (DM <38%). Remarkably, purified hawthorn pectins presented lower molecular weight than commercial citrus pectins (98–126 kDa vs 164–235 kDa) together with a higher proportion of homogalacturonan (HG) domain and a significantly greater emulsifying activity and stability. Specifically, MI showed a higher HG proportion and a less branched rhamnogalacturonan-I (RG-I) domain [Branching calculated as (Arabinose + Galactose)/Rhamnose = 2.2] than DA (Branching = 3.1), with significantly shorter arabinan and galactan side chains (evidenced by more terminal arabinose and galactose). The yield and structure of MI pectin strongly indicates that MI berry is an excellent pectin source with distinguished functionality.

Soil carbon characterization in a subtropical drained peatland

Peatlands store a significant portion of the global carbon (C) budget. Peatland drainage triggers soil subsidence and is a threat to soil conservation. Differences in C composition as soils get shallower in drained peatlands are not clearly understood. Soil C quality has been considered as one of the possible causes for changes in soil subsidence rates in drained peatlands. The purpose of this research was to characterize soil C in drained peats experiencing soils subsidence by using a fractionation procedure and 13C Nuclear Magnetic Resonance (13C NMR) spectroscopy. The study was done in the Everglades Agricultural Area (EAA), located south of Lake Okeechobee in south Florida, US. The EAA is a subtropical peatland that has been drained for more than 100 years. Subsidence rates at the EAA have shown a reduction in recent decades possibly due to higher water tables and increases in inorganic and recalcitrant C (Shih et al., 1998). Analyses were performed for the top and bottom of sampled peat soils collected from shallow and deep soil areas within the EAA. Hot water (80 °C) and acid extractions were used to determine operational C fractions with residues characterized by magic angle spinning (MAS) 13C NMR spectroscopy before and after extraction to quantify C compound classes. Recalcitrant C is the dominant C pool in EAA soils with 85% of total carbon (TC) on average, while acid extracted C, hot water extracted C, and inorganic C comprise 19%, 1%, and 0.7% of TC, respectively. Shallow soils had significantly less organic matter (OM), hot water extracted C, and recalcitrant C, and showed a reduction of OM and C fractions deeper in the soil profile. The 13C NMR spectra analyses indicate that average C compounds in EAA peats are O-alkyl C (36.9%), followed by alkyl C (28.2%), aromatic C (24%), and carboxyl C (10.8%), with shallow and deep soils having a similar distribution of these C compounds. Extracted recalcitrant C fractions of both shallow and deep soils showed an increase in aromatic C (34.3%) and a reduction in O-alkyl C (26.6%). Subsidence reduced OM in shallow soils and can reduce soil C, including the recalcitrant C pool, which might affect N cycling and nutrient availability. Addition of fresh biomass into the soil (e.g. sugarcane crop residue) might increase labile C reducing subsidence and improving soil conservation in the EAA and other drained peatlands.

Physicochemical properties of dragon fruit peel pectin and citrus peel pectin: a comparison

Dragon fruit is a tropical fruit belongs to Cactae family of genus Hylocereus. Popular as buah naga in Malay, dragon fruit is not only sought after for its wonderful taste, but this fruit is also nutritionally and medicinally attractive for consumers. The dragon fruit flesh is usually eaten raw or it is processed into juices and the remaining peel will be discarded. To minimize the waste created from dragon fruit consumption, an idea of transforming the peel of dragon fruit into edible pectin has been proposed. Pectin can be found in food products as a gelling agent and it is used to maintain the quality of foods. Recent market demand for pectin is increasing annually and to meet the supply-demand, researchers are working towards obtaining pectin from available non-conventional sources. In this study, pectin was extracted from dragon fruit peel by hot acid extraction at pH 3.5 and 75 mins of extraction. Distilled water was used as a solvent and the acidic environment was achieved with dilute HCl. Degree of esterification (DE) analysis was performed by FTIR. The extracted pectin was categorized as high methoxyl pectin based on DE (52%). The endothermic properties of dragon fruit pectin analyzed by DSC indicating the stability of extracted pectin compared to citrus peel pectin. Pectin extracted was characterized in terms of moisture (14.03±1.925), ash content (8.73±1.218), as well as water and oilholding capacity (4.08±0.0.81) (2.18±0.096), swelling capacity (5.94±1.271) and texture profile in terms of gumminess (33.66±6.05), cohesiveness (1.06±0.08) and hardness (31.63±3.81). All characteristics were compared with citrus peel pectin.

Hot Acid Extraction, Characterisation and Scavenging Activity of Pectin from Hylocereus polyrhizus

Gelatin is extensively added to the food products for quality improvements of food entities. The role of gelatin as food thickener, texturizer, stabilizer, ingredient and as an animal based source has restricted its liberal use. However, the usage of this animal-based food quality improver has become less popular due to religious constraints and health restrictions. In fact, it is now direly needed to replace animal-based gelatin by plant-based. Pectin, the basic building material of cell walls in the terrestrial plant has great potential to be gelatin replacer as it can work as a gelling agent, thickener and also a stabilizer. Dragon fruit contains pectin which has high-value functional food as well as healthenhancing properties to substitute gelatin’s function in foods production. The current study aims to extract pectin from dragon fruit peels by using hot acid extraction. The optimum conditions for extraction were found to be at 75ºC and pH 3.5 based on the highest percentage of pectin yield (33%). The FTIR result proved that dragon fruit peel contained pectin, which can be used as gelatin replacer are free from any religious and health-wise prohibitions. Pectin extracted was characterized in terms of moisture (14.03 ± 1.925) and ash content (8.73 ± 1.218). The extracted pectin of dragon fruit peel acts as the best gelatin replacer compared to commercial pectin and gelatins from the market. The prepared fruit peels also exhibit high DPPH scavenging activity (57.94%) with methanol extract (2mg/ml).

The biological activities of the antitumor drug Grifola frondosa polysaccharide.

Grifola frondosa, a polypore fungus that grows at the base of trees, is an edible and medicinal mushroom with a large fruiting body characterized by overlapping caps. Japanese scholars found that Grifola frondosa polysaccharide or D-fraction is the major biologically active ingredient, which is a protein-bound glucan or proteoglucan, consisting of β-glucan (either β-1,6-linked glucan with β-1,3 branches or β-1,3-linked glucan branched with β-1,6 glucosides, but it also contains d-xylose, d-fucose, d-mannose, l-arabinose, uronic acid, and galactose with largely unknown linkages. The Grifola frondosa polysaccharides with different molecular weight and monosaccharide compositions can be obtained by using different extraction methods, such as hot water extraction, acid or alkaline extraction, or microwave extraction methods from the fruiting bodies, mycelia or the fermentation broth. Grifola frondosa polysaccharide-based drug was developed in China and approved as an adjunctive therapeutic drug for cancer treatment by the State Food and Drug Administration (SFDA) in 2010. There are eight fungal glycan-based drugs, some of them have to be injected in order to be effective in vivo but the Grifola frondosa polysaccharide-based drug can be taken either orally or by injection. In this article, based on the search results of Chinese VIP, CNKI, Wanfang database and PubMed database, 108 independent studies were summarized. The chemical structure, the antitumor, immunomodulatory, anti-diabetic, anti-hyperlipidemia, and antiviral activity and molecular mechanisms of GFP are reviewed and discussed. Our goal is to provide a molecular picture that would allow in-depth evaluation of Grifola frondosa polysaccharide as an adjunctive drug for cancer therapy.

CHEMICAL CONSTITUENTS AND ANTIOXIDANT PERSPECTIVES OF EXTRACTS OF CHARA GLOBULARIS AND CLADOPHORA SPECIES (STRING ALGAE) SPECIES

Objectives: Marine organisms are capable of producing unusual bioactive compounds that are not observed in terrestrial sources. Algae are now drawing a greater interest following the increase in demand for biodiversity in the screening programs seeking therapeutic drugs from natural products.Methods: Hot acid extraction and cold alkali extraction of Chara globularis and Cladophora species (string algae), respectively, were carried out successfully. The extracted materials were tested for the qualitative reactions and subjected for thin-layer chromatography, ultraviolet, and infrared spectral studies so as to characterize the extracted materials of two algae. They were estimated for their antioxidant perspectives by hydrogen peroxide radical scavenging and reducing power assay methods.Results: Percentage yield of the extracts was found to be 80% and 40%, respectively, for the two algal species. The IC50 value of hydrogen peroxide scavenging activity of C. globularis and Cladophora species was found to be 30 μg/ml and 20 μg/ml, respectively, and the same for the standard ascorbic acid was 20 μg/ml. The results were found to be dose dependent, i.e., higher the concentration, and more was the scavenging activity.Conclusion: Despite the widespread uses and claimed advantages of the algae, only a few investigations on the chemical composition have been reported. A good correlation between the structure and activities of these most popular categories can be brought about.

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 (&lt;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.

Quantification and characterization of chemically-and thermally-labile and recalcitrant biochar fractions

The C:N ratios of biochar labile fractions is important for assessing biochar stability and N cycling in soil. Here we compare chemically and thermally labile fractions for nine biochars produced from five biomass feedstocks using four production techniques. Biochar fractionation methods included proximate analysis, hot water extraction, acid and base extractions (0.05 M, 0.5 M, 1 M, 2 M, 3 M, and 6 M of either H2SO4 or NaOH), and oxidation with 15% H2O2 and 0.33 M KMnO4 (pH 7.2). Results show chemical addition reactions cause underestimation of mass of the labile fraction for chemical extraction and oxidation procedures but not the thermal procedure. Estimates of C and N in labile and recalcitrant fractions were not adversely affected by addition reactions, because solvents were independent of C or N. Results indicate that herbaceous biochars may be a source of N fertility while hardwood biochars may immobilize N during the first few years after biochar application to soils.

Bioactivity of fucoidan extracted from Laminaria japonica using a novel procedure with high yield

Due to antitumor and antioxidant activities, there has been increasing interest in fucoidans, sulfated polysaccharides, from brown algae. Currently, the classic hot water extraction and acid extraction are time-consuming, and can cause the partial cleavage of sulfate esters, leading to bioactivity loss. The present study developed a novel process for extracting fucoidans from Laminaria japonica with 0.5% ethylenediaminetetraacetic acid at 70 °C. Crude fucoidans (CFs) obtained with a yield (∼16%) was purified to different fractions of F1, F2 and F3. The fractions displayed similar anticancer activity against Hela cells. Due to the differences in sulfate content, molar ratio of sulfate to fucose and monosaccharide composition, F1 and F2 exhibited stronger antioxidant ability than CFs and F3. This novel extraction provides an efficient procedure for extracting fucoidans from brown seaweeds with high extraction yield and removing pigments with one single step.

Processes involving selective precipitation for the recovery of purified pectins from mango peel

Three methods for the recovery of purified pectins from directly dried mango peel were developed, using selective precipitation of mango pectin in propan-2-ol (IPA) of adequate volume concentrations for purification. Yields, composition, macromolecular and gelling properties of the resultant pectins were compared. Effluent analyses proved postextractive removal of fruit exudate arabinogalactans. The recovery processes involved (A) washing of raw-pectin powder in IPA of defined volume concentration, (B) fractional alcoholic precipitation of dissolved raw pectin, or (C) selective pectin precipitation from the hot-acid extract of mango peel in adequately diluted IPA. High galacturonic acid contents (≥ 721g/kg) and intrinsic viscosities (≥ 320mL/g) enabled ∼2.2-fold gelling capacities compared to raw mango pectin, which resulted from the standard procedure mimicking industrial pectin recovery from established sources. Removal of the predominant impurities (coextractable exudate arabinogalactans, ash) diminished the yields to ∼49% of the raw-pectin yield. Technical feasibility of the proposed procedures was discussed.

Comparing of hot water and acid extraction of polysaccharides from proso millet

The extraction of polysaccharides from proso millet was investigated experimentally using hot water and acid aqueous solution. Response surface methodology, based on a three-level, three- or four-variable Box-Behnken design for hot water extraction or acid extraction, respectively, was employed to obtain the best possible combination of acid concentration, liquid-solid ratio, extraction time, and extraction temperature for maximum polysaccharides yield. The obtained experimental data were fitted to a second-order polynomial equation and analyzed by appropriate statistical methods. The corresponding optimum extraction conditions of each method were obtained. Under the optimum conditions, the experimental yield was well in close agreement with the predicted value by the model. The results showed that the polysaccharides yield of acid extraction was 42.13 mg g-1, significantly higher than 20.07 mg g-1 of the yield of hot water extraction, the obtained equation could be used to predict the extraction experimental results.