Fabrication and characterization of an economical active packaging film based on chitosan incorporated with pomegranate peel.

Antioxidant and antimicrobial chitosan (CS) films incorporated with different concentrations (0, 3, 6 and 9% w/w based on chitosan) of pomegranate peel powder (PPP) were prepared through a simple and low-cost process and characterized. The physicochemical property, antioxidant and antibacterial properties of the films were investigated. Results showed that incorporation with PPP increased the thickness, water solubility (WS), water vapor permeability (WVP), opacity and total phenolic content (TPC) of chitosan films, but decreased the moisture content (MC) and mechanical property. Fourier transform infrared (FTIR) spectroscopy indicated the formation of hydrogen bonds between chitosan and PPP. In addition, scanning electron microscopy (SEM) analysis presented that microstructural attributes of chitosan film changed by enriching with pomegranate peel. The films with concentrations of PPP at 6 and 9% presented great ultraviolet-visible light barrier properties. Moreover, the antioxidant ability of films with PPP was significantly increased compared to the chitosan film. The addition of PPP also promoted the antibacterial capacity of the control film. These results revealed that incorporation of PPP in chitosan film could fabricate an economical active film with antioxidant and antibacterial properties, and which had the potential for developing food-grade packaging material.

Selective capture of toxic anionic dyes of a novel prepared DMDAAC-grafted chitosan/genipin/cellulose hydrogel beads with antibacterial activity.

Novel eco-friendly and green dimethyldiallylammonium chloride (DMDAAC) grafted chitosan/genipin/cellulose hydrogel beads (CCBG-g-PDMDAAC), were fabricated as selective adsorbents for anionic dyes. The physical and chemical structural changes of the prepared hydrogels were evaluated by FTIR, XRD, SEM and TG-DSC analysis. Results showed CCBG-g-PDMDAAC efficiently and selectively adsorb anionic dyes (Reactive Red 195-RR195 and Methyl orange-MO) from mixture of dye solutions. Endowed chitosan-based hydrogels the advantage of acid insolubility and good adsorption. RR195 and MO adsorption process were described better with pseudo-second-order kinetic model and Langmuir isotherm model with a maximum adsorption capacity of 1333.52 and 190.48 mg/g, respectively, indicating that monolayer chemisorption controlled the sorption process. Moreover, the hydrogels exhibited nice reusability and against S. aureus and E. coli. The hydrogels are promising for the potential application in wastewater treatment and antibacterial simultaneously.

A Novel and High-Effective Biosynthesis Pathway of Hesperetin-7-O-Glucoside Based on the Construction of Immobilized Rhamnosidase Reaction Platform.

Hesperetin-7-O-glucoside (HMG) is a precursor for synthesizing a sweetener named neohesperidin dihydrochalcone, and the coordination toward flavonoids of metal ions tends to increase the water solubility of flavonoids. In order to achieve effective synthesis of HMG, an immobilized enzyme catalysis platform was constructed using an immobilized rhamnosidase on Fe3O4@graphene oxide (Fe3O4@GO), a novel reaction pathway based on the platform was designed for preparing a hesperidin complex as a soluble substrate, and ammonium hydroxide as a ligand dissociation agent to obtain HMG. The Fe3O4@GO was characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), and thermal methods (TG/DSC) analysis to evaluate the immobilization matrix properties. The enzyme activity in free and immobilized form at different pH and temperature was optimized. The reusability of immobilized enzyme was also determined. In addition, the kinetic parameters (K m and V max) were computed after experiment. Results indicated that rhamnosidase immobilized on Fe3O4@GO using a green cross-linker of genipin hydrolyzed successfully and selectively the soluble hesperidin-Cu (II) complex into HMG-Cu (II), a permanent magnet helped the separation of immobilized enzyme and hydrolytes, and ammonium hydroxide was an effective ligand dissociation agent of translating HMG-Cu (II) into HMG with high purity determined by ultraviolet-visible (UV-Vis) spectra analysis and time-of-flight mass spectrometry (TOF-MS). As a result, a novel and high-effective biosynthesis pathway of HMG based on a selectively catalytic reaction platform were constructed successfully. The pathway based on the platform has great potential to produce valuable citrus monoglycoside flavonoid HMG, and the designed reaction route are feasible using the hesperidin-Cu (II) complex with good solubility as a reaction substrate and using ammonium water as a dissociation agent.