Development of polylactic acid/ZnO composite membranes prepared by ultrasonication and electrospinning for food packaging

Improving the performance of kraft paper by cinnamon essential oil/soybean protein isolate microcapsules and konjac glucomannan for citrus preservation

In order to reduce the quality loss of citrus and extend its storage time after harvest, it is essential to develop coated kraft papers with antibacterial and fresh-keeping properties. In this study, cinnamon essential oil (CEO)/soybean protein isolate (SPI) microcapsules were prepared by the coagulation method, and their properties were optimized. Then, the microcapsules were added to konjac glucomannan (KGM) as a coating solution to enhance the physical, and chemical properties of kraft paper by a coating method. The release behavior of CEO, tensile properties, antibacterial properties and preservation effects of the paper were investigated. The results show that when the ratio of wall to core was 7:3, the highest encapsulation rate was 92.20 ± 0.43 %. The coating treatment significantly reduced the oxygen and water vapor transmission rates of kraft paper. The shelf life of citrus treated with coated Kraft was extended by >10 days. Thus, the CEO/SPI microencapsulation and KGM coating could improve the properties of kraft paper and have the potential for citrus preservation.

Mussel-inspired polydopamine-modified biochar microsphere for reinforcing polylactic acid composite films: Emphasizing the achievement of excellent thermal and mechanical properties

Having poor interfacial compatibility between biochar microsphere (BM) and polylactic acid (PLA) should be responsible for the unbalance of composite film strength and toughness. Elucidating the effect of polydopamine (PDA) on BM and BM/PLA composite films is the ultimate goal of this study based on the mussel bionic principle. It was found that the strong adhesion of PDA on the BM surface was achieved, which improved the surface roughness and thermal stability. Also, PDA modification can facilitate crystallization, increase thermal properties, improve interfacial compatibility, and enhance the tensile properties of BM/PLA composite films. Silane-based PDA modified BM/PLA composite film exhibited the best tensile strength, tensile modulus, and elongation at break with 77.95 MPa, 1.87 GPa, and 7.30%. These noteworthy findings, achieving a simultaneous improvement in PLA strength and toughness, hold promising implications for its sustainability.

Polycaprolactone/polyacrylic acid/graphene oxide composite nanofibers as a highly efficient sorbent to remove lead toxic metal from drinking water and apple juice

Due to the characteristics of electrospun nanofibers (NFs), they are considered a suitable substrate for the adsorption and removal of heavy metals. Electrospun nanofibers are prepared based on optimized polycaprolactone (PCL, 12 wt%) and polyacrylic acid (PAA, 1 wt%) polymers loaded with graphene oxide nanoparticles (GO NPs, 1 wt%). The morphological, molecular interactions, crystallinity, thermal, hydrophobicity, and biocompatibility properties of NFs are characterized by spectroscopy (scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Thermogravimetric analysis), contact angle, and MTT tests. Finally, the adsorption efficacy of NFs to remove lead (Pb2+) from water and apple juice samples was determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). The average diameter for PCL, PCL/PAA, and PCL/PAA/GO NFs was 137, 500, and 216 nm, respectively. Additionally, the contact angle for PCL, PCL/PAA, and PCL/PAA/GO NFs was obtained at 74.32º, 91.98º, and 94.59º, respectively. The cytotoxicity test has shown non-toxicity for fabricated NFs against the HUVEC endothelial cell line by more than 80% survival during 72 h. Under optimum conditions including pH (= 6), temperature (25 °C), Pb concentration (25 to 50 mg/L), and time (15 to 30 min), the adsorption efficiency was generally between 80 and 97%. The adsorption isotherm model of PCL/PAA/GO NFs in the adsorption of lead metal follows the Langmuir model, and the reaction kinetics follow the pseudo-second-order. PCL/PA/GO NFs have shown adsorption of over 80% in four consecutive cycles. The adsorption efficacy of NFs to remove Pb in apple juice has reached 76%. It is appropriate and useful to use these nanofibers as a high-efficiency adsorbent in water and food systems based on an analysis of their adsorption properties and how well they work.

Modified Biomass-Reinforced Polylactic Acid Composites

Polylactic acid (PLA), as a renewable and biodegradable green polymer material, is hailed as one of the most promising biopolymers capable of replacing petroleum-derived polymers for industrial applications. Nevertheless, its limited toughness, thermal stability, and barrier properties have restricted its extensive application. To address these drawbacks in PLA, research efforts have primarily focused on enhancing its properties through copolymerization, blending, and plasticization. Notably, the blending of modified biomass with PLA is expected not only to effectively improve its deficiencies but also to maintain its biodegradability, creating a fully green composite with substantial developmental prospects. This review provides a comprehensive overview of modified biomass-reinforced PLA, with an emphasis on the improvements in PLA's mechanical properties, thermal stability, and barrier properties achieved through modified cellulose, lignin, and starch. At the end of the article, a brief exploration of plasma modification of biomass is presented and provides a promising outlook for the application of reinforced PLA composite materials in the future. This review provides valuable insights regarding the path towards enhancing PLA.

Optimization and characterization of carrageenan/gelatin-based nanogel containing ginger essential oil enriched electrospun ethyl cellulose/casein nanofibers

This study aimed to evaluate the effects of nano-gels containing ginger essential oil (GEO) (NGs) made from gelatin and carrageenan gum on ethyl cellulose/casein nano-fibers (NFs). For this purpose, the mechanical, thermal, morphological, antibacterial, antioxidant, hemocompatibility, and biocompatibility properties of the NFs were assessed. It was observed that incorporating NGs into ethyl cellulose/casein NFs improved their morphology, porosity, mechanical properties, and thermal stability. Analysis of the SEM images revealed that adding NGs resulted in NFs with appropriate morphology, devoid of beads, and smaller diameters. The NFs containing NGs exhibited favorable antioxidant properties and inhibited the growth of Escherichia coli and Staphylococcus aureus. Cell viability studies demonstrated that none of the NFs were toxic to normal cells (Human umbilical vein endothelial cells (HUVEC)) and exhibited hemocompatibility. Considering these properties, ethyl cellulose/casein NFs containing NGs and GEO can be utilized as food packaging materials.

Fabrication of PLA-Based Electrospun Nanofibers Reinforced with ZnO Nanoparticles and In Vitro Degradation Study

In this work, electrospun nanofibers based on polylactic acid, PLA, reinforced with ZnO nanoparticles have been studied, considering the growing importance of electrospun mats based on biopolymers for their applications in different fields. Specifically, electrospun nanofibers based on PLA have been prepared by adding ZnO nanoparticles at different concentrations, such as 0.5, 1, 3, 5, 10 and 20 wt%, with respect to the polymer matrix. The materials have been characterized in terms of their morphological, mechanical, and thermal properties, finding 3 wt% as the best concentration to produce PLA nanofibers reinforced with ZnO nanoparticles. In addition, hydrolytic degradation in phosphate buffer solution (PBS) was carried out to study the effect of ZnO nanoparticles on the degradation behavior of PLA-based electrospun nanofiber mats, obtaining an acceleration in the degradation of the PLA electrospun mat.

Novel electrospun nanofibers based on gelatin/oxidized xanthan gum containing propolis reinforced by Schiff base cross-linking for food packaging

Gelatin-based electrospun fibers are promising materials for food packaging but suffer from high hydrophilicity and weak mechanical properties. To overcome these limitations, in the current study, gelatin-based nanofibers were reinforced by using oxidized xanthan gum (OXG) as a crosslinking agent. The nanofibers' morphology was investigated through SEM, and the observations showed that the fibers' diameter was decreased by enhancing OXG content. The resultant fibers with more OXG content exhibited high tensile stress so the optimal sample obtained showed a tensile stress of 13.24 ± 0.76 MPa, which is up to 10 times more than neat gelatin fiber. Adding OXG to gelatin fibers reduced water vapor permeability, water solubility, and moisture content properties while increasing thermal stability and porosity. Additionally, the nanofibers containing propolis displayed a homogenous morphology with high antioxidant and antibacterial activities. In general, the findings suggested that the designed fibers could be used as a matrix for active food packaging.

Role of silk nanocrystal (SNC)-ZnO as an antibacterial nucleating nanohybrid for a patterned mimic poly(lactic acid) based nanofabric

This new investigation deals with the synthesis of an organic-inorganic nanohybrid using SNC with magnificent flower bud-shaped ZnO, termed SNC-ZnO by precipitation method. The nanohybrid (with concentrations 1 wt%, 3 wt%, and 5 wt%) was in situ incorporated into the PLA matrix to prepare the electrospun solution. The functionalized PLA composite nanofibres produced by electrospinning with SNC-ZnO nanohybrid were systematically studied using different structural and morphological analyses to meet the challenging processing requirements. The FESEM analysis gives an average diameter of nanofibres 246 ± 10.2 nm where nanohybrid tends to adhere on the surface of the PLA nanofabric increasing hydrophobicity up to water contact angle 135.3 ± 0.25 °C with 5 wt% nanohybrid incorporation. The nanofabric has significant antibacterial activity against E.Coli and S.Aureus bacteria. Further, an extensive study has been made on thermally stipulated processes using DSC on non-isothermal crystallization kinetics using different models: Avrami, Ozawa, Mo, and Tobin. The results revealed sites for heterogeneous nucleation and improvement in crystallinity, t_1/2, and nucleation effects due to the incorporation of crystalline nanohybrid in PLA nanofibres. Further, the Avrami plot has confirmed both primary and secondary crystallization processes thereby considering its potential to utilize functionalized PLA nanofabric for applications in protective textile.

Evaluation of the Antioxidant and Antimicrobial Potential of SiO2 Modified with Cinnamon Essential Oil (Cinnamomum Verum) for Its Use as a Nanofiller in Active Packaging PLA Films

One of the main causes of food spoilage is the lipid oxidation of its components, which generates the loss of nutrients and color, together with the invasion of pathogenic microorganisms. In order to minimize these effects, active packaging has played an important role in preservation in recent years. Therefore, in the present study, an active packaging film was developed using polylactic acid (PLA) and silicon dioxide (SiO₂) nanoparticles (NPs) (0.1% w/w) chemically modified with cinnamon essential oil (CEO). For the modification of the NPs, two methods (M1 and M2) were tested, and their effects on the chemical, mechanical, and physical properties of the polymer matrix were evaluated. The results showed that CEO conferred to SiO₂ NPs had a high percentage of 2,2-diphenyl-l-picrylhydrazyl (DPPH) free radical inhibition (>70%), cell viability (>80%), and strong inhibition to E. coli, at 45 and 11 µg/mL for M1 and M2, respectively, and thermal stability. Films were prepared with these NPs, and characterizations and evaluations on apple storage were performed for 21 days. The results show that the films with pristine SiO₂ improved tensile strength (28.06 MPa), as well as Young's modulus (0.368 MPa) since PLA films only presented values of 27.06 MPa and 0.324 MPa, respectively; however, films with modified NPs decreased tensile strength values (26.22 and 25.13 MPa), but increased elongation at break (from 5.05% to 10.32-8.32%). The water solubility decreased from 15% to 6-8% for the films with NPs, as well as the contact angle, from 90.21° to 73° for the M2 film. The water vapor permeability increased for the M2 film, presenting a value of 9.50 × 10^-8 g Pa^-1 h^-1 m^-2. FTIR analysis indicated that the addition of NPs with and without CEO did not modify the molecular structure of pure PLA; however, DSC analysis indicated that the crystallinity of the films was improved. The packaging prepared with M1 (without Tween 80) showed good results at the end of storage: lower values in color difference (5.59), organic acid degradation (0.042), weight loss (24.24%), and pH (4.02), making CEO-SiO₂ a good component to produce active packaging.

Construction of compostable packaging with antibacterial property and improved performance using sprayed coatings of modified cellulose nanocrystals

Increasing concerns about food safety and the environment have facilitated the development of eco-friendly antibacterial packaging. This study aimed to demonstrate a facile way to fabricate active packaging materials with modified cellulose nanocrystals (CNCs) and compare the effects of different modified CNCs on the performance of compostable materials. Polylactic acid (PLA) film was selected as a model, and CNCs were modified with methacrylamide, cetyltrimethylammonium bromide, and zinc oxide, respectively, and then applied on the surface of PLA films by spray-coating. All modified CNCs showed excellent antibacterial activity against S. aureus and E. coli (>99.999 %). The effects of different CNC modifications on the performance of PLA films were investigated. Compared to neat PLA films, PLA/CNC films exhibited improved mechanical strength with maintained flexibility, lower gas permeability, and faster compost disintegration rate, and extended the shelf life of wrapped pork samples from 3 days to >10 days. Therefore, this work will also facilitate the applications of PLA materials in eco-friendly packaging.

Antimicrobial Nano-Zinc Oxide Biocomposites for Wound Healing Applications: A Review

Chronic wounds are a major concern for global health, affecting millions of individuals worldwide. As their occurrence is correlated with age and age-related comorbidities, their incidence in the population is set to increase in the forthcoming years. This burden is further worsened by the rise of antimicrobial resistance (AMR), which causes wound infections that are increasingly hard to treat with current antibiotics. Antimicrobial bionanocomposites are an emerging class of materials that combine the biocompatibility and tissue-mimicking properties of biomacromolecules with the antimicrobial activity of metal or metal oxide nanoparticles. Among these nanostructured agents, zinc oxide (ZnO) is one of the most promising for its microbicidal effects and its anti-inflammatory properties, and as a source of essential zinc ions. This review analyses the most recent developments in the field of nano-ZnO–bionanocomposite (nZnO-BNC) materials—mainly in the form of films, but also hydrogel or electrospun bandages—from the different preparation techniques to their properties and antibacterial and wound-healing performances. The effect of nanostructured ZnO on the mechanical, water and gas barrier, swelling, optical, thermal, water affinity, and drug-release properties are examined and linked to the preparation methods. Antimicrobial assays over a wide range of bacterial strains are extensively surveyed, and wound-healing studies are finally considered to provide a comprehensive assessment framework. While early results are promising, a systematic and standardised testing procedure for the comparison of antibacterial properties is still lacking, partly because of a not-yet fully understood antimicrobial mechanism. This work, therefore, allowed, on one hand, the determination of the best strategies for the design, engineering, and application of n-ZnO-BNC, and, on the other hand, the identification of the current challenges and opportunities for future research.

Regulation of polylactic acid using irradiation and preparation of PLA-SiO2-ZnO melt-blown nonwovens for antibacterial and air filtration

Since the COVID-19 pandemic, polypropylene melt-blown nonwovens (MBs) have been widely used in disposable medical surgical masks and medical protective clothing, seriously threatening the environment. As a bio-based biodegradable polymer, polylactic acid (PLA) has attracted great attention in fabricating MBs. However, there are still issues with the undesirable spinnability of PLA and the limited filtration and antibacterial performance of PLA MBs. Herein, a high-efficiency, low-resistance, and antibacterial PLA filter is fabricated by melt-blown spinning and electret postprocessing technology. The irradiation technique is used to tune PLA chain structure, improving its spinnability. Further, silica (SiO₂) nanoparticles are added to enhance the charge storage stability of PLA MBs. With a constant airflow rate of 32 L min^-1, the PLA-based MBs exhibit a high particulate filtration efficiency of 94.8 ± 1.5%, an ultralow pressure drop of 14.1 ± 1.8 Pa, and an adequate bacterial filtration efficiency of 98 ± 1.2%, meeting the medical protective equipment standard. In addition, the zinc oxide (ZnO) masterbatches are doped into the blend and the antibacterial rate of PLA-based MBs against Escherichia coli and Staphylococcus aureus is higher than 99%. This successful preparation and modification method paves the way for the large-scale production of PLA MBs as promising candidates for high-efficacy and antibacterial filters.

Recent Advances in the Investigation of Poly(lactic acid) (PLA) Nanocomposites: Incorporation of Various Nanofillers and their Properties and Applications

Poly(lactic acid) (PLA) is considered the most promising biobased substitute for fossil-derived polymers due to its compostability, biocompatibility, renewability, and good thermomechanical properties. However, PLA suffers from several shortcomings, such as low heat distortion temperature, thermal resistance, and rate of crystallization, whereas some other specific properties, i.e., flame retardancy, anti-UV, antibacterial or barrier properties, antistatic to conductive electrical characteristics, etc., are required by different end-use sectors. The addition of different nanofillers represents an attractive way to develop and enhance the properties of neat PLA. Numerous nanofillers with different architectures and properties have been investigated, with satisfactory achievements, in the design of PLA nanocomposites. This review paper overviews the current advances in the synthetic routes of PLA nanocomposites, the imparted properties of each nano-additive, as well as the numerous applications of PLA nanocomposites in various industrial fields.

Green nanocomposite: fabrication, characterization, and photocatalytic application of vitamin C adduct-conjugated ZnO nanoparticles†

Recently, the conjugation of metal oxide nanoparticles with organic moieties has attracted the attention of many researchers for various applications. In this research, the green and biodegradable vitamin C was employed in a facile and inexpensive procedure to synthesize the vitamin C adduct (3), which was then blended with green ZnONPs to fabricate a new composite category (ZnONPs@vitamin C adduct). The morphology and structural composition of the prepared ZnONPs and their composites were confirmed by several techniques: Fourier-transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), UV-vis differential reflectance spectroscopy (DRS), energy dispersive X-ray (EDX) analysis, elemental mapping, X-ray diffraction (XRD) analysis, photoluminescence (PL) spectroscopy, and zeta potential measurements. The structural composition and conjugation strategies between the ZnONPs and vitamin C adduct were revealed by FT-IR spectroscopy. The experimental results for the ZnONPs showed that they possessed a nanocrystalline wurtzite structure with quasi-spherical particles with a polydisperse size ranging from 23 to 50 nm, while the particle size appeared greater in the FE-SEM images (band gap energy of 3.22 eV); after loading with the l-ascorbic acid adduct (3), the band gap energy dropped to 3.06 eV. Later, under solar light irradiation, the photocatalytic activities of both the synthesized ZnONPs@vitamin C adduct (4) and ZnONPs, including the stability, regeneration and reusability, catalyst amount, initial dye concentration, pH effect, and light source studies, were investigated in detail in the degradation of Congo red dye (CR). Furthermore, an extensive comparison between the fabricated ZnONPs, composite (4), and ZnONPs from previous studies was performed to gain insights to commercialize the catalyst (4). Under optimum conditions, the photodegradation of CR after 180 min was 54% for ZnONPs and 95% for the ZnONPs@l-ascorbic acid adduct. Moreover, the PL study confirmed the photocatalytic enhancement of the ZnONPs. The photocatalytic degradation fate was determined by LC-MS spectrometry.

The photocatalytic efficiency of ZnO NPs is dramatically improved through the conjugation with benign l-ascorbic acid adduct.

Stimuli-Activable Metal-Bearing Nanomaterials and Precise On-Demand Antibacterial Strategies

Bacterial infections remain the leading cause of death worldwide today. The emergence of antibiotic resistance has urged the development of alternative antibacterial technologies to complement or replace traditional antibiotic treatments. In this regard, metal nanomaterials have attracted great attention for their controllable antibacterial functions that are less prone to resistance. This review discusses a particular family of stimuli-activable metal-bearing nanomaterials (denoted as SAMNs) and the associated on-demand antibacterial strategies. The various SAMN-enabled antibacterial strategies stem from basic light and magnet activation, with the addition of bacterial microenvironment responsiveness and/or bacteria-targeting selectivity and therefore offer higher spatiotemporal controllability. The discussion focuses on nanomaterial design principles, antibacterial mechanisms, and antibacterial performance, as well as emerging applications that desire on-demand and selective activation (i.e., medical antibacterial treatments, surface anti-biofilm, water disinfection, and wearable antibacterial materials). The review concludes with the authors' perspectives on the challenges and future directions for developing industrial translatable next-generation antibacterial strategies.

ZnO@Polyvinyl Alcohol/Poly(lactic acid) Nanocomposite Films for the Extended Shelf Life of Pork by Efficient Antibacterial Adhesion

The proliferation of microorganisms is an important reason for meat spoilage and deterioration. Freezing and packaging by polymer films and preservatives are commonly used to preserve meat. While the energy consumption of freezing is very big, the polymer films made by petroleum bring up heavy environmental pressure. In the present study, biodegradable antibacterial ZnO@PLA (ZP) and ZnO@PVA/PLA (ZPP) nanocomposite films used as food packaging have been synthesized by the solvent evaporation method and coating method, respectively. Compared with films without ZnO NPs, ZP and ZPP both had long-term bacteriostasis for 24 and 120 h at temperatures of 25 and 4 °C, respectively. Moreover, the antibacterial effect showed positive relevance with the increase of the ZnO NP concentration. In addition, the antibacterial effect of ZPP was better than that of ZP in the same condition. Scanning electron microscopy showed that the numbers of methicillin-resistant staphylococcus aureus (MRSA) on ZP and ZPP were significantly reduced compared to that in the blank film, and ZPP caused the morphology of MRSA to change, which means that the antibacterial mechanism of ZP and ZPP composite films might be related to antibacterial adhesion. In conclusion, ZPP films have great potential to be regarded as the candidate of food packing to extend the shelf life of pork.

Effect of Non-Thermal Food Processing Techniques on Selected Packaging Materials

In the last decade both scientific and industrial community focuses on food with the highest nutritional and organoleptic quality, together with appropriate safety. Accordingly, strong efforts have been made in finding appropriate emerging technologies for food processing and packaging. Parallel to this, an enormous effort is also made to decrease the negative impact of synthetic polymers not only on food products (migration issues) but on the entire environment (pollution). The science of packaging is also subjected to changes, resulting in development of novel biomaterials, biodegradable or not, with active, smart, edible and intelligent properties. Combining non-thermal processing with new materials opens completely new interdisciplinary area of interest for both food and material scientists. The aim of this review article is to give an insight in the latest research data about synergies between non-thermal processing technologies and selected packaging materials/concepts.

Fabrication of Chitosan/Hydroxyethyl Cellulose/TiO2 Incorporated Mulberry Anthocyanin 3D-Printed Bilayer Films for Quality of Litchis

In this study, a bilayer antibacterial chromogenic material was prepared using chitosan (CS) and hydroxyethyl cellulose (HEC) as inner substrate, mulberry anthocyanins (MA) as a natural tracer, and titanium dioxide nanoparticles (nano-TiO₂)/CS:HEC as a bacteriostatic agent for the outer layer. By investigating their apparent viscosity and suitability for 3D printing links, the optimal ratio of the substrates was determined to be CS:HEC = 3:3. Viscosity of the CH was moderate. The printing process was consistent and exhibited no breakage or clogging. The printed image was highly stable and not susceptible to collapse and diffusion. Scanning electron microscopy and infrared spectroscopy indicated that intermolecular binding between the substances exhibited good compatibility. Titanium dioxide nanoparticles (nano-TiO₂) were evenly distributed in the CH and no agglomeration was observed. The inner film fill rates affected the overall performance of the chromogenic material, with strong inhibitory effects against Escherichia coli and Staphylococcus aureus at different temperatures, as well as strong color stability. The experimental results indicated that the double-layer antibacterial chromogenic material can, to a certain extent, extend the shelf life of litchi fruit and determine the extent of its freshness. Therefore, from this study, we can infer that the research and development of active materials have a certain reference value.

Effect of water-in-oil-in-water (W/O/W) double emulsions to encapsulate nisin on the quality and storage stability of fresh noodles

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Ultrasonic and microwave treatment improved the extraction rate of rock bean protein.

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Rock bean protein has a high content of 7S and 11S globulin components.

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The prepared W/O/W microcapsules can keep the noodles fresh.

Rock-bean protein (RP) was extracted from wild rock beans by ultrasonic treatment and microwave extraction. The RP has a high content of 7S and 11S globulin components and good heat stability. Subsequently, water-oil-water double emulsions were prepared using a water core containing nisin, momordica charantia extract (MCE), and Lactobacillus plantarum as functional additives, corn oil as the intermediate wall, and RP/gum arabic (GA) as the outer wall material. For a ratio of corn oil to water of 5:1, the maximum encapsulation efficiency was 28.22%, and RP/GA had good dispersion characteristics, where the smallest average particle size was achieved for a 1:1 ratio. Finally, the microcapsules were used to study the effect of its addition to noodles. The addition of 2 wt% of the microcapsules to low-gluten flour resulted in a dough with suitable rheology, and can extend the shelf life of the fresh noodles prepared using this dough.

New perspectives on electrospun nanofiber applications in smart and active food packaging materials

Packaging plays a critical role in determining the quality, safety, and shelf-life of many food products. There have been several innovations in the development of more effective food packaging materials recently. Polymer nanofibers are finding increasing attention as additives in packaging materials because of their ability to control their pore size, surface energy, barrier properties, antimicrobial activity, and mechanical strength. Electrospinning is a widely used processing method for fabricating nanofibers from food grade polymers. This review describes recent advances in the development of electrospun nanofibers for application in active and smart packaging materials. Moreover, it highlights the impact of these nanofibers on the physicochemical properties of packaging materials, as well as the application of nanofiber-loaded packaging materials to foods, such as dairy, meat, fruit, and vegetable products.

Electrospinning of PLA Nanofibers: Recent Advances and Its Potential Application for Food Packaging

Poly(lactic acid), also abbreviated as PLA, is a promising biopolymer for food packaging owing to its environmental-friendly characteristic and desirable physical properties. Electrospinning technology makes the production of PLA-based nanomaterials available with expected structures and enhanced barrier, mechanical, and thermal properties; especially, the facile process produces a high encapsulation efficiency and controlled release of bioactive agents for the purpose of extending the shelf life and promoting the quality of foodstuffs. In this study, different types of electrospinning techniques used for the preparation of PLA-based nanofibers are summarized, and the enhanced properties of which are also described. Moreover, its application in active and intelligent packaging materials by introducing different components into nanofibers is highlighted. In all, the review establishes the promising prospects of PLA-based nanocomposites for food packaging application.

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.

Enhanced Antimicrobial Cellulose/Chitosan/ZnO Biodegradable Composite Membrane

In this study, chitosan and sugarcane cellulose were used as film-forming materials, while the inorganic agent zinc oxide (ZnO) and natural compound phenyllactic acid (PA) were used as the main bacteriostatic components to fabricate biodegradable antimicrobial composite membranes. The water absorption and antimicrobial properties were investigated by adjusting the concentration of PA. The scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results demonstrated that the components of the composite membrane were successfully integrated. The addition of ZnO improved the mechanical and antimicrobial properties of the composite membrane, while the addition of PA with high crystallinity significantly reduced the water absorption and swelling. Moreover, the addition of 0.5% PA greatly improved the water absorption of the composite membrane. The results of antimicrobial experiments showed that PA improved the antimicrobial activity of the composite membrane against Staphylococcus aureus, Escherichia coli, Aspergillus niger and Penicillium rubens. Among them, 0.3% PA had the best antimicrobial effect against S. aureus, E. coli and A. niger, while 0.7% PA had the best antimicrobial effect against P. rubens.

Encapsulation of Natural Bioactive Compounds by Electrospinning-Applications in Food Storage and Safety

Packaging is used to protect foods from environmental influences and microbial contamination to maintain the quality and safety of commercial food products, to avoid their spoilage and to extend their shelf life. In this respect, bioactive packaging is developing to additionally provides antibacterial and antioxidant activity with the same goals i.e., extending the shelf life while ensuring safety of the food products. New solutions are designed using natural antimicrobial and antioxidant agents such as essential oils, some polysaccharides, natural inorganic nanoparticles (nanoclays, oxides, metals as silver) incorporated/encapsulated into appropriate carriers in order to be used in food packaging. Electrospinning/electrospraying are receiving attention as encapsulation methods due to their cost-effectiveness, versatility and scalability. The electrospun nanofibers and electro-sprayed nanoparticles can preserve the functionality and protect the encapsulated bioactive compounds (BC). In this review are summarized recent results regarding applications of nanostructured suitable materials containing essential oils for food safety.

An In Vitro Study of Antibacterial Properties of Electrospun Hypericum perforatum Oil-Loaded Poly(lactic Acid) Nonwovens for Potential Biomedical Applications

The growth of population and increase in diseases that cause an enormous demand for biomedical material consumption is a pointer to the pressing need to develop new sustainable biomaterials. Electrospun materials derived from green polymers have gained popularity in recent years for biomedical applications such as tissue engineering, wound dressings, and drug delivery. Among the various bioengineering materials used in the synthesis of a biodegradable polymer, poly(lactic acid) (PLA) has received the most attention from researchers. Hypericum perforatum oil (HPO) has antimicrobial activity against a variety of bacteria. This study aimed to investigate the development of an antibacterial sustainable material based on PLA by incorporating HPO via a simple, low-cost electrospinning method. Chemical, morphological, thermal, thickness and, air permeability properties, and in vitro antibacterial activity of the electrospun nonwoven fabric were investigated. Scanning electron microscopy (SEM) was used to examine the morphology of the electrospun nonwoven fabric, which had bead-free morphology ultrafine fibers. Antibacterial tests revealed that the Hypericum perforatum oil-loaded poly(lactic acid) nonwoven fabrics obtained had high antibacterial efficiency against Escherichia coli and Staphylococcus aureus, indicating a strong potential for use in biomedical applications.

Poly(lactic Acid): A Versatile Biobased Polymer for the Future with Multifunctional Properties-From Monomer Synthesis, Polymerization Techniques and Molecular Weight Increase to PLA Applications

Environmental problems, such as global warming and plastic pollution have forced researchers to investigate alternatives for conventional plastics. Poly(lactic acid) (PLA), one of the well-known eco-friendly biodegradables and biobased polyesters, has been studied extensively and is considered to be a promising substitute to petroleum-based polymers. This review gives an inclusive overview of the current research of lactic acid and lactide dimer techniques along with the production of PLA from its monomers. Melt polycondensation as well as ring opening polymerization techniques are discussed, and the effect of various catalysts and polymerization conditions is thoroughly presented. Reaction mechanisms are also reviewed. However, due to the competitive decomposition reactions, in the most cases low or medium molecular weight (MW) of PLA, not exceeding 20,000-50,000 g/mol, are prepared. For this reason, additional procedures such as solid state polycondensation (SSP) and chain extension (CE) reaching MW ranging from 80,000 up to 250,000 g/mol are extensively investigated here. Lastly, numerous practical applications of PLA in various fields of industry, technical challenges and limitations of PLA use as well as its future perspectives are also reported in this review.

Electrospun nanofibers food packaging: trends and applications in food systems

Food safety is a bottleneck problem. In order to provide information about advanced and unique food packaging technique, this study summarized the advancements of electrospinning technique. Food packaging is a multidisciplinary area involving food science, food engineering, food chemistry, and food microbiology, and the interest in maintaining the freshness and quality of foods has grown considerably. For this purpose, electrospinning technology has gained much attention due to its unique functions and superior processing. Sudden advancements of electrospinning have been rapidly incorporated into research. This review summarized some latest information about food packaging and different materials used for the packaging of various foods such as fruits, vegetables, meat, and processed items. Also, the use of electrospinning and materials used for the formation of nanofibers are discussed in detail. However, in food industry, the application of electrospun nanofibers is still in its infancy. In this study, different parameters, structures of nanofibers, features and fundamental properties are described briefly, while polymers fabricated through electrospinning with advances in food packaging films are described in detail. Moreover, this comprehensive review focuses on the polymers used for the electrospinning of nanofibers as packaging films and their applications for variety of foods. This will be a valuable source of information for researchers studying various polymers for electrospinning for application in the food packaging industry.

Recent advances in functionalized nanomaterials for the diagnosis and treatment of bacterial infections

The growing problem of resistant infections due to antibiotic misuse is a worldwide concern that poses a grave threat to healthcare systems. Thus, it is necessary to discover new strategies to combat infectious diseases. In this review, we provide a selective overview of recent advances in the use of nanocomposites as alternatives to antibiotics in antimicrobial treatments. Metals and metal oxide nanoparticles (NPs) have been associated with inorganic and organic supports to improve their antibacterial activity and stability as well as other properties. For successful antibiotic treatment, it is critical to achieve a high drug concentration at the infection site. In recent years, the development of stimuli-responsive systems has allowed the vectorization of antibiotics to the site of infection. These nanomaterials can be triggered by various mechanisms (such as changes in pH, light, magnetic fields, and the presence of bacterial enzymes); additionally, they can improve antibacterial efficacy and reduce side effects and microbial resistance. To this end, various types of modified polymers, lipids, and inorganic components (such as metals, silica, and graphene) have been developed. Applications of these nanocomposites in diverse fields ranging from food packaging, environment, and biomedical antimicrobial treatments to diagnosis and theranosis are discussed.