Ferric- and calcium-loaded red soil assist colonization of submerged macrophyte for the in-situ remediation of eutrophic shallow lake: From mesocosm experiment to field enclosure application.

Eutrophication and its resulting harmful algal blooms greatly reduce the ecosystem services of natural waters. The use of modified clay materials to assist the phytoremediation of eutrophic water is a promising technique. In this study, ferric chloride and calcium hydroxide were respectively loaded on red soil for algal flocculation and phosphorus inactivation. A two-by-two factorial mesocosm experiment with and without the application of ferric- and calcium- loaded red soil (FA), and with and without planting the submerged macrophyte Vallisneria natans was conducted for the in-situ repair of eutrophic water and sediment. Furthermore, field enclosure application was carried out to verify the feasibility of the technology. At the end of the mesocosm experiment, the total phosphorus, total nitrogen, and ammonia nitrogen concentrations in water were reduced by 81.8 %, 63.3 %, and 62.0 %, respectively, and orthophosphate phosphorus concentration in the sediment-water interface decreased by 90.2 % in the FA + V. natans group compared with those in the control group. The concentration and proportion of chlorophyll-a in cyanobacteria decreased by 89.8 % and 71.2 %, respectively, in the FA + V. natans group. The content of active phosphorus in V. natans decreased and that of inert phosphorus increased in the FA + V. natans group, compared with those in the V. natans alone group, thus may reducing the risk of phosphorus release after decomposing of V. natans. The sediment bacterial diversity index did not change significantly among treatments. Field enclosure application have also been successful, with chlorophyll-a concentration in the water of treated enclosure decreased from above 200 µg/L to below 10 µg/L, and phosphorus concentration in the water decreased from >0.6 mg/L to <0.02 mg/L. These results demonstrated that the FA in combination with submerged macrophyte planting had great potential for the in-situ remediation of eutrophic water, especially those with severe algal blooms.

Hypolipidemic effects of macadamia oil are related to AMPK activation and oxidative stress relief: In vitro and in vivo studies.

Macadamia oil is rich in monounsaturated fatty acids, especially a high level of palmitoleic acid, which may have beneficial health effects by lowering blood lipid levels. In our study, the hypolipidemic effects of macadamia oil and its potential mechanisms of action were investigated using a combination of in vitro and in vivo assays. The results showed that macadamia oil significantly reduced lipid accumulation, and improved triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) levels in oleic acid-induced high-fat HepG2 cells. The macadamia oil treatment also exhibited antioxidant effects, as seen by its ability to reduce reactive oxygen species and malondialdehyde (MDA) levels, and increase superoxide dismutase (SOD) activity. The effects of 1000 µg/mL of macadamia oil were comparable to that of 4.19 µg/mL simvastatin. The results of qRT-PCR and western blotting analyses indicated that macadamia oil effectively inhibited hyperlipidemia by reducing the expression levels of SREBP-1c, PPAR-γ, ACC and FAS and by enhancing the expression levels of HO-1, NRF2 and γ-GCS, via AMPK activation and oxidative stress relief, respectively. In addition, different doses of macadamia oil were found to significantly improve liver lipid accumulation, reduce serum and liver TC, TG, and LDL-C levels, increase HDL-C levels, increase antioxidant enzyme (SOD, GSH-Px, and T-AOC) activity, and decrease the MDA content of mice on a high-fat diet. These results indicated that macadamia oil had a hypolipidemic effect and provide insights that might facilitate the development of functional food and dietary supplements.

Ripening induced degradation of pectin and cellulose affects the far infrared drying kinetics of mangoes.

The quality parameters of mangoes change during ripening, which has a vital impact on processing characteristics. Effects of ripening stage (four stages from the lowest to highest degree-RS-1, RS-2, RS-3, RS-4) on cell wall polysaccharides and far infrared drying kinetics of mangoes were investigated. As ripening progressed, the water-soluble pectin contents increased by 213.5%; while the chelate-, sodium carbonate-soluble pectin and hemicellulose contents decreased by 44.0%, 59.5% and 65.8%, respectively. Moreover, the molecular weight reduction confirmed the degradation of pectin. These further caused the alteration of cell wall structure and changes in water distribution. Meanwhile, the drying time of mangos with different ripeness were in the order: RS-3 > RS-4 > RS-2 > RS-1. It correlated with the degradation of cell wall polysaccharides, the destruction of cell wall and the increases in free water during ripening. The ripeness classification could effectively improve the uniformity and efficiency of fruits drying processing.

Extraction, characterization and spontaneous gelation mechanism of pectin from Nicandra physaloides (Linn.) Gaertn seeds.

Nicandra physaloides (Linn.) Gaertn seeds (NPGS) could be manually scrubbed to obtain water-soluble pectin, which forms gel at room temperature without additives. The extraction, characterization and spontaneous gelation (SG) mechanism of the pectin were studied. The results showed that the pectin was located on the surface of NPGS and easily to be dissolved. Chemically, the pectin was low methoxy pectin with esterification degree of 46.93%, Gal-A content of 65.80%, and average molar weight of 631.15 kDa. The SG occurred at the pectin concentration of 1.5%, it can be destroyed by urea and SDS, however, EDTA cannot. In addition, KCl and NaCl induced the gelation of 1.0% pectin solution and the ions of K, Mg, Ca and Na were detected in the pectin. Hydrogen bonding, electrostatic and hydrophobic interaction contributed to the SG. This study could promote the commercial applications of the pectin in the field of edible colloids and cosmetics.

Preparation of pectin/poly(m-phenylenediamine) microsphere and its application for Pb2+ removal.

Novel pectin/poly(m-phenylenediamine) (P/PmPDA) microspheres with different content of PmPDA were prepared by assembling PmPDA on the surface of pectin microsphere. The successful preparation was confirmed by the results of Fourier Transform Infrared spectra (FTIR), scanning electron microscopy (SEM) and elemental analysis. Compared with pectin microsphere, the Pb2+ adsorption performance of P/PmPDA microspheres was significantly improved. The results of batch adsorption experiments were in good agreement with the Langmuir isotherm model for Pb2+ adsorption, indicating the adsorption was monolayer. The maximum adsorption capacity of Pb2+ was found to be 390.9 mg/g. The kinetic adsorption process was well described by the pseudo-second-order model and chemical adsorption dominated the adsorption process. The potential mechanisms of Pb2+ adsorption were speculated as ion exchange and chelation, which were supported by X-ray photoelectron spectroscopy (XPS). The P/PmPDA microspheres showed good recyclability after five adsorption/desorption cycles. All these results indicated the potential of P/PmPDA microspheres for removing Pb2+.

Effects of proanthocyanidins on the pasting, rheological and retrogradation properties of potato starch.

BACKGROUND: Proanthocyanidins (PAS) were complexed with potato starch (PS) to prepare polyphenol-starch complexes. The pasting, rheological and retrogradation properties of the complexes were investigated. RESULTS: The addition of PAS markedly affected the pasting, rheological and retrogradation properties of PS, especially at a concentration of 5% (w/w). Rapid viscosity analysis indicated that PAS significantly changed the viscosity, breakdown and setback value of PS. The rheological results showed that PAS decreased the flow behavior index and consistency coefficient, but increased the viscoelasticity of PS. Differential scanning calorimetry and X-ray diffraction indicated that PAS delayed the retrogradation of PS. Furthermore, scanning electron microscopy indicated that the morphologies of retrograded PS gels were greatly altered to a less compact structure with the presence of PAS. Moreover, Fourier transform infrared spectroscopy elucidated that PAS interacted with PS via a noncovalent interaction, and inhibited the retrogradation of PS. CONCLUSIONS: The findings suggested that supplementing PS with PAS might be an effective and convenient method for modifying the physicochemical properties of PS. © 2021 Society of Chemical Industry.

Impact of pH, ferrous ions, and tannic acid on lipid oxidation in plant-based emulsions containing saponin-coated flaxseed oil droplets.

The influence of pH (pH 3, 5 and 7), ferrous ions (0 or 100 µM Fe2+), and tannic acid (0 to 0.1% TA) on the rate of lipid oxidation in plant-based emulsions containing quillaja saponin-coated flaxseed oil droplets was studied. Tannic acid formed complexes with Fe2+ whose properties depended on TA:Fe2+ ratio and pH. Emulsions were incubated at 37 °C in the dark, and changes in their particle size, surface potential, appearance, microstructure, and lipid oxidation status were monitored over time. The initial ζ-potential and mean particle diameter of the emulsions were -68 mV and 0.18 µm, respectively. In the absence of TA, the particle size increased appreciably during storage due to droplet coalescence, as rapid oxidation occurred. In the presence of TA, the emulsions were more resistant to both droplet aggregation and lipid oxidation, as a result of its strong ferrous ion-binding properties. The lipid oxidation rate increased with decreasing pH, which was attributed to an increase in ferrous ion's water-solubility and activity in acidic solutions. The addition of Fe2+ greatly accelerated lipid oxidation, but the oxidation rate was decreased by also adding TA. These results suggest that tannic acid is an effective antioxidant in emulsions, which can be attributed to its ferrous ion-chelation properties.

Low-dose biochar added to sediment improves water quality and promotes the growth of submerged macrophytes.

Biochar is a good adsorbent for water pollutants. However, the effects of biochar on aquatic organisms are not well understood. In this study, different amounts of biochar (CK, 0 mg/g; T1, 10 mg/g; T2, 30 mg/g) were added to sediment to study changes in water quality and its impact on three submerged macrophytes (Hydrilla verticillata, Vallisneria natans, and Ceratophyllum demersum) and the sediment microbial community. The results indicated that biochar treatments significantly increased the water pH and conductivity. Compared with the initial values, the total phosphorus (P) contents in the water of the CK, T1, and T2 treatments decreased by 78.5%, 95.0%, and 58.3%, respectively, while the total nitrogen contents increased by 26.26%, -5.81%, and 19.70%, respectively. Compared with those in CK, the relative growth rates of H. verticillata, V. natans, and C. demersum in T1 increased by 28.4%, 163.1%, and 61.3%, respectively, while those in T2 showed no significant difference except that the growth rates of H. verticillata decreased by 17.7%. The P contents of the three submerged macrophytes increased with the increase of biochar addition, except that there was no significant difference between T2 and CK for H. verticillata. Biochar treatments reduced the biomass of total microbial, bacterial, and fungal phospholipid fatty acids in the sediment for H. verticillata and V. natans, and they increased fungal: bacterial ratios in the low-dose biochar treatments for V. natans and C. demersum. This study demonstrates that the addition of biochar to sediment significantly increased the pH and conductivity, and decreased total P contents in the water. Low-dose biochar treatments were more beneficial for water quality improvements and the growth of submerged macrophytes than high-dose biochar.

Utilization of plant-based protein-polyphenol complexes to form and stabilize emulsions: Pea proteins and grape seed proanthocyanidins.

Plant-based proteins and polyphenols are increasingly being explored as functional food ingredients. Colloidal complexes were prepared from pea protein (PP) and grape seed proanthocyanidin (GSP) and the ability of the PP/GSP complexes to form and stabilize oil-in-water emulsions were investigated. The main interactions between PP and GSP were hydrogen bonding. The stability of PP-GSP complexes to environmental changes were studied: pH (2-9); ion strength (0-0.3 M); and temperature (30-90 °C). Emulsions produced using PP-GSP complexes as emulsifiers had small mean droplet diameters (~200 nm) and strongly negative surface potentials (~-60 mV). Compared to PP alone, PP-GSP complexes slightly decreased the isoelectric point, thermostability, and salt stability of the emulsions, but increased their storage stability. The presence of GSP gave the emulsions a strong salmon (red-yellow) color, which may be beneficial for some specific applications. These results may assist in the creation of more efficacious food-based strategies for delivering proanthocyanidins.

Fabrication of pea protein-tannic acid complexes: Impact on formation, stability, and digestion of flaxseed oil emulsions.

There is growing interest in the identification of plant-based functional ingredients for utilization within the food industry. Complexes were fabricated from pea protein (PP) and tannic acid (TA) and then their ability to act as antioxidant emulsifiers in flaxseed oil-in-water emulsions was studied. PP-TA complex formation was investigated using isothermal titration calorimetry and turbidity analysis, which suggested hydrogen bonding and hydrophobic interactions were important in their assembly. PP-TA-stabilized emulsions containing small droplets could be formed at relatively high TA levels. Moreover, PP-TA complexes had strong antioxidant activity, which extended the shelf life of flaxseed oil emulsions. The composition of the PP-TA complexes impacted the aggregation state of the lipid droplets under simulated gastric conditions, which affected the rate and extent of lipid digestion. This study shows PP-TA complexes can be used for fabricating flaxseed oil delivery systems with enhanced oxidative stability and good digestibility.

A new pre-gelatinized starch preparing by gelatinization and spray drying of rice starch with hydrocolloids.

Rice starch with hydrocolloids (pectin, xanthan gum, sodium alginate or ι-carrageenan) was gelatinized and subsequently spray dried to prepare pre-gelatinized rice starch (PRS) with hydrocolloids (PRS-H). The PRS-H displayed concave granular shape with amorphous structure, indicating rice starch in PRS-H was completely gelatinized. Cold paste viscosity of PRS-H was enhanced in comparison with that of PRS. Especially, xanthan and ι-carrageenan increased cold paste viscosity of PRS-H more than pectin and alginate did. Cold paste viscosity of physically mixed PRS and hydrocolloids (PRS+H), and flow behavior of hydrocolloids themselves as well as gelatinized starch-hydrocolloids without spray drying (GRS-H) indicated interactions existed between starch and hydrocolloids during the preparation. Swelling power, water solubility index, and dynamic viscoelastic properties of PRS-H were also adjusted by different hydrocolloids. These results showed that premixing hydrocolloids with starch before gelatinization in method of spray drying would be a suitable methodology for manufacture PRS with altered properties.

Amino acid-amidated pectin: Preparation and characterization.

There is interest in extending the functionality of natural polymers using simple chemical derivatization methods. In this study, the ability of pectin to react with various amino acids (40 °C) in aqueous solution without a catalyst was investigated, including glutamic acid, glycine, cysteine, lysine, and arginine. Only glycine, lysine, and arginine could form conjugates with pectin under these conditions. Amino acid-amidated pectin (AAAP) conjugates with a degree of amidation of 6.50% were prepared and characterized using elemental analysis, FT-IR, and 1H NMR. Size exclusion chromatography combined with multiangle light scattering and refractive index detection indicated pectin degradation occurred during the reaction. These results were supported by measurements of apparent viscosities. Scanning electron microscopy showed appreciable differences among the surface topographies of samples. Cell culture experiments showed the AAAP conjugates exhibited no cytotoxic effects. Our results suggested the AAAP conjugates may be suitable for use as new functional ingredients in food industry.

Antioxidant activity of proanthocyanidins-rich fractions from Choerospondias axillaris peels using a combination of chemical-based methods and cellular-based assay.

An extract isolated from Choerospondias axillaris peels was separated into five fractions using size-exclusion chromatography. The structural composition and mean degree of polymerization (mDP) of these fractions were then characterized by acid-catalysis followed by HPLC analysis. The antioxidant activity of each fraction was determined using a combination of chemical-based methods (DPPH, ABTS(+) radical scavenging activity, ferric-reducing antioxidant power, and phosphomolybdate assay) and a cellular-based assay. All fractions tested were found to have high total phenolics contents and were rich in proanthocyanidins. The mDP of fractions (F1-F5) ranged from 1.92 to 9.25. When tested by the chemical-based assays, the antioxidant activity of the fractions did not depend on molecular weight of the phenolics. Conversely, when tested by the cellular-based assay the antioxidant activity actually decreased with increasing molecular weight of the proanthocyanidins. These experiments highlight the limitations of using chemical-based assays to establish the antioxidant activity of proanthocyanidins within biological systems.

Proanthocyanidins, Isolated from Choerospondias axillaris Fruit Peels, Exhibit Potent Antioxidant Activities in Vitro and a Novel Anti-angiogenic Property in Vitro and in Vivo.

The production of new blood vessels (angiogenesis) is an important stage in the growth and spread of cancerous tumors. Anti-angiogenesis is one strategy for controlling tumor progression. This study evaluated the antioxidant and anti-angiogenic activities of a proanthocyanidins (PAs) extract from Choerospondias axillaris peels. HPLC-MS analysis revealed that numerous oligomeric forms of the PAs were detected in the PAs extract, including dimers, trimers, tetramers, and flavan-3-ol monomers. The PAs extract possessed appreciable free radical scavenging activity (IC50/DPPH = 164 ± 7 µg/mL, IC50/ABTS = 154 ± 6 µg/mL), potent reducing power (0.930 ± 0.030 g AAE/g), and strong cellular antioxidant activity (EC50 = 10.2 ± 1.4 and 38.9 ± 2.1 µg/mL without or with PBS-wash, respectively). It could also retard various stages of angiogenesis, such as the migration of endothelial cells and the creation of tubes, without causing toxicity to the cells. With regard to intracellular signal transduction, the PAs extract attenuated the phosphorylation of Akt, ERK, and p38MAPK dose-dependently in endothelial cells from human umbilical veins. In transgenic zebrafish embryo, new blood vessel formation was suppressed by PAs extract in a concentration-dependent manner at 72 h post fertilization. Thus, these results suggest that PAs from C. axillaris peels could be a good source of natural inhibitors to target angiogenesis.