Investigation into the performance and mechanism of SiO2 nanoparticles and starch composite films

Nanomaterials are often introduced to improve the properties of polymers. In this article, the effects of SiO₂ nanoparticles with lager specific areas and special microstructural characters on the properties of starch films were investigated. Firstly, the ultrasonic mixing was used to disperse the SiO₂ nanoparticles under different dispersion times, and then the dispersed SiO₂ nanoparticles with various ratios were added into starch size. The effects of the dispersion time and the SiO₂ content on the mechanical properties of the SiO₂/starch composite size were analysed. It was found that the dispersion time and the SiO₂ content had significant effects on the tensile and abrasion behaviour of the nanocomposite films. The mechanism of the enhanced mechanical properties of the composite films was examined by analysing the size of the dispersed SiO₂ nanoparticles in the dispersion, the surface characters of the films and the structures of the fractured surfaces. And the morphology of the abraded surface was analysed by atomic force microscopy, scanning electron microscope and video zoom microscope.     

Recent advances in biobased and biodegradable polymer nanocomposites,nanoparticles, and natural antioxidants for antibacterial and antioxidant food packaging applications

Inorganic nanoparticles (NPs) and natural antioxidant compounds are an emerging trend in the food industry. Incorporating these substances in biobased and biodegradable matrices as polysaccharides (e.g., starch, cellulose, and chitosan) and proteins has highlighted the potential in active food packaging applications due to more significant antimicrobial, antioxidant, UV blocking, oxygen scavenging, water vapor permeability effects, and low environmental impact. In recent years, the migration of metal NPs and metal oxides in food contact packaging and their toxicological potential have raised concerns about the safety of the nanomaterials. In this review, we provide a comprehensive overview of the main biobased and biodegradable polymer nanocomposites, inorganic NPs, natural antioxidants, and their potential use in active food packaging. The intrinsic properties of NPs and natural antioxidant actives in packaging materials are evaluated to extend shelf-life, safety, and food quality. Toxicological and safety aspects of inorganic NPs are highlighted to understand the current controversy on applying some nanomaterials in food packaging. The synergism of inorganic NPs and plant-derived natural antioxidant actives (e.g., vitamins, polyphenols, and carotenoids) and essential oils (EOs) potentiated the antibacterial and antioxidant properties of biodegradable nanocomposite films. Biodegradable packaging films based on green NPs—this is biosynthesized from plant extracts–showed suitable mechanical and barrier properties and had a lower environmental impact and offered efficient food protection. Furthermore, AgNPs and TiO₂ NPs released metal ions from packaging into contents insufficiently to cause harm to human cells, which could be helpful to understanding critical gaps and provide progress in the packaging field.     

Soluble soybean polysaccharide/TiO2 nanocomposites: Biological activity,release behavior,biodegradability, and biosafety

This study aimed to produce and characterize eco-friendly SSPS nanocomposites incorporated with various concentrations of TiO₂ nanoparticles (NPs) (1%, 3%, and 7%). The antimicrobial activity of the nanocomposite films against five strains of pathogenic bacteria was examined. Salmonella typhi PTCC 1609 was the most sensitive species to TiO₂ NPs at concentrations equal to the synthetic antibiotic. The migration of TiO₂ to ethanol and acetic acid, as two food simulants increased when the initial nano-TiO₂ content increased. The release profiles for TiO₂ in two simulants of ethanol and acetic acid indicated a non-Fickian release, and the release kinetics were concentration-dependent. SSPS/TiO₂ nanocomposites degraded easily and thus have the potential to be applied as an eco-friendly packaging system. Oral administration of doses of 1, 12.5, 25, 50, and 75 mg/kg TiO₂ revealed that the dose of 50 and 75 mg/kg increased malondialdehyde (p < .001) concentration in the liver tissue. In addition, it decreased glutathione (p < .001) concentration in the liver tissue.     

Preparation,characterization, antibacterial properties and hydrophobic evaluation of SiO2/Ag nanosol coated cotton/linen fabric

Abstract

Surface modification is an important element of textile manufacturing. The SiO₂/Ag sol–gel was coated on the cotton/linen fabric by a simple two-dipping-two-rolling coating machine. SEM, Zeta-potential, (ATR)-FTIR and XRD, physical properties, water-droplet adsorption, antibacterial performance and water-resisting property have been adopted as the characterization techniques. The Zeta-potential showed that the nano-Ag particles affected the size of SiO₂ nanoparticles. The results showed that antibacterial activity and hydrophobic property of cotton/linen fabric increased with the increasing concentration of the AgNO₃. Air permeability was not decreased considerably, whereas tensile strength was increased significantly after coating twice. The SiO₂/Ag coating cotton/linen fabric had an excellent antibacterial performance. Our results demonstrate that this SiO₂/Ag coated cotton/linen fabric is a step towards better hydrophobic performance of textile materials.     

Characterization and quantification of engineered nanoparticles in food by epithermal instrumental neutron activation analysis and electron microscopy

Engineered nanoparticles (NPs) have increasingly been used in various areas including agriculture and food packaging, which may potentially cause contamination in food products. In this study, a combination of analytical techniques was used to detect, characterize, and quantify engineered NPs (cerium (IV) oxide (CeO₂), silica (SiO₂) NPs, and their mixture) in food matrices. A series of concentrations of CeO₂, SiO₂, and their mixtures from 0 to 0.75 wt% were mixed in soybean powders. The presence of engineered NPs was investigated using transmission electron microscopy and scanning electron microscopy coupled with energy dispersive spectroscopy. The average size of CeO₂ and SiO₂ was 28.5 and 30.5 nm in diameter, respectively. CeO₂ NPs were irregular octahedral and cubic in shape, while SiO₂ NPs were spherical. The concentration of NPs in soybean powders was analyzed by epithermal instrumental neutron activation analysis (EINAA). Calibration curves were plotted for quantification of NPs in soybean powders (R ² = 0.996 and 0.994 for CeO₂, SiO₂ NPs in soybean powders, respectively; R ² = 0.995 and 0.997 for CeO₂ and SiO₂ NP in a mixture in soybean powders, respectively). The study of the detection limit (DL) demonstrates that at 99 % confidence interval, EINAA can detect both NPs at 0.1 wt% in soybean powders. Satisfactory recoveries were obtained for samples with a concentration at and higher than the DL (86.2–104.7 % for CeO₂ NPs and 85.7–95.2 % for SiO₂ NPs; 87.5–101.3 and 85.6–93.5 % for CeO₂ and SiO₂ NPs in a mixture in soybean powders, respectively).     

Characterization and Quantification of Zinc Oxide and Titanium Dioxide Nanoparticles in Foods

There has been growing concern in recent years about contamination of foods by engineered nanoparticles (NPs) due to their increasing applications in food packaging materials, pesticides, and other products. In this study, we report a systematic approach to detect, characterize, and quantify engineered NPs (i.e., zinc oxide (ZnO) and titanium dioxide (TiO₂) NPs) in food products. A series of concentrations of ZnO and TiO₂ NPs from 0.05 to 1 wt% were spiked into corn starch, yam starch, and wheat flour. The presence of engineered NPs in foods was detected and measured by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and transmission electron microscopy. The average sizes of ZnO and TiO₂ NPs were around 38 and 40 nm in diameter, respectively. Most ZnO NPs were in either spherical or rod-like shape, while most TiO₂ NPs were in a spherical shape. The concentrations of engineered NPs in food samples were measured by inductively coupled plasma optical emission spectrometry. Calibration curves were plotted for quantification of NPs in foods (R ²?=?0.984 and 0.995 for ZnO NPs in corn starch and wheat flour, respectively; R ²?=?0.992 and 0.998 for TiO₂ NPs in yam starch and wheat flour, respectively). The results of this study could help develop systematic methodologies for detection, characterization, and quantification of NPs in food matrices.     

Engineered Nanoparticles as Potential Food Contaminants and Their Toxicity to Caco‐2 Cells

Engineered nanoparticles (ENPs), such as metallic or metallic oxide nanoparticles (NPs), have gained much attention in recent years. Increasing use of ENPs in various areas may lead to the release of ENPs into the environment and cause the contamination of agricultural and food products by ENPs. In this study, we selected two important ENPs (zinc oxide [ZnO] and silver [Ag] NPs) as potential food contaminants and investigated their toxicity via an in vitro model using Caco‐2 cells. The physical properties of ENPs and their effects on Caco‐2 cells were characterized by electron microscopy and energy dispersive X‐ray spectroscopic (EDS) techniques. Results demonstrate that a significant inhibition of cell viability was observed after a 24‐h of exposure of Caco‐2 cells to 3‐, 6‐, and 12‐mM ZnO NPs or 0.5‐, 1.5‐, and 3‐mM Ag NPs. The noticeable changes of cells include the alteration in cell shape, abnormal nuclear structure, membrane blebbing, and cytoplasmic deterioration. The toxicity of ZnO NPs, but not that of Ag NPs after exposure to simulated gastric fluid, significantly decreased. Scanning transmission electron microscopy shows that ZnO and Ag NPs penetrated the membrane of Caco‐2 cells. EDS results also confirm the presence of NPs in the cytoplasm of the cells. This study demonstrates that ZnO and Ag NPs have cytotoxic effects and can inhibit the growth of Caco‐2 cells.     

Physicochemical,Microstructural, and Antibacterial Properties of β‐Chitosan and Kudzu Starch Composite Films

Abstract: This study investigated physicochemical, microstructural, and antibacterial properties of β‐chitosan–kudzu starch composite films with addition of 0%, 20%, 60%, or 100% kudzu starch (w starch/w chitosan) in 1% chitosan solution. Molecular interactions between chitosan and kudzu starch and the crystal structure of the films were also determined. Adding 60% kudzu starch reduced water vapor permeability and solubility of pure β‐chitosan film by about 15% and 20%, respectively, whereas mechanical strength and flexibility of the film were increased about 50% and 25%, respectively. Micrograph showed that β‐chitosan film was totally amorphous, and the composite films generally became rougher with more starch added. Fourier transform infrared and X‐ray diffraction spectra showed that the 2 film‐forming components were compatible with each other. Pure β‐chitosan film resulted in 9.5 and 11.5 log CFU/mL reduction in Escherichia coli and Listeria innocua based on plate count method, respectively. Addition of kudzu starch reduced the antibacterial activity of film, but still achieved 8.3 and 10.3 log CFU/mL reduction in E. coli and L. innocua, respectively when kudzu starch to chitosan weight ratio was 1:1. Reduced antibacterial activity might attribute to the interaction of amino groups in β‐chitosan with the hydroxyl groups in kudzu starch. This study demonstrated that kudzu starch effectively improved water barrier of β‐chitosan film, and the composite films retained strong antibacterial ability. Practical Application: One percent of β‐chitosan containing 60% kudzu starch (w/w chitosan) composite films possessed better mechanical and water barrier properties than pure β‐chitosan films, and showed strong antibacterial activity against both Gram‐positive and Gram‐negative bacteria. The films may be used as wraps or coatings to prolong the shelf life of different foods or other similar applications.     

Physical properties of cassava starch–carnauba wax emulsion films as affected by component proportions

Properties of glycerol‐plasticised cassava starch–carnauba wax emulsion films were studied as functions of carnauba wax/starch (CW/S) ratios. Increases in CW concentrations improved elongation, but impaired tensile strength and elastic modulus, suggesting a plasticising effect by CW and/or the emulsifier. CW reduced water solubility of the films and decreased their water vapour permeability (WVP) up to CW/S ratios of 0.15–0.20, probably because of the decreased water solubility. Higher CW concentrations resulted in increased WVP, possibly due to starch matrix loosening. The opacity imparted by high CW concentrations in films could compromise some applications. The T_g of starch and the expected CW effects on it were not evidenced by DSC thermograms, but CW seems to have affected starch crystallisation, maybe by forming complexes with amylose and/or amylopectin.     

Influence of Heat‐Moisture Treatment and Acid Modifications on Physicochemical,Rheological, Thermal and Morphological Characteristics of Indian Water Chestnut (Trapa natans) Starch and its Application in Biodegradable Films

Water chestnut starch was subjected to acid modification and heat‐moisture treatment. Hydrochloric acid was used for acid modification at three different concentrations (0.25 M, 0.5 M and 1 M) for 2 h. Modifications did not alter the granule morphology. Heat‐moisture treatment (HMT) resulted in slight reduction in the granular size of the starch granules. Acid modification lowered the amylose content, swelling power, water‐ and oil‐binding capacity but improved the solubility of starch to a considerable level. Light transmittance of acid‐modified (AM) starches improved significantly. A significant reduction in peak, trough, final and setback viscosity was observed by acid‐thinning. In case of heat‐moisture treated starch the final viscosity (F_v) was found to be even higher than the peak viscosity (P_v). Native water chestnut starch exhibited a lower onset temperature (T_o) and peak temperature (T_p) of gelatinization than the corresponding acid‐treated starches. Starch films prepared from native starch exhibited excellent pliability, whereas those prepared from AM and HMT starches showed good tensile strength. Starch films prepared from acid‐treated starches provided better puncture and tensile strength.     

The Potential Application of Antimicrobial Silver Polyvinyl Chloride Nanocomposite Films to Extend the Shelf-Life of Chicken Breast Fillets

Silver (Ag) nanoparticles (NPs) were synthesised and characterised, and their antimicrobial activity against Escherichia coli, Staphylococcus aureus, Bacillus cereus, Pseudomonas fluorescens and microflora derived from raw chicken, beef or cooked ham was determined. Polyvinyl chloride (PVC) films or antimicrobial Ag/PVC nanocomposite films were manufactured via a solvent casting method and the mechanical and thermal properties of these materials determined. Manufactured antimicrobial Ag/PVC nanocomposite films were used to wrap chicken breast fillets, followed by modified atmosphere packaging (using conventional laminates and employing a gas mix of 60 % N₂/40 % CO₂), and compared against PVC control films. In general, Gram-negative bacteria were more sensitive to Ag NPs than Gram-positive bacteria and microflora isolated from meat products were more resistant than pure culture bacteria. However, the most sensitive bacteria to Ag NPs were Pseudomonas fluorescens. No significant differences (p?>?0.05) in tensile strength and elongation at break were observed, but glass transition temperatures (T _g) of Ag/PVC nanocomposite films were lower (p?<?0.05) when compared to PVC control films. Results also indicated that antimicrobial Ag/PVC nanocomposite films significantly (p?<?0.05) extended the shelf-life of chicken breast fillets and reduced lipid oxidation of chicken breast fillets compared to PVC-wrapped equivalents. Overall, results indicated that antimicrobial Ag/PVC nanocomposite films can potentially be used as antimicrobial packaging for food packaging applications.     

Ag nanoparticles-coated cotton fabric for durable antibacterial activity: derived from phytic acid–Ag complex

Abstract

This study focuses on the preparation of functional cotton with high and durable antibacterial activity by in situ formation of Ag nanoparticles (NPs) onto cotton fabric derived from phytic acid-Ag complex. The route can be divided into two simple steps, adsorption of silver ions onto cellulose matrix with phytic acid as a capture agent and subsequent reduction of Ag⁺ to Ag NPs by sodium borohydride. The successful deposition of Ag NPs on cotton fabric was verified by SEM, EDS and XPS. The bacterial reduction rate against E. coli and S. aureus for the as-treated fabrics was above 99%, even after 10 laundry cycles. The phytic acid was found of benefit to distribution and bonding of silver on the cotton fabric, which might lead to the enhancement of antibacterial property and durability against wash. This study may provide a green, novel and simple strategy to manufacture Ag-based antibacterial cotton for potential applications in textile industry.     

Fungal Inactivation by Mexican Oregano (Lippia berlandieri Schauer) Essential Oil Added to Amaranth,Chitosan, or Starch Edible Films

ABSTRACT: Edible films can incorporate antimicrobial agents to provide microbiological stability, since they can be used as carriers of a wide number of additives that can extend product shelf life and reduce the risk of pathogenic bacteria growth on food surfaces. Addition of antimicrobial agents to edible films offers advantages such as the use of low antimicrobial concentrations and low diffusion rates. The aim of this study was to evaluate inhibition of Aspergillus niger and Penicillium spp. by selected concentrations of Mexican oregano (Lippia berlandieri Schauer) essential oil added to amaranth, chitosan, or starch edible films. Oregano essential oil was characterized by gas chromatography-mass spectrometry (GC/MS) analysis. Amaranth, chitosan, and starch edible films were formulated with essential oil concentrations of 0%, 0.25%, 0.50%, 0.75%, 1%, 2%, and 4%. Mold radial growth was evaluated inoculating spores in 2 ways: edible films were placed over inoculated agar, Film/Inoculum mode (F/I), or the edible films were first placed in the agar and then films were inoculated, Inoculum/Film mode (I/F). The modified Gompertz model adequately described growth curves. There was no significant difference (P > 0.05) in growth parameters between the 2 modes of inoculation. Antifungal effectiveness of edible films was starch > chitosan > amaranth. In starch edible films, both studied molds were inhibited with 0.50% of essential oil. Edible films added with Mexican oregano essential oil could improve the quality of foods by controlling surface growth of molds.     

Characterisations of cassava starch and poly(butylene adipate-co-terephthalate) blown film with silicon dioxide nanocomposites

Films with high permeability are necessary for the packaging of agricultural products that respire to avoid anoxic conditions. This research developed and characterised bioplastic nanocomposite films with enhanced permeation and increased strength. Thermoplastic starch (TPS) was compounded with silicon dioxide (SiO₂) and blended with poly (butylene adipate-co-terephthalate) (PBAT) to produce bioplastic PBAT/TPS blend films via blown-film extrusion. Different SiO₂ contents (0.5%–1%) were dispersed in the matrices, causing interaction via hydrogen bonding with the TPS phase. SiO₂ at 1% significantly improved melting of the polymer blends, giving increasing amorphous ratios of the polymeric films. Microstructures and surface topography indicated voids between incompatible components and porous structures that improved permeation. Increasing SiO₂ content linearly enhanced oxygen and water vapour permeability by up to 39% and 16%, respectively. Tensile strength and elongation at break increased and decreased up to 40% and 32%, respectively, indicating increased rigidity due to adding solid nanoparticles to 1%. Migration phenomena of the film components, that is molecules with diol structures and silicon compounds depended on types of simulant and microstructures that induced swelling and release of the compounds. Film permeabilities increased, thereby facilitating air and humidity flow through the packaging.     

Increasing the shelf life of pikeperch (Sander lucioperca) fillets affected by low-density polyethylene/Ag/TiO2 nanocomposites experimentally produced by sol-gel and melt-mixing methods

Sol-gel and melt-mixing processes, which are used for the synthesis of low-density polyethylene/silver/titanium dioxide nanocomposites, can inactivate pathogens. In the sol-gel method, the nanocomposites were used to treat four selected microorganisms using the disk-diffusion method. In the melt-mixing method, fish coverage films were used to examine the shelf life of fish. TiO₂ along with different concentrations of Ag (0%, 1%, 3%, and 5%) generated the nanocomposites. The maximum inhibition zone diameters (mm) for Staphylococcus aureus, Escherichia coli, Candida albicans, and Aspergillus niger in 3% Ag were measured. It was concluded that applying the LDPE/Ag/TiO₂ nanocomposites produced could be beneficial for inactivation of pathogens.     

Protection of silica-coated ZnO nanoparticles on pre-dyed polyester fabrics against photofading

This work was designed to investigate the ability of silica-coated ZnO (ZnO&SiO₂) nanoparticles (NPs) as ultraviolet (UV) absorbers for protecting pre-dyed polyester fabrics against photofading. Despite that ZnO NPs are excellent UV absorbers, their strong photocatalytic activity limits the application in UV protection. In this study, a silica layer was coated onto ZnO NPs to form a physical barrier between the ZnO and a polyester substrate, which allowed effective UV shielding while minimising the harmful effects of photocatalytic activity on the substrate. The structure and optical proprieties of ZnO&SiO₂ NPs were observed. The bare ZnO and ZnO&SiO₂ NPs were, respectively, applied to polyester fabrics coloured with three kinds of dyes by a dip coating method. The photofading level of treated fabrics after exposure under simulated sunlight was evaluated. The ZnO&SiO₂ NPs exhibited excellent protection on pre-dyed polyester fabrics against photofading.     

The influence of Cu(II) ions on physicochemical properties of potato starch oxidised by hydrogen peroxide

The study investigates the influence of Cu(II) ions used as a catalyst on the effectiveness of potato starch oxidation by hydrogen peroxide, and compares the physicochemical properties of the modified starches. The starch was oxidised by H₂O₂ alone and with the addition of Cu(II) ions at three concentrations: 0.1, 0.2 or 0.3 g per 100 g d.m. of starch. The oxidised starches were examined for the content of carboxyl groups, carbonyl groups, amylose and copper, and for water‐binding capacity and water solubility at temperatures of 60 and 80°C. Colour parameters (L*a*b*), susceptibility to retrogradation, thermodynamic characteristics of pasting, intrinsic viscosity and pasting characteristic by RVA were also determined. The results indicate that the concentration of Cu(II) ions added as a catalyst has an effect on both the effectiveness of the oxidation process and the physicochemical properties of starch.     

Influence of silver nanoparticles on the fabrics functions prepared by in-situ technique

The development of multifunctional fabrics is an important purpose for their application in many fields. This study provided a simple approach for innovative textile design by applying the optical properties of Plasmonic noble metal nanoparticles. The utilization of feasible technique to functionalize both semi-synthetic and synthetic fabrics namely viscose and acrylic fabric has been accomplished. Where, fabrics functions have been developed by in situ synthesis of silver nanoparticles (Ag NPs) into their surface using trisodium citrate as multifunctional agent (reductant, stabilizer, and linker). The silver NPs incorporated into fabrics has been characterized by UV–visible spectroscopy, scanning electron microscopy, energy dispersive X-ray, and X-ray photoelectron spectroscopy. The mechanism of assembling Ag NPs in situ incorporated fabric matrix has been discussed. The influence of silver nanoparticles on the coloration, UV-protection, and antibacterial properties of the fabrics has also been examined. The overall results indicated that, the in situ Ag NPs-incorporated into fabrics has been applied as a colorant for both viscose and acrylic fabrics effectively beside the improvement for UV-blocking and anti-bacterial properties.     

Migration analysis,antioxidant, and mechanical characterization of polypropylene-based active food packaging films loaded with BHA,BHT, and TBHQ

Polypropylene (PP) based active composite films were prepared by adding butylated hydroxy anisole (BHA), butylated hydroxytoluene (BHT), and tertiary butylated hydroquinone (TBHQ) antioxidants using the extrusion molding process. All concentrations of BHT, 2% to 3% BHA, and 3% TBHQ significantly increased the tensile strength (TS) of the composite films compared with control films. Increasing antioxidant concentration decreased TS values for BHT films, whereas an opposite trend was observed for BHA and TBHQ films. BHA at < 2%, BHT at > 2%, and TBHQ at all added concentrations significantly reduced elongation at break (E_b) of the composite films compared to control films. Water vapor permeability (WVP) of 1% BHT film was not significantly different from control. However, other antioxidants especially at increased concentrations significantly increased WVP values. TBHQ films with 300% to 662% increase had the highest WVP and BHT films with 5% to 81% increase had the lowest WVP among composite films. All three antioxidants had a negative effect on the transparency of the films; however the effect of BHA at higher concentrations was greater. The antioxidants did not change the color attributes of the films. Films containing all antioxidants showed 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity, which increased with increase in their concentration, especially for those containing 3 wt.% BHT and TBHQ. Overall, incorporating BHA and BHT into a PP matrix improved mechanical, barrier, antioxidant properties, and film appearance and consequently were proposed for the development of antioxidant active PP films. TBHQ film is not recommended for food packaging because of its weak mechanical properties (lower E_b and TS values, higher WVP, and greater migration).     

The relationship between entanglement concentration and physicochemical properties of potato and sweet potato starch dispersions

Entanglement concentration (c_e) is defined as the onset of overlap and interpenetration of random‐coil chains in a polymer solution and is important in determining rheological, dynamic and fracture properties. However, few studies have reported in detail how c_e influences physicochemical properties of starch dispersions. So, the effects of c_e on the physicochemical properties of the potato and sweet potato starch dilute and semi‐dilute dispersions were investigated. The results showed that for the two starch dispersions with concentrations ≥c_e, the gelatinisation temperature increased more significantly with increasing concentrations, and storage modulus increased faster than loss modulus with increasing frequency. The potato starch dispersion with concentrations ≥c_e possessed higher entanglement density of the chain segments. The two starch dispersions with concentrations >c_e exhibited shear thinning with increasing frequency. The two starches could only form film at concentrations ≥c_e. So, c_e will be a suitable concentration for regulating the concentration of starch dispersions to obtain the expected physicochemical properties.