Preparation and Properties of Organically Modified Na-Montmorillonite.

This study investigates the montmorillonite (MMT) content, rotational viscosity, and colloidal index of sodium montmorillonite (Na-MMT) as a function of the sodium agent dosage, reaction time, reaction temperature, and stirring time. Na-MMT was modified using different octadecyl trimethyl ammonium chloride (OTAC) dosages under optimal sodification conditions. The organically modified MMT products were characterized via infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. The results show that the Na-MMT with good properties (i.e., the maximum rotational viscosity and highest Na-MMT content with no decrease in the colloid index) was obtained at a 2.8% sodium carbonate dosage (measured based on the MMT mass), a temperature of 25 °C, and a reaction time of two hours. Upon organic modification of the optimized Na-MMT, OTAC entered the NA-MMT interlayer, and the contact angle was increased from 20.0° to 61.4°, the layer spacing was increased from 1.58 to 2.47 nm, and the thermal stability was conspicuously increased. Thus, MMT and Na-MMT were modified by the OTAC modifier.

Antimicrobial activity of gamma-poly (glutamic acid), a preservative coating for cherries.

We investigated the minimum inhibitory concentration (MIC), antibacterial activity, and preservation ability of four molar masses of γ-polyglutamic acid (PGA) against Escherichia coli, Bacillus subtilis, and yeast. The antibacterial mechanism was determined based on the cell structure, membrane permeability, and microscopic morphology of the microorganisms. We then measured the weight loss, decay rate, total acid, catalase activity, peroxidase activity, and malondialdehyde content toward the possible use of PGA as a preservative coating for cherries. When the molar mass was greater than 700 kDa, the MIC for Escherichia coli and Bacillus subtilis was less than 2.5 mg/mL. The mechanism of action of the four molar masses of PGA was different with respect to the three microbial species, but a higher molar mass of PGA corresponded to stronger inhibition against the microbes. PGA of 2000 kDa molar mass damaged the microbial cellular structure, resulting in excretion of alkaline phosphatase, but PGA of 1.5 kDa molar mass affected the membrane permeability and the amount of soluble sugar. Scanning electron microscopy indicated the inhibitory effect of PGA. The antibacterial mechanism of PGA was related to the molar mass of PGA and the microbial membrane structure. Compared with the control, a PGA coating effectively inhibit the spoilage rate, delay the ripening, and prolong the shelf life of cherries.

Preparation and Properties of Fractionated Soybean Protein Isolate Films.

Soybean protein isolate (SPI) and its four fractionated products (7S globulin, 11S globulin, upper soybean residue, and lower soybean residue) were compared by fabricating films and film liquids. The separation and grading effects, rheological properties of the film liquids, and difficulty in uncovering the films, in addition to the mechanical properties, water vapor permeability, oil permeability, and surface morphology of the films, were investigated. Results showed that the centrifugal precipitation method could be used to produce fractionated products. The 7S and 11S globulin films exhibited better hydrogels at lower shear rates than the other SPIs; however, they were more difficult to uncover. The tensile strength of the graded films decreased by varying degrees. However, the elongation at the break of the upper soybean residue film considerably increased, reaching 70.47%. Moreover, the permeability and surface morphology of the film were enhanced or weakened. The fractionated products, 7S and 11S globulin films, exhibited better performance. Overall, this study provides a basis for the improved development and use of fractioned SPI products.

New Opportunities in the Valorization of Technical Lignins.

Sugar-based biorefineries have faced significant economic challenges. Biorefinery lignins are often classified as low-value products (fuel or low-cost chemical feedstock) mainly due to low lignin purities in the crude material. However, recent research has shown that biorefinery lignins have a great chance of being successfully used as high-value products, which in turn should result in an economy renaissance of the whole biorefinery idea. This critical review summarizes recent developments from our groups, along with the state-of-the-art in the valorization of technical lignins, with the focus on biorefinery lignins. A beneficial synergistic effect of lignin and cellulose mixtures used in different applications (wood adhesives, carbon fiber and nanofibers, thermoplastics) has been demonstrated. This phenomenon causes crude biorefinery lignins, which contain a significant amount of residual crystalline cellulose, to perform superior to high-purity lignins in certain applications. Where previously specific applications required high-purity and/or functionalized lignins with narrow molecular weight distributions, simple green processes for upgrading crude biorefinery lignin are suggested here as an alternative. These approaches can be easily combined with lignin micro-/nanoparticles (LMNP) production. The processes should also be cost-efficient compared to traditional lignin modifications. Biorefinery processes allow much greater flexibility in optimizing the lignin characteristics desirable for specific applications than traditional pulping processes. Such lignin engineering, at the same time, requires an efficient strategy capable of handling large datasets to find correlations between process variables, lignin structures and properties and finally their performance in different applications.