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Background: Our living environment is being increasingly polluted by petroleum-based plastics and there is an increasing demand for biodegradable food packaging. In this study, the effect of various ultrahigh-pressure (UHP) treatments (0, 200 and 400 MPa) on the microstructure and thermal, barrier and mechanical properties of poly(lactic acid) (PLA)/ZnO nanocomposite films was studied., Results: The film-forming solution was processed using UHP technology. The crystallinity, strength and stiffness of the composite film after UHP treatment increased. In addition, barrier property analysis showed that the UHP treatment significantly (P < 0.05) reduced the oxygen permeability and water vapor permeability (WVP) coefficient of the PLA/ZnO nanocomposite film. Furthermore, the WVP value of the film treated at 400 MPa (50 g kg -1 nano-ZnO content) was the lowest and reduced by 47.3% compared with that of pure PLA film. The improvement in these properties might be due to the interaction between nano-ZnO and PLA matrix promoted by UHP treatment., Conclusions: Therefore, the application of UHP technology on the film-forming solution could improve the crystallinity and functional properties of the nanocomposite film, and has great potential in the production of food packaging films with ideal functions. © 2021 Society of Chemical Industry., (© 2021 Society of Chemical Industry.)

A pH indicator film was prepared by mixing natural polymeric chitosan (CH) with natural dye from butterfly pudding extract (BP). The films were determined by color changes at different pH value, absorbance, thickness, moisture content, swelling property, water contact angle, mechanical property, barrier property, and microstructure of films. The structural change of film was analyzed by Fourier transform infrared spectra. The application to monitor fish freshness was also studied. The prepared film was sensitive to the changes in pH value and showed distinct color changes from pink purple to yellow, with pH value ranging from 1 to 14. The films showed visible color changes from purple-blue to dark green during fish preservation. The total volatile basic nitrogen (TVB-N) content and pH value changes of tilapia were closely related to the visual color changes in film. The result indicated that the fabricated film was a highly pH-sensitive film for monitoring fish freshness., (Copyright © 2021. Published by Elsevier B.V.)

The poly(lactic acid) (PLA)/nano-TiO 2 composite films with different nano-TiO 2 loading (0 wt%, 1 wt%, 5 wt%, 10 wt%, 15 wt%, and 20 wt%) were prepared and contacted with 50% (v/v) ethanol solution as food simulant to study the behavior of nano-TiO 2 migration. The structural changes and intermolecular interactions were determined by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The migration amount increased with the increase of initial nano-TiO 2 content. SEM images demonstrated that the microstructure of PLA nanocomposite films became rougher as exposure to ethanol solution in a few days. XRD spectra indicated that a decrease in the intensity of specific diffraction peak occurred as the decrease in nano-TiO 2 content of PLA nanocomposite films during exposure to ethanol simulant. DSC analysis confirmed that the higher crystallinity percentage obtained during the different degradation times. The reasonable food packaging application of the nano-TiO 2 composite films with restrained nano-TiO 2 migration could be accomplished by controlling the nano-TiO 2 loading., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The effects of poly(lactic acid) (PLA)-based film with inorganic antimicrobial nano-TiO₂ and nano-Ag on the physicochemical and microbial quality of Tremella aurantialba stored at 4 ± 1 °C for 16 days was investigated. Rosemary essential oil (REO, 9 wt %) was added into PLA film as plasticizer. Low-density polyethylene (LDPE) and PLA film was used as the controls. The experiment measured physicochemical properties and microbial levels, such as weight loss, firmness, vitamin C, color, microbiological quality, and sensory quality. Although Tremella aurantialba packed by nano-composite films had the highest weight loss (4.96% and 5.17%) at the end of storage, it was still in the vicinity of 5%. Tremella aurantialba packed with nano-composite films were significantly ( p < 0.05) firmer than those packed by LDPE, PLA, and PLA/REO films. The nano-composite films were more effective in reducing vitamin C and microbial counts and preserving the color of Tremella aurantialba than the other three groups. The overall acceptability of Tremella aurantialba packed by the nano-composite films still remained good and within the limits of marketability after 12 days of storage. The results suggested that the proposed nano-composite films could maintain the quality of Tremella aurantialba and extend its postharvest life.

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 © 2014 Elsevier B.V. All rights reserved.)

Smart film is widely used in the field of food packaging. The smart film was prepared by adding anthocyanin-rich Robusta coffee peel (RCP) extract into a chitosan (CS)–glycerol (GL) matrix by a solution-casting method. By changing the content of RCP (0, 10%, 15% and 20%) in the CS–GL film, the related performance indicators of CS–GL–RCP films were studied. The results showed that the CS–GL–RCP films had excellent mechanical properties, and CS–GL–RCP15 film maintained the tensile strength (TS) of 16.69 MPa and an elongation-at-break (EAB) of 18.68% with RCP extract. CS–GL–RCP films had the best UV-vis light barrier property at 200–350 nm and the UV transmittance was close to 0. The microstructure observation results showed that CS–GL–RCP films had a dense and uniform cross section, which proved that the RCP extract had good compatibility with the polymer. In addition, the CS–GL–RCP15 film was pH-sensitive and could exhibit different color changes with different pH solutions. So, the CS–GL–RCP15 film was used to detect the fermentation process of pickles at 20 ± 1 °C for 15 days. The pickles were stored in a round pickle container after the boiling water had cooled. The color of the CS–GL–RCP15 film changed significantly, which was consistent with the change of pickles from fresh to mature. The color of the smart film changed significantly with the maturity of pickles, and the difference of ΔE of film increased to 8.89 (15 Days), which can be seen by the naked eye. Therefore, CS–GL–RCP films prepared in this study provided a new strategy for the development of smart packaging materials. [ABSTRACT FROM AUTHOR]

Summary: This work prepared a controlled release food packaging film by solvent volatilization using polylactic acid (PLA) and mesoporous silica nanoparticles (MSNs) loaded with clove essential oil (CEO). White button mushrooms were packaged with PLA and CEO‐loaded MSN PLA composite films to investigate postharvest qualities. The result indicated that PMC‐3 film improves the postharvest qualities of Agaricus bisporus, as reflected by lower weight loss (7.03%), higher total phenolics (2.29 g/kg), and ascorbic acid (27.1 mg/kg) compared with A. bisporus packaged with PLA film. In addition, PMC‐1, PMC‐2, and PMC‐3 treatment significantly improved the antioxidant system of A. bisporus, which inhibited the activity of polyphenol oxidase and peroxidase, as well as control the release of clove essential oil during the storage period. These findings suggest that PMC film is a promising method in postharvest preservation of A. bisporus. [ABSTRACT FROM AUTHOR]

Summary: This work aimed to prepare a controlled‐release antibacterial food packaging film by solvent volatilisation using chitosan (CS) and acidified modified montmorillonite (MMt) loaded with CIN (acid‐MMt‐CIN). MMt was successfully acidified and CIN was successfully loaded into acid‐MMt, which had been confirmed by X‐ray diffraction. The coordination of acid‐MMt‐CIN significantly increased the barrier properties of CS film to water vapour, as well as the rigidity and ductility of the film. Furthermore, the CS/acid‐MMt‐CIN film could significantly improve their UV resistance. It was found that the CIN release time of CS/acid‐MMt‐CIN film in isooctane (simulated fatty food) could reach 168 h, which was 72 h longer than that of CS/CIN film. The addition of acid‐MMt‐CIN had a significant inhibitory effect on Staphylococcus aureus and Escherichia coli. In short, CS/acid‐MMt‐CIN film could potentially be used as an antibacterial active food packaging film. [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]

A novel antimicrobial packaging system was prepared by incorporating TiO2 or Ag nanoparticles into poly(lactic acid) (PLA) matrix. The effect of PLA, PLA/TiO2, and PLA/TiO2 + Ag film on the physicochemical and microbiological properties of Yunnan cottage cheese stored at 5 ± 1 °C for 25 days was investigated. The low density polyethylene (LDPE) film was used as the control. The weight loss, pH value, lactic acid bacteria count (LAB), texture, sensory quality, and antimicrobial activity were determined. Cheeses packed by PLA/TiO2 and PLA/TiO2+Ag film provided better retention in pH value, LAB, sensory quality, and antimicrobial activity compared with those packed by PLA and LDPE film. Migration of Ti and Ag nanoparticles was lower than the limit of 10 mg/kg as defined by EFSA for food contact materials. The results indicated that the incorporation of TiO2 or Ag nanoparticles into PLA matrix could maintain cheese quality and prolong its shelf life to 25 days. Practical applications Yunnan cottage cheese is one of the most popular cheeses in China. However, the shelf life of unpacked Yunnan cottage cheese is only 5-7 days under refrigerated condition. PLA film incorporated with antimicrobial TiO2 or Ag nanoparticles has great potential to prolong cheese shelf life. The novel packaging material may be an effective alternative for cheese preservation. [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]

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]

Highlights: [•] XRD and DSC indicated that the crystallinity of PLLA-PTMC/Talc composites increased. [•] FTIR suggested that there were strong interactions between PLLA-PTMC and talc filler. [•] SEM image of composite films revealed certain homogeneity between PLLA-PTMC and Talc. [•] PLLA-PTMC/Talc composites performed well in mechanical and barrier properties. [•] PLLA-PTMC/Talc composites can be used for development of food packaging materials. [Copyright &y& Elsevier]

The worsening environment and the demand for safer food have accelerated the development of new food packaging materials. The objective of this research is to prepare antimicrobial food packaging film with controlled release by loading cinnamaldehyde (CIN) on etched halloysite nanotubes (T-HNTs) and adding it to sodium alginate (SA) matrix. The effects of T-HNTs-CIN on the physical functional properties and antibacterial activity of the film were systematically evaluated, and the release of CIN in the film was also quantified. Transmission electron microscopy and nitrogen adsorption experiments showed that the halloysite nanotubes had been etched and CIN was successfully loaded into the T-HNTs. The addition of T-HNTs-CIN significantly improved the water vapor barrier properties and tensile strength of the film. Similarly, the presence of T-HNTs-CIN in the film greatly reduced the negative effects of ultraviolet rays. The release experiment showed that the diffusion time of CIN in SA/T-HNTs-CIN film to fatty food simulation solution was delayed 144 h compared with that of SA/CIN film. Herein, the antibacterial experiment also confirmed the controlled release effect of T-HNTs on CIN. In conclusion, SA/T-HNTs-CIN film might have broad application prospects in fatty food packaging. [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 use of biodegradable packaging films for post-harvest preservation of wild edible mushrooms is an eco-friendly method. In this study, the nanocomposite films were prepared based on poly (lactic acid) and mesoporous silica (2, 4 and 6 wt% based on polylactide) loaded with citral. The effects of nanocomposite film on the postharvest quality and specific spoilage bacteria of Russula virescens wild mushroom were evaluated. The results showed that firmness, weight loss, color, electrolyte leakage for Russula virescens treated with mesoporous silica loaded with citral based on poly (lactic acid) films were maintained compared to the control group. In particular, the 4% mesoporous silica loaded with citral group prolonged the freshness of mushroom by 6 days. Acinetobacter , Lactococcus, Weissella, Serratia, unclassified Enterobacteriaceae , and unclassified Gammaproteobacteria were identified as the main dominant bacteria. After 12 d of storage, the relative abundance of these bacterial for mushrooms packed by 4 wt% mesoporous silica loaded with citral based on poly (lactic acid) film was reduced, except Lactococcus. This revealed that the poly (lactic acid) film prepared by 4 wt% mesoporous silica loaded with citral could be used to extend the shelf life of Russula virescens. • The MSN/CIT/PLA film inhibited POD and PPO enzyme activities. • The MSN/CIT/PLA film retarded the browning of R. virescens wild mushroom. • The relative abundance of bacteria for MSN/CIT/PLA group was reduced. • The MSN/CIT/PLA film could extend the shelf life of R. virescens. • 4MSN/CIT/PLA film was the most effective in preserving freshness of R. virescens. [ABSTRACT FROM AUTHOR]

The effects of nano-Ag content, high pressure treatment, and migration time on nano-Ag migration and properties of polylactide (PLA)/nano-Ag composite films were investigated. The PLA films incorporated with 1 wt%, 5 wt%, 10 wt%, 15 wt%, and 20 wt% nano-Ag were treated by 100, 200, 300, and 400 MPa high pressure for 10, 20, and 30 min, respectively, and then soaked in isooctane food simulant at 40 °C for 49 days. The migration of nano-Ag in the PLA nanocomposite films increased by the addition of nano-Ag, the pressure of high pressure treatment, and migration time. Thermal and mechanical properties showed that high pressure and migration time would make the films rougher and increase the crystallization temperature of the PLA nanocomposite films. Moreover, the addition of nano-Ag could improve the barrier properties of the PLA nanocomposite films. However, the longer the migration time, the worse the barrier property. The results indicated that the migration amount of nano-Ag and performance of the PLA/nano-Ag composite films were greatly affected by the migration time. • This paper applied high pressure technology to the preparation of composite film materials. • The addition of nano-Ag could increase the crystallinity of the composite films. • The migration of the nano-Ag/PLA composite films in the oily food simulating liquid was safe. • As the migration time increased, the barrier and mechanical properties of the composite films deteriorated. • The results indicated that the migration of nano-Ag in the composite films increased as the initial addition quantity of nano-Ag. [ABSTRACT FROM AUTHOR]

In this work, we prepared chitosan/eugenol-loaded IRMOF-3 nanoparticles (CS/IRMOF-3-EU) composite films using (0, 2, 4, and 6 wt%) isoreticular metal-organic framework (IRMOF-3) nanoparticles loaded with eugenol (IRMOF-3-EU), co-blended with chitosan to develop environmentally friendly food packaging materials with sustained antimicrobial activity. The microstructure and physicochemical properties of the composite films were investigated. The addition of IRMOF-3-EU to the CS matrix significantly enhanced the UV-blocking property and elongation at the break of the composite films; the CS/IRMOF-3-EU composite films inherited the antioxidant and antibacterial properties of eugenol (EU), and the DPPH radical scavenging ability was increased to 53.8% with the addition of 6% IRMOF-3-EU, while it showed excellent antibacterial ability; in addition, the CS/IRMOF-3-EU composite films achieved the sustainable release of eugenol to achieve the long-lasting antibacterial effect. Experiments on strawberry preservation applications showed that the CS/IRMOF-3-EU films slowed down the deterioration of strawberry quality, delayed the decline of hardness, effectively suppressed weight loss, H 2 O 2 content, and malondialdehyde content, and delayed the decline of catalase activity and peroxidase activity. It showed that the CS/IRMOF-3-EU composite films could be used to maintain the postharvest quality and prolong the shelf life of strawberries. • Composite films were prepared from chitosan and eugenol-loaded IRMOF-3 nanoparticles. • IRMOF-3-EU improves the physical property of CS/IRMOF-3-EU composite films. • The CS/IRMOF-3-EU composite films exhibits excellent antioxidant properties. • Composite films has the ability to continuously release antimicrobial substances. • The CS/IRMOF-3-EU composite films has good effect on strawberry storage. [ABSTRACT FROM AUTHOR]