Development of pullulan/carboxylated cellulose nanocrystal/tea polyphenol bionanocomposite films for active food packaging

Effects of starch filling on physicochemical properties, functional activities, and release characteristics of PBAT-based biodegradable active films loaded with tea polyphenols

In this work, the modification of poly(butylene adipate-co-terephthalate) (PBAT) was combined with the development of active packaging films. PBAT, starch, plasticizer, and tea polyphenols (TP) were compounded and extrusion-blown into thermoplastic starch (TPS)/PBAT-TP active films. Effects of TPS contents on physicochemical properties, functional activities, biodegradability, and release kinetics of PBAT-based active films were explored. Starch interacted strongly with TP through hydrogen bonding and induced the formation of heterogeneous structures in the films. With the increase in TPS contents, surface hydrophilicity and water vapor permeability of the films increased, while mechanical properties decreased. Blending starch with PBAT greatly accelerated degradation behavior of the films, and the T30P70-TP film achieved complete degradation after 180 days. As TPS contents increased, swelling degree of the films increased and TP release were improved accordingly, resulting in significantly enhanced antioxidant and antimicrobial activities. This work demonstrated that filling starch into PBAT-based active films could achieve different antioxidant and antimicrobial activities of the films by regulating film swelling and release behavior.

Effect of plasticizers on the rheological properties of xanthan gum - starch biodegradable films

The effect of plasticizers, namely glycerol, sorbitol, and citric acid, on the structural and mechanical properties of biodegradable films obtained from xanthan gum (XG) and starch was studied. The plasticizing effect of glycerol, sorbitol, and citric acid on XG-starch films is justified by the destruction of intermolecular contacts between starch and XG macromolecules and the redistribution of hydrogen bonds in the system as a result of the hydrotropic action of plasticizer molecules. The use of glycerol proved to be the most effective for regulating the deformation of films, while the use of sorbitol to preserve strength. The dependence of the film roughness on the type and concentration of plasticizers was characterized. The smallest values of protrusions on the surface of XG-starch films were found in the presence of sorbitol. Considering the effect of the concentration of plasticizers on the stickiness of the surface of XG-starch films and their structural and mechanical properties, 1.5 % concentration of glycerol, sorbitol and citric acid was determined as optimal.

Development of CO2-sensitive antimicrobial bilayer films based on gellan gum and sodium alginate/sodium carboxymethyl cellulose and its application in strawberries

To effectively extend the shelf life of fruits meanwhile facilitating consumers to judge their freshness, in this work, a double-layer multifunctional film combining CO2 sensitivity and antibacterial properties was successfully prepared by adding methyl red (MR), bromothymol blue (BTB) into gellan gum (GG) as the sensing inner layer, and doping tannic acid (TA) into sodium alginate with sodium carboxymethyl cellulose (CMC) as the antimicrobial outer layer, which was applied to the freshness indication of strawberries. Microscopic morphology and spectral analysis demonstrated that the bi-layer films were fabricated successfully. The mechanical characteristics, thermal stability, water vapor resistance, and antibacterial capabilities of the bilayer films improved as TA concentration rose. They exhibited noticeable color changes at pH = 2-10 and different concentrations of CO2. Application of the prepared films to strawberries revealed that the GG-MB@SC-6%TA film performed most favorably under 4 °C storage conditions, not only monitoring strawberry freshness but also retaining high soluble solids and titratable acidity, resulting in a slight decrease in hardness and weight loss. Therefore, taking into account all of the physical-functional characteristics, the GG-MB@6%TA film has a broad application prospect for intelligent food packaging.

Exploring the potential of pullulan-based films and coatings for effective food preservation: A comprehensive analysis of properties, activation strategies and applications

Pullulan is naturally occurring polysaccharide exhibited potential applications for food preservation has gained increasing attention over the last half-century. Recent studies focused on efficient preservation and targeted inhibition using active composite ingredients and advanced technologies. This has led to the emergence of pullulan-based biofilm preservation. This review extensively studied the characteristics of pullulan-based films and coatings, including their mechanical strength, water vapor permeability, thermal stability, and potential as a microbial agent. Furthermore, the distinct characteristics of pullulan, production methods, and activation strategies, such as pullulan derivatization, various compounded ingredients (plant extracts, microorganisms, and animal additives), and other technologies (e.g., ultrasound), are thoroughly studied for the functional property enhancement of pullulan-based films and coatings, ensuring optimal preservation conditions for diverse food products. Additionally, we explore hypotheses that further illuminate pullulan's potential as an eco-friendly bioactive material for food packaging applications. In addition, this review evaluates various methods to improve the efficiency of the film-forming mechanism, such as improving the direct coating process, bioactive packaging films, and implementing layer-by-layer coatings. Finally, current analyses put forward suggestions for future advancement in pullulan-based bioactive films, with the aim of expanding their range of potential applications.

Intelligent active films of sodium alginate and konjac glucomannan mixed by Lycium ruthenicum anthocyanins and tea polyphenols for milk preservation and freshness monitoring

To achieve real-time monitoring of food freshness, a pH-responsive film based on sodium alginate-konjac glucomannan loaded with Lycium ruthenicum anthocyanins (LRA) was prepared, with the addition of tea polyphenols (TP) to enhance the stability of LRA. The surface structure of the films was observed by AFM. The results of FTIR and molecular docking simulation showed that LRA and TP were bound to polysaccharide by hydrogen bonds. The mechanical properties, barrier properties, and antioxidant/antibacterial properties of the films were significantly improved and the films showed obvious color response to pH. Notably, the AFM images showed TP and LRA could lead to more severe damage to the bacterial structure. The results of molecular docking simulation suggested that TP and LRA could act on different components of the bacterial cell wall, indicating their synergistic mechanism in antimicrobial activity. Moreover, the stability of LRA was improved due to the interactions of TP and polysaccharides with LRA. The aggregates formed by TP and LRA were clearly observed by AFM. Finally, the film showed excellent preservation and freshness monitoring effect in milk. In conclusion, TP-LRA-SA-KGM intelligent film exhibited excellent performance and represented a promising novel food packaging material with potential applications.

Construction of protein-, polysaccharide- and polyphenol-based conjugates as delivery systems

Natural polymers, such as polysaccharides and proteins, have been used to prepare several delivery systems owing to their abundance, bioactivity, and biodegradability. They are usually modified or combined with small molecules to form the delivery systems needed to meet different needs in food systems. This paper reviews the interactions of proteins, polysaccharides, and polyphenols in the bulk phase and discusses the design strategies, coupling techniques, and their applications as conjugates in emulsion delivery systems, including traditional, Pickering, multilayer, and high internal-phase emulsions. Furthermore, it explores the prospects of the application of conjugates in food preservation, food development, and nanocarrier development. Currently, there are seven methods for composite delivery systems including the Maillard reaction, carbodiimide cross-linking, alkali treatment, enzymatic cross-linking, free radical induction, genipin cross-linking, and Schiff base chemical cross-linking to prepare binary and ternary conjugates of proteins, polysaccharides, and polyphenols. To design an effective target complex and its delivery system, it is helpful to understand the physicochemical properties of these biomolecules and their interactions in the bulk phase. This review summarizes the knowledge on the interaction of biological complexes in the bulk phase, preparation methods, and the preparation of stable emulsion delivery system.

Fabrication, performance, and potential environmental impacts of polysaccharide-based food packaging materials incorporated with phytochemicals: A review

Although food packaging preserves food's quality, it unfortunately contributes to global climate change since the considerable carbon emissions associated with its entire life cycle. Polysaccharide-based packaging materials (PPMs) are promising options to preserve foods, potentially helping the food industry reduce its carbon footprint. PPMs incorporated with phytochemicals hold promise to address this critical issue, keep food fresh and prolong the shelf life. However, phytochemicals' health benefits are impacted by their distinct chemical structures thus the phytochemicals-incorporated PPMs generally exhibit differential performances. PPMs must be thoughtfully formulated to possess adequate physicochemical properties to meet commercial standards. Given this, this review first-time provides a comprehensive review of recent advances in the fabrication of phytochemicals incorporated PPMs. The application performances of phytochemicals-incorporated PPMs for preserving foods, as well as the intelligent monitoring of food quality, are thoroughly introduced. The possible associated environmental impacts and scalability challenges for the commercial application of these PPMs are also methodically assessed. This review seeks to provide comprehensive insights into exploring new avenues to achieve a greener and safer food industry via innovative food packaging materials. This is paramount to preserve not only food shelf life but also the environment, facilitating the eco-friendly development of the food industry.

Light calcium carbonate improves pullulan biosynthesis by Aureobasidium pullulans under high concentration of sugar

The effects of light calcium carbonate (CaCO₃) on pullulan biosynthesis by Aureobasidium pullulans NCPS2016 were investigated. Light CaCO₃ enhanced pullulan production by 12.4 % when added to the low concentration of fructose broth compared with K₂HPO₄. Pullulan production was further improved when increasing both the concentrations of light CaCO₃ and fructose. Compared to K₂HPO₄, light CaCO₃ improved the activities of UDP-glucose pyrophosphorylase, α-phosphoglucose mutase, UDP-glucosyltransferase, and glucosyltransferase relevant to pullulan biosynthesis, and the gene transcriptional levels of UDP-glucose pyrophosphorylase, α-phosphoglucose mutase, UDP-glucosyltransferase, and glucose kinase were enhanced. During 30-liter fermentation, 144.3 g/L of purified pullulan was produced from 200 g/L of fructose and 15 g/L of light CaCO₃ within 168 h, with the yield and productivity of 0.72 g/g and 0.86 g/L/h respectively. This is the first report that light CaCO₃ improves pullulan production significantly.

Nanotechnology in Food and Plant Science: Challenges and Future Prospects

Globally, food safety and security are receiving a lot of attention to ensure a steady supply of nutrient-rich and safe food. Nanotechnology is used in a wide range of technical processes, including the development of new materials and the enhancement of food safety and security. Nanomaterials are used to improve the protective effects of food and help detect microbial contamination, hazardous chemicals, and pesticides. Nanosensors are used to detect pathogens and allergens in food. Food processing is enhanced further by nanocapsulation, which allows for the delivery of bioactive compounds, increases food bioavailability, and extends food shelf life. Various forms of nanomaterials have been developed to improve food safety and enhance agricultural productivity, including nanometals, nanorods, nanofilms, nanotubes, nanofibers, nanolayers, and nanosheets. Such materials are used for developing nanofertilizers, nanopesticides, and nanomaterials to induce plant growth, genome modification, and transgene expression in plants. Nanomaterials have antimicrobial properties, promote plants' innate immunity, and act as delivery agents for active ingredients. Nanocomposites offer good acid-resistance capabilities, effective recyclability, significant thermostability, and enhanced storage stability. Nanomaterials have been extensively used for the targeted delivery and release of genes and proteins into plant cells. In this review article, we discuss the role of nanotechnology in food safety and security. Furthermore, we include a partial literature survey on the use of nanotechnology in food packaging, food safety, food preservation using smart nanocarriers, the detection of food-borne pathogens and allergens using nanosensors, and crop growth and yield improvement; however, extensive research on nanotechnology is warranted.

Composite films of sodium alginate and konjac glucomannan incorporated with tea polyphenols for food preservation

At present, food waste has become a serious issue and the use of petroleum-based food packaging films has resulted in a series of potential hazards. Therefore, more attention has been focused on the development of new food packaging materials. The polysaccharide-based composite film loaded with active substances considered to be an excellent preservative material. A novel packaging film based on sodium alginate and konjac glucomannan (SA-KGM) blended with tea polyphenols (TP) was prepared in the present study. The excellent microstructure of films was shown by atomic force microscopy (AFM). It was indicated by FTIR spectra that the components could interact with each other through hydrogen bonds, which was also confirmed by molecular docking simulation. Meanwhile, the mechanical properties, barrier property, oxidation property, antibacterial activity, and stability of the structure of the TP-SA-KGM film were significantly improved. The AFM images and results of molecular docking simulation indicated that TP could affect the cell wall of bacteria by acting with peptidoglycan. Finally, the film showed excellent preservation effects in both beef and apples, which suggested that TP-SA-KGM film could be a novel bioactive packaging material with wide application potential in food preservation.

Biopolymer-Based Sustainable Food Packaging Materials: Challenges, Solutions, and Applications

Biopolymer-based packaging materials have become of greater interest to the world due to their biodegradability, renewability, and biocompatibility. In recent years, numerous biopolymers-such as starch, chitosan, carrageenan, polylactic acid, etc.-have been investigated for their potential application in food packaging. Reinforcement agents such as nanofillers and active agents improve the properties of the biopolymers, making them suitable for active and intelligent packaging. Some of the packaging materials, e.g., cellulose, starch, polylactic acid, and polybutylene adipate terephthalate, are currently used in the packaging industry. The trend of using biopolymers in the packaging industry has increased immensely; therefore, many legislations have been approved by various organizations. This review article describes various challenges and possible solutions associated with food packaging materials. It covers a wide range of biopolymers used in food packaging and the limitations of using them in their pure form. Finally, a SWOT analysis is presented for biopolymers, and the future trends are discussed. Biopolymers are eco-friendly, biodegradable, nontoxic, renewable, and biocompatible alternatives to synthetic packaging materials. Research shows that biopolymer-based packaging materials are of great essence in combined form, and further studies are needed for them to be used as an alternative packaging material.

Hydrophobic, Sustainable, High-Barrier Regenerated Cellulose Film via a Simple One-Step Silylation Reaction

With the increasing importance of environmental protection, high-performance biopolymer films have received considerable attention as effective alternatives to petroleum-based polymer films. In this study, we developed hydrophobic regenerated cellulose (RC) films with good barrier properties through a simple gas-solid reaction via the chemical vapor deposition of alkyltrichlorosilane. RC films were employed to construct a biodegradable, free-standing substrate matrix, and methyltrichlorosilane (MTS) was used as a hydrophobic coating material to control the wettability and improve the barrier properties of the final films. MTS readily coupled with hydroxyl groups on the RC surface through a condensation reaction. We demonstrated that the MTS-modified RC (MTS/RC) films were optically transparent, mechanically strong, and hydrophobic. In particular, the obtained MTS/RC films exhibited a low oxygen transmission rate of 3 cm³/m² per day and a low water vapor transmission rate of 41 g/m² per day, which are superior to those of other hydrophobic biopolymer films.

Preparation and characterization of carboxymethyl chitosan/pullulan composite film incorporated with eugenol and its application in the preservation of chilled meat

To solve the problem of easy spoilage of chilled meat during storage, we fabricated a novel composite film using carboxymethyl chitosan (CMCS)/pullulan (Pul)/eugenol (E) by casting method. The results showed that the mechanical properties of the films were better when the CMCS/Pul ratio was 2.5/2.5. The Fourier transform infrared spectroscopy (FTIR) results showed that intermolecular hydrogen bonds were formed among E, CMCS, and Pul, which was consistent with the rheological test results. Scanning electron microscopic (SEM) images showed that eugenol was well dispersed in the CMCS/Pul matrix. The addition of eugenol significantly increased the antibacterial properties and antioxidant properties. Moreover, when 5% eugenol was added, the water vapor permeability (WVP) of the film reduced to 2.41 × 10^-11 g/m·s·Pa. Finally, the freshness of the chilled meat wrapped with the eugenol-containing composite film was prolonged, thereby offering a potential alternative to synthetic materials.

Development of chitosan/rice protein hydrolysates/ZnO nanoparticles films reinforced with cellulose nanocrystals

In the present work, the composite films were obtained by the solution casting method from chitosan and rice protein hydrolysates, reinforced with cellulose nanocrystals (CNC) of different contents (0 %, 3 %, 6 % and 9 %). The influence of different CNC loadings on the mechanical, barrier and thermal properties was discussed. SEM showed the formation of intramolecular interactions between the CNC and film matrices, leading to more compact and homogeneous films. These interactions had a positive influence on the mechanical strength properties, which was reflected in higher breaking force of 4.27 MPa. The elongation dwindled from 132.42 % to 79.37 % with increasing CNC levels. The linkages formed between the CNC and film matrices reduced the water affinity, leading to a reduction in their moisture content, water solubility and water vapor transmission. Thermal stability of the composite films was also improved in the presence of CNC, by increasing maximum degradation temperature from 311.21 to 325.67 °C with increasing CNC contents. The strongest DPPH inhibition of the film was 45.42 %. The composite films exhibited the highest inhibition zone diameter against E. coli (12.05 mm) and S. aureus (12.48 mm), and the hybrid of CNC and ZnO nanoparticles exhibited stronger antibacterial activity than their single existent forms. The present work shows the possibility of obtaining CNC-reinforced films with improved mechanical, thermal and barrier properties.

Extrusion-blown starch/PBAT biodegradable active films incorporated with high retentions of tea polyphenols and the release kinetics into food simulants

To reduce thermal degradation of tea polyphenols (TP) in final active packaging materials, poly(butylene adipate-co-terephthalate) (PBAT), starch, plasticizer, and TP were directly synthesized into masterbatches by one-pot method in this study without pre-dispersion, and then blown into active films. TP interacted with starch through hydrogen bonds, with little interaction with PBAT. Barrier properties were improved by incorporating TP into the films, whereas mechanical properties slightly decreased. Blending starch into PBAT greatly accelerated the degradation of the film. And the incorporation of TP slowed down the short-term degradation of the starch/PBAT film, but accelerated the long-term degradation. The initial total polyphenol content in the active film was positively related to the TP loading, whereas the initial retention rate remained above 95 % regardless of TP loadings. The retention rate of TP in active films decreased with storage time, but it was still above 80 % after 12 months, with a favorable stability. TP-loaded films displayed efficient antioxidant and antimicrobial activities with strong dose dependence. The release of TP into food simulants was mainly induced by random diffusion, with little effect from polymer swelling. The short-term release kinetics was well described by Fick's second law. This work has demonstrated the feasibility of TP being incorporated into the active films with high retention through high-throughput fabrication, which provides formula and technical options for the industrial development of active packaging materials.

Locust bean gum/carboxycellulose nanocrystal coating incorporating ZnO clusters built by the accretion of micro spindles or sheets for strawberries preservation

Two shapes of ZnO clusters constructed by the growth of spindle-like (I-ZnO) and sheet-like (II-ZnO) microparticles added to Locust bean gum/carboxycellulose nanocrystal (LBG/C-CNC) coating for improving properties as the enhancers and antibacterial agents. Subsequently, active LBG/C-CNC/ZnO (LCZ) coatings were evaluated to combat the fruits rot triggered by microorganisms aiming to extend their shelf life. The results showed that II-ZnO clusters with flower-shape enhanced the properties more obviously due to more interaction sites. The oxygen and water vapor permeability of the coating containing 5 % II-ZnO (LCZII-5) decreased from 2.00 and 5.98 × 10^-11 to 0.6 cm³ mm m^-2 day^-1 atm^-1 and 1.85 × 10^-11 g m^-1 s^-1 Pa^-1, respectively. And the antibacterial rate against E. coli and S. aureus could reach more than 75 %. Meanwhile, the tensile strength (TS) increased by 50.95 %. The inhibition rates on strawberries of weight and Vc loss by LCZII-5 coating were 30.64 % and 53.59 %, respectively. More importantly, the coatings could be easily washed off with water in spite of tightly being connected with the surface of the strawberries. As was expected, this study provides a feasible method for preparing novel fruit coatings with an effective preservation.

An Active Bio-Based Food Packaging Material of ZnO@Plant Polyphenols/Cellulose/Polyvinyl Alcohol: DESIGN, Characterization and Application

Active packaging materials protect food from deterioration and extend its shelf life. In the quest to design intriguing packaging materials, biocomposite ZnO/plant polyphenols/cellulose/polyvinyl alcohol (ZnPCP) was prepared via simple hydrothermal and casting methods. The structure and morphology of the composite were fully analyzed using XRD, FTIR, SEM and XPS. The ZnO particles, plant polyphenols (PPL) and cellulose were found to be dispersed in PVA. All of these components share their unique functions with the composite's properties. This study shows that PPL in the composite not only improves the ZnO dispersivity in PVA as a crosslinker, but also enhances the water barrier of PVA. The ZnO, PPL and cellulose work together, enabling the biocomposite to perform as a good food packaging material with only a 1% dosage of the three components in PVA. The light shielding investigation showed that ZnPCP-10 can block almost 100% of both UV and visible light. The antibacterial activities were evaluated by Gram-negative Escherichia coli (E. coli) and Gram-positive staphylococcus aureus (S. aureus), with 4.4 and 6.3 mm inhibition zones, respectively, being achieved by ZnPCP-10. The enhanced performance and easy degradation enables the biocomposite ZnPCP to be a prospect material in the packaging industry.

Ultrasound-assisted development and characterization of novel polyphenol-loaded pullulan/trehalose composite films for fruit preservation

A novel food packaging film was developed by incorporating a tea polyphenols-loaded pullulan/trehalose (TP@Pul/Tre) into a composite film with ultrasound-assisted treatment of dual-frequency (20/35 kHz, 40 W/L) for 15 min to assess the physicochemical and mechanical properties of a composite film. The optimized ultrasound-assisted significantly increases elongation at break, tensile strength, and improves the composite film's UV/water/oxygen barrier properties. Structure analysis using attenuated total reflectance-Fourier transform infrared, X-ray diffraction and thermal stability revealed that these improvements were achieved through ultrasound-enhanced H-bonds, more ordered molecular arrangements, and good intermolecular compatibility. Besides, the ultrasound-assisted TP@Pul/Tre film has proven to have good antibacterial performance against Escherichia coli and Staphylococcus aureus, with approximately 100 % lethality at 4 h and 8 h, respectively. Moreover, the ultrasound-assisted TP@Pul/Tre film effectively delayed moisture loss, oxidative browning, decay, and deterioration in fresh-cut apples and pears, thereby extending their shelf life. Thus, ultrasound has proved to be an effective tool for improving the quality of food packaging films, with a wide range of applications.

Bioactive Edible Sodium Alginate Films Incorporated with Tannic Acid as Antimicrobial and Antioxidative Food Packaging

Currently, biodegradable and functional food packaging materials have attracted more and more attention due to their potential advantages. Biopolymers are one of the promising materials used to produce biodegradable food packaging films, and sodium alginate (SA) is one of the most used polysaccharides. In this work, we explored a novel edible sodium alginate (SA)/tannic acid (TA) film as biodegradable active food packaging material. The impact of TA concentration on the UV light blocking ability, transparency, water vapor barrier ability, mechanical strength, antioxidant, and antimicrobial activity of the SA-TA films was comprehensively investigated. Fourier transform infrared spectroscopy results revealed that strong hydrogen bonding was the main intermolecular interaction between SA and TA. As TA concentration in the films increased, the water vapor permeability (WVP) decreased from 1.24 × 10^-6 to 0.54 × 10^-6 g/m/h/Pa, the DPPH radical scavenging activity increased from 0.008% to 89.02%. Moreover, the incorporation of TA effectively blocked UV light and elevated antimicrobial activity against Escherichia coli. Overall, the SA films with TA exhibited better water vapor barrier ability, remarkable UV-light barrier ability and antioxidant activity while showing a slight decrease in light transmittance. These results indicated the potential application of TA as a functional additive agent for developing multifunctional food packaging materials.

Recent Advances in Prodigiosin as a Bioactive Compound in Nanocomposite Applications

Bionanocomposites based on natural bioactive entities have gained importance due to their abundance; renewable and environmentally benign nature; and outstanding properties with applied perspective. Additionally, their formulation with biological molecules with antimicrobial, antioxidant, and anticancer activities has been produced nowadays. The present review details the state of the art and the importance of this pyrrolic compound produced by microorganisms, with interest towards Serratia marcescens, including production strategies at a laboratory level and scale-up to bioreactors. Promising results of its biological activity have been reported to date, and the advances and applications in bionanocomposites are the most recent strategy to potentiate and to obtain new carriers for the transport and controlled release of prodigiosin. Prodigiosin, a bioactive secondary metabolite, produced by Serratia marcescens, is an effective proapoptotic agent against bacterial and fungal strains as well as cancer cell lines. Furthermore, this molecule presents antioxidant activity, which makes it ideal for treating wounds and promoting the general improvement of the immune system. Likewise, some of the characteristics of prodigiosin, such as hydrophobicity, limit its use for medical and biotechnological applications; however, this can be overcome by using it as a component of a bionanocomposite. This review focuses on the chemistry and the structure of the bionanocomposites currently developed using biorenewable resources. Moreover, the work illuminates recent developments in pyrrole-based bionanocomposites, with special insight to its application in the medical area.

Characterization and Antifungal Activity of Pullulan Edible Films Enriched with Propolis Extract for Active Packaging

Active pullulan films with the addition of 3, 5 or 10% propolis extract produced by the casting method were tested in the study. Propolis extracts from Bochnia County, Siedlce County and Ełk County (Poland) were used. The appearance of the films was characterized, as well as physical parameters (thickness, moisture content, water solubility), tensile strength (TS), elongation at break (EB), optical characteristics (light transparency, UV barrier, color) and antifungal properties. The antifungal activity of the films was tested by the disc diffusion method against yeast (Candida albicans, C. krusei, Saccharomyces cerevisiae, Rhodotorula mucilaginosa) and mold (Alternaria solani, Fusarium solani, Rhizopus stolonifer, Colletotrichum gloeosporioides, C. cladosporioides, Aspergillus niger, A. ochraceus, Mucor mucedo, Penicillium expansum, P. chrysogenum). The origin of propolis influenced the color and water solubility of the films. The addition of increasing concentrations of propolis extract increased the film thickness and the intensity of the yellow color, extended the water dissolution time of the film and reduced the values of TS and EB. The addition of propolis extract in the pullulan film improved UV radiation protection but decreased light transparency. The antifungal activity increased significantly with the increasing concentration of propolis extract in the film, regardless of the origin of propolis. Molds showed greater sensitivity to pullulan films containing propolis extract than yeasts. In general, films made of pullulan with the addition of propolis extract can be considered as natural active packaging to protect against the growth of fungi in food.

Fabrication and characterization of pullulan-based composite films incorporated with bacterial cellulose and ferulic acid

Pullulan-based composite films incorporated with bacterial cellulose (BC) and ferulic acid (FA) were prepared by solution casting method. The rheological, morphological, barrier, optical, anti-fogging, and antioxidant properties of pullulan-based composite films doped with BC and FA were investigated. The rheological results showed that all film-forming solution was pseudoplastic fluid and its viscosity increased with the increase of BC content. An appropriate BC (2 %) and FA were uniformly dispersed in pullulan to form uniform and dense composite films. With the increase of BC content, the roughness and opacity of composite films increased while their UV-vis barrier performance was improved by incorporating BC and FA. Fourier transform infrared spectrometer analysis demonstrated that hydrogen bond interactions among pullulan, BC, and FA were found, and incorporating BC could increase the crystallinity of the composite films, thus enhancing their mechanical, barrier, hydrophobic, and thermal stability properties. Pullulan-based composite films incorporated with 2 % BC and FA (P-BC2-FA) showed better mechanical properties, water, oxygen, and carbon dioxide barrier performances, and its water contact angle value also increased compared with control, respectively. P-BC2-FA film showed superior anti-fogging and antioxidant activities. These results indicate that the P-BC2-FA film are expected to be a potential target of bioactive packaging.

Levan-chitosan blend films: Preparation, structural, physical properties and application in pork packaging

Conventional fossil fuel-based packaging materials often brings of food safety and serious environmental pollution. It is significant to develop an environmentally-friendly packaging material. In this work, a levan-chitosan (LE/CS) blend film was fabricated via the solution casting method. The films were evaluated by Fourier transform infrared spectroscopy and X-ray diffraction, indicating the formation of hydrogen bonds between chitosan and levan. The mechanical properties of LE/CS films demonstrated a mechanical strength higher than CS films, and the best tensile strength appeared at a ratio of LE/CS (1:1) up to 18.78 ± 0.73 MPa. The addition of levan caused a significant increase in absorption of UV light with a reduction in swelling water of the blend films from 29.13 ± 0.53 % of chitosan film to 2.07 ± 0.27 % of LE/CS (1:1) film. A higher contact angle and lower WVP were observed for LE/CS blend films. LE/CS blend films were then used as packaging material for fresh pork and were well maintained the qualities. The study suggested that the new blend film might have a good prospect as a food packaging material.

Antimicrobial Nanomaterials for Food Packaging

Food packaging plays a key role in offering safe and quality food products to consumers by providing protection and extending shelf life. Food packaging is a multifaceted field based on food science and engineering, microbiology, and chemistry, all of which have contributed significantly to maintaining physicochemical attributes such as color, flavor, moisture content, and texture of foods and their raw materials, in addition to ensuring freedom from oxidation and microbial deterioration. Antimicrobial food packaging systems, in addition to their function as conventional food packaging, are designed to arrest microbial growth on food surfaces, thereby enhancing food stability and quality. Nanomaterials with unique physiochemical and antibacterial properties are widely explored in food packaging as preservatives and antimicrobials, to extend the shelf life of packed food products. Various nanomaterials that are used in food packaging include nanocomposites composing nanoparticles such as silver, copper, gold, titanium dioxide, magnesium oxide, zinc oxide, mesoporous silica and graphene-based inorganic nanoparticles; gelatin; alginate; cellulose; chitosan-based polymeric nanoparticles; lipid nanoparticles; nanoemulsion; nanoliposomes; nanosponges; and nanofibers. Antimicrobial nanomaterial-based packaging systems are fabricated to exhibit greater efficiency against microbial contaminants. Recently, smart food packaging systems indicating the presence of spoilage and pathogenic microorganisms have been investigated by various research groups. The present review summarizes recent updates on various nanomaterials used in the field of food packaging technology, with potential applications as antimicrobial, antioxidant equipped with technology conferring smart functions and mechanisms in food packaging.

Preparation of flexible and UV-blocking films from lignin-containing cellulose incorporated with tea polyphenol/citric acid

Lignin-containing bamboo cellulose, fractionated from a pilot-scale microwave liquefaction of bamboo was dissolved in tetrabutylammonium acetate/dimethyl sulfoxide (TBAA/DMSO) for the fabrication of highly flexible, transparent and UV-blocking films. Tea polyphenol (TP) or citric acid (CA) was added during the dissolving process in order to modify the film's properties. The results showed that the addition of TP obviously improved the elongation at break (triple that of the control) and UV-blocking ability of the films. Both the addition of TP and CA could increase the water contact angle of the films. The films incorporated with TP and CA were much more thermal stable than previously reported similar films. The proposed film fabrication mechanism revealed that stable hydrogen bonds formed between the lignin-cellulose matrix and TP/CA, resulting in the enhancement on the properties of the films. This present study showed that lignin-containing cellulose with the incorporation of TP/CA had great potential in the preparation of films in place of plastic.

Preparation and Characterization of New Electrospun Poly(lactic acid) Nanofiber Antioxidative Active Packaging Films Containing MCM-41 Mesoporous Molecular Sieve Loaded with Phloridzin and Their Application in Strawberry Packaging

Health concerns about food safety have increased in recent years. In order to ensure the safety and increase the shelf-life of food, many methods have been used to slow down the oxidation rate of food fat. In order to solve this problem, a new type of antioxidant-active packaging has emerged. Poly(lactic acid) (PLA) films containing phloridzin adsorbed on to an MCM-41 mesoporous molecular sieve were prepared by electrostatic spinning, using PLA as a film-forming substrate, phloridzin as an antioxidant, and MCM-41 as the adsorption and controlled release carrier. The physical properties of the new films—including microscopic structure, water vapor transmission rate, and fresh-keeping effects, as well as the mechanical, thermal, antioxidant, and antibacterial properties—were studied. When the mass ratio of MCM-41 to phloridzin is 1:2, the nanofiber membrane achieves a 53.61% free-radical scavenging rate and better antibacterial performance (85.22%) due to the high content of phloridzin (30.54%). Additionally, when the mass ratio of the molecular sieve to phloridzin is 1:2 and 3:4 (with the best antibacterial performance of 89.30%), the films significantly delay lipid oxidation in the strawberry packaging, allowing the fresh-keeping time to be extended to up to 21 days before mildew appears. In this study, an MCM-41 mesoporous molecular sieve was used to load phloridzin for the first time. The packaging film with phloridzin, MCM-41, and poly(lactic acid) were used as the raw materials and electrospinning technology was used to prepare the packaging film with antioxidant activity. The packaging film was used for the first time in the packaging of strawberries.

Combining carvacrol and nisin in biodegradable films for antibacterial packaging applications

In this work, the feasibility of antibacterial biopolymeric films containing carvacrol (CRV) and a nisin commercial formulation (Nis) for potential food packaging applications was investigated. As polymer matrix, a commercial biodegradable polymer formulation of Mater-Bi (MB) was chosen due to its significant food packaging applications. CRV and Nis were chosen due to their well-established antibacterial properties and their potential synergistic effect. MB/CRV, MB/Nis, and MB/CRV/Nis systems were produced by melt mixing and compression molding. The mechanical properties of the films were evaluated by tensile tests. Differential scanning calorimetry was assessed aiming at investigating the effect of the two compounds and their mixture on the thermal properties of MB. The release profile of CRV and Nis from the MB-based films was evaluated in water at 4 °C by UV-Vis measurements and it was fitted with a power-law model. The antibacterial activity of MB-based films was tested in vitro against Listeria monocytogenes, Salmonella enteritidis, Escherichia coli, and Staphylococcus aureus. The combination of CRV and Nis strongly affected the properties of the MB-based films and ensured higher antibacterial activity if compared to MB/CRV and MB/Nis systems.

Evaluation of the Mechanical and Biocidal Properties of Lapacho from Tabebuia Plant as a Biocomposite Material

The aim of this article is to discuss in detail the physicochemical properties of polylactide (PLA) reinforced by cortex fibers, which may cause bacterial mortality and increased biodegradation rates. PLA biocomposites containing cortex Lapacho fibers from Tabebuia (1-10 wt%) were prepared by extrusion and injection moulding processes. The effects of Lapacho on the mechanical and biocidal properties of the biocomposites were studied using tensile and impact tests, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), thermogravimetry (TG), and the method of evaluating the antibacterial activity of antibacterial treated according to the standard ISO 22196:2011. It also presented the effects of Lapacho on the structural properties and biodegradation rates of biocomposites. This research study provides very important results complementing the current state of knowledge about the biocidal properties of Lapacho from Tabebuia plants and about cortex-reinforced biocomposites.