Search

Polylactic acid (PLA) is one of the most promising biodegradable materials, which can reduce the environmental pollution caused by food and material industry. The effect of the addition proportion of nano‐silver and different food simulant on the migration and the performance changes of film during migration were evaluated, revealing the association between the performance changes and nano‐silver migration. The results showed that nano‐silver had the largest migration amount and the fastest migration rate in 4% (v/v) acetic acid solution, followed by 50% (v/v) ethanol solution, and the lowest in isooctane solution. Performance changes were affected by the compatibility of silver nanoparticles and PLA, and the strength of the interaction between the film and acetic acid. Performances of composite film deteriorated during high proportions of nano‐silver addition and long soaking. Adding a small amount of nano‐silver to the composite was the effective method considering the balance between good performances and migration. [ABSTRACT FROM AUTHOR]

The migration study of nano‐Ag migration from polylactic acid (PLA) films was studied. Samples treated by high‐pressure food processing (0, 100, 200, 300, and 400 MPa pressure) were soaked in acetic acid solution and incubated at 20 °C for 90 days. At the end of storage, nano‐Ag particles (AgNPs) migration from the PLA/AgNPs composite film treated under 200 MPa high pressure was the lowest. However, AgNPs migration was accelerated under 400 MPa high pressure. High‐pressure processing (200 MPa) could cause denser structure and higher crystallinity degree in films than other treatments. Lower amount of AgNPs induced a decline in the intensity of specific characteristic peaks. The diffraction peak intensity of α‐crystal for the film sample treated with 400 MPa was the lowest on day 60. The crystallization index of the PLA matrix changed with different high‐pressure processing. The result indicated that appropriate high‐pressure food processing could effectively suppress AgNPs migration from PLA‐based film while contacting with acidic acid food simulant. Practical Application: The release of nanoparticles from food packaging material is a very important matter when the migration is concerned with regulatory and toxicity issues. The study described the migration kinetic of AgNPs from PLA nanocomposite film into acidic food simulant after different high‐pressure food processing. The results indicated that the PLA/AgNPs nanocomposite film was safe for acidic food after high‐pressure treatment. [ABSTRACT FROM AUTHOR]

An active packaging film based on poly(lactic acid) (PLA) incorporated with 9 wt% bergamot, lemongrass, rosemary, or clove essential oils was developed. The influence of essential oils on the properties of the PLA/essential oil blends was studied. The mechanical and antimicrobial properties of PLA/essential oil blends were found to be superior to pure PLA. The WVP of PLA/essential oil blend films was significantly ( p < 0.05) higher than that of pure PLA film. All FTIR spectra of PLA/essential oil blends displayed the characteristic bands of PLA-based materials. The addition of essential oils in the polymer matrix resulted in a two-step degradation process of TGA. Furthermore, essential oils led to the decrease of the glass transition temperature according to the DSC results. [ABSTRACT FROM AUTHOR]

In this study, poly( l-lactide) (PLA) films were fabricated by melt processing and the plasticizing effect of hexadecyl lactate (HL) (0, 5, 7.5, 10, and 12.5 wt% on PLA were investigated by scanning electron microscopy (SEM), differential scanning calorimetry, thermogravimetric analysis, tensile, transparency, and water vapor permeability tests. The SEM analysis revealed that PLA with 10 wt% HL appeared uniform with extra small bumps, confirmed the interaction between PLA and HL. The thermal analysis revealed a glass transition temperature of 57.4 °C for neat PLA film, but the addition of HL elicited a decrease in the temperature of the peak (43.8 °C). The incorporation of plasticizer into PLA resulted in the increase of elongation at break, as well as the decrease of tensile strength and tensile modulus. Even though a decrease in transparency was recorded, the PLA/HL blend films appeared transparent by visually observation. The water vapor permeability of PLA/HL blend films increased with the increase of HL. The PLA/HL blend films could effectively extend the shelf-life of fresh-cut pears as the commercial low density polyethylene films. The results indicated that the properties of PLA films can be modified with the addition of HL and PLA/HL blend films could serve as an alternative as food packaging materials to reduce environmental problems associated with synthetic packaging films. [ABSTRACT FROM AUTHOR]

Poly(lactic acid)/poly(trimethylene carbonate) (PLA/PTMC) films incorporated with cinnamaldehyde (0, 3, 6, 9, and 12 wt%) were prepared by solvent casting and characterized by physical, mechanical, and antimicrobial properties. SEM analysis revealed that the surface of film became rougher with certain porosity when cinnamaldehyde was incorporated into the PLA/PTMC blends. Cinnamaldehyde acted as plasticizers which reduce the intermolecular forces of polymer chains, thus improving the flexibility and extensibility of the films. Differential scanning calorimetry showed that the crystallinity of PLA phase decreased by the presence of cinnamaldehyde in the composite films. Water vapor permeability of films increased with the increase of cinnamaldehyde loading. However, the active PLA/PTMC/cinnamaldehyde composite films showed adequate barrier properties for food packaging application. Incorporation of cinnamaldehyde to the PLA/PTMC polymer matrix improved the antimicrobial activity of active packaging films. These results indicated that the best compromise between mechanical, barrier, thermal, and antimicrobial properties could be achieved by the addition of 9 wt% cinnamaldehyde into PLA/PTMC blends. [ABSTRACT FROM AUTHOR]

The effect of biobased poly(lactic acid) (PLA)/poly(ɛ-caprolactone) (PCL) blend films with different cinnamaldehyde contents (0, 3, and 9 wt%) on the physicochemical and microbial quality of button mushrooms ( Agaricus bisporus ) stored at 4 ± 1 °C for 16 days was investigated. The low-density polyethylene (LDPE) film was used as the control. The microbial levels and physicochemical properties such as weight loss, firmness, total soluble solids, O 2 and CO 2 concentrations, microbiological quality, color, and sensory quality of mushrooms were measured. Although the highest weight loss (3.08%) was observed in the PLA/PCL/C9 treatment at the end of storage, it was still lower than 5%. Mushrooms packaged in the PLA/PCL/cinnamaldehyde blend films were significantly ( p < 0.05) firmer than those packaged in the control and PLA/PCL film. The CO 2 level inside the PLA/PCL film with cinnamaldehyde was lower than those inside the control and PLA/PCL film, but the O 2 level was similar in all packages. The PLA/PCL/C9 film was more effective in reducing microbial counts and preserving the color of mushrooms than the other three films. The overall acceptability of mushrooms packaged in the PLA/PCL/C9 film still remained good and within limit of marketability after 12 d of storage. The results suggested that the PLA/PCL/C9 film with higher water vapor permeability could be used to maintain the quality of fresh button mushroom and extend its postharvest life. [ABSTRACT FROM AUTHOR]

Antimicrobial active films based on poly(lactic acid) (PLA) were prepared with poly(e-caprolactone) (PCL) and thymol (0, 3, 6, 9, and 12 wt%) by solvent casting methods. The films were characterized by thermal, structural, mechanical, gas barrier, and antimicrobial properties. Scanning electron microscopy analysis revealed that the surface of film became rougher with certain porosity when thymol was incorporated into the PLA/PCL blends. Thymol acted as plasticizers, which reduce the intermolecular forces of polymer chains, thus improving the flexibility and extensibility of the films. The addition of PCL into the pure PLA film decreased the glass transition temperature of the films. The presence of thymol decreased the crystallinity of PLA phase, but did not affect the thermal stability of films. Water vapor barrier properties of films slightly decreased with the increase of thymol loading. The antimicrobial properties of thymol containing films showed a significant activity against Escherichia coli and Listeria monocytogenes. The results indicated the potential of PLA/PCL/thymol composites for applications in antimicrobial packaging. [ABSTRACT FROM AUTHOR]

Abstract: Films of poly(l-lactide) (PLA) plasticized with varying levels of N-octyl lactate (NOL) were prepared by extrusion. The thermal and functional properties of the blends were investigated by SEM, DSC, TGA, tensile, opacity, water vapor permeability, and water contact angle tests. The compatibility of the plasticizer with PLA was confirmed by DSC and SEM analysis. A higher plasticizing effect on the thermal properties of PLA was generally observed with the increase in NOL content. Additionally, the mechanical properties were improved with the increase in NOL content. The mechanical resistance of the films could be related to their glass transition temperature. The effect of the concentration of plasticizer on the opacity of the films was negligible. The water vapor permeability of the PLA/NOL composite films increased with the increase in the concentration of NOL; however, the values observed were still lower than the water vapor permeability of commercial LDPE films. In conclusion, the extruded PLA-based films with NOL plasticizers could be used as food-packaging materials. [Copyright &y& Elsevier]

ABSTRACT Poly( l-lactic acid) (PLA) is now a very attractive polymer for food packaging applications. In this study, PLA/poly(trimethylene carbonate) (PTMC)/talc composite films were prepared by solvent casting. The influence of the talc loading (0, 1, 2, and 3 wt %) on the phase morphology of the PLA/PTMC/talc composites and the improvement in the resulting properties are reported in this article. The scanning electron microscopy images of the composite films demonstrated good compatibility between the PLA and PTMC, whereas talc was not thoroughly distributed in the PLA matrix at talc contents exceeding 3 wt %. The tensile strength and elongation at break of the composite films significantly improved ( p < 0.05). On the contrary, the water vapor permeability and oxygen properties of the composite films decreased by 24.7 and 39.2%, respectively, at the 2 wt % talc loading. Differential scanning calorimetry showed that the crystallinity of the PLA phase increased with the presence of talc filler in the PLA/PTMC/talc composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 40016. [ABSTRACT FROM AUTHOR]

This study aimed to reinforce the barrier performance (i.e., oxygen–gas and water–vapor permeability) of poly(lactic acid) (PLA)-based films. Acetyltributylcitrate and zinc oxide nanoparticle (nano-ZnO), serving as plasticizer and nanofiller, respectively, were blended into a PLA matrix through a solvent-volatilizing method. The structural, morphological, thermal, and mechanical performances were then studied. Scanning electron microscopic images showed a significant dispersion of nano-ZnO in PLA ternary systems with low nano-ZnO content. The interaction between PLA matrix and ZnO nanoparticles was further analyzed by Fourier-transform infrared spectroscopy. Wide-angle X-ray scattering spectroscopy demonstrated high compatibility between PLA matrix and ZnO nanoparticles. Mechanical property studies revealed good tensile strength and low flexibility. Differential scanning calorimetry curves proved that an amorphous structure mostly existed in PLA ternary systems. The improvements in barrier property and tensile strength indicated that the PLA/nano-ZnO composite films could be used for food packaging application. [ABSTRACT FROM AUTHOR]

To study the relationship between performance changes and nanoparticles migration of the composite film at different migration stages, the poly (lactic acid) (PLA)/nano-TiO2 composite film treated by high pressure was immersed in 50% (v/v) ethanol solution for 45 days at 40 °C, and the film characteristics and migration behavior were analyzed. The results showed that the migration of the composite film with the highest loading of nano-TiO2 (20 wt. %) in alcoholic food simulated solution was far less than 10 mg/kg during the 45-day migration process. Although with the increase of migration time, the micro-morphology of composite film became rougher, the crystallinity decreased and the gas permeability increased, but the internal crystal structure of the composite film remained basically unchanged. The PLA/nano-TiO2 composite films treated by high pressure treatment were relatively stable, and had good performance and migration behavior in alcoholic food simulated solution, the nanocomposite film after high pressure treatment could be used to reduce nano-TiO2 particle migration and subsequently reduce human exposure as the packaging film for the packaging of alcoholic food, which provide a theoretical basis for the applications of high pressure treatment of PLA/nano-TiO2 composite films in food packaging material and broaden its application prospects. [ABSTRACT FROM AUTHOR]

The microstructure, thermal properties, mechanical properties and oxygen and water vapor barrier properties of a poly(lactic acid) (PLA)/nano-TiO2 composite film before and after high pressure treatment were studied. Structural analysis showed that the functional group structure of the high pressure treated composite film did not change. It was found that the high pressure treatment did not form new chemical bonds between the nanoparticles and the PLA. The micro-section of the composite film after high pressure treatment became very rough, and the structure was depressed. Through the analysis of thermal and mechanical properties, high pressure treatment can not only increase the strength and stiffness of the composite film, but also increase the crystallinity of the composite film. Through the analysis of barrier properties, it is found that the barrier properties of composite films after high pressure treatment were been improved by the applied high pressure treatment. [ABSTRACT FROM AUTHOR]

Effects of high pressure treatment (0, 200 and 400 MPa) on water vapour barrier, microstructure, thermal, and mechanical properties of poly (lactic acid) (PLA)/Ag nanocomposite films were investigated. The migration behavior of nano-Ag from the nanocomposite films in the presence of 50% (v/v) ethanol as a food simulant was also studied. The water vapour barrier properties increased as pressure was applied to film-forming solutions. High pressure treatment enhanced the mutual effect between PLA and nanoparticles, leading to a more compact network structure in PLA/Ag nanocomposite films. Furthermore, PLA/Ag nanocomposite films treated by high pressure were significantly affected by microstructure, thermal, and mechanical properties when, compared with untreated samples. High pressure treatment at 200 to 400 MPa significantly (p < 0.05) reduced the migration of nano-Ag from the films. Overall, high pressure treatment on film-forming solutions showed potential in improving the functional properties of nanocomposite films, especially in relation to water vapour barrier properties. [ABSTRACT FROM AUTHOR]

Different percentages (0%, 1%, 5%, and 10%) of nano-Ag particles were added to polylactic acid (PLA) to make an active nanocomposite packaging film. Strawberries were packaged by the nanocomposite films and stored at 4 ± 1 °C for 10 days. The freshness of strawberries was assessed by regularly measuring the physicochemical properties of the strawberries in each packaging film. The difference in the freshness of strawberries was evaluated by determining the following parameter changes: weight loss, hardness, soluble solids, titratable acid, color, vitamin C, total phenol, free radical scavenging activity, peroxidase activity, and sensory evaluation. The results revealed that the active nanocomposite packaging film has better preservation effect when compared with pure PLA film. Its preservation effect is mainly reflected in the more effective reduction of vitamin C loss, delaying the decline of total phenols and 1-Diphenyl-2-picrylhydrazyl (DPPH) in strawberries. It also showed better physical properties. The results showed that the PLA nanocomposite packaging film could effectively preserve freshness of strawberries. [ABSTRACT FROM AUTHOR]

Highlights • A film was prepared by adding TiO 2 and Ag nanoparticles into PLA matrix. • Weight loss in PLA nanocomposite group was lower than that for PLA and PLA/BEO group. • The PLA nanocomposite films provided better retention in firmness, color, and Vit C. • The PLA nanocomposite films had an obvious inhibition on the microorganism growth. • Mango sample packed by the PLA nanocomposite films achieved a shelf-life of 15 days. Abstract The effects of polylactic acid (PLA) film, PLA/bergamot essential oils (BEO) film, and PLA nanocomposite film (PLA/BEO/nano-TiO 2 film and PLA/BEO/nano-TiO 2 +nano-Ag film) on the physicochemical and microbial quality of mangoes stored at room temperature for 15 days was evaluated. The measured properties of mangoes included weight loss, fruit firmness, color, total soluble solids content, total acidity, vitamin C, microbial property, and sensory quality. The weight loss of mangoes packed by PLA nanocomposite films was significantly (p < 0.05) lower than that for PLA and PLA/BEO groups from day 9 to day 12. The PLA nanocomposite films could effectively delay the loss of mango firmness during the entire storage period. The PLA nanocomposite films could also retard the harmful changes in color, total acidity, vitamin C, and microbial property when compared with PLA and PLA/BEO films. The overall acceptability of mangoes packed by the PLA nanocomposite films was still higher than 5 scores and within limit of marketability at the end of storage period. The result indicated that the PLA nanocomposite films could be used to maintain the quality of fresh mango and extend its postharvest life to 15 days. [ABSTRACT FROM AUTHOR]