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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 [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]

Poly(lactic acid) (PLA) is the most suitable for biodegradable packaging film because of its excellent integrated property, but the poor gas barrier property is its weakness. In this study, a nanocomposite film based on PLA incorporated with 0‐, 1‐, 3‐, 5‐, 10‐, or 15‐wt% nano‐Ag was developed. Effect of multiscale structure on the barrier properties of PLA/nano‐Ag films was studied. The PLA nanocomposite film with 5‐wt% nano‐Ag had the lowest water vapor permeability (WVP) value. Oxygen transmission rate (OTR) value for PLA nanocomposites with 3‐wt% nano‐Ag was found to be the lowest among all the samples. Multiscale structure was demonstrated by the scanning electron microscopy, Fourier transform‐infrared spectroscopy, X‐ray diffraction measurement, and differential scanning calorimetry results. The crystallinity of the PLA phase increased with the content of nano‐Ag in the PLA composites. The evolution of the PLA phase crystallinity could improve the barrier properties of PLA/nano‐Ag composite films for food packaging applications. From the view of multiscale structure, it is better to achieve a balance among short‐range conformation in the amorphous region, long‐range‐ordered structure, and ordered aggregated structure to improve the barrier properties of PLA/nano‐Ag composite films. [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]

The effect of poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL)/thymol(TH) composite film, PLA/PCL film, and polyethylene (PE) film on the microbial and physicochemical quality of hot pepper ( Capsicum frutescens L.) stored at 4 ± 1 °C for 28 days was studied. The measured properties of hot peppers included weight loss, color, firmness, headspace atmosphere in package, vitamin C, total phenolic content, microbial, and sensory quality. The results indicated that the PLA/PCL/TH packaging can retard the harmful change of microbial, weight loss, anaerobic respiration, firmness, vitamin C, total phenolic content, and sensory quality. The color of hot peppers did not show significant ( p < 0.05) changes during the whole storage time. The results suggested that the PLA/PCL/TH composite film could maintain the quality of fresh hot peppers and extend its postharvest life. [ABSTRACT FROM AUTHOR]

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]

Nisin was loaded in mesoporous silica nanoparticles (MSN) (0, 1, 2 and 3 wt%) and incorporated into poly (lactic acid) (PLA) matrix by casting method. The mechanical property, water vapor permeability, thermal property, and antimicrobial property of PLA nanocomposite films were measured. And the internal structure of the composite film was observed through the Scanning electron microscope. Meanwhile, the kinetic of nisin releasing from food simulated solution was investigated and the migration model was established. The result showed that mesoporous silica had an effect on the mechanical and thermal property of the composite films. Both water vapor transmission rate (WVP) and oxygen permeation rate (OTR) decreased, especially for 3MSN/NI/PLA, where WVP decreased by about 9.64% and OTR decreased by 35.19%, which was beneficial to improve the preservation effect. With the addition of MSN, the amount of loaded nisin increased, and at 3MSN/NI, the nisin loading reached 88.75%, and the mesoporous silica could effectively control the release of nisin, thus prolonging the preservation effect. The release kinetic of nisin was described by Fick's law and Weibull's model. In short, the PLA nanocomposite film has the potential to be used as an antimicrobial active film by adding nisin as an antimicrobial agent. Highlights: A biodegradable antimicrobial food grade film was prepared.Nisin was added to the films as an antimicrobial agent.The ordered mesoporous structure of MSN was used as a carrier of antimicrobial agent.The film effectively inhibits E. coli and S. aureus by controlling the release of nisin.Fick's law and Weibull's model were used to describe the release kinetics of Nisin. [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 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. • PLA/nano-TiO 2 films were contacted with 50% (v/v) ethanol solution as food simulant. • The migration amount increased with the increase of initial nano-TiO 2 content. • PLA nanocomposite films became rougher as exposure to ethanol solution in a few days. • A decrease in the peak intensity occurred during exposure to ethanol simulant. • Restrained nano-TiO 2 migration could be accomplished by controlling nano-TiO 2 loading. [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]