Esterification Modification Research Articles

De-Methyl Esterification Modification of Root Pectin Mediates Cd Accumulation of Lactuca sativa.

Cadmium (Cd) contamination in agricultural soil brings severe health risks through the dietary intake of Cd-polluted crops. The comprehensive role of pectin in lowering Cd accumulation is investigated through low Cd accumulated (L) and high Cd accumulated (H) cultivars of L. sativa. The significantly different Cd contents in the edible parts of two L. sativa cultivars are accomplished by different Cd transportations. The pectin is the dominant responsive cell wall component according to significantly increased uronic acid contents and the differential Cd absorption between unmodified and modified cell wall. The chemical structure characterization revealed the decreased methyl esterification in pectin under Cd treatment compared with control. Significantly brighter LM19 relative fluorescence density and 40.82% decreased methanol in the root pectin of L cultivar under Cd treatment (p < 0.05) supported that the de-methyl esterification of root pectin is more significant in L cultivar than in H cultivar. The pectin de-methyl esterification of L cultivar is achieved by the upregulation of pectin esterases and the downregulation of pectin esterase inhibitors under Cd treatments, which has facilitated the higher Cd-binding of pectin. Our findings provide deep insight into the differential Cd accumulation of L. sativa cultivars and contribute to the understanding the pollutant behaviors in plants.

Controlling strategies of methanol generation in fermented fruit wine: Pathways, advances, and applications.

Methanol is widely existed in fermented fruit wines (FFWs), and the concentration is excessive at times due to inappropriate fermentation conditions. Methanol is neurotoxic, and its metabolites of formaldehyde and formic acid can cause organic lesions and central respiratory system disorders. FFWs with unspecified methanol limits are often produced with reference to grape wine standards (250/400mg/L). To clarify the causes of methanol production in FFWs and minimize the methanol content, this study summarizes the current process methods commonly applied for methanol reduction in FFWs and proposes novel potential controlling strategies from the perspective of raw materials (pectin, pectinase, and yeast), which are mainly the low esterification modification and removal of pectin, passivation of the pectinase activity, and the gene editing of yeast to target the secretion of pectinases and modulation of the glycine metabolic pathway. The modified raw materials combined with optimized fermentation processes will hopefully be able to improve the current situation of high methanol content in FFWs. Methanol detection technologies have been outlined and combined with machine learning that will potentially guide the production of low-methanol FFWs and the setting of methanol limits for specific FFW.

Preparation and slow-release properties of nanocellulose composite hydrogels

Nanocellulose (CNF) was obtained from carrots using a combination of chemical treatment, mechanical milling, and ultrasonic treatment. Ultrafast preparation of maleic anhydride esterified nanocellulose was achieved by a hydrated hydrogen ion-driven dissociation, chemical cross-linking strategy based on a “one-pot” reaction method. Esterification modification with maleic anhydride reduced the crystallinity of nanocellulose and enhanced its thermal stability. High-strength drug-carrying hydrogels (MACNF/SA) with different drug loading capacities were prepared using cefixime (CFX) as a drug model and maleic anhydride esterified nanocellulose (MACNF) and sodium alginate (SA) as the main raw materials. The compressive strength of MACNF/SA hydrogels made from MACNF reached a maximum of 80.3 kPa when the mass ratio of CNF to MA was 2.5:12. Rheological property tests showed that the MACNF/SA hydrogels were pseudoplastic fluids with shear thinning. The drug release from the drug-carrying hydrogels followed non-Fickian diffusion.

Insight into esterified and granular esterified-pregelatinized starch formation during esterification modification: Key role of temperature

The formation conditions and functional property differences of esterified starch (ES) and granular esterified-pregelatinized starch (EPS) synchronously prepared by octenyl succinic anhydride (OSA) modification remain unclear. In this study, we explored the formation conditions and physicochemical properties of ES and EPS after OSA modification. The modification temperature controlled the formation amount and time for both starch types during OSA modification. Compared to ES, EPS exhibited a higher degree of substitution, cold-water swelling power, water-absorption capacity and apparent viscosity in cold water. The structural characterization confirmed the molecular weight and short/long-range molecular order of ES and EPS decreased. Moreover, scanning electron microscopy indicated EPS retained its granular morphology. The X-ray diffraction patterns confirmed the presence of more starch–lipid complexes formed in EPS than in ES. This study provides a novel method for preparing esterified and granularly esterified–pregelatinized starches that could be used as promising additives in low-energy formula foods.

Tunning the hydrophobic performance and thermal stability of pectin film by acetic anhydride esterification

Pectin, a polysaccharide found in plant cell walls, is characterized by a high abundance of hydroxyl groups and carboxylic acid groups, which results in a strong affinity for water and limits its suitability as a film material. This study aimed to modulate the esterification degree of PEC films by adjusting the concentration of acetic anhydride, and assess the impact of acetic anhydride esterification modification on the properties of the resultant PEC films. The results demonstrated successful grafting of acetic anhydride onto the galacturonic acid ring in the PEC molecule through the esterification process. The hydrophobicity, thermal stability, barrier properties, and mechanical properties of the esterified PEC films were investigated. Among the various concentrations tested, the E-PEC-0.25 film exhibited the highest contact angle of 103.46° and tensile strength of 33.44 MPa, showcasing optimal performance. The E-PEC-0.1 film achieved the highest esterification degree of 0.94 and elongation at a break of 21.11 %. It also exhibited the transparency of 11.66 and the lowest water vapor transmission rate of 0.56 g·mm/(m2·h·kpa). Additionally, TGA and DSC tests revealed enhanced thermal stability of the esterification-prepared films. These findings highlight the potential of acetic anhydride tuning as a promising strategy for optimizing pectin film production.

Inhibition of GRK2 ameliorates the pristane-induced mouse SLE model by suppressing plasma cells differentiation

Systemic lupus erythematosus (SLE) is a multifaceted autoimmune disorder characterized by diverse clinical manifestations and organ damage. Despite its elusive etiology, dysregulated subsets and functions of B cells are pivotal in SLE pathogenesis. Peoniflorin-6′-O-benzene sulfonate (CP-25), an esterification modification of Paeoniflorin, exhibits potent anti-inflammatory and immunomodulatory properties in autoimmune diseases (AID). However, the involvement of CP-25 and its target, GRK2, in SLE development has not been explored. In this study, we demonstrate that both genetic deficiency and pharmacological inhibition of GRK2 attenuate autoantibodies production, reduce systemic inflammation, and mitigate histopathological alterations in the spleen and kidney in the pristane-induced mouse SLE model. Importantly, our findings highlight that both genetic deficiency and pharmacological inhibition of GRK2 suppress plasma cells generation and restore dysregulated B-cell subsets by modulating two crucial transcription factors, Blimp1 and IRF4. Collectively, targeting GRK2 with CP-25 emerges as a promising therapeutic approach for SLE.

Effect of amylose partial extraction on citrate esterification of potato starch and its role in structure and physicochemical modification

This study examines the impact and influence of amylose on the starch esterification reaction through partial extraction of amylose. Citric acid was added for the esterification reaction, and then the esterified starches' multiscale structure, physicochemical, and functional properties were evaluated. As the extraction time of amylose increased, the amylose content in the starch decreased. Higher concentrations of citric acid will lead to samples with a higher degree of substitution, with DS rising from 0.203 % (0 h) to 0.231 % (3.5 h) at CA3 treatment. While removing amylose had minimal effects on the crystal structure of starch granules, it did decrease the ratio of A and B1 chains and the molecular weight of amylose. Acid hydrolysis exacerbated these changes upon the addition of citric acid. Furthermore, removing amylose followed by citrate esterification resulted in lower pasting viscosity, enthalpy of gelatinization (from 13.37 J to 2.83 J), and degree of short-range ordering. Also, digestion shows a decrease caused by the increasing content of slow-digesting starch. The presence of amylose in starch granules does affect the formation of starch esters, and removing it before esterification modification may improve production efficiency and reduce costs to some extent.

Esterification modification of graphene oxide for Metronidazole release: Optimization and modelling using response surface methodology and artificial neural Networks

The esterification modification of graphene oxide was performed by the reaction with the terephthalic acid and allyl alcohol in the presence of p-toluene sulfonic acid as a catalyst for metronidazole delivery. The artificial neural network was used for properly modelling and predicting the percentage of metronidazole sorption. The artificial neural network model with the topology of 3:6:1 (three input variables, six neurons in two and three hidden layers, and one output variable) using feed-forward back-propagation learning was developed. The influence of various parameters, e.g., pH, contact time, and initial drug concentration on the sorption process was investigated through central composite design using response surface methodology at five levels. The maximum adsorption efficiency of the drug was observed at 94.26 % under optimal conditions. The Levenberg-Marquardt algorithm performed better than the scaled conjugate gradient algorithm. Layer 2 with 6 neurons with the least mean square error with 3 epochs was chosen as the optimal layer and neuron for drug sorption. The experimental results were examined by using linear and non-linear forms of the isotherms and kinetics models. According to the coefficient of determination and sum of squares of errors, it was shown that the non-linear forms of Langmuir isotherm and pseudo-2nd-order kinetic models are best fit the experimental results. The thermodynamic factors indicated that the drug sorption on adsorbent is endothermic and spontaneous. The in-vitro release study showed that the drug release in simulated gastric fluid (pH = 1.2) was significantly lower compared to the release in simulated intestinal media (pH = 7.4). At pH = 1.2, 27.60 % of the drug has been released over 1 h compared to 98.97 % in simulated intestinal media over 6 h. The fitting of kinetic results by the pharmacokinetic models shows the non-Fickian diffusion from the nanocarrier.

Esterified starches enhance short-term satiety in mice via structural and physicochemical alterations.

Starch is the main carbohydrate in the human diet, of which resistant starch (RS) has positive effects on satiety. This study examined the impact of esterified starch with varying degrees of substitution on short-term satiety in mice. Three forms of esterified starch were investigated: phosphorylated starch (SP), acetylated starch (SA), and octenylsuccinic acid starch (OSA). The findings showed that esterified starch increased the RS content by altering the short-range ordered structure. Additionally, esterification modification increased chewiness and viscosity, thereby delaying gastric emptying. Esterified starch stabilized the postprandial blood glucose concentration and increased the secretion of GLP-1 in mice, thereby generating short-term satiety effects, particularly in the SP-8%, SA-8%, and OSA-3% groups. The short-range ordered structure of starch significantly affects the 4-hour intake of mice. The phosphorylation modification exhibited the highest content of RS and the most pronounced effect in reducing postprandial fluctuations in blood glucose concentration, whereas the acetylation modification resulted in the highest increase in GLP-1 concentration. This study lays a theoretical foundation for the production and application of high-satiety foods.

Fabrication of multi-functional biodegradable liquid mulch utilizing xyloglucan derived from tamarind waste for agricultural application

Biodegradable liquid mulch is considered a promising alternative to plastic mulch for sustainable agriculture. This work proposed a xyloglucan-based liquid mulch with multi-function using a combination of chemical modification and blending methods. The esterification product of tamarind xyloglucan (TXG) from forestry wastes was synthesized with benzoic anhydride (BA). The effect of esterification modification was investigated, and BA-TXG was utilized as a film-forming and sand-fixation agent. The rheological properties, thermal stability, and hydrophobicity were improved following esterification. Additionally, waterborne polyurethane and urea were incorporated into the mulch to enhance its mechanical strength (23.28 MPa, 80.71 %), and homogeneity, as well as improve its nutritive properties. The xyloglucan-based liquid mulch has excellent UV protection, a high haze value (approximately 90 %), and retains water at a rate of 80.45 %. SEM and immersion experiment showed the effect of xyloglucan-based liquid mulch on sustainable sand-fixation. Moreover, the liquid mulch treatment demonstrated an impressive germination rate of 83.8 % and degradation rate of 51.59 % (60 days). The modified polysaccharide film increases stability and slows down the degradation rate. Tamarind xyloglucan-based liquid mulch exhibits powerful and diverse optical properties as well as sand fixation functions, indicating their great potential in sustainable agriculture as an alternative to plastic mulch.

Investigating the influence of CaCl2 induced surface gelatinization of red adzuki bean starch on its citric acid esterification modification: Structure–property related mechanism

This study prepared starch with different degrees of gelatinization (10 % and 30 %) by CaCl2, and further combined with citric acid at different concentrations (10 %, 20 %, and 30 %) for esterification. The results indicated that CaCl2 induced surface gelatinization and the esterification promoted its fragmentation. This synergistic modification induced depolymerization of starch chains and a decrease in molecular weight, although starch's Maltese cross, growth rings, and crystal type remained unchanged. Moreover, the synergistic modification induces a short-range ordered structure loss and the enthalpy decrease of starch, which induce starch pasting properties decrease and solubility increase. Furthermore, the introduction of ester groups by esterification increases the resistant starch content by limiting the binding sites for digestive enzymes. In conclusion, surface gelatinization can increase active reaction sites by disrupting the starch shell structure, and serves as a potential pretreatment to enhance the deep application of esterified starch in food and pharmaceutical fields.

Preparation of lauric acid esterified starch by ethanol solvothermal process and its Pickering emulsion

In this paper, the esterification modification of different kinds of starches such as waxy maize, normal maize, high-amylose maize, cassava and potato in high temperature closed system were studied by solvothermal method. The oil-in-water Pickering emulsion were prepared with esterified starches as granule stabilizer. The microscopic state of granules in the emulsion and the physical and oxidation stability of emulsion were studied. The results show that starches are not gelatinized and can be esterified at a temperature (100 °C) much higher than that of gelatinization, and the granule morphology is almost unchanged. DS (degree of substitution) values of esterified starches range from 0.0333 to 0.0512. Pickering emulsion with 50 vol% oil volume fraction prepared with 3.0 wt% granule concentration did not show any instability such as oil-water separation after storage at room temperature for 30 days. Atomic force microscope (AFM) analysis showed that all esterified starch granules had the characteristics of granular cold-water swelling starch (GCWSS). The granules completely swelled into a dense molecular chain in the emulsion, and this three-dimensional network structure improved the stability of emulsion. Therefore, the preparation of esterified starch granules by ethanol solvothermal method is a simple and effective method.

Mechanism of the effect of esterified modified polystyrene-maleic anhydride on the dispersion and stability of carbon black in colour paste

An aqueous carbon black slurry was prepared by esterifying polystyrene-maleic anhydride with isobutanol as the esterifying agent and using the esterified product as a dispersant for carbon black. The effects of grinding time and dispersant addition on the ground particle size of carbon black before and after the esterification modification were investigated, as well as the effect of SMA dispersant on the dispersion stability of carbon black. The carbon black slurry was investigated by introducing external conditions such as temperature and pH, and the microscopic dispersion of the ink was observed by SEM. The results showed that the dispersion effect of the isobutanol-modified SMA was stronger than that of the unmodified SMA, the particle size of the carbon black paste reached 84 nm with the best stability when the dispersant was added at 4 % and the grinding time was 120 min. FTIR and XRD results showed that the surface groups of the carbon black interacted with the groups of the dispersant to achieve dispersion stability. This study not only provides directions for the selection of dispersant for carbon black in new aqueous media but also confirms the practicality of black colour pastes in gel inks and provides a theoretical reference for the development of pigment-based gel inks.

Preparation of Bio-Foam Material from Steam-Exploded Corn Straw by In Situ Esterification Modification.

In this work, we engineered a corn-straw-based bio-foam material under the inspiration of the intrinsic morphology of the corn stem. The explosion pretreatment was applied to obtain a fibrillated cellulose starting material rich in lignin. The in situ esterification of cellulose was adopted to improve the cross-linking network of the as-developed foam bio-material. The esterification of lignin was observed in the same procedure, which provides a better cross-linking interaction. The esterified corn-straw-derived bio-foam material showed excellent elastic resilience performance with an elastic recovery ratio of 83% and an elastic modulus of 20 kPa. Meanwhile, with surface modification by hexachlorocyclotriphosphazene-functionalized lignin as the flame retardant (Lig-HCCP), the as-obtained bio-foam material demonstrated quite a good flame retardancy (with 27.3% of the LOI), as well as a heat insulation property. The corn-straw-derived bio-foam material is prospected to be a potential substitution packaging material for widely used petroleum-derived products. This work provides a new value-added application of the abundant agricultural straw biomass resources.

Wood-Derived Polymers from Olefin-Functionalized Lignin and Ethyl Cellulose via Thiol-Ene Click Chemistry.

Lignin and cellulose derivatives have vast potential to be applied in polymer materials. The preparation of cellulose and lignin derivatives through esterification modification is an important method to endow cellulose and lignin with good reactivity, processability and functionality. In this study, ethyl cellulose and lignin are modified via esterification to prepare olefin-functionalized ethyl cellulose and lignin, which are further used to prepare cellulose and lignin cross-linker polymers via thiol-ene click chemistry. The results show that the olefin group concentration in olefin-functionalized ethyl cellulose and lignin reached 2.8096 mmol/g and 3.7000 mmol/g. The tensile stress at break of the cellulose cross-linked polymers reached 23.59 MPa. The gradual enhancement in mechanical properties is positively correlated with the olefin group concentration. The existence of ester groups in the cross-linked polymers and degradation products makes them more thermally stable. In addition, the microstructure and pyrolysis gas composition are also investigated in this paper. This research is of vast significance to the chemical modification and practical application of lignin and cellulose.

Enhancing the solubility and antimicrobial activity of cellulose through esterification modification using amino acid hydrochlorides

Most amino acid molecules have good water solubility and are rich in functional groups, which makes them a promising derivatizing agent for cellulose. However, self-condensation of amino acids and low reaction efficiency always happen during esterification. Here, amino acid hydrochloride ([AA]Cl) is selected as raw material to synthesize cellulose amino acid ester (CAE). Based on TG-MS coupling technology, a significantly faster reaction rate of [AA]Cl compared to raw amino acid can be observed visually. CAE with the degree of substitution 0.412–0.516 is facilely synthesized under 130–170 °C for 10–50 min. Moreover, the effects of amounts of [AA]Cl agent, temperature, and time on the esterification are studied. The CAE can be well dissolved in 7 wt% NaOH aq., resulting in a 7.5 wt% dope. The rheological test of the dope demonstrated a shear-thinning behavior for Newtonian-like fluid, and a high gel temperature (41.7 °C). Further, the synthesized products show distinct antibacterial activity and the bacteriostatic reduction rate against E. coli can reach 99.5 %.

Esterification modification and characterization of polyvinyl alcohol anion exchange membrane for direct methanol fuel cell

Esterification modification and characterization of polyvinyl alcohol anion exchange membrane for direct methanol fuel cell

Utilization of lignin upon successive fractionation and esterification in polylactic acid (PLA)/lignin biocomposite

The study presents the preparation of novel biocomposites based on different lignin fractions and polylactic acid (PLA). Based on the improvement of PLA mechanical properties, we proposed a process to assemble a series of lignin samples and PLA matrix using melt blending to investigate the effects on PLA properties from the perspective of the structure and molecular weight for lignin. The lignin was extracted from pine residue using deep eutectic solvent (DES) and was subjected to fractionation with ethanol and acetone as well as esterification modification with succinic anhydride (SAn). The treated lignin samples were used as additives, which not only improved the mechanical properties of PLA on the basis of retaining its thermal stability, but also granted excellent antimicrobial and biocompatibility properties. The results showed that the molecular weight of lignin was negatively correlated with the phenolic hydroxyl content, and the mechanical properties of the composites were also significantly affected by different molecular weights of lignin, indicating that the inhomogeneity of lignin affects its value-added utilization. The enhanced mechanical properties, antibacterial effect, and steady biocompatibility provide potential possibilities for lignin-based composites in biomedical applications.

Synthesis and characterization of methyltetrahydrophthalic anhydride esterified corn starch by wet method

The main purpose of this paper is to synthesize a novel esterified starch with an alicyclic structure. Herein, methyltetrahydrophthalic anhydride (MeTHPA), an alicyclic anhydride, was used to synthesize esterified corn starch (CS) with different degrees of substitution (DS) by a wet method. Compared with CS, the crystallinity and thermal degradation temperature of MeTHPA esterified CS (MeCS) decreased, while the hydrophobicity and light transmittance of MeCS films increased. The esterification modification significantly improved the toughness of the starch film. Between CS and MeCS films, the 15% Me/CS film shows a maximum elongation at break of 24.2% and a tensile strength of 8.0 MPa. Furthermore, 15% Me/CS was blended with CS as a sizing agent for polyester/cotton blended yarns and showed significantly increased adhesion to the blended yarns. Hence, the CS blended MeCS has a potential application in wrap sizing.

Fabrication of hydrophobic and high-strength packaging films based on the esterification modification of galactomannan

There is an increasing interest in substituting current packaging films with biologically-derived films without compromising mechanical properties and hydrophobicity. In this work, the esterified galactomannan (E-GM) films with good hydrophobicity, excellent oxygen barrier performance and high tensile mechanical strength were synthesized using anhydride esterification method prior to film formation. The hydrophobicity, mechanical properties, barrier properties, thermal stability and ultraviolet absorption of the prepared films were determined to fully investigate the features of galactomannan-based films. The results indicated that GM films can be successfully obtained by esterification. Compared to neat GM film, E-GM-1.5 film (acetic anhydride to GM of 1.5:1) achieved the highest degree of esterification (0.05), hydrophobicity (107°) and mechanical strength (92.0 MPa). In addition, the esterified GM films had lower toxicity for macrophages cells. The prepared E-GM films may provide more opportunities for further advancement and applications in the development of food packaging from natural resources.