Yasir Ali Arfat

Deciphering the potential of guar gum/Ag-Cu nanocomposite films as an active food packaging material

Guar gum (GG) based nanocomposite (NC) films were prepared by incorporating silver-copper alloy nanoparticles (Ag-Cu NPs) through solution casting method. Effect of NP loadings (0.5-2%) on the thermo-mechanical, optical, spectral, oxygen barrier and antimicrobial properties of the GG/Ag-Cu NC films were investigated. Tensile testing showed an improvement in the mechanical strength, and a decrease in elongation at break for all NP loadings. NP incorporation into GG films showed a marked influence on the color values. The NC films showed excellent UV, light and oxygen barrier capability. Thermal properties of the NC films were improved as evidenced from the differential scanning calorimetry and the thermal conductivity data. NC films became rough and coarse over neat GG film as visualized through the scanning electron microscopy. A strong antibacterial activity was exhibited by NC films against both Gram-positive and Gram-negative bacteria, and therefore, the film could be considered as an active food packaging.

Mechanical, structural and thermal properties of Ag-Cu and ZnO reinforced polylactide nanocomposite films

Plasticized polylactic acid (PLA) based nanocomposite films were prepared by incorporating polyethylene glycol (PEG) and two selected nanoparticles (NPs) [silver-copper (Ag-Cu) alloy (<100 nm) and zinc oxide (ZnO) (<50 and <100 nm)] through solvent casting method. Incorporation of Ag-Cu alloy into the PLA/PEG matrix increased the glass transition temperature (Tg) significantly. The crystallinity of the nanocomposites (NCs) was significantly influenced by NP incorporation as evidenced from differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. The PLA nanocomposite reinforced with NPs exhibited much higher tensile strength than that of PLA/PEG blend. Melt rheology of NCs exhibited a shear-thinning behavior. The mechanical property drastically reduced with a loading of NPs, which is associated with degradation of PLA. SEM micrographs exhibited that both Ag-Cu alloy and ZnO NPs were dispersed well in the PLA film matrix.

Preparation and characterization of agar-based nanocomposite films reinforced with bimetallic (Ag-Cu) alloy nanoparticles

Agar-based active nanocomposite films were prepared by incorporating silver-copper (Ag-Cu) alloy nanoparticles (NPs) (0.5-4wt%) into glycerol plasticized agar solution. Thermo-mechanical, morphological, structural, and optical properties of the nanocomposite films were characterized by texture analyzer, differential scanning calorimetry (DSC), scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectroscopy, and surface color measurement. Tensile strength and the melting temperature of the film increased linearly with NPs loading concentration. Color, transparency and UV barrier properties of agar films were influenced by the reinforcement of Ag-Cu NPs. XRD analysis confirmed the crystalline structure of the Agar/Ag-Cu nanocomposite films, whereas the smoothness and the homogeneity of film surface strongly reduced as observed through the SEM. The nanocomposite films exhibited a profound antibacterial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Salmonella enterica sv typhimurium) bacteria. Overall, the agar nanocomposite films could be used as packaging material for food preservation by controlling foodborne pathogens and spoilage bacteria.

Particle size, rheological and structural properties of whole wheat flour doughs as treated by high pressure

ABSTRACT Effect of high-pressure treatment (300–600 MPa) and flour-to-water ratio (1:1, 1:2, 1:3, and 1:4) on functional, rheological, thermal, and structural properties of whole wheat flour dough were investigated. The particle size distribution, especially Dv90 (90% of the volume distribution), was significantly reduced by the pressure treatment. The damaged starch content increased significantly with the applied pressure and water content. The damaged starch absorbed more water, and subsequently increased the water holding capacity. Thermal transitions and mechanical property of pressure-treated samples were measured by differential scanning calorimetry, and rheometry, respectively. The peak viscosity, hot paste viscosity, and final viscosity decreased significantly with increasing pressure intensity. Hardness increased with the increasing pressure level while stickiness decreased at similar conditions. Fourier-transform infrared spectroscopy showed changes in the amide I region of the wheat protein. The sodium dodecyl sulfate polyacrylamide gel electrophoresis further indicated changes in the protein subunits that occurred after pressurization.

Comparative effects of untreated and 3-methacryloxypropyltrimethoxysilane treated ZnO nanoparticle reinforcement on properties of polylactide-based nanocomposite films

Polylactide (PLA) nanocomposites characterized by antimicrobial properties are gaining increasing attention for food packaging. In this contribution, the PLA based nanocomposite films with multifunctional end-use properties were achieved by incorporating ZnO nanoparticles (NPs) [untreated: ZnO(UT) and 3-methacryloxypropyltrimethoxysilane treated: ZnO(ST)] into polymer matrix via solvent casting method. The ZnO(ST) prevented the degradation of PLA at higher temperature and improved the mechanical property. Color, transparency, and anti-UV properties of composite films were influenced by the incorporation of ZnO NPs. Contrary to untreated ZnO, the treated NPs were more effective in enhancing the tortuosity of the diffusive path for the oxygen molecules to diffuse through the film. The glass transition (Tg) and crystallization (Tc) temperatures of composites were improved by the addition of ZnO, whereas a higher Tg was recorded for ZnO(ST) loaded films. XRD demonstrated the change in crystallinity of the films with NPs addition. Nanoparticles well distributed in the composite films as observed through SEM however spots of agglomeration were observed for PLA/ZnO(UT) films. Developed films especially incorporated with ZnO(ST) were found to be active against both Gram-negative (Salmonella Typhimurium) and Gram-positive (Listeria monocytogenes) bacteria. Therefore, PLA/ZnO nanocomposite films could be considered as environment-friendly active packaging material for food preservation.

Polylactide/graphene oxide nanosheets/clove essential oil composite films for potential food packaging applications

Antimicrobial nanopackaging films were developed by incorporating clove essential oil (CLO) (15-30% w/w) and graphene oxide (GO) nanosheets (1% w/w) into polylactide (PLA), suitable for use as food packaging, via solution casting. Addition of CLO into PLA matrix improved the flexibility of the composite films by lowering tensile stress, complex viscosity (η*), and glass transition temperature (Tg). GO improved the Tg, η* and lowered the oxygen permeability of the plasticized PLA matrix. Optical and anti-UV properties of the film were influenced by both GO and CLO incorporation. FTIR spectra exhibited a change in the molecular organization of the plasticized PLA film after incorporation with CLO. Microstructural studies revealed that the reinforcement of GO prevented porosity of plasticized PLA/CLO film surface. The developed composite film showed excellent antibacterial activity against Staphylococcus aureus and Escherichia coli and therefore, has a potential to be used as active packaging material for food safety and preservation.

Functional, rheological, microstructural and antioxidant properties of quinoa flour in dispersions as influenced by particle size

Nutritionally, particle size has significant impact on food digestibility in the gastrointestinal system. Controlling the rheological behaviors of particles in dispersion has been of major interest in the industry. In this work, the quinoa seed was ground into flour, followed by fractionating into a selected particle size [+30-mesh (>595-μm) to +200-mesh (>74-μm)]. The effect of particle size on composition, antioxidant, and several functional and mechanical properties of all particle fractions were studied. The protein, crude fat, crude fiber, dietary fiber contents increased with decreasing the particle size while the starch content decreased. The water holding capacity and sediment volume fraction increased with the reduction of particles. Rheological measurement indicated that there were significant differences among rheograms between coarser and finer particles of QF. The finest particles produced a lower complex viscosity and lower mechanical rigidity. The final and setback viscosities decreased as particle size decreased. Microscopy showed irregular-shaped polygon structure for the QF. The particle fractions ranged between +100 and +200-mesh showed compositional resemblances and, subsequently, the properties. The highest extractability of phenolics and antioxidant properties were observed for the finest particles. The information generated from this work would help the industry to develop products with the desired particle size with optimum functional and nutritional properties.