Characterization of physicochemical properties of hypochlorite- and peroxide-oxidized cassava starches

Calcium content mediated hemostasis of calcium-modified oxidized microporous starch

Blood coagulates are closely related to calcium ions (coagulation factor IV), and calcium-doped biomaterials have been reported to be effective in hemostasis. However, the effects exerted by calcium on hemostatic agents have not been previously investigated. The aims of this work were to develop calcium-modified oxidized microporous starch (CaOMS) with controllable calcium contents and to explore the relationship between calcium content and hemostatic effects. The results showed that low calcium content promoted coagulation, while high calcium content inhibited coagulation. CaOMS3 with 2.2 mg/g calcium content was optimal because of its excellent water absorption performance that enhanced physical coagulation, the rapid initiation of coagulation cascade reactions, and the enhanced chemical coagulation by RBC aggregation and platelet activation. The synergistic effects of chemical activation and physical absorption endowed CaOMS with the potential to control internal organ bleeding. These results suggested that CaOMS may be a promising hemostatic agent with wide spread applications.

Effects of carboxyl and aldehyde groups on the antibacterial activity of oxidized amylose

Dialdehyde-amyloses, dicarboxyl-amyloses and dialdehyde-carboxyl-amyloses with different oxidation levels were prepared and used to study the effects of aldehyde and carboxyl groups on the antibacterial activity of oxidized amyloses. The results showed that dicarboxyl-amyloses presented antibacterial activity through acidic pH effect produced by carboxyl groups, which was easily reduced or eliminated by adjusting pH. Dialdehyde-amyloses possessed a broad-spectrum antibacterial activity owing to the reactivity of aldehyde groups rather than acidic pH effect. Aldehyde would irreversibly damage bacterial cell wall and cytoplasmic membrane, resulting in decay and death of bacterial cells. It is interesting that the antibacterial properties of dialdehyde-carboxyl-amyloses were improved to some extent compared to dialdehyde-amyloses. The improvement of antibacterial effect of dialdehyde-carboxyl-amyloses may be due to the increasing dispersibility endowed by carboxyl groups, which could effectively enhance the interaction between dialdehyde-carboxyl-amyloses and bacteria. As a result, carboxyl group could act as a promising synergistic group against bacteria with aldehyde group.

The effect of NaOH and NaClO/NaBr modification on the structural and physicochemical properties of dextran

Dextran was modified at different pH levels by using NaClO/NaBr and also this method was compared with just using NaOH. Then the properties of the products were investigated.

Preparation of a novel palladium catalytic hydrogel based on graphene oxide/chitosan NPs and cellulose nanowhiskers

Pd NPs dispersed on a polysaccharide-based hydrogel as a novel catalyst show high catalytic activity and recyclability for coupling reactions.

Chemically induced alterations in the characteristics of fouling-causing bio-macromolecules - Implications for the chemical cleaning of fouled membranes

Chemical cleaning is an essential process for the permeability recovery of fouled membranes, which is highly related to the interactions between chemicals and bio-macromolecules in fouling layers. In this study, three bio-macromolecules (i.e., effluent biopolymers (i.e., 0.45 μm-100 kDa) from a full-scale municipal wastewater treatment plant, bovine serum albumin (BSA) and dextran) were exposed to different chemicals (i.e., NaClO, H₂O₂, NaOH, and HCl) with varied concentrations to understand the changes in their properties and functional groups. The results showed that exposure to oxidants and alkali decreased the consistency index of all bio-macromolecules. With an increased oxidant dose, the molecular sizes of effluent biopolymers and dextran continuously reduced because of the oxidative cleavage of the long molecule chains. However, the molecular size of BSA sharply increased after being treated with oxidants and alkali, likely due to the cross-linkage of protein molecules. Three-dimensional fluorescence excitation-emission matrix (3D-EEM) spectra showed that the aromatic protein-like and humic substances in the effluent biopolymers were destructed readily during the treatments of oxidants and alkali. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analyse further confirmed that exposures to NaClO, H₂O₂ and NaOH led to the destruction of protein structures (i.e., amide I, II and III), the increase of carbonyl and carboxyl groups, and the decrease of fatty acids/lipids, all of which could make the bio-macromolecules more hydrophilic. Most importantly, the bio-macromolecules exposed to chemicals had better filterability, and their permeability through membranes also significantly increased, which could be explained well by the above analysis. The chemical cleaning mechanisms of fouled membranes are understood in depth in this study, and all of the results shed light on the implementation of on-line chemical enhanced backwashing in membrane processes.

Effect of Ozone Treatment on Deoxynivalenol and Wheat Quality

Deoxynivalenol (DON) is a secondary metabolite produced by Fusarium fungi, which is found in a wide range of agricultural products, especially in wheat, barley, oat and corn. In this study, the distribution of DON in the wheat kernel and the effect of exposure time to ozone on DON detoxification were investigated. A high concentration of toxin was found in the outer part of the kernel, and DON was injected from the outside to the inside. The degradation rates of DON were 26.40%, 39.16%, and 53.48% after the samples were exposed to 75 mg/L ozone for 30, 60, and 90 min, respectively. The effect of ozonation on wheat flour quality and nutrition was also evaluated. No significant differences (P > 0.05) were found in protein content, fatty acid value, amino acid content, starch content, carbonyl and carboxyl content, and swelling power of ozone-treated samples. Moreover, the ozone-treated samples exhibited higher tenacity and whiteness, as well as lower extensibility and yellowness. This finding indicated that ozone treatment can simultaneously reduce DON levels and improve flour quality.

Theoretical Insights into Three Types of Oxidized Starch-Based Adhesives: Chemical Stability, Water Resistance, and Shearing Viscosity from a Molecular Viewpoint

To better understand the origin and difference associated with chemical stability, water resistance, and shearing viscosity of three types of different oxidized modified starch-based adhesives, a detailed theoretical investigation from a molecular viewpoint has been performed using the AM1 semiempirical level and the DFT-B3LYP level, respectively. As a result, our findings suggest that, by Mulliken population analysis (MPA), frontier orbital analysis, and electrostatic potential (EP) analysis based on B3LYP/6-31G calculations, the chemical stability, water resistance, and shearing viscosity of the oxidized modified starch-based adhesives are uniformly improved and corresponding difference for each property presents an identical order: the oxidized grafted cross-linked starch-based adhesive > the oxidized grafted starch-based adhesive > the oxidized starch-based adhesive, which is well consistent with experimental results.

Chemical Modifications of Starch: Microwave Effect

This paper presents basic methods of starch chemical modification, the effect of microwave radiation on the modification process, and the physicochemical properties of starch. It has been shown that the modifications contribute to improvement of the material performance and likewise to significant improvement of its mechanical properties. As a result, more and more extensive use of starch is possible in various industries. In addition, methods of oxidized starch and starch esters preparation are discussed. Properties of microwave radiation and its impact on starch (with particular regard to modifications described in literature) are characterized.

Preparation and properties of a starch-based wood adhesive with high bonding strength and water resistance

A Highly efficient method was developed for preparing starch-based wood adhesives with high performance, using H2O2, a silane coupling agent and an olefin monomer as an oxidant, cross-linking agent and comonomer, respectively. The effects of various parameters on the shear adhesive strength were investigated in the dry state (DS) and wet state (WS). The results indicated that the bonding strength of starch-based wood adhesives could reach 7.88 MPa in dry state and 4.09 MPa in wet state. The oxidation could reduce the content of the hydroxyl transforming into carboxyl and aldehyde groups, and the graft copolymerization enhanced the thermal stability, which improved the bonding strength and water resistance. The starch-based adhesive and the fractures in the bonded joints were analyzed via Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The improved properties were attributed to the modified of microstructure of the graft-copolymerized starch-based adhesive.

Preparation of Oxidized Starch Using Environment Friendly Chlorine Dioxide as Oxidant

In the present work, the oxidized corn starch was prepared by using chlorine dioxide as novel oxidant. It was characterized by X-ray diffraction, scanning electron microscope (SEM), and transmission electron microscope (TEM). The main factors that affect the oxidation process were studied, and the oxidation degree of oxidized starch was determined by the carboxyl content and viscosity of the product. The results show that carboxyl groups are introduced into the starch chains successfully, and the oxidation reaction mainly carries out at the amorphous area. Compared with native starch, the light transmittance and anti-retrogradation of oxidized starch increase, whereas the viscosity reduces. The best oxidized starch can be obtained at the sodium chlorate dosage of 3%, hydrochloric acid 4%, and sulfuric acid 3% (all based on the initial starch weight), while the oxidation reaction is conducted at 50°C for 5 h.

Ultra‐microstructural features of perborate oxidized starch

Ultrafine structures of low, medium, and highly oxidized starches, symbolized as LOS, MOS, and HOS, respectively, were thoroughly investigated. These oxidized starches were obtained by treatment of native starch (NS) with three different concentrations of sodium perborate (SPB). Thus, obtained products were studied with respect to major chemical and fine physical characteristics vis‐a‐vis these of NS (a) acidic and reduced groups creation along with mode of association, (b) significant increase in solubility, and (c) outstanding decrease in apparent viscosity. Thermogravimetric analysis (TGA) revealed thermal stability of the said substrates follows order: HOS > MOS > LOS > NS. Scanning electron micrographs (SEM) showed polygonal or irregular shape with particle size ranging from 2 to 20 μ. After oxidation, the starch surface became rough and the edges lost their definiteness completely. In conclusion, SPB is an efficient oxidant to produce oxidized starches with useful characteristics, which advocate them to wide applications in textile sizing and medicinal domains. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40170.

Properties of Edible Films Based on Oxidized Starch and Zein

The objective of this work was to investigate the effect of zein and film formulation on mechanical and structural properties of native (FNS), and oxidized with 2.5% (FOSA) and 3.5% (FOSB) banana starch. The oxidized starch showed differences from native starch due to the oxidation process, showing a decrease in lipids, proteins, and amylose. The increase of the sodium hypochlorite increased the content of carbonyl and carboxyl groups in the ranges 0.015–0.028% and 0.022–0.031%, respectively. The film obtained from FOSB displayed the highest tensile strength (5.05 MPa) and satisfactory elongation value (27.1%). The zein addition caused a decrease in these mechanical properties, as well as a significant decrease in water vapour permeability (WVP). However, films from FOSA and FOSB showed higher permeability than that of the native starch. The addition of glycerol and the level of oxidation increased the films moisture. Micrographs showed that, during the oxidation process, impurities were largely eliminated from the starch granule, noting more homogeneous structures both in granules and films.