Effect of extraction pH on the yield and physicochemical properties of polysaccharides extracts from peanut sediment of aqueous extraction process

Structure, functionality and bioactivity of sulfated polysaccharide extracted from rainbow trout byproducts: pH-shift method vs enzymatic hydrolysis

Here, a novel method for sequentially extracting sulfated polysaccharides (SPs) from Oncorhynchus mykiss byproducts using alkaline/acid solubilization followed by isoelectric precipitation is compared with conventional enzymatic hydrolysis. Alkaline solubilization (SP-Alk) yielded SPs (2.46 %) comparable to the enzymatic method (SP-Enz, 2.77 %), while acidic solubilization (SP-Aci) yielded 1.96 %. SP-Alk showed comparable carbohydrate and sulfate content but lower protein than SP-Enz. Additionally, SP-Alk showed the highest monosaccharide content of rhamnose, mannose, glucose, and galactose. The extraction method affected the Molecular weight of SPs with SP-Enz having the lowest (44.95 kDa). Structural and thermal properties of the SPs were similar as revealed by FTIR/XRD and DSC, respectively. While SP-Enz exhibited slightly better antioxidant and functional properties (foaming, stability, emulsifying activity), SP-Alk showed a considerable performance with similar antimicrobial activity. Altogether, the pH-shift method can be a promising alternative for sequential extraction of SPs compared with enzymatic hydrolysis, avoiding enzymatic degradation of proteins.

Comparative study of Idesia polycarpa Maxim cake meal polysaccharides: Conventional versus innovative extraction methods and their impact on structural features, emulsifying, antiglycation, and hypoglycemic properties

Idesia polycarpa Maxim (IPM) cake meal, a major by-product of oil extraction, is often discarded in large quantities, resulting in considerable waste. This study explored the extraction of IPM polysaccharides (IPMPs) from cake meal using the innovative ultrasonic-assisted three-phase partitioning (UTPP) method, in comparison with conventional techniques, including acid, medium-temperature alkali, chelating agent, and enzyme extraction methods. The IPMP-UT prepared via UTPP method achieved superior extraction efficiency (10.05 %), increased uronic acid content (39.12 %), and a greater proportion of the rhamnogalacturonan I (RG-I) domain (42.88 %), along with improved homogeneity (Mw/Mn: 2.79) and enhanced functional properties, including improved thermal stability, emulsion ability, and emulsion stability. Compared to IPMPs extracted via conventional methods, emulsions stabilized with IPMP-UT exhibited superior performance across different pH levels and polysaccharide concentrations. At pH 6.0, IPMP-UT emulsion formed thicker interfacial layers and exhibited the strongest storage (G') and loss (G″) module. Bioactivity assays further revealed that IPMP-UT had the most potent in vitro inhibition of α-glucosidase and was the most effective at reducing the formation of fructosamine, α-dicarbonyl compounds, and advanced glycation end products (AGEs). All IPMPs inhibited α-glucosidase through a combined mechanism, primarily reducing fluorescence via static quenching, with IPMP-UT demonstrating the greatest binding affinity. Fluorescence and FT-IR spectroscopy confirmed that IPMPs induced structural rearrangements in the enzyme. In conclusion, the UTPP method emerged as the most promising and environmentally sustainable technique for producing pectic polysaccharides with optimal functional properties from IPM cake meal.

Ultrasonic-assisted plasma-activated water extraction of polysaccharide from Hemerocallis citrina Baroni: Structural characterization and antioxidant mechanism in vitro

Natural polysaccharides derived from Hemerocallis citrina Baroni exhibit significant biological activity. To enhance extraction efficiency and antioxidant activity, ultrasonic-assised plasma-activated water (PAW) was utilized to extract polysaccharides from Hemerocallis citrina Baroni. PAW demonstrated enhanced permeability and diffusion capabilities due to a reduced percentage of fully hydrogen-bonded structures, along with optimal pH (3.4) and conductivity (157.20 μS/cm). Compared to other methods, PAW significantly improved the extraction efficiency of polysaccharides to 38.24 %. Hemerocallis citrina Baroni polysaccharides predominantly consisted of α-pyranose sugars with sugar uronic acids, and ultrasound-assisted PAW did not alter their major functional groups. The extracted Hemerocallis citrina Baroni polysaccharides exhibited a semi-rigid triple-helical structure. Importantly, these polysaccharides displayed strong antioxidant activity, with ABTS+, DPPH, and O2- radical scavenging rates of 66.31 %, 65.98 %, and 47.73 % respectively. This study provides an effective method for extracting natural plant polysaccharides and offers valuable insights into their potential applications in the food industry and beyond.

Research progress on extraction techniques, structure-activity relationship, and biological functional mechanism of berry polysaccharides: A review

In recent years, polysaccharides extracted from berries have received great attention due to their various bioactivities. However, the preparation and application of berry polysaccharides have been greatly limited due to the lack of efficient extraction techniques, unclear structure-activity relationships, and ambiguous functional mechanisms. This review discusses the technological progress in solvent extraction, assisted extraction, critical extraction, and combination extraction. The structure-activity relationship and functional mechanism (antioxidation, hypoglycemic, immunoregulation etc.) of berry polysaccharides are reviewed. After systematic exploration, we believe that industrial production is more suitable for using efficient and low-cost extraction methods, such as ultrasonic assisted extraction and microwave assisted extraction. And some of the bioactivities (antioxidant activity, hypoglycemic activity, etc.) of berry polysaccharides are closely related to their structure (molecular weight, monosaccharide composition, branching structure, etc.). Besides, berry polysaccharides exhibit bioactivities by regulating enzyme activity, cellular metabolism, gene expression, and other pathways to exert their effects on the body. These findings indicate the potential of berry polysaccharides as functional foods and drugs. This paper will contribute to the preparation, bioactivity research, and application of berry polysaccharides.

Physicochemical Characterization and Biological Properties of Polysaccharides from Alpiniae oxyphyllae Fructus

Polysaccharides (AOPs) were extracted from Alpiniae oxyphyllae fructus using three distinct methods: hot water (AOP-HW), hydrochloric acid (AOP-AC), and NaOH/NaBH4 (AOP-AL). This study systematically investigated and compared the physicochemical properties, structural characteristics, antioxidant activities, and α-amylase inhibitory activities of the extracted polysaccharides. Among the three AOPs, AOP-AC exhibited the highest yield (13.76%) and neutral sugar content (80.57%), but had the lowest molecular weight (121.28 kDa). Conversely, AOP-HW had the lowest yield (4.54%) but the highest molecular weight (385.42 kDa). AOP-AL was predominantly composed of arabinose (28.42 mol%), galacturonic acid (17.61 mol%), and galactose (17.09 mol%), while glucose was the major sugar in both AOP-HW (52.31 mol%) and AOP-AC (94.77 mol%). Functionally, AOP-AL demonstrated superior scavenging activities against DPPH, hydroxyl, and ABTS radicals, whereas AOP-AC exhibited the strongest inhibitory effect on α-amylase. These findings indicate that the extraction solvent significantly influences the physicochemical and biological properties of AOPs, thus guiding the selection of appropriate extraction methods for specific applications. The results of this study have broad implications for industries seeking natural polysaccharides with antioxidant and enzymatic inhibitory properties.

A comparison study on polysaccharides extracted from banana flower using different methods: Physicochemical characterization, and antioxidant and antihyperglycemic activities

This work investigated and compared the physicochemical characteristics, and antioxidant and antihyperglycemic properties in vitro of polysaccharides from a single banana flower variety (BFPs) extracted by different methods. BFPs extracted using hot water (HWE), acidic (CAE), alkaline (AAE), enzymatic (EAE), ultrasonic (UAE) and hot water-alkaline (HAE) methods showed different chemical composition, monosaccharide composition, molecular weight, chain conformation and surface morphology, but similar infrared spectra characteristic, main glycosidic residues, crystalline internal and thermal stability, suggesting that six methods have diverse impacts on the degradation of BFPs without changing the main structure. Then, among six BFPs, the stronger antioxidant activity in vitro was found in BFP extracted by HAE, which was attributed to its maximum uronic acid content (21.67 %) and phenolic content (0.73 %), and moderate molecular weight (158.48 kDa). The highest arabinose and guluronic acid contents (18.59 % and 1.31 % in molar ratios, respectively) and the lowest uronic acid content (14.30 %) in BFP extracted by HWE contributed to its better α-glucosidase inhibitory activity in vitro (66.55 %). The data offered theoretical evidence for choosing suitable extraction methods to acquire BFPs with targeted biological activities for applications, in which HAE and HWE could serve as beneficial methods for preparing antioxidant BFP and antihyperglycemic BFP, respectively.

Acid-induced conformation regulation of peanut polysaccharide and its effect on stability and digestibility of oil-in-water emulsion

BACKGROUND

Developing the stable and healthy emulsion-based food is in accord with the needs of people for health. In the present study, acidification at pH 3.0 of peanut polysaccharide (APPSI) was employed to regulate its conformation and further improve its advantages in preparing oil-in-water emulsion.

RESULTS

The results indicated that acidification induced conversion of PPSI aggregates into linear chains. Increasing concentration promoted formation of cross-linked network structure shown in transmission electron microscopy images. Consequently, the viscosity, yield stress, storage modulus and flow activation energy significantly increased, further fabricating gel structure. Moreover, aggregation behavior suggested that more exposed proteins were involved in gel structure, thereby forming many hydrophobic cores as verified by fluorescence spectroscopy of pyrene. Afterwards, emulsion characteristics indicated that APPSI produced strong and thick steric hindrance around oil droplets and the coil-like interweaved chains locked the continuous phase, bringing strong elasticity and resistance to stress and creaming. Meanwhile, the lower fatty acid in APPSI-emulsion was released after simulated gastrointestinal digestion, mainly as a result of the high retention ratio of emulsion droplets. Furthermore, the elastic and viscous Lissajous curves suggested that the structure strength of APPSI-emulsion was similar to that of the salad dressing within the strain 53.22%.

CONCLUSION

The conformation of PPSI after acidification at pH 3.0 was suitable for preparing the stable emulsion. The obtained emulsion could resist digestion and maintain a strong structure, comprising a cholesterol-free and low-fat salad dressing substitute. © 2023 Society of Chemical Industry.

Comparative Study on the Impact of Different Extraction Technologies on Structural Characteristics, Physicochemical Properties, and Biological Activities of Polysaccharides from Seedless Chestnut Rose (Rosa sterilis) Fruit

Seedless chestnut rose (Rosa sterilis S. D. Shi, RS) is a fresh type of R. roxburghii Tratt with copious functional components in its fruit. Polysaccharides are recognized as one of the vital bioactive compounds in RS fruits, but their antioxidant and hypoglycemic properties have not been extensively explored. Hence, in this study, accelerated solvent extraction (RSP-W), citric acid (RSP-C), 5% sodium hydroxide/0.05% sodium borohydride (RSP-A), and 0.9% sodium chloride (RSP-S) solution extraction were individually utilized to obtain RS fruit polysaccharides. The physicochemical properties, structural characteristics, and biological activities were then compared. Results indicated that extraction methods had significant influences on the extraction yield, uronic acid content, monosaccharide composition, molecular weight, particle size, thermal stability, triple-helical structure, and surface morphology of RSPs apart from the major linkage bands and crystalline characteristics. The bioactivity tests showed that the RSP-S, which had the greatest amount of uronic acid and a comparatively lower molecular weight, exhibited more potent antioxidant and α-glucosidase inhibitory property. Furthermore, all RSPs inhibited α-glucosidase through a mixed-type manner and quenched their fluorescence predominantly via a static quenching mechanism, with RSP-S showing the highest binding efficiency. Our findings provide a theoretical basis for utilizing RSPs as functional ingredients in food industries.

Immunomodulatory Activity of Polysaccharides Isolated from Saussurea salicifolia L. and Saussurea frolovii Ledeb

The genus Saussurea has been used in the preparation of therapies for a number of medical problems, yet not much is known about the therapeutic high-molecular-weight compounds present in extracts from these plants. Since polysaccharides are important in immune modulation, we investigated the chemical composition and immunomodulatory activity of Saussurea salicifolia L. and Saussurea frolovii Ledeb polysaccharides. Water-soluble polysaccharides from the aerial parts of these plants were extracted using water at pHs of 2 and 6 and subsequently precipitated in ethanol to obtain fractions SSP2 and SSP6 from S. salicifolia and fractions SSF2 and SSF6 from S. frolovii. The molecular weights of fractions SSP2, SSP6, SFP2, and SFP6 were estimated to be 143.7, 113.2, 75.3, and 64.3 kDa, respectively. The polysaccharides from S. frolovii contained xylose (67.1-71.7%) and glucose (28.3-32.9%), whereas the polysaccharides from S. frolovii contained xylose (63.1-76.7%), glucose (11.8-19.2%), galactose (4.7-8.3%), and rhamnose (6.8-9.4%). Fractions SSP2, SSP6, and SFP2 stimulated nitric oxide (NO) production by murine macrophages, and NO production induced by SSP2, SSP6, and SFP2 was not inhibited by polymyxin B treatment of the fractions, whereaspolymyxin B treatment diminished the effects of SFP6, suggesting that SFP6 could contain lipopolysaccharide (LPS). The LPS-free fractions SSP2, SSP6, and SFP2 had potent immunomodulatory activity, induced NO production, and activated transcription factors NF-κB/AP-1 in human monocytic THP-1 cells and cytokine production by human MonoMac-6 monocytic cells, including interleukin (IL)-1α, IL-1β, IL-6, granulocyte macrophage colony-stimulating factor (GM-CSF), interferon-γ, monocyte chemotactic protein 1 (MCP-1), and tumor necrosis factor (TNF). These data suggest that at least part of the beneficial therapeutic effects reported for water extracts of the Saussurea species are due to the modulation of leukocyte functions by polysaccharides.

Structural characterization of Euglena gracilis polysaccharide and its in vitro hypoglycemic effects by alleviating insulin resistance

Diabetes mellitus, characterized by hyperglycemia and insulin resistance, is a disorder of the endocrine metabolic system which has emerged as a common chronic disease worldwide. Euglena gracilis polysaccharides have ideal development potential in the treatment of diabetes. However, their structure and bioactivity are largely unclear. A novel purified water-soluble polysaccharide (EGP-2A-2A) from E. gracilis with a molecular weight of 130.8 kDa consisted of xylose, rhamnose, galactose, fucose, glucose, arabinose, and glucosamine hydrochloride. The SEM image for EGP-2A-2A suggested a rough surface with the presence of globule-like protrusions. Methylation and NMR spectral analyses revealed that EGP-2A-2A was mainly composed of →6)-β-D-Galp-(1 → 2)-α-D-Glcp-(1 → 2)-α-L-Rhap-(1 → 3)-α-L-Araf-(1 → 6)-β-D-Galp-(1 → 3)-α-D-Araf-(1 → 3)-α-L-Rhap-(1 → 4)-β-D-Xylp-(1 → 6)-β-D-Galp-(1 → with complex branching structure. EGP-2A-2A significantly increased glucose consumption and glycogen content in IR-HeoG2 cells and modulates glucose metabolism disorders by regulating PI3K, AKT, and GLUT4 signaling pathways. EGP-2A-2A significantly suppressed TC, TG, and LDL-c levels, and enhanced that of HDL-c. EGP-2A-2A ameliorated abnormalities caused by disorders of glucose metabolism and the hypoglycemic activity of EGP-2A-2A may be mainly positively related to its high glucose content and the β-configuration in the main chain. These results suggested that EGP-2A-2A played an important role in alleviating disorders of glucose metabolism through insulin resistance and has the potential for development as a novel functional food with nutritional and health benefits.

Comparative study on the structural characterization and α-glucosidase inhibitory activity of polysaccharide fractions extracted from Sargassum fusiforme at different pH conditions

Sargassum fusiforme polysaccharides (SFPs), including SFP-3-40, SFP-3-60, SFP-3-80, SFP-7-40, SFP-7-60, SFP-7-80, SFP-10-40, SFP-10-60, and SFP-10-80, were extracted at different pH (3, 7, and 10), and then precipitated with graded precipitation of 40%, 60% and 80% (v/v) ethanol solution, respectively. Their physicochemical properties and α-glucosidase inhibitory activity were determined. Results showed that SFPs significantly differed in the contents of total sugar, protein, uronic acid, sulfate, the zeta potential, and molecular weight distribution. SFPs, including SFP-10-40, SFP-10-60, and SFP-10-80, had bigger absolute zeta potential value and higher respective average molecular weight in the same ethanol concentration precipitate. All samples were mainly composed of fucose, glucuronic acid, and mannose with different molar ratios. The extraction pH and precipitation ethanol solution concentration caused little changes in functional groups, but significantly altered surface morphology of SFPs. Congo red test revealed that all polysaccharides were not helical polysaccharides. Rheological measurements indicated that SFPs were pseudoplastic fluids and showed elastic behavior of the gel. Except SFP-3-40 and SFP-3-60, all other samples had a stronger α-glucosidase inhibitory activity than that of acarbose. The inhibition type of SFPs against α-glucosidase varied owing to different extraction pH and precipitation ethyl concentration. This study shows that extraction pH can significantly affect the structure and hypoglycemic activity of SFPs and provide a data support for the scientific use of Sargassum fusiforme in industrial production.

Emulsifying capacity of peanut polysaccharide: Improving interfacial property through the co-dissolution of protein during extraction

The co-dissolution of residual protein from byproduct (PPSI) was employed to improve the interfacial property of peanut polysaccharide (PPS). Protein content in the PPSI and PPS were 16.89% and 2.58%, respectively. The convent bonding and intermolecular interaction maintained the complex structure in PPSI. More protein promoted the shift from linear chain conformation to spherical particle, weakened surface charge, induced stronger intermolecular attraction and wettability, which facilitated interfacial adsorption of PPSI. Concomitantly, the linear chain after adsorbing the O/W interface was observed in PPSI-polystyrene, promoting the cross-linking between adsorption layers and thereby forming the elastic interfacial film. Consequently, the emulsion borne smaller size. Subsequently, the particles in continuous phase moved to the adsorption layer via intermolecular interaction and then formed a gel, enhancing stability against oil coalescence, the thermal and refrigerated treatments. Additionally, the acidified (pH 3.0) PPSI further strengthened the emulsion structure and improved its creaming and freeze-thaw stability.

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

BACKGROUND

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

RESULTS

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

CONCLUSION

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

Comparative study on the effect of extraction solvent on the physicochemical properties and bioactivity of blackberry fruit polysaccharides

In this study, hot water, 0.1 M HCl and 0.1 M NaOH and 0.1 M NaCl solution were separately used for extraction of blackberry polysaccharides (BPs: Hw, Ac, Al and Na). The physicochemical properties and biological activities were then investigated and compared. Results showed that the extraction yield, molecular weight, monosaccharide composition, particle size, triple-helical structure, surface morphology and rheological properties of BPs were greatly affected by extraction solvents. Bioactivity assays implied that the four BPs showed that the polysaccharides (Hw and Na) with higher molecular weight had stronger antioxidant and α-glucosidase inhibitory activity. Moreover, anti-glycated assay indicated that BPs with higher molecular weight and higher content of galacturonic acid possessed better inhibition of AGEs formation. These results suggested that the higher molecular weight of blackberry polysaccharide could be developed as a beneficial bioactive ingredient for diabetes mellitus and complications.

Structure and chain conformation characterization of arabinoglucan from by-product of peanut oil processing

A neutral polysaccharide (NPP) from peanut sediment of aqueous extraction process was purified via anion-exchange and gel-filtration chromatography. The weight-average molecular weight and polydispersity index were 3.36 × 10⁴ Da and 1.06. Composition of glucose (82.66 %, molar percentage) and arabinose (17.34 %) suggested an arabinoglucan structure. Multiple medium-length chains consisting of many 1,4-linked α-Glcp and a few 1,5-linked α-Araf maintained the main chain structure. The backbone was substituted at O-6 and O-3 positions, attached by side chains consisting of two to six α-Glcp and terminated with Araf and Glcp. Degree of branching was 42.50 %. Aggregates formed in NPP aqueous solution. They were eliminated by DMSO combining with sonication. Consequently, the average radius of gyration (R_g), hydrodynamic radius (R_h), and R_g/R_h ratio were 17.0 nm, 5.8 nm and 2.93, respectively, indicating extended rigid chain conformation. The backbone substituted at O-3 and short branching chains probably together induced this conformation.

Characteristics of alkali-extracted peanut polysaccharide-protein complexes and their ability as Pickering emulsifiers

An alkaline isolation method was applied to extract polysaccharide from residues of peanut oil processing while retaining high protein content, in order to enhance the emulsifying ability of these materials. The obtained complexes (PECs) containing protein (13-18%, dry basis) were named as PEC8.0, PEC10.0 and PEC12.0 according to extraction pH values. The protein content of PECs increased with increasing extraction pH value, thereby the hydrophobicity was improved. Additionally, as extraction pH value increased to 10.0, the protein of PECs covalently bonded to polysaccharide and polysaccharide conformation unfolded simultaneously, thus particle size was enlarged. Furthermore, the increasing concentration of PECs further induced the formation of large complex particles. Then, they were used to stabilize the Pickering emulsions with oil fractions (φ) of 0.4-0.7. The emulsions stability especially the gel structure was maintained by the interactions of large particles adsorbed in the interface and those in the continuous phase. Stability analysis indicated the emulsifying capacity of PEC10.0 and PEC12.0 was superior to that of PEC8.0, due to difference of their particle properties. This suggested the promoting effect of alkali in preparation of polysaccharide-protein complex as good Pickering stabilizer.

Chain conformation and rheological properties of an acid-extracted polysaccharide from peanut sediment of aqueous extraction process

A polysaccharide (PPS) in peanut sediment of aqueous extraction process was obtained at pH4.0, purified via anion-exchange chromatography. The composition, chain conformation and rheological properties were investigated. PPS mainly consisted of arabinose, galacturonic acid, xylose, and rhamnose. The intrinsic viscosity [η] was 0.71 dL/g in 0.1 M NaNO₃ solution. The weight-average molar mass Mw and polydispersity index were 3.77 × 10⁵ g/mol and 1.25, suggesting high homogeneity. The average radius of gyration (R_g), hydrodynamic radius (R_h), R_g/R_h ratio and conformation parameter v were 25.5, 18.2, 1.40 and 0.21, respectively, indicating compact coil chain conformation with branched structure. Molecular morphology revealed that PPS displayed chain shape comprised of spheres with a diameter range of 15-50 nm and apparent length of chains mainly ranged from 100 to 300 nm. The aggregation caused by molecular self-association enhanced with concentration increasing. Additionally, Newtonian behavior was observed at various concentrations. Increase in temperature effectively broke this behavior. 10.0 wt.% PPS possessed activation energy of 21.7 KJ/mol, was structured liquid and almost fitted Cox-Merz rule. These closely related with its conformation and molecular self-association behavior.