Tensile Strength Of Films Research Articles

Effectiveness of bacteriophage JN01 incorporated in gelatin film with protocatechuic acid on biocontrol of Escherichia coli O157:H7 in beef

SummaryA new gelatin‐protocatechuic acid (PCA) film with Escherichia coli O157:H7 phage JN01 was developed and characterised. After incorporated with JN01, swelling value, water vapour permeability, water solubility and elongation at break of gelatin‐PCA film were not significantly different. The addition of JN01 increased b value and transparency of film, while it decreased L value, a value and tensile strength of film. Moreover, the gelatin‐PCA‐JN01 film presented antioxidant activity of 60.07%. Furthermore, JN01 could be steadily released from gelatin‐JN01 and gelatin‐PCA‐JN01 films in aqueous solution, and their release rates were 7.56% and 0.12% after 11 h, respectively. The microstructure analysis showed that JN01 particles were clustered and uniformly distributed in film, and the aggregation would be attenuated in the presence of PCA. Meanwhile, E. coli O157:H7 counts were 1.13 log10CFU mL−1 and 0.45 log10CFU mL−1 lower in gelatin‐JN01 and gelatin‐PCA‐JN01 films compared with pure gelatin film in vitro at 4 °C for 24 h, respectively. After stored at 4 °C for 7 days, Escherichia coli O157:H7 counts were 1.00 log10CFU g−1 and 0.80 log10CFU g−1 lower in beef packed with these two gelatin films, compared with beef without gelatin film, respectively. In conclusion, the developed gelatin‐PCA‐JN01 film has potential application in food preservation.

Effect of low‐pressure cold plasma on the properties of edible film based on alginate enriched with Dunaliella salina powder

AbstractEdible films based on sodium alginate enriched with different percentages of Dunaliella salina powder were prepared and treated by cold plasma for diverse durations in the presence of oxygen and argon. The results demonstrated that plasma treatment, especially in the presence of argon, improves film tensile strength and Young's modulus but reduces its flexibility. Surface morphologies and topography clearly show that cold plasma's physical and chemical etching affected the microstructure of films and increased surface roughness and contact angle. Also, water vapor permeability decreased due to the reduced pores of the film and surface hydrophilicity after treatment. The results of total phenolic content and antioxidant activity of treated films containing D. salina were interestingly increased by both O2 and Ar plasma. The colorimetric findings indicated that plasma increased the intensity of redness in samples containing D. salina, with the color of these samples being more vivid.

Development of Single Layer Edible Film Composite from Chitosan Nanoparticles-based as Fruit Packaging Materials

This experiment was conducted to develop chitosan-based edible films and chitosan nanoparticles with cellulose nanocrystals (CNCs) as stabilizers and fillers. Chitosan nanoparticles were synthesized based on ionic cross-linking with sodium tripolyphosphate and glycerol as plasticizer. The experiment began with making 1% w/v chitosan solution, stirred using a magnetic stirrer at 300 rpm for 24 hours then making CNP-TPP colloid solution, the chitosan solution was heated at 50 o C then added TPP solution with a concentration of 5% as much as 20% by weight. dry chitosan dropwise under constant stirring at 1000 rpm using a magnetic stirrer for five minutes. Making CNP-TPP-CNC-KMnO4 matrix, CNP-TPP colloid solution, added glycerol solution with variations of 5,10 and 15% w/w dry chitosan base and added CNC with variation 1-5% w/w dry chitosan base, stirred at 300 rpm for 30 minutes at room temperature. 8% w/w of dry chitosan base was added with KMnO 4 at a temperature of 50 o C under constant stirring at 1000 rpm for five minutes. The film solution was poured into a petri dish and then heated using an oven at 62 o C for 12 hours. Various properties were characterized, mechanical properties and functional group characterization. The experimental results determined the optimum results of the film tensile strength test at 5% CNC and 10% glycerol variations. The tensile strength of the composite film reached a maximum value of 464.1 Mpa on a chitosan-based film and 266.3 MPa on a nano chitosan-based film. The addition of active agent KMnO 4 as much as 8% can reduce the value of tensile strength by 46.3%.

Characterization of biodegradable films based on extracellular polymeric substances extracted from the thermophilic microalga Graesiella sp.

In this research, a new type of biodegradable film based on the extracellular polymeric substances (EPS) and isolated from the thermophilic microalga Graesiella sp., was formulated and characterized. The EPS film was 0.221 mm thick. Atomic force microscopy and scanning electron microscopy images revealed a homogeneous character with a lamellar microstructure. The EPS film displayed yellowish color, high transparency, high ultraviolet barrier properties, and low oxygen (0.008 SI), and water-vapor permeability (0.037 SI). Film tensile strength (16.24 MPa) and elongation at break (4.76%) were in the range of common biofilms and the thermal analyses showed high transition temperature (126 °C) and high thermal stability (up to 800 °C). Compared to ascorbic acid, results indicated that the EPS film shows a higher antioxidant activity, mainly as β-carotene anti-bleaching (84%), DPPH- free radical scavenging ability (80%), and ferrous iron-chelating (55%).Graesiella sp., EPS film effects on beef meat packaging were studied during nine days of cold storage. Compared to polyvinylchloride-packed meat, EPS-packed meat samples showed higher stability of color (redness = 13.6) and pH (5.85) during storage and low proliferation of total viable counts (4.04 CFU·g−1) and Pseudomonas bacteria (4.09 CFU·g−1). They also exhibit lower drip loss (9%) and less metmyoglobin (32%), heme iron (4.87 μg·g−1) total volatile basic nitrogen (TVB-N = 22.96 mg·kg−1), and lipid oxidation (MDA = 0.025 mg·kg−1). The obtained results highlight the potential for use of microalgae EPS as a new film-forming material that could be applied in beef meat preservation.

Physico-mechanical and water absorption properties of LDPE/cassava starch film

Plastic waste is a global crisis, and Malaysia is the 8th worst country worldwide for plastic waste. With this trend, growing market demands for green product have imposed pressure on industries to find an alternative to petroleum-based plastic. Degradable plastic is introduced to overcome this limitation. The present work investigates degradable plastic film of low-density polyethylene incorporated with cassava starch (LDPE-CS). The compounding of the LDPE-CS was prepared via pre-mixing, blending, resin crushing, and film hot pressing. Film thickness, tensile strength, elongation, water absorption, and field test were conducted on the LDPE-CS and commercial LDPE (control). Experimental data of LDPE-CS and commercial LDPE films were evaluated and compared. Thickness of LDPE-CS film was 0.18 mm which was 51% thicker than the control film. Tensile strength and elongation of the LDPE-CS were 7.04 MPa and 5.39%, while control film was 12.77 MPa and 921.5%, respectively. The tensile strength and elongation of the LDPE-SC were significantly lower than the control film, which may be due to the weak interface between LDPE and starch. The water absorption test revealed that the LDPE-CS film absorbed water by 4.8%, which indicates its degradability in the water. The field test shows that the LDPE-CS is biodegradable and comparable with the commercial plant polybag in terms of its capability in planting.

Potential use of glycerol- and/or spermidine-plasticized secalin films as leaf surface coatings for sustainable plant disease management

The effects of spermidine (SPD) on the properties of both secalin (SCL)-based film-forming solutions (FFSs) and their resultant films were studied in the absence or presence of glycerol (GLY) used as primary plasticizer. The average size of SCL particles significantly increased with the increase of SPD concentration, mainly in the presence of GLY, while the negative zeta potential values parallely decreased suggesting a greater stability of the FFSs containing SPD concentrations lower than 1.0 mM. In addition, the decreased contact angle value, compared to water and ethanol solution, indicated that SCL FFSs were highly hydrophobic and that it might be spreaded easily on hydrophobic biological surfaces. SPD could replace GLY in obtaining handleable, homogeneous and performing SCL-based films. The film tensile strength and the Young's module strongly increased in the absence of GLY, reaching values higher than 5 times with respect to controls, whereas elongation at break value of GLY-plasticized films containing 5.0 mM SPD was twice of that of the films prepared without SPD. Conversely, the film moisture content, water solubility and swelling ratio progressively decreased, both in the presence and absence of GLY, up to a SPD concentration of 1.0 mM, whereas the film contact angle increased, confirming the enhancement of its hydrophobicity determined by SPD incorporation. SPD also increased the film barrier properties to gases and water vapor, while the presence of GLY hindered these effects. Finally, SEM analysis of the cross-sections of the SPD containing films showed heterogeneous microstructures, whereas their surfaces appeared rougher than those of the control films. Preliminary experiments carried out by Rosa chinensis Jacq. leaf coating suggest the potential use of SCL-based FFSs spraying in plant disease control. High spreading of the SCL-based FFSs on the entire leaf surfaces, both in the presence and absence of Bordeaux mixture tested as agrochemical, was observed, and the SEM images showed the formation of an evident coating of the leaves. Therefore, these findings suggest the possibility to coat the leaf surface also in vivo with different SCL-based FFSs, giving rise to films possessing tailored functional properties and able to carry and release different agrochemicals.

Effects of high-intensity ultrasound on the structural, optical, mechanical and physicochemical properties of pea protein isolate-based edible film

Pea protein is a promising alternative to animal-based protein and the interest in its application in food industry has been rapidly growing. In this study, pea protein isolates (PPI) were used to form protein-based edible films and the effect of ultrasound treatment on the structure of PPI and the structural, optical, mechanical and physicochemical properties of PPI-films were investigated. Ultrasound induced unfolding of PPI and exposed interior hydrophobic groups to protein surface while both PPI dissociation and formation of large aggregates were observed, as confirmed by measuring intrinsic emission fluorescence, surface hydrophobicity, surface charge, and particle size distribution and polydispersity index, respectively. FE-SEM showed that ultrasound decreased the cracks and protein aggregates at the surface of PPI-film. The film structure was also investigated by FTIR, which showed peak shift in amide I and II region and noticeable difference of protein secondary structure as affected by ultrasound. As a result of such structural changes caused by ultrasound, the properties of PPI-films were improved. Results showed that ultrasound greatly improved the film transparency, significantly increased film tensile strength but not elongation at break, and decreased moisture content and water vapor permeability of the film. This study provided structural data as evidence for utilizing ultrasound technique to develop PPI-films with improved optical, mechanical and water barrier properties.

Development of active packaging films based on quaternary ammonium chitosan, polyvinyl alcohol and litchi (Litchi chinensis Sonn.) pericarp extract

Litchi (Litchi chinensis Sonn.) pericarp contains abundant polyphenols that are suitable materials for developing active packaging films. In this study, 1 wt%, 3 wt% and 5 wt% of litchi pericarp extract (LPE) was added into quaternary ammonium chitosan (QAC) and polyvinyl alcohol (PVA) matrix to develop active packaging films. The structural, physical and functional properties of QAC-PVA (QP) films were compared with LPE (QP-LPE films) and without LPE (QP films). Results showed QP film had a heterogenous cross-section whereas QP-LPE films displayed rough and uneven cross-sections. After adding LPE, the N–H, O–H, C – H and C=O stretching bands of QP films shifted due to the formation of intermolecular interactions between LPE and film matrix. LPE made the colorless QP film turned brown. QP-LPE films presented lower ultraviolet–visible light transmittance than QP film. After adding LPE, film thickness increased from 0.091 to 0.103 mm, film water vapor permeability increased from 14.98 × 10−11 to 17.21 × 10−11 g m−1 s−1 Pa−1, film oxygen permeability increased from 0.16 to 0.22 cm3 mm m−2 day−1 atm−1, film tensile strength increased from 14.10 to 17.41 MPa, and film elongation at break decreased from 36.94% to 25.13%. QP-LPE films quickly released polyphenols in distilled water within 4 h and displayed potent antioxidant activity. The antimicrobial ratio of the film against Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Listeria monocytogenes was elevated from 50.40−68.04% to 58.93−91.38% after adding LPE. Results suggested QP-LPE films could be utilized as antioxidant and antimicrobial packaging materials in food industry.

Thermo Compression of Thermoplastic Agar-Xanthan Gum-Carboxymethyl Cellulose Blend.

There is a gap in the literature for the preparation of agar-xanthan gum-carboxymethyl cellulose-based films by thermo compression methods. The present work aims to fill this gap by blending the polysaccharides in a plastograph and preparation of films under high pressure and temperature for a short duration of time. The pivotal aim of this work is also to know the effect of different mixing conditions on the physical, chemical, mechanical and thermal properties of the films. The films are assessed based on results from microscopic, infrared spectroscopic, permeability (WVTR), transmittance, mechanical, rheological and thermogravimetric analysis. The results revealed that the mixing volume and mixing duration had negative effects on the films’ transparency. WVTR was independent of the mixing conditions and ranged between 1078 and 1082 g/m2·d. The mixing RPM and mixing duration had a positive effect on the film tensile strength. The films from the blends mixed at higher RPM for a longer time gave elongation percentage up to 78%. Blending also altered the crystallinity and thermal behavior of the polysaccharides. The blend prepared at 80 RPM for 7 min and pressed at 140 °C showed better percent elongation and light barrier properties.

Fundamental study of colloidal stability and dispersion of novel nanosized conductive polyaniline (PANI)/prevulcanised latex (PVL) film for antimicrobial applications

A smart material possessed enhanced conductivity integrated in prevulcanized latex (PVL) film produced throughout this work. Also recognizing the synthesis route of PANI was vast and vary, choosing suitable method was great importance corresponding to the aim of study. PANI was prepared through chemical oxidative polymerization of aniline carried out in aqueous solution which aniline dissolved in strong acidic solution (1 M HCl) with the presence of Ammonium Persulphate (APS) as the oxidizing agent and Sodium Dodecyl Sulphate (SDS) as surfactant. However, PANI was readily in acidic condition while PVL in basic and consequently causes a state of immiscibility upon mixing. Hence, PANI formed then mixed with 0.1 – 0.5 % KOH via homogenizer to increase the pH and maintain the homogeneity as well as dispersion to be combined with PVL. Various studies on PANI synthesis and incorporation with latex had been reported but very limited in focusing the colloidal and dispersion stability of the mixture. Zeta potential measurements revealed an effective dispersion and the colloidal stability as the pH of PANI increases. Analysis of mechanical performance using Universal testing Machine revealed that addition of PANI improves greatly in novel film tensile strength and Young’s Modulus by 109 % and 230 %, respectively.

Low-density polyethylene (LDPE) building films – Tensile properties and surface morphology

The paper presents results of strength tests of selected low-density polyethylene (LDPE) building films with various thicknesses, including the assessment of their surface microstructure before and after failure with the use of digital and scanning electron microscopes. Films came from one manufacturer and encompassed: vapor-proof films and construction films. A significant correlation between the film thickness and tensile strength was found only for vapor-proof films. Increasing the film thickness by 1 μm increases the tensile strength value by 0.14 MPa on average when stretching in both longitudinal (MD) and transversal (TD) directions. Furthermore, significant differences in the strain at tensile strength and strain at break for MD and TD were observed in some cases. The coefficient of variation of the strain at break of the samples, varies from ca. 2%–20% depending on the set of the samples, what caused by low mass per unit area and proves high heterogeneity of the samples and presence of local defects or lumps which affect the elongation value of the tested LDPE film sample. It was also proven that the influence of roughness parameters on tensile strength exists, and the parameters maximum height of the surface (Sz) and skewness of height distribution (Ssk) are good indicators of construction film tensile strength. The results emphasize the importance of maintaining the useable features declared by manufacturers, especially the thickness of the product, and of continuously monitoring the quality of their products with the use of relatively simple tests such as roughness measurements at the stage of factory production control (FPC).

Effect of cellulose nanocrystal-stabilized cinnamon essential oil Pickering emulsions on structure and properties of chitosan composite films

The low water-resistance and limited antibacterial activity of chitosan (CS) film hinder its practical applications in food preservation field. To solve these issues, we have facilely and effectively fabricated cinnamon essential oil (CEO)-loaded composite films via incorporating cellulose nanocrystal (CNC)-stabilized CEO Pickering emulsions into CS-based film-forming matrix. Research results show the well distribution of emulsion droplets in film matrix. The insertion of CEO emulsions can improve film water-resistance and antibacterial activity, but reduces its mechanical strength. Concretely, the water contact angle and inhibition zone of composite films can increase by about 12.3° and 2 times compared with CS control film. Compared with tween-80, CNCs can increase film tensile strength by about 3.52 MPa and observably offset the decline of film mechanical property by CEO. Moreover, the film prepared with 3 w/v% CNC stabilized 30 v/v% CEO Pickering emulsion not only enhances pork preservation, but also maintain its structural stability. The fabricated antimicrobial films have considerable potential for packaging application.

Ameliorating effect of γ-aminobutyric acid on the physical performance of whey protein films

γ-Aminobutyric acid (GABA) is a non-protein amino acid that possesses various health benefits. In this study, whey protein isolate (WPI)-based films incorporated with GABA at different concentrations (0, 0.1, 0.5, and 1.0% w/v) were characterized for color, water vapor permeability (WVP), microstructure, GABA leachability, and hydration, optical, mechanical and thermal properties. All the tested WPI films exhibited a colorless and transparent appearance. The addition of GABA increased the elongation at break and WVP while decreased tensile strength and light transmittance of the WPI films. The hydration and thermal properties of the WPI films were enhanced when low concentrations of GABA (0.1, 0.5% w/v) were incorporated, but were impaired in the presence of 1.0% (w/v) GABA. This was attributed to the different microstructures of the WPI films at different GABA concentrations. Our findings demonstrated that GABA could be a promising ingredient for improving the physical properties of WPI films.

Preparation and characterization of Enset starch (ES) based films: plasticized by glycerol and sorbitol

Abstract Films were prepared using casting method from enset starch, as a filler material, glycerol & sorbitol as plasticizers at different concentrations (15, 25 and 35%). And glucose, fructose and sucrose were added to enhance flexibility. The films were characterized and compared the effect of plasticizer type (glycerol and sorbitol) and concentration some physicochemical properties of ES based films. The films were analyzed for moisture content, film density, and thickness, swelling capacity, tensile strength and percentage elongation. The study indicated that moisture content, film thickness, film density, swelling capacity, tensile strength and percentage elongation are dependent on the type of plasticizer and its concentration. Increasing the plasticizer concentration from 15 to 35 % increases moisture content, film thickness; decreases the film density, water swelling capacity and tensile strength of films, regardless of the plasticizer type used.

Synthesis and Characterization of Hyperbranched and Organosilicone Modified Waterborne Polyurethane Acrylates Photosensitive Resin

A new type of waterborne polyurethane acrylate was synthesized for use as a UV curing coating. The N,N-dihydroxy methyl ethyl-3-Methyl aminopropanoate monomer was first prepared via adding reactions of methyl acrylate and diethanol amine with methyl alcohol as the solvent. Then, the hyperbranched prepolymer was obtained by addition of trimethylolpropane with toluenesulfonic acid as catalyst and N,N-dimethyl formamide as solvent. The resulting hyperbranched and organosilicone modified waterborne polyurethane acrylates was synthesized through the mixed reaction of prepolymer and Hydroxy silicone oil, polyethylene glycol-1000, toluene diisocynate, dimethylolpropionic acid, 1,2-propylene glycol, hydroxyethyl acrylate, and triethylamine with dibutyltin dilaurate as the catalyst. The molecular structures were characterized by FT-IR and 1H NMR spectroscopy and GPC analysis and the thermal stability was studied by using TGA. Moreover, the influence of contemodnt of hydroxyl silicone oil, dimethylolpropionic acid, polyethylene glycol-1000, and prepolymer to various of properties such as glossiness, hardness, adhesive force, abrasion resistance, water absorption, elongation at break and tensile strength of films were analyzed. The temperature and catalyst dosage impact on percent conversion of isocyanate group (–NCO) were also studied. It was proven that the best dosage of hydroxyl silicone oil and dimethylolpropionic acid were 4.6%, the dosage of polyethylene glycol-1000 was 50%, and the amount of hyperbranched prepolymer was 0.5%, which could make the film achieve the optimum properties. The percent conversion of isocyanate group (–NCO) was maximum when reacting two hours at 80 °C with 0.2% catalyst.

Effect of De-Twinning on Tensile Strength of Nano-Twinned Cu Films.

Tensile tests were carried on the electroplated Cu films with various densities of twin grain boundary. With TEM images and a selected area diffraction pattern, nano-twinned structure can be observed and defined in the electroplated Cu films. The density of the nano-twin grain structure can be manipulated with the concentration of gelatin in the Cu-sulfate electrolyte solution. We found that the strength of the Cu films is highly related to the twin-boundary density. The Cu film with a greater twin-boundary density has a larger fracture strength than the Cu film with a lesser twin-boundary density. After tensile tests, necking phenomenon (about 20 μm) occurred in the fractured Cu films. Moreover, by focused ion beam (FIB) cross-sectional analysis, the de-twinning can be observed in the region where necking begins. Thus, we believe that the de-twinning of the nano-twinned structure initiates the plastic deformation of the nano-twinned Cu films. Furthermore, with the analysis of the TEM images on the nano-twinned structure in the necking region of the fractured Cu films, the de-twinning mechanism attributes to two processes: (1) the ledge formation by the engagement of the dislocations with the twin boundaries and (2) the collapse of the ledges with the opposite twin-boundaries. In conclusion, the plastic deformation of nano-twinned Cu films is governed by the de-twinning of the nano-twinned structure. Moreover, the fracture strength of the nano-twinned Cu films is proportional to the twin-boundaries density.

Immobilization of roselle anthocyanins into polyvinyl alcohol/hydroxypropyl methylcellulose film matrix: Study on the interaction behavior and mechanism for better shrimp freshness monitoring

The roselle anthocyanin extracts (RAE) were immobilized into polyvinyl alcohol (PVA)/hydroxypropyl methylcellulose (HPMC) film matrix, their interaction behavior and mechanism was fully understood for better shrimp freshness monitoring. Structural characterizations revealed RAE was firmly immobilized PVA/HPMC matrix by hydrogen bonds. With increasing RAE contents, dramatic increases of film thickness (from 15.90 ± 0.14 to 23.20 ± 3.35 μm), tensile strength (from 45.66 ± 1.07 to 56.98 ± 0.24 MPa), light barrier and active properties (increased by 83.18% for antioxidant and 146.91%, 59.18% for antibacterial activity against E. coli and S. aureus) were observed, while hydrophobic properties decreased significantly. Owing to great ammonia-sensitive ability, the PVA/HPMC/RAE (PHR) films were applied on shrimp freshness qualitative monitoring and greater visible color variations were identified with increasing RAE contents. Furthermore, mathematical models were established for quantitative monitoring. In conclusion, with the increasing RAE contents, the tighter interaction between RAE and PVA/HPMC matrix contributed to the better functional properties and freshness monitoring effects of PHR films.

Preparation and performance of lignin-based waterborne polyurethane emulsion

The unmodified industrial Alkali Lignin (AL) was used as a hydrophilic chain extender to prepare a series of Lignin-based Waterborne Polyurethane (LWPU) emulsions with different lignin contents by step-growth addition polymerization with polypropylene glycol (PPG) and isophorone diisocyanate (IPDI). The lignin content in the series of LWPUs was determined by elemental analysis, with a maximum content of 24.68 wt%. The infrared spectrum and SEM diagram of the LWPU film show that the AL reacts well with isocyanate, the section of the film is flat and smooth, and there are no agglomerated lignin particles in the film, which indicates that the film is homogeneous. With the increase of AL content, the particle size of the LWPU emulsion decreased gradually from 233 nm to 127 nm, the Zeta potential decreased gradually from -44.8 mV to -56.9 mV, and the emulsion has good stability in the pH range of 5–12. The thermogravimetric analysis of the LWPU film show that the introduction of AL can improve the thermo stability of the polyurethane material, and the mechanical properties test results show that the highest tensile strength of the LWPU film can reach 1.29 times that of the pure polyurethane film. Ultraviolet aging test show that the introduction of AL can significantly improve the UV aging resistance of the polyurethane film. The lignin-based waterborne polyurethane emulsion prepared in this study can be used as a new type of bio-based polyurethane material.

Synergistic Antimicrobial Activities of Thai Household Essential Oils in Chitosan Film.

Foodborne pathogens mostly contaminate ready-to-eat (RTE) meat products by post-process contamination and cause foodborne disease outbreaks. Preventing post-process contamination and controlling microbial growth during storage by packing the RTE meats with active antimicrobial film from chitosan combined with the synergism of Thai household essential oils was investigated. Here, we analyzed antimicrobial activity and mechanical properties of chitosan films incorporated with essential oil of fingerroot (EOF) and holy basil (EOH) based on their fractional inhibitory concentration and isobolograms. We showed that antimicrobial activities of chitosan film and chitosan films formulated with EOF:EOH displayed a dramatical reduction of Listeria monocytogenes Scott A concentration by 7 Log in 12 h. Chitosan film incorporated with EOF:EOH at ratio 0.04:0.04% v/v/w strongly retarded growth of total viable count of L. monocytogenes on vacuum-packed bologna slices during seven days of storage at 4 and 10 °C. Combined EOF and EOH added to chitosan films did not alter thickness, elongation (%) and colors (L*, a* and b*) of the chitosan film, but it increased water vapor transmission rate and decreased film tensile strength. Results suggested that chitosan film had strong antibacterial properties. Its effectiveness in inhibiting foodborne pathogenic bacteria in ready-to-eat meat products was enhanced by adding a combination of EOF:EOH.

Colloidal lignin nanoparticles from acid hydrotropic fractionation for producing tough, biodegradable, and UV blocking PVA nanocomposite

Colloidal lignin nanoparticles (LNPs) from low temperature acid hydrotropic fractionation (AHF) of poplar wood and commercial alkali lignin using p-Toluenesulfonic acid (p-TsOH) were directly mixed with PVA to make PVA/AHF-LNP nanocomposite films. p-TsOH itself acted as a plasticizer for PVA; however the application of p-TsOH alone reduced PVA film tensile strength and therefore toughness. At proper loadings of LNPs and p-TsOH, both the failure strain and tensile strength of PVA/AHF-LNP composites were improved. The formation of hydrogen bonding between the p-TsOH/AHF-LNP aggregates with hydroxyl groups on PVA molecular chains, and the breakage and reforming of p-TsOH/AHF-LNP aggregates, along with the nanophase crazing due to the presence of p-TsOH/AHF-LNP aggregates were identified as the main mechanisms for improving the toughness of PVA/AHF-LNP nanocomposite. The composite also had improved UV shielding performance and biodegradability due to the presence of p-TsOH and LNPs compared with neat PVA. This nanocomposite film could be used as biodegradable anti-ultraviolet packing film.