Dietary fiber extraction from citrus peel pomace: Yield optimization and evaluation of its functionality, rheological behavior, and microstructure properties.

Citrus fruits were widely used in processing and production, generating a large amount of peel pomace and a low utilization rate, resulting in substantial economic losses and environmental risks. It was important to extract compounds from citrus peel pomaces and find suitable preparation methods to improve their yield and physicochemical properties. Grapefruit peel pomace (GP) and navel orange peel pomace (OP) were used as raw materials in this study to prepare green and edible soluble dietary fiber (SDF) and insoluble dietary fiber (IDF). Analysis was done on the effects of solid-liquid ratio, cellulase hydrolysis time, cellulase dosage, and ultrasonic time on dietary fiber (DF) yield. To obtain the best DF preparation conditions, we used range analysis, variance analysis, and orthogonal experimental design. We also analyzed the structural, physicochemical, and rheological characteristics of SDF and IDF. According to the study's findings, SDF and IDF showed a loose and expansive structure with reduced particle size, higher specific surface area, and noticeably better physical and chemical properties after treating GP and OP with ultrasound-assisted composite enzyme method. Both SDF solution and IDF suspension were discovered through rheological analysis to be non-Newtonian pseudoplastic fluids, which was advantageous for expanding their applications in the field of food packaging. In conclusion, DF prepared using the ultrasound-assisted composite enzyme method was an excellent source of edible packaging materials, offering a benchmark for the recycling of other citrus peel wastes and ultimately paving the way for new methods of recycling citrus waste.

A Theoretical Study of the Sensing Mechanism of a Schiff-Based Sensor for Fluoride.

In the current work, we studied the sensing process of the sensor (E)-2-((quinolin-8ylimino) methyl) phenol (QP) for fluoride anion (F-) with a "turn on" fluorescent response by density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations. The proton transfer process and the twisted intramolecular charge transfer (TICT) process of QP have been explored by using potential energy curves as functions of the distance of N-H and dihedral angle C-N=C-C both in the ground and the excited states. According to the calculated results, the fluorescence quenching mechanism of QP and the fluorescent response for F- have been fully explored. These results indicate that the current calculations completely reproduce the experimental results and provide compelling evidence for the sensing mechanism of QP for F-.

Rheological behaviors of polypropylene/calcium carbonate nanocomposites under axial vibration force field.

Structures and data processing method of the self-developed multi-function and all-electric rheometer (MAR) for polymer composites were introduced. Polypropylene (PP)/Calcium Carbonate (CaCO3) nanocomposites were prepared. And the homogeneity of the composite was characterized by its rheological behavior. With MAR, the effects of vibration parameters on apparent shear viscosity of PP/CaCO3 nanocomposites were investigated. The results show that, the viscosity of the nanocomposites is much lower in dynamic test with proper vibration, comparing with it in corresponding steady-state test at same shear rate. This may be caused by the change of microstructure of the composites under vibration. The shear viscosity sharply decreases with the increase of vibration amplitude. However, the influence of vibration frequency on the shear viscosity of PP/CaCO3 nanocomposites is insignificant. Therefore, it is a good way to increase the superimposed vibration amplitude rather than the frequency to decrease the flow resistance. It is useful for discovering the energy saving mechanic of the polymer processing introduced the vibration energy into.

Rheological behaviors of nylon 6/silica modified melamine cyanurate non-halogen flame retardant composites.

Nylon 6 (PA 6)/silica modified melamine cyanurate (MCA) flame retardant (FR) composites were prepared by melt blending method. The morphology and rheological behaviors of composites were characterized using scanning electron microscopy and capillary rheometer. The results show that the presence of silica can improve the dispersion of mMCA in PA 6. The rheological behaviors are significantly affected by temperature, shear rate and the structure of composites. With increase of temperature and shear rate the apparent viscosities of composites decrease. All composites are pesudoplastic fluids. At same temperature and shear rate PA 6 composites, which contain different flame retardants (FRs) and different loadings, exhibit different viscosities. The presence of MCA can enhance the non-Newtonian index of composites. The flow activation energies (E) of PA 6/silica modified MCA (S-mMCA) composites are larger than that of PA 6/pure MCA composites, and, with the increasing shear rate the flow activation energies of composites decrease. At a fixed FRs content, with the increase of silica loading, E of PA 6/S-mMCA composites increases firstly and then decreases. These results would be useful for the processing of FR PA 6 composites and for further understanding their flame retardant mechanisms.