Effect of aloe vera (Aloe barbadensis Miller) gel on the physical and functional properties of fish gelatin films as active packaging

Present study was conducted to investigate the feasibility of the combination of fish gelatin and Aloe gel in producing composite films and to determine the effect of Aloe gel concentrations (1, 3, 5, 7 and 9% wt/wt) on the physical properties and antioxidant activity of the composite films. The moisture content of the composite films was proportional to the concentration of Aloe gel. Also, the water solubility and tensile strength of the films decreased with increasing Aloe gel concentration. However, Aloe gel did not cause any significant effect (p ≥ 0.05) on thickness, water vapour permeability (WVP) and colour of the composite films. The gelatin/Aloe composite films exhibited smooth surface microstructures similar to non-composite gelatin film when observed under scanning electron microscope (SEM). The gelatin/Aloe composite films also showed concentration dependant ABTS and DPPH radical scavenging activities

Development of chitosan-graphene oxide nanocomposite films for active margarine packaging

Chitosan (CS) has gained significant attention as a food packaging material due to its film-forming ability, biocompatibility, and biodegradability. However, its applications have been limited by its weak mechanical properties and hydrophilicity. The aim of this study was to develop a chitosan-graphene oxide (CSGO) nanocomposite film with improved mechanical properties as well as water vapour, oxygen, and light barrier properties in comparison to pure CS film, for the antioxidant active packaging of palm olein-based margarine. In the first objective, GO samples with four different degrees of oxidation were synthesized by controlling the ratio of graphite to the oxidizing agent, potassium permanganate (KMnO4). The sample GO4, synthesized with a 1:8 w/w graphite:KMnO4 ratio was embedded with abundant oxygen-containing groups, as supported by the Fourier-transform infrared (FTIR) and Raman spectra. The addition of GO4 into CS increased (p < 0.05) the mechanical strength and UV light barrier of the CS/GO4 composite. In the second objective, the effects of sonication time of GO4 (30, 60, and 120 min) and heating temperature of the films (30, 60, and 120 ºC) on the structural and physical properties of the CSGO4 composites were investigated. After 120 min of sonication in a sonicator bath, graphene oxide nanosheets (GO120) of ~1 nm thick were obtained, as demonstrated using dynamic light scattering (DLS) technique and atomic force microscopy (AFM). The incorporation of GO120 decreased (p < 0.05) the light transmittance of CS films whereas heating the composites at 120 °C lowered (p < 0.05) the water solubility and water vapour permeability (WVP). All of the films were\ud completely decomposed within 28 days in a soil burial test. In the third objective, trisodium citrate (CIT) and sodium tripolyphosphate (TPP) solutions of different concentrations (0.5, 1.0. 2.0, and 3.0% w/v) were used as crosslinking agents for the films. Successful crosslinking was confirmed by FTIR spectroscopy. The hydrophilicity and light transmittance decreased (p < 0.05) with the increase in CIT and TPP. At 3.0% w/v, the elongation at break and tensile strength of the TPP-crosslinked CSGO films increased (p < 0.05) by 42 and 82%, respectively, outperforming CIT as a crosslinking agent. In the final objective, the effect of the concentrations of CS (1.5 and 2.0% w/v) and GO4 (0.5, 1.0, and 2.0% w/w CS) on the properties of nanocomposite films were investigated. The WVP and oxygen permeability (OP) decreased (p < 0.05) by 43 and 54%, respectively. The antioxidant properties of the composite film increased (p < 0.05) with the concentration of GO4, as supported by the DPPH radical scavenging assay. The changes in the peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) of the margarine samples were monitored for 30 d at 4 ºC. For the margarine sample that was wrapped with the GOCS1.5 GO2.0 film (CS 1.5% w/v, GO 2.0% w/w CS), the PV and TBARS values were 36 and 79% lower (p < 0.05) in comparison to the low-density polyethylene films. The combination of these properties such as low WVP, OP, and light transmittance, as well as the radical scavenging activities suggests that the CS1.5 GO2.0 film could be a potential antioxidant active packaging for margarine

Graphene-based polymer nanocomposites in food packaging and factors affecting the behaviour of graphene-based materials: a review

In recent years, there is a rapid advancement in the reinforcement of polymers using graphene-based materials (GBMs) such as graphene (thickness =  ~ 0.34 nm), graphene oxide (GO, thickness =  ~ 1.1 nm), and reduced graphene oxide (rGO). GBMs and their nanocomposites have been widely applied in numerous industries. Due to their remarkable properties, GBMs have also been incorporated in food packaging materials, providing efficient reinforcement in mechanical strength, barriers to light, water vapour, and gases, as well as antimicrobial and antioxidant properties, which are crucial in preventing food spoilage. This review aims to assess and summarize the published data in the use of GBMs in polymeric composites, particularly for food packaging. Then, we highlight the main factors that influence the behaviour and properties of the GBMs during the fabrication of the composites. Lastly, this review provides a brief summary of the current limitations as well as the food safety concerns regarding GBMs in food packaging

Physicochemical properties of chitosan/graphene oxide composite films and their effects on storage stability of palm-oil based margarine

This study investigated the application of active packaging from chitosan (CS) incorporated with graphene oxide (GO) to maintain the quality and extend the storage life of palm-oil based margarine. Composite films containing various concentrations of CS (1.5 and 2.0%w/v) and GO (0, 0.5, 1.0, and 2.0%w/w CS) were produced using the solution casting method and were characterized regarding their mechanical, barrier, and antioxidant properties. For both concentrations of CS, the composite films with 2.0% GO exhibited significantly (p < 0.05) lower water vapor permeability and oxygen permeability by ~43 and ~55%, respectively. The transmittance of UV light was virtually undetectable in CSGO composites. In addition, the radical scavenging activity increased (p < 0.05) with the increasing GO concentration, as demonstrated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The changes in the peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) of the margarine samples were monitored for 30 d at 4 °C. The margarine sample that was wrapped with the CS1.5 GO2.0 film sample showed lower (p < 0.05) PV and TBARS values in comparison to the samples wrapped with CS1.5 and low-density polyethylene (LDPE) films. In conclusion, the CSGO composite film in this study shows great potential as an antioxidant food packaging material

Effect of oxidation degrees of graphene oxide (GO) on the structure and physical properties of chitosan/GO composite films

Graphene oxide (GO) samples with different oxidation degrees were prepared using the modified and improved Hummers’ method by varying the ratios of graphite to potassium permanganate (KMnO4) at 1:2 (GO1), 1:4 (GO2), 1:6 (GO3), and 1:8 (GO4). Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy confirmed the increase in oxygen-containing groups in GO with the increase in KMnO4 concentration. Composite films comprising chitosan (CS) and GO were synthesized using the solution casting method and were characterized by mechanical tests, scanning electron microscopy (SEM), FTIR spectroscopy, and contact angle analysis. GO4 yielded a significant (p < 0.05) improvement in mechanical strength and lower UV light transmission without significantly (p ≥ 0.05) increasing the water vapor permeability (WVP), compared to a neat CS film. Films with GO4 also had denser structure and all films were completely degradable within 20 days in soil compost. This study presents the effect of GO oxidation degrees on the properties of CS/GO composite films as potential materials for food packaging

Novel drug targets for asthma and COPD: Lessons learned from in vitro and in vivo models

Asthma and chronic obstructive pulmonary disease (COPD) are highly prevalent respiratory diseases characterized by airway inflammation, airway obstruction and airway hyperresponsiveness. Whilst current therapies, such as beta-agonists and glucocorticoids, may be effective at reducing symptoms, they do not reduce disease progression. Thus, there is a need to identify new therapeutic targets. In this review, we summarize the potential of novel targets or tools, including anti-inflammatories, phosphodiesterase inhibitors, kinase inhibitors, transient receptor potential channels, vitamin D and protease inhibitors, for the treatment of asthma and COPD. (C) 2014 Published by Elsevier Ltd