Active polyvinyl alcohol films with enhanced strength, antioxidant and antibacterial properties by incorporating nanocellulose and tannin

There is an increasing demand of food packaging materials from sustainable bio- polymers. In this study, tannin-cellulose nanocrystal (TCNCs) fillers were first prepared using dialdehyde cellulose nanocrystal (DACNCs) and tannin through the nucleophilic addition reaction, and then added to PVA matrix as reinforcement fillers to fabricate active food packaging films. FT-IR analysis confirmed the successful reaction between PVA and TCNCs. The incorporation of TCNCs imparted high antibacterial, UV blocking and antioxidant capabilities to the composite films, maximumly achieving a 75 % DPPH free radical scavenging rate while blocking all UV rays. The addition of TCNCs resulted in an increase in water contact angle, alongside decreases in swelling ratio and solubility, indicating the enhanced water resistance. The composite films exhibited a 66.7 % decrease in oxygen permeability (OP) compared to the PVA film, with a slight increase observed in water vapor permeability (WVP). The tensile strength increased from 49.65 MPa to 74.17 MPa by adding 15 % of TCNCs due to the chemical crosslinking between PVA and TCNCs. Wrapping cherry tomatoes with these films prolonged the postharvest life compared to using polyethylene (PE) and pure PVA films. Films derived from sustainable biopolymers show great potential for use in fresh produce packaging.

Effect of pre-acidification induction on the physicochemical features, myofibrillar protein microstructure, and headspace volatiles of ready-to-cook goose meat

This study examined the impact of pre-acidification induction on the quality attributes and flavor retention of ready-to-cook (RTC) goose meat products. The results demonstrated that pre-acidification could influence the eating qualities of RTC goose meat by effectively regulating the physicochemical properties of goose myofibrillar proteins (MP) including solubility and water-holding capacity. Elevated carbonyl contents indicated an enhanced gel-forming capacity in RTC goose meat during storage, accompanied with reduced total sulfhydryl contents from enhanced protonation pretreatment and augmented lipid oxidation. Structural characterization of MP via sodium dodecyl sulfate-polyacrylamide gel electrophoresis, circular dichroism spectroscopy, and intrinsic fluorescence revealed the formation of a dense protein matrix under highly acidic conditions. Furthermore, the headspace concentration of aldehydes increased by 3.23 times upon enhancing the pre-acidification intensity, resulting in the production of esters and acidic flavor compounds with favorable aromas. Correlation analysis demonstrated the dependence of headspace concentrations of volatile constituents on the acidification-enhanced surface hydrophobicity of MP, attributed to the modified binding sites of proteins after pre-acidification. Current results have indicated both the positive and negative influence of pre-acidulation induction on the eating quality of goose meat products, suggesting the necessity of introducing extra processes to modulate the quality of prefabricated products.

Polysaccharide-Based Composite Films: Promising Biodegradable Food Packaging Materials

With growing concerns about environmental protection and sustainable development, the development of new biodegradable food packaging materials has become a significant focus for the future of food packaging. Polysaccharides, such as cellulose, chitosan, and starch, are considered ideal biodegradable packaging materials due to their wide availability, good biocompatibility, and biodegradability. These materials have garnered extensive attention from researchers in food packaging, leading to considerable advancements in the application of polysaccharide-based food packaging films, coatings, aerogels, and other forms. Therefore, this review focuses on the application of polysaccharide-based packaging films in food storage and preservation and discusses their preparation methods, application progress, challenges, and future development directions. Through an in-depth analysis of the existing literature, this review aims to provide sustainable and environmentally friendly solutions for the food packaging industry.

Combining the Powerful Antioxidant and Antimicrobial Activities of Pomegranate Waste Extracts with Whey Protein Coating-Forming Ability for Food Preservation Strategies

Different solvents water, ethanol and ethanol/water (6:4 v/v), were compared in the extraction of pomegranate peels and seeds (PPS) in terms of recovery yields, antioxidant properties, and antimicrobial action against typical spoilage bacterial and fungal species. The best performing extract (ethanol/water (6:4 v/v) was shown to contain mostly ellagic acid and punicalagin as phenolic compounds (5% overall) and hydrolysable tannins (16% as ellagic acid equivalents) and was able to inhibit the growth of the acidophilic Alicyclobacillus acidoterrestris at a concentration as low as 1%. The preservation of the organoleptic profile of A. acidoterrestris-inoculated apple juice with extract at 1% over 20 days was also observed thanks to the complete inhibition of bacterial growth, while the extract at 0.1% warranted a significant (40%) inhibition of the enzymatic browning of apple smoothies over the first 30 min. When incorporated in whey proteins' isolate (WPI) at 5% w/w, the hydroalcoholic extract conferred well appreciable antioxidant properties to the resulting coating-forming hydrogel, comparable to those expected for the pure extract considering the amount present. The WPI coatings loaded with the hydroalcoholic extract at 5% were able to delay the browning of cut fruit by ca. 33% against a 22% inhibition observed with the sole WPI. In addition, the functionalized coating showed an inhibition of lipid peroxidation of Gouda cheese 2-fold higher with respect to that observed with WPI alone. These results open good perspectives toward sustainable food preservation strategies, highlighting the potential of PPS extract for the implementation of WPI-based active packaging.

Evaluation biodegradable films with green tea extract for interleafing sliced meat products

A selection of formulations with different polymers and concentrations of green tea extract was conducted for application as interleafs in sliced meat products. Films were formulated using cellulose acetate, corn starch, and chitosan with the addition of 1.0, 2.5, and 5.0% green tea extract. Higher antioxidant activity was observed with the 1.0% concentration of green tea extract (P < 0.05), regardless of the formulation, with continuous release of the extract for up to 60 days and average IC50 of 0.09 and 0.31 mg/mL for the corn starch and chitosan active films, respectively. Interleafing the sliced ham resulted in lower lipid oxidation after 60 days of storage (P < 0.05). Starch-based films with green tea extract were effective, significantly reducing lipid oxidation in sliced and interleafed cooked ham, suggesting their potential to extend the shelf life of these refrigerated products.

A biocompatible cellulose gum based CMC/PVA/SBA-15 film as a colloidal antibacterial agent against MRSA

The development of biocompatible antibacterial films plays a crucial role in the fight against antibiotic-resistant bacteria strains. Here, we developed an SBA-15-NH2 decorated biocompatible CMC/PVA film containing Ag NPs as an antibacterial material against Gram-positive and Gram-negative bacteria strains. The structure of the manufactured film was studied by XRD, SEM, mapping, and TGA analysis showing its formation and firm structure. The prepared film has a flexible structure which makes it suitable for a variety of bio-related applications. The CMC/PVA/SBA-15-NH2@AgNPs film was used as a bactericidal agent against pathogens (especially MRSA; methicillin-resistant Staphylococcus aureus) isolated from surgical site infections, showing promising results.

Colorimetric ammonia-sensing nanocomposite films based on starch/sodium alginate and Cu-Phe nanorods for smart packaging application

The development of colorimetric ammonia-sensing smart packaging materials with real-time freshness detection ability are crucial for ensuring food safe. This research involved the construction of Cu-based framework (Cu-Phe) nanorods with colorimetric ammonia-sensing ability through an easy-to-perform aqueous solution method, and their subsequent utilization as nano inclusions in starch/sodium alginate (ST/SA) substrate to foster the creation of high-performance smart packaging materials. Research findings revealed that the addition of Cu-Phe nanorods (3, 6, 9 wt%) within ST/SA substrate led to the formation of compatible nanocomposite films with significantly augmented physical performance and functionality. Especially, the film containing 9 wt% Cu-Phe presented the highest tensile strength (30.32 MPa), elongation at break (19.12 %), UV-shielding efficacy (blocking >99 % of UV passage), water vapor barrier effectiveness (1.90 × 10-6 g/m·h·Pa) and oxygen barrier ability (2.26 × 10-3 g/m2·s). In addition, the developed ST/SA/Cu-Phe nanocomposite film possessed excellent antibacterial activity (over 99.9 %) against Escherichia coli and Staphylococcus aureus, superior colorimetric ammonia-sensing ability, and long-term colour stability. Also of note, the Cu-Phe added ST/SA nanocomposite film allowed for detecting prawn and pork freshness reduction in real-time via discernible colour transition, suggesting its extensive promise for smart packaging applications.

Effects of guar gum/chitosan edible films functionalized with citronellal/HPβCD inclusion complex on Harbin red sausage preservation

Harbin red sausage is a traditional local pork meat product in China, but it is susceptible to microbial contamination and lipid oxidation, leading to quality deterioration. Herein, guar gum (GG)/chitosan (CS) edible films functionalized with citronellal/hydroxypropyl-β-cyclodextrin inclusion complex (CIT/HPβCD-IC) were fabricated for Harbin red sausage preservation. Results demonstrated CIT/HPβCD-IC was successfully prepared and observed by SEM due to the bathochromic shift of maximum absorption peak of CIT, and the formation of new bonds was confirmed by FTIR analysis, suggesting the embedding of CIT into HPβCD cavity. The changes of functional groups stretching vibrations suggested successful loading of CIT/HPβCD-IC into the GG/CS edible films. Furthermore, the incorporation of CIT/HPβCD-IC enhanced the microstructural, mechanical and barrier properties, and improved the antibacterial activities, biodegradability and thermal stability of the GG/CS edible films. Particularly, the GG/CS edible films incorporated with 1 % CIT/HPβCD-IC (GG/CS-IC 1 %) enhanced the storage stability of Harbin red sausage at 4 °C by decreasing the weight loss rate, maintaining the pH, color, and textural stabilities, retarding the microbial growth and lipid oxidation of the sausage samples. Findings here suggested that GG/CS-IC 1 % edible films showed great potential as novel multi-functional edible packaging materials for Harbin red sausage preservation.

Smart and Sustainable 3D-Printed Nanocellulose-Based Sensors for Food Freshness Monitoring

Annually, about one-third of the food produced around the world is wasted due to spoilage. Food contamination and spoilage, along with the use and disposal of nondegradable packaging materials, impact human health and have huge economic and sustainability implications. Achieving sustainability within the food system requires innovative solutions to reduce the environmental footprint. Herein, we describe the formulation, scalable manufacturing, and characterization of three-dimensional (3D)-printed sensors prepared from a mixture of edible biopolymer hydrogels, 8% alginate, and 10% gelatin and nanocellulose (CNC) as a reinforcement filler. We demonstrate that incorporating CNC improves the overall mechanical performance of the printed film and enables the stabilization of pH-responsive dyes for monitoring the release of total volatile basic nitrogen (TVB-N), an indicator of food freshness. Mechanical performance enhancement includes increases of 43% in load-depth indentation, 28.2% in hardness, and 17.4% in elastic modulus. This enhancement facilitates its use as a smart label technology, enabling the visual assessment of spoilage when placed inside packaging over a period of 3 days at room temperature. The 3D-printed film exhibits excellent durability, flexibility, shape memory, and robustness, along with pH responsiveness, showing distinctive color changes over the pH range of 2 to 13. These performances are demonstrated in packaged meat and fish, enabling monitoring over several days and illustrating potential as a real-time freshness indicator. The material formulations developed in this work are biodegradable, eco-friendly, and inexpensive, making them suitable candidates for smart and sustainable food packaging.

7-(Diethylamino) coumarin-3-carboxylic acid as a novel antibrowning agent: Activity and mechanism

Browning caused by polyphenol oxidase (PPO) and microorganisms significantly impacts the nutritional quality of fruits and vegetables. This study identified 7-(Diethylamino) coumarin-3-carboxylic acid (7-DCCA) as an effective inhibitor of both PPO and bacteria. Enzyme assays revealed that 7-DCCA competitively inhibits PPO activity with an IC50 value of 0.275 ± 0.002 mM. Fluorescence and molecular simulation methods demonstrated that 7-DCCA forms a complex with PPO through hydrogen bonding and hydrophobic interactions, altering the enzyme's structure and reducing its activity. Thermogravimetric and differential scanning calorimetry (DSC) assays showed that 7-DCCA stabilizes PPO, delaying its thermal decomposition. Antibacterial tests proved that 7-DCCA inhibits Staphylococcus aureus and Escherichia coli by disrupting cell membranes. Additionally, 7-DCCA suppressed PPO and peroxidase activities, delaying phenolic oxidation and preventing browning in fruits and vegetables. Cytotoxicity assays confirmed its safety, with over 85 % cell viability at concentrations up to 0.1 mM. Stability experiments verified that 7-DCCA had greatly light and thermal stability. This study highlighted 7-DCCA as a promising antibrowning agent with potential application in food preservation.

Activity of Bambara Groundnut Seed Coat Extract Against Shewanella Species: Efficacy and Mechanisms of Action

The Bambara groundnut is the indigenous legume in the southern part of Thailand. It contains a seed coat rich in polyphenols, which can serve as natural antimicrobial agents. The extracts from red and white seed coats of Bambara groundnuts, namely RSC and WSC, respectively, were prepared using an ultrasound-assisted extraction process. The extraction yield, total phenolic content (TPC), and antimicrobial activity of both extracts were examined. The RSC extract demonstrated a significantly higher extraction yield (8.35%) than WSC extract (2.34%) (p < 0.05). Furthermore, the TPC of RSC extract (420.98 ± 0.27 mg of gallic acid/g dry extract) was higher than that of WSC extract (28.29 ± 0.91 mg of gallic acid/g dry extract). The RSC extract exhibited stronger inhibition against Shewanella putrefaciens and S. algae than its WSC counterpart. Liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF/MS) analysis indicated that the RSC extract was rich in flavonoids and polyphenols, while the WSC extract contained more triterpenoid saponins. Time-kill kinetics showed that the RSC extract reduced bacterial loads in a dose-dependent manner. Scanning electron microscopic images revealed that drastic bacterial cell membrane damage with a rough surface and the deformation of cells was caused by the extract. Furthermore, confocal laser scanning microscopic (CLSM) images confirmed the inhibition of S. algae biofilm formation by RSC extract. RSC extract also suppressed bacterial motility, induced protein leakage, and reduced extracellular protease activity, thus highlighting its potent bactericidal effects. These findings suggested that the RSC extract rich in phenolic compounds could serve as an antimicrobial agent and hold promise as a natural preservative for perishable foods, especially seafoods.

Development of polyvinyl alcohol/carboxymethylcellulose-based bio-packaging film with citric acid crosslinking and clove essential oil encapsulated chitosan nanoparticle pickering emulsion

This study developed polyvinyl alcohol (PVA)/carboxymethylcellulose (CMC)-based films, using citric acid (CA) as a non-toxic crosslinking agent, to enhance the shelf life of water-soluble packaging films. Clove essential oil (CEO)-loaded chitosan nanoparticles (CSNPs) were prepared via Pickering emulsion and incorporated into PVA/CMC/CA composite films. The encapsulation of CEO was confirmed by FTIR and optical microscopy. Thermal properties were analyzed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), revealing improved thermal stability and a decrease in glass transition temperature (Tg) upon crosslinking. The formation of ester bonds was confirmed by ATR-FTIR and 13CNMR. Water contact angle (WCA) measurements showed a decrease in hydrophilicity, enhancing the barrier properties of the films. SEM images demonstrated good dispersion of CSNP/CEO within the matrix, improving mechanical and barrier properties. The films exhibited a 30 % reduction in water vapor permeability and water solubility. Controlled release studies indicated that the composite films sustained CEO release, extending the shelf life of cherry tomatoes. Thus, these PVA/CMC/CA-CSNP/CEO composite films offer strong potential for food preservation applications.

Fabrication and characterization of double-layer active intelligent film based on chitosan, polyvinyl alcohol, grape skin anthocyanin and selenium nanoparticle

This study involved the fabrication of double-layer intelligent films using chitosan (CS), polyvinyl alcohol (PVA), grape skin anthocyanin (GSA), gellan gum (GG) and selenium nanoparticles (SeNPs). The CS/PVA/GSA layer functioned as the internal indicator layer, and the GG/SeNPs layer acted as the external layer for antioxidant and antimicrobial purposes. SEM, FTIR, XRD, and TGA results confirmed the successful fabrication of double-layer films as well as the presence of hydrogen bonding interaction between the two layers. The tensile strength of double-layer films (8.06 MPa-9.61 MPa) fallen between that of single-layer CS/PVA/GSA film (12.51 MPa) and GG/SeNPs film (1.50 MPa-7.67 MPa). The double-layer films demonstrated good UV-blocking abilities, as well as outstanding antioxidant (ABTS scavenging rate can be up to ∼80 %) and antimicrobial properties. Compared with single-layer CS/PVA/GSA film, the double-layer film incorporated with 6.6 wt% SeNPs (CPG/GS2 film) possessed a more rapid and stronger response towards NH3/acetic acid as well as enhanced storage stability. Furthermore, the CPG/GS2 film can increase the shelf life of strawberries at 25 °C by 4 days, and its visible color change showed strong correlation with the weight loss rate (R2 = 0.99) and hardness (R2 = 0.98) of strawberries.

Phytolacca americana extract as a quality-enhancing factor for biodegradable double-layered films based on furcellaran and gelatin - Property assessment

For the first time, novel active double-layered films based on furcellaran (FUR) and gelatin (GEL) with the addition of Phytolacca americana (PA) extract were obtained. The 1st layer consisted of FUR and GEL, while the aqueous extract of P. americana berries was added in three different concentrations to the 2nd FUR-based layer. The films were characterised by good mechanical (TS range of 0.0011-0.0013 MPa, EAB range between 30.38 %-33.51 %) and water properties (WVTR range of 574.74-588.49 g/m2xd). Structural analysis (SEM and AFM) confirmed good film structure: regular, without cracks or air bubbles. The films showed antioxidant activity tested via the Folin-Ciocâlteu method (4.77-20.70 mg GAExg-1), FRAP assay (0.18-3.40 mM TExg-1) and CUPRAC assay (48.63-53.99 mM TExg-1). The film with the highest PA concentration (6 %) demonstrated the ability to neutralise free radicals, DPPH• and ABTS2+•, at the levels of 1.97 % and 17.34 %, respectively. The ecotoxicity test performed on Lepidium sativum seeds confirmed the lack of ecotoxic film aspects. The biodegradation test indicated that the films are biodegradable. The obtained films can be a good alternative to plastic packaging films (used in the food packaging industry), which are currently a global problem related to the development of post-consumer plastics.

Fabrication of gallic acid containing poly(vinyl alcohol)/chitosan electrospun nanofibers with antioxidant and drug delivery properties

Chitosan-based nanofibers with excellent properties are attractive materials for specific industrial applications of contemporary interest. This work aims to fabricate functional nanofibers based on poly(vinyl alcohol)/chitosan (CS) with an antioxidant and model drug molecule, gallic acid (GA), by electrospinning, followed by cross-linking through glutaraldehyde (PVA-CS-GAs). PVA-CS-GAs were electrospun at two different concentrations by the adjustment of the CS feeding ratio. The detailed characteristics of the as-prepared electrospun nanofibers were elucidated by Fourier Transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), water contact angle (WCA) measurements, thermogravimetric and differential scanning calorimetry (TGA and DSC) analyses. SEM images indicated that the average fiber diameter distribution was in the range of 90-110 nm. The results show that morphology, mean diameter, wettability, and thermal characteristics of the composite nanofibers were affected by the CS feeding ratio. Although the increase in the amount of polar -OH groups with the addition of GA caused an improvement in the hydrophilicity and thermal stability of the electrospun nanofibers, it also caused a decrease in the thermal transition temperatures. Furthermore, antioxidant tests based on DPPH radical scavenging ability and in vitro release studies demonstrated that the cross-linked PVA-CS-GA composite nanofibers have good antioxidant activity and a pH-dependent drug release rate, indicating their potential for implementation in wound healing and drug delivery applications.

3D printing cassava starch-ovalbumin intelligent labels: Co-pigmentation effects of gallic acid on anthocyanins

Anthocyanins are often chosen as signal converters of intelligent labels. However, they are degraded by high-temperature oxidation in the process of intelligent label preparation. The color fading seriously affects the sensitivity of color development. In this study, a green 3D printing intelligent label preparation technique was developed, in which gallic acid (GA) was added to a blueberry anthocyanin (BA) solution to enhance the color of the co-pigment to ensure the color sensitivity. The combined effect of GA-BA reduced the fade rate of the anthocyanins from 35.13 % to 26.44 % at 90 °C. The printing ink has shear-thinning viscosity characteristics and yield stresses in the range of 500-600 MPa for high-quality printing. Structural analysis revealed that GA-BA co-pigmentation enhanced the interaction between ovalbumin and cassava starch. In addition, the method of 3D printing to prepare labels was conducive to solving the problem of waste in traditional labeling process. The results of freshness testing of sea shrimp proved that labels can be applied to fresh boxes to reflect the freshness of food. We provide a method for enhancing the color of 3D-printed smart ink to prepare intelligent labels with reproducible and customizable batch shapes.

Characterization of exopolysaccharide/potato starch nanocomposite films loading g-C3N4 and Ag and their potential applications in food packaging

The interest in nanocomposite films incorporating edible ingredients and active nanoparticles has surged due to their potential to enhance food quality and prolong shelf-life. This research focused on developing innovative exopolysaccharides (EPS)/potato starch (PS) nanocomposite films integrated with g-C3N4 and AgNO3. Extensive analysis was conducted to assess the microstructure, physical attributes and antimicrobial properties of these films. Fourier transform infrared (FT-IR) analysis revealed electrostatic and hydrogen bonding interactions within the film components. X-ray diffraction (XRD) and X-ray photoelectron spectrometer (XPS) data indicated a high level of compatibility among EPS, PS, g-C3N4, and AgNO3, with no new absorption peaks or characteristic signals of C3N4 and Ag appearing in the nanocomposite films patterns. The thickness, water solubility and water vapor permeability (WVP) of the EPS-PS-C3N4-Ag nanocomposite film increased due to the addition of g-C3N4, reached 0.31 ± 0.03 nm, 36.61 ± 1.76 % and 1.42 ± 0.34 × 10-10 g-1 s-1 Pa-1, respectively. While transparency, swelling degree, and oxygen permeability (OP) significantly decreased, reached 26.18 ± 2.38 %, 63.01 ± 2.51 % and 41.98 ± 1.28 %, respectively. Scanning electron microscopy (SEM) and atomic force microscope (AFM) images depicted an augmented roughness and porosity on the film surface upon integration of g-C3N4 and AgNO3. Moreover, the EPS-PS-C3N4-Ag nanocomposite film displayed enhanced mechanical strength due to the presence of g-C3N4. The melting temperature (Tm) of EPS-PS-C3N4-Ag nanocomposite film was 313.3 °C, the removal rates of DPPH and ABTS was 66.11 ± 2.87 % and 45.09 ± 1.23 % respectively. Significant inhibition of microbial growth was observed in film containing g-C3N4 and AgNO3, which demonstrated no toxicity towards NIH-33 cells, suggesting their potential application as promising active packaging material for food preservation.

Double layer bacterial nanocellulose - poly(hydroxyoctanoate) film activated by prodigiosin as sustainable, transparent, UV-blocking material

Synthetic materials alternatives are crucial for reaching sustainable development goals and waste reduction. Biomaterials and biomolecules obtained through bacterial fermentation offer a viable solution. Double-layer active UV-blocking material composed of bacterial nanocellulose as an inner layer and poly(hydroxyoctanoic acid) containing prodigiosin as an active compound was produced by layer-by-layer deposition. This study referred the new material consisted of the three components produced in sustainable manner, by bacterial activity: bacterial bio-pigment prodigiosin, bacterial nanocellulose and poly(hydroytoctanoate) - biopolymer obtained by microbial fermentations. Prior the final double layer film was produced, PHO films containing different PG concentrations as a layer in charge of the bioactivity (0.2, 0.5 and 1 wt%) was casted and systematically characterized (FTIR, DSC, XRD, wettability, SEM, transparency, mechanical tests) to optimize their properties. The formulation with the best UV-blocking properties and less toxicity effect tested using MRC5 cells was chosen as an outer layer in double-layer films production. Water contact angle measurements confirmed that hydrophilic - hydrophobic double layer film was obtained with the improved mechanical properties in comparison to the native BNC. Migration test indicated release of PG in all tested media as a consequence of bilayer formulation, while the PG release from PHO in 10 % ethanol was not detected. All findings from the study suggested this activated, UV-blocking material as a candidate with excellent potential in packaging industry.

Ready-to-Cook Foods: Technological Developments and Future Trends-A Systematic Review

Ready-to-cook (RTC) foods can significantly improve the cooking experience of busy or unskillful consumers, based on production involving technical combinations of food processing and packaging. Initialized by a market survey of 172 products in Beijing, this systematic review analyzes RTC foods' development status according to ingredients, packaging, and storage conditions to further clarify the scope of RTC foods. The working principles and efficacy of various food processing techniques, such as washing, cutting, marinating, and frying, and packaging design or innovations such as modified atmosphere packaging (MAP) were both summarized in detail, with attention to their ability to extend shelf life, reduce safety risks, and maximize production efficiency in RTC food production. The cutting-edge technologies that may potentially apply in the RTC food processing or packaging sector were compared with current approaches to visualize the direction of future developments. In conclusion, we have observed the specific pattern of RTC food varieties and packaging formats in the Beijing market and revealed the advancements in RTC food technologies that will continue playing a critical role in shaping this growing market, while challenges in scalability, cost-efficiency, and sustainability remain key areas for future research. The data and perspectives presented will articulate the conceptions and existing challenges of RTC food, foster consumer perception and recognition of similar products, and deliver useful guidance for stakeholders interested in such products.

Mechanical and Thermal Characteristics of Films from Glycerol Mixed Emulsified Carnauba Wax/Polyvinyl Alcohol

Poly(vinyl alcohol) (PVA)-based films have drawn significant attention owing to their potential applications in various industries. The application of wax to PVA films enhanced their resistance to dissolution and water infiltration. Nevertheless, waxed PVA films often exhibit inadequate mechanical properties owing to crack formation. In this study, we evaluated the impact of glycerol as a plasticizer in varying concentrations of Carnauba wax (CW). The addition of glycerol to the PVA/CW blend led to enhanced mechanical properties compared to the blend without glycerol. The functional group and morphology of the blends confirm glycerol compatibility with PVA/CW films. Glycerol was fully dispersed to form a consistent polymer matrix and equally improved the film's contact angle. Furthermore, the thermal property from differential scanning calorimetry and thermogravimetric analysis highlights the plasticizing effect of glycerol in PVA/CW films, potentially broadening their use in food packaging and wrapping applications.

Use of natural peptide TP4 as a food preservative prevents contamination by fungal pathogens

Molecules of natural origin often possess useful biological activities. For instance, the natural peptide Tilapia Piscidin 4 (TP4) exhibits potent antimicrobial activity against a broad spectrum of pathogens. In this study, we explored the potential application of TP4 as a food preservative, asking whether it can prevent spoilage due to microbial contamination. A preliminary in silico analysis indicated that TP4 should interact strongly with fungal cell membrane components. Hence, we tested the activity of TP4 toward Candida albicans within fruit juice and found that the addition of TP4 could abolish fungal growth. We further determined that the peptide acts via a membranolytic mechanism and displays concentration-dependent killing efficiency. In addition, we showed that TP4 inhibited growth of Rhizopus oryzae in whole fruit (tomato) samples. Based on these findings, we conclude that TP4 should be further evaluated as a potentially safe and green solution to prevent food spoilage.

Assessment of chitosan coating enriched with Citrus limon essential oil on the quality characteristics and shelf life of beef meat during cold storage

The present work aimed to assess the effects of chitosan coating comprising Citrus limon essential oil (CLEO) as an antimicrobial and antioxidant on the quality and the shelf-life of beef meat during storage in cold temperatures. The microbial, chemical, and sensory characteristics of beef meat were repeatedly evaluated. The outcomes showed that CLEO had a substantial preservative effect on refrigerated beef meat by reducing total volatile basic nitrogen compounds (TVB-N), inhibiting the replication of microorganisms (p < 0.05), and decreasing oxidation (p < 0.05) during storage. The incorporation of CLEO into chitosan coating significantly reduced (p < 0.05), TBARS, especially for the Nano-CS- ClEO 2 % and 4 % groups, with values at the end of storage of approximately 0.68 and 1.01 mg MDA/kg respectively. Moreover, the meat treatments with essential oils led to lower carbonyl content production in compared to other groups that treated without essential oils. Coated beef meat had the highest inhibitory effects against microbial growth. The counts of Enterobacteriaceae, lactic acid bacteria (LAB), psychrophilic, and mesophilic bacteria were significantly lower (p < 0.05) in the Nano-CS- ClEO 2 % (1.1, 4.2, 6.2, and 6.32 Log CFU/g, respectively) at day 16. The sensory evaluation indicated that this coating with chitosan nanoemulsions in combination with ClEOs could significantly preserve sensory characteristics of beef meat during storage. Moreover, concerning sensory features, the control samples gained the maximum score. Additionally, the group that contains chitosan in combination with 4 % ClEO nanoliposomes had the highest inhibition of microbial growth, reduced sensory changes, and extending the shelf life of beef meat (p < 0.05). In conclusion, nanoemulsions containing Citrus limon essential oil had a significant preservation effect on beef meat during refrigerated storage by preventing the microorganism's proliferation and decreasing the oxidation of fat and protein (p < 0.05). Therefore, they are suggested to extend the durability of fresh meat products during refrigerated storage.

Development of dual-channel starch-based film incorporated with betanin@β-cyclodextrin inclusion complex and berberine for indicating shrimp freshness

In this study, the β-cyclodextrin encapsulated betanin (BET@β-CD) with improved thermal stability and retention as well as the berberine (BBR) with aggregate induced luminescence effect were incorporated into corn amylose (CA) biomatrix to develop colorimetric/fluorescent dual-channel smart film. Results shown that the added functional components were uniformly distributed in the film matrix. The high tensile strength (78.87%), low water solubility (31.15%) and water vapor permeability (1.24 × 10-10 g Pa-1 s-1 m-1) of the film predicted its acceptable stability. It was worth mentioning that the film displayed excellent responsiveness to volatile ammonia (0.025-25 mg/mL) with at least 4 times recyclability. Application experiment demonstrated that the film can achieve macroscopic dynamic monitoring of the freshness of shrimps stored at 25 °C, 4 °C, -20 °C under daylight (red to yellow) and UV light (yellow-green to blue-green). Thus, the study suggests an attractive and effective strategy for constructing dual-mode smart packaging materials for food freshness detection.

Water-resistant and barrier properties of poly(vinyl alcohol)/nanocellulose films enhanced by metal ion crosslinking

Polyvinyl alcohol (PVA) is a promising alternative to non-biodegradable flexible packaging materials, and nanocellulose is often used to enhance the properties of PVA films, but the composite films still have poor water resistance and barrier properties. To address this issue, iron ions (Fe3+) were introduced into PVA/cellulose nanofibrils (CNF) films, and Fe3+ formed coordination bonds with carboxyl and hydroxyl groups on the surface of CNF and PVA chains. Therefore, constructing a strong coordination crosslinking network within the film and improving the interfacial interaction between PVA and CNF. The water resistance, mechanical and barrier properties of the crosslinked films were significantly improved. Compared with the un-crosslinked film, the oxygen transmission rate (OTR) was decreased by up to 67 %, and the water swelling ratio was significantly reduced from 1085 % to 352 %. The tensile strength of the film with 1.5 wt% Fe3+ reached 41.93 MPa, which was 62 % higher than that of the un-crosslinked film. Furthermore, the composite film demonstrated good recyclability, almost recovering its original mechanical properties in two recycling tests. This simple and effective method for preparing water resistance and barrier films shows potential applications in flexible packaging areas.

Preparation, characterization, antimicrobial evaluation, and grape preservation applications of polyvinyl alcohol/gelatin composite films containing zinc oxide@quaternized chitosan nanoparticles

This study employed a precipitation method to synthesize zinc oxide@quaternised chitosan nanoparticles (ZnO@QAC NPs) containing different concentrations of zinc oxide, namely ZnO@QAC-2, ZnO@QAC-4, and ZnO@QAC-6. Subsequently, these nanoparticles were incorporated into matrices consisting of gelatine (Gn) and polyvinyl alcohol (PVA) separately, which were prepared by casting to form a biodegradable film. We assessed the physicochemical properties of ZnO@QAC NPs and physicochemical characteristics, antioxidant properties, antimicrobial activity and grape preservation efficacy of the film. Compared to the control group, the films showed a reduction in water vapor permeability by >9.38 %, an increase in tensile strength by over 51.95 %, over 70 % scavenging of ABTS free radicals, and good biocompatibility. Additionally, the antimicrobial activity of the films containing ZnO@QAC-6 increased by 37.6 %. In the grape preservation experiment, the weight loss of grapes wrapped in ZnO@QAC-2 film was reduced by 40.13 % on day 15 compared to unwrapped grapes. These results demonstrate that ZnO@QAC/PVA/Gn films have considerable potential for food packaging applications.

Multifunctional engineering of Mangifera indica L. peel extract-modified bacterial cellulose hydrogel: Unveiling novel strategies for enhanced heavy metal sequestration and cytotoxicity evaluation

The escalating interest in bacterial cellulose (BC) confronts a substantial obstacle due to its biologically inert properties. Hence, BC was modified with ethanolic mango peel extract (EEMP) for various industrial and medical applications of the novel nanocomposite (BC/EEMP). High-performance liquid chromatography (HPLC) delineated the phenolic composition of EEMP, revealing a repertoire of polyphenolic compounds, notably chlorogenic acid, gallic acid, catechin, and ellagic acid. EEMP exhibited broad-spectrum antimicrobial activity against Candida albicans and Staphylococcus aureus, with MIC of 0.018 mg/mL and 0.009 mg/mL, respectively. The removal mechanism of Pb2+ and Ni2+ by BC/EEMP nanocomposite membrane via SEM, EDX, FT-IR, and XRD was characterized, indicating deposition and aggregation of heavy metals with diminished porosity. Heavy metal removal optimization using the Box-Behnken design achieved maximal removal of 95.5 % and 90 % for Pb2+ and Ni2+, respectively. Moreover, BC/EEMP nanocomposite demonstrated selective dose-dependent anticancer activity toward hepatoma (HepG-2, IC50 of 208.8 μg/mL), skin carcinoma (A431, IC50 of 216.7 μg/mL), and breast carcinoma (MDA, IC50 of 197.5 μg/mL), attributed to the enhanced availability of biologically active polyphenolic compounds and physical characteristics of BC. This study underscores the remarkable potential of BC/EEMP nanocomposite for multifaceted industrial and biomedical applications, marking a pioneering contribution to the field.

Development and characterization of polyvinyl alcohol/chitosan crosslinked malic acid composite films with curcumin encapsulated in β-cyclodextrin for food packaging application

Considering that fruits are vulnerable to damage and waste during stockpiling, transport and marketing. Given this, an innovative curcumin inclusion compound (Cur@β-CD) was devised in this study to introduce oil-soluble curcumin (Cur) into water-soluble polyvinyl alcohol (PVA) materials, thereby fabricating food packaging films endowed with excellent properties. DPPH test manifested that the oxidation resistance for PCOMC-Cur@β-CD film was 95 % above PVA material. It was ascribed to the fact that the Cur@β-CD elevated the water solubility of Cur while the increase of water solubility heightened the antioxidant effect for Cur in the film. Additionally, the chitosan (CS) was crosslinked with malic acid (MA), which elevated the barrier property of the film, reduced the amount of oxygen transmission and further retarded the oxidation reaction of the fruits for packaging. The antibacterial test demonstrated that the antibacterial rates of PCOMC-Cur@β-CD film against E. coli and S. aureus reached 92 % and 95 %, respectively, which was attributed to the slow release of Cur when Cur@β-CD was dissolved in PVA material and the Schiff base reaction between Cur and amino groups on CS. These findings indicate that the PCOMC-Cur@β-CD film developed in this work can provide certain insights into the field of food packaging.

Development and characterization of eco-friendly guar gum-agar-beeswax-based active packaging film for cheese preservation

In this work, an attempt has been made to develop a novel natural polysaccharide-based composite packaging biofilm prepared through a solution casting method. The biofilm is prepared from guar gum (GG) and agar-agar (AA) beeswax (BE). The incorporation of 20 % wt./wt.glycerol BE in the blended polymer GG/AA (50:50) (GG/AA/BE20 (50:50)) film shows a reduction in water solubility (66.67 %), water vapour permeability (69.28 %) and oxygen permeability (72.23 %). Moreover, GG/AA/BE20 (50:50) shows an increment in the tensile strength and elongation of a break by 48.32 % and 26.05 %, respectively, compared to pristine GG film. The scanning electron microscopy (SEM) image reveals defects-free smooth surfaces of the film. The Fourier transform-infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) demonstrated the strong hydrogen bonding between GG, AA, and BE. The biodegradable film shows 99 % degradation within 28 days when placed in the soil. The developed film plays a crucial role in extending the shelf life of cheese, effectively maintaining its moisture content, texture, colour, and pH over a span of up to two months from the point of packaging. These results suggest that GG/AA/BE20 (50:50) composite film is a promising packaging film for cheese preservation.

High-performance carboxymethyl starch/PVA based intelligent packaging films engineered with Cu-Trp nanocrystal as functional compatibilizer

A spindle-like Cu-based framework (Cu-Trp, Trp = L-Tryptophan) nanocrystal with ammonia-responsiveness was fabricated via simple aqueous solution approach, and it was subsequently explored as a functional compatibilizer of carboxymethyl starch/polyvinyl alcohol (CMS/PVA) blend toward constructing high-performance intelligent packaging films. The results showed that incorporation of Cu-Trp nanocrystal into CMS/PVA blend resulted in significant promotions regarding to the compatibility, mechanical strength (42.92 MPa), UV-blocking (with UV transmittance of only 2.4%), and water vapor barrier effectiveness of the blend film. Besides, the constructed CMS/PVA/Cu-Trp nanocomposite film exhibited superb long-term color stability, favorable antibacterial capacity (over 98.0%) toward both E. coli and S. aureus bacteria, as well as color change ability under ammonia environment. Importantly, the application trial confirmed that the CMS/PVA/Cu-Trp nanocomposite film is capable of visually monitoring shrimp spoilage during storage. These results implied that the CMS/PVA/Cu-Trp nanocomposite film holds tremendous potential as an intelligent active packaging material.

Antimicrobial gelatin-based films with cinnamaldehyde and ZnO nanoparticles for sustainable food packaging

Cinnamaldehyde (CIN), a harmless bioactive chemical, is used in bio-based packaging films for its antibacterial and antioxidant properties. However, high amounts can change food flavor and odor. Thus, ZnO nanoparticles (NPs) as a supplementary antimicrobial agent are added to gelatin film with CIN. The CIN/ZnO interactions are the main topic of this investigation. FTIR-Attenuated Total Reflection (ATR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were utilized to investigate CIN/ZnO@gelatin films. Transmission electron microscope (TEM) images revealed nanospheres morphology of ZnO NPs, with particle sizes ranging from 12 to 22 nm. ZnO NPs integration increased the overall activation energy of CIN/ZnO@gelatin by 11.94%. The incorporation of ZnO NPs into the CIN@gelatin film significantly reduced water vapour permeability (WVP) of the CIN/ZnO@gelatin film by 12.07% and the oxygen permeability (OP) by 86.86%. The water sorption isotherms of CIN/ZnO@gelatin were described using Guggenheim-Anderson-de Boer (GAB) model. The incorporation of ZnO NPs into the CIN@gelatin film reduced monolayer moisture content (M0) by 35.79% and significantly decreased the solubility of CIN/ZnO@gelatin by 15.15%. The inclusion of ZnO into CIN@gelatin film significantly decreased tensile strength of CIN/ZnO@gelatin by 13.32% and Young`s modulus by 18.33% and enhanced elongation at break by 11.27%. The incorporation of ZnO NPs into the CIN@gelatin film caused a significant decrease of antioxidant activity of CIN/ZnO@gelatin film by 9.09%. The most susceptible organisms to the CIN/ZnO@gelatin film included Candida albicans, Helicobacter pylori, and Micrococcus leutus. The inhibition zone produced by the CIN/ZnO@gelatin film versus Micrococcus leutus was 25.0 mm, which was comparable to the inhibition zone created by antibacterial gentamicin (23.33 mm) and cell viability assessment revealed that ZnO/CIN@gelatin (96.8 ± 0.1%) showed great performance as potent biocompatible active packaging material.

Locust Bean Gum/κ-Carrageenan Film Containing Blueberry or Beetroot Extracts as Intelligent Films to Monitoring Hake (Merluccius merluccius) Freshness

The main goal of this work was to develop bio-based and ecofriendly intelligent films as freshness indicators to monitor European hake (Merluccius merluccius) quality during storage by using a visual, non-destructive, and real-time technique. Locust bean gum (LBG)/κ-carrageenan (Car) films incorporating blueberry extract (BLE) or beetroot extract (BEE) were developed and their effectiveness to detect hake deterioration during 7 days of storage at 4 °C was evaluated. A visible color response from pink to blue was observed on the BLE films at the end of hake storage, which correlated with the hake deterioration profile, namely an increase in pH values (from 6.60 ± 0.04 to 8.02 ± 0.03), total viable count (TVC, from 4.61 ± 0.36 to 8.61 ± 0.21 log CFU/g), and total volatile basic nitrogen content (TVB-N, from 10.21 ± 1.97 to 66.78 ± 4.81 mg/100 g) beyond the spoilage threshold. The results of this study are very promising, since it was possible to develop a new effective intelligent bio-based responsive indicator film incorporating natural dye BLE, which has the potential to contribute to food waste reduction and improve food safety by detecting the hake freshness status.

Green synthesized CeO2 nanoparticles-based chitosan/PVA composite films: Enhanced antimicrobial activities and mechanical properties for edible berry tomato preservation

The current study is intended to enhance unique bioactive and eco-friendly composite films following a simple solvent-casting approach by incorporating cerium oxide nanoparticles (CeO2 NPs) with a chitosan (CS)/polyvinyl alcohol (PVA) matrix. Antimicrobial activity, preservation impact, mechanisms for the edible berry tomatoes and physicochemical properties of the produced films were tested. FTIR, SEM-EDX, XRD, UV-vis spectroscopy and contact angle were used to characterize the films. Incorporated (3.0 wt%) CeO2 NPs practically developed composite film's thermal stability, structural, mechanical, bioactive, antioxidant, barrier and wettability properties. The tomatoes' look, weight loss and stiffness were better preserved after 25 days of storage at room temperature (25 ± 5 °C) when 3.0 wt% CeO2 NPs films were used instead of the original CS/PVA film. CS and CeO2 NPs have unique physiochemical and antibacterial properties. Food packaging extensively investigates the modified films as antimicrobials and preservatives to increase the shelf life of packaged foods, owing to their ability to inhibit gram-positive bacteria (Bacillus cereus and Staphylococcus aureus), gram-negative bacteria (Klebsiella pneumoniae and Pseudomonas aeruginosa), and filamentous fungi (Bipolaris sorokiniana, Fusarium op., and Alternaria sp.). Our findings indicated that the CeO2/CS/PVA composite films could be used as effective wrapping materials for food preservation.

Potential Use and Chemical Analysis of Some Natural Plant Extracts for Controlling Listeria spp. Growth In Vitro and in Food

Listeria are Gram-negative intracellular foodborne pathogens that can cause invasive infections with high mortality rates. In this work, the antibacterial activity of ten essential oils, infusion extracts, and decoction extracts of some medicinal plants was tested against Listeria monocytogenes and listeria ivanovii strains. The effects of different physical conditions including temperature, pH, sodium chloride, and some organic acids were studied. The results showed that the water extracts gave the maximum bacterial inhibition, while ethanolic extract was inactive against the tested Listeria spp. The antibiotic sensitivity of L. monocytogenes LMG10470 and L. ivanovii LMZ11352 was tested against five antibiotics including imipenem, levofloxacin, amikacin, ampicillin, and amoxicillin. Imipenem was the most effective antibiotic, resulting in inhibition zones of 40 mm and 31 mm for L. monocytogenes and L. ivanovii, respectively. When imipenem mixed with Syzygium aromaticum oil, Salvia officinalis oil, Pimpinella anisum infusion, and Mentha piperita infusion each, the water extract of Moringa oleifera leaves and seeds against LMG10470 and LMZ11352 resulted in broader antibacterial activity. The antimicrobial activity of both Pimpinella anisum and Mentha piperita plant extracts is related to a variety of bioactive compounds indicated by gas chromatography-mass spectrometry analysis of these two plant extracts. These two plant extracts seemed to contain many chemical compounds elucidated by gas chromatography-mass spectrometry (GC-MS) and infrared radiation spectra. These compounds could be classified into different chemical groups such as ethers, heterocyclic compounds, aromatic aldehydes, condensed heterocyclic compounds, ketones, alicyclic compounds, aromatics, esters, herbicides, saturated fatty acids, and unsaturated fatty acids. The use of these natural compounds seems to be a useful technological adjuvant for the control of Listeria spp. in foods.

Inhibition of Pectobacterium carotovorum-mediated potato soft rot by carboxymethyl cellulose-based antibacterial edible coating containing green tea extract

This study was conducted to propose a new strategy for preventing Pectobacterium carotovorum-mediated potato soft rot through the development of a carboxymethyl cellulose (CMC)-based antibacterial coating incorporated with green tea extract (GTE). GTE/CMC films resulted in increased water vapor permeability due to the incorporation of polar groups in GTE. In the antibacterial test against P. carotovorum, the MBC value of GTE was 2 mg/mL. The time-kill assay demonstrated that GTE/CMC (2 × MBC) completely eradicated bacteria within 0.5 h (~6.4 log CFU/mL reduction). The potential of GTE/CMC to prevent potato soft rot was evaluated by monitoring the potato appearance, maceration area, and texture properties. The GTE/CMC-coated potatoes exhibited significantly reduced maceration area and remained firm for 3 days. Moreover, there was no change in the antimicrobial efficacy for 8 weeks. The developed GTE/CMC could be used as a biological coating system for postharvest storage and soft rot prevention.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-024-01548-6.

Green synthesis of non-isocyanate hydroxyurethane and its hybridization with carboxymethyl cellulose to produce films

Non-isocyanate polyurethanes (NIPUs) have attracted increasing attention as a sustainable alternative to conventional isocyanate-based polyurethanes. This study synthesized non-isocyanate hydroxyurethanes (NIHUs) through an addition reaction between propylene carbonate (PC) and 1,2-ethylenediamine (EDA). The resulting NIHU was then hybridized with carboxymethyl cellulose (CMC) to investigate its hybridization potential. Structural analysis through FTIR, NMR, and XRD confirmed the crystalline nature of NIHU, featuring urethane bonds and abundant hydroxyl groups. It was found that NIHU and CMC interacted by forming hydrogen bonds between hydroxyl groups of NIHU and carboxyl groups of CMC, resulting in a dense CMC/NIHU hybrid structure. NMR and XRD analyses revealed changes in the hybrids' chain mobility, the Young's modulus of the hybrid with 30 % NIHU content decreased from 1627 MPa to 502 MPa relative to CMC, and the elongation at break increased from 4.44 % to 17.2 %. Increasing the concentration of NIHU in CMC reduced the hydrophobicity, in terms of water contact angle, from 70° to 41.7°. The simplicity of the synthesis method for NIHU, coupled with the desirable structure, strength, and balanced flexibility of CMC/NIHU hybrids, is expected to facilitate the production of NIHU-rich hybrids and increase their application in packaging.

Impact of Antioxidant-Enriched Edible Gel Coatings and Bio-Based Packaging on Cherry Tomato Preservation

This research investigates the effects of using edible gel coatings and bio-based packaging materials on extending the shelf life of cherry tomatoes. Two edible gel coatings (guar gum and guar gum +5% of a lemon (Citrus limon (L.) Osbeck pomace extract obtained in the research laboratory) were applied on cherry tomatoes, then they were packaged in bio-based materials (cellulose tray + PLA lid). Guar gum, glycerol, sorbitol, extra virgin olive oil, and tween 20 were used in coating formulation. Uncoated tomatoes packed in bio-based materials and conventional plastic (PET trays + lid) were tested as a control. Samples were stored for 45 days at 20 °C and their quality parameters were evaluated. Coated tomatoes maintained firmness and weight, and the enriched coated samples showed a significant increase in phenol content, derived from the antioxidant extract. Samples packed in PET showed a sensory unacceptability (<4.5) after 45 days correlated with a greater decline in firmness (from 10.51 to 5.96 N) and weight loss (from 7.06 to 11.02%). Therefore, edible gel coating and bio-based packaging proved to be effective in maintaining the overall quality of cherry tomatoes for 45 days, offering a promising approach to reduce plastic polymer use and food waste.

Starch-Based Functional Films Enhanced with Bacterial Nanocellulose for Smart Packaging: Physicochemical Properties, pH Sensitivity and Colorimetric Response

Starch-based pH-sensing films with bacterial nanocellulose (BNC) and red cabbage anthocyanins (RCA) as active components were investigated in this research. Their structural, physical, surface and colorimetric properties were analyzed, mainly as a function of BNC concentration. The aim of the research was to relate the changes in the intermolecular interactions between the components of the films (starch, anthocyanins and BNC) to the physical, surface and colorimetric properties that are important for the primary intended application of the produced films as pH indicators in smart packaging. The results showed that maize starch (MS) was more suitable as a matrix for the stabilization of anthocyanins compared to potato starch (PS). PS-based films showed a lower value of water contact angle than MS-based films, indicating stronger hydrophilicity. The swelling behavior results indicate that the concentrations of BNC in MS-based films (cca 10%) and the concentration of about 50% BNC in PS-based films are required if satisfactory properties of the indicator in terms of stability in a wet environment are to be achieved. The surface free energy results of PS-based films with BNC were between 62 and 68 mJ/m2 and with BNC and RCA between 64 and 68 mJ/m2; for MS-based films, the value was about 65 mJ/m2 for all samples with BNC and about 68 mJ/m2 for all samples with BNC and RCA. The visual color changes after immersion in different buffer solutions (pH 2.0-10.5) showed a gradual transition from red/pink to purple, blue and green for the observed samples. Films immersed in different buffers showed lower values of 2 to 10 lightness points (CIE L*) for PS-based films and 10 to 30 lightness points for MS-based films after the addition of BNC. The results of this research can make an important contribution to defining the influence of intermolecular interactions and structural changes on the physical, surface and colorimetric properties of bio-based pH indicators used in smart packaging applications.

Heat-sealable, transparent, and degradable arabinogalactan/polyvinyl alcohol films with UV-shielding, antibacterial, and antioxidant properties

Petroleum-based packaging materials are nondegradable and unsustainable and thus are harmful to the environment. Renewable packaging films prepared from bio-based raw materials are promising alternatives to petroleum-based packaging materials. In this study, colorless and transparent bio-based films were successfully cast using a solution containing a mixture of arabinogalactan (AG) and poly (vinyl alcohol) (PVA). Vanillin was incorporated into the mixture to endow the films with UV-shielding, antioxidant, and antibacterial properties. The morphological, physical, antioxidant, and antibacterial properties of the blend films were then characterized. At an AG:PVA weight ratio of 1:3, and the vanillin content was 0.15 %, the tensile strength of the AG/PVA/Vanillin (APV) films reached ~28 MPa, while their elongation at break reached ~475 %. The addition of vanillin significantly affected the antioxidant and antibacterial properties of the blend films, which exhibited superb UV barrier capacity. The APV films exhibited extremely low oxygen transmittance, delaying the onset of mold/rot in strawberries and reducing their weight loss. Because of the heat sealability of the blend films, they can be used for encapsulating various substances, such as concentrated laundry liquid. Moreover, the blend films were recyclable and biodegradable. Thus, these films have great potential for applications that require sustainable packaging.

Recent advancements in chitosan-based intelligent food freshness indicators: Categorization, advantages, and applications

With an increasing emphasis on food safety and public health, there is an ongoing effort to develop reliable, non-invasive methods to assess the freshness of diverse food products. Chitosan-based food freshness indicators, leveraging properties such as biocompatibility, biodegradability, non-toxicity, and high stability, offer an innovative approach for real-time monitoring of food quality during storage and transportation. This review introduces intelligent food freshness indicators, specifically those utilizing pH-sensitive dyes like anthocyanins, curcumin, alizarin, shikonin, and betacyanin. It highlights the benefits of chitosan-based intelligent food freshness indicators, emphasizing improvements in barrier and mechanical properties, antibacterial activity, and composite film solubility. The application of these indicators in the food industry is then explored, alongside a concise overview of chitosan's limitations. The paper concludes by discussing the challenges and potential areas for future research in the development of intelligent food freshness indicators using chitosan. Thus, chitosan-based smart food preservation indicators represent an innovative approach to providing real-time data for monitoring food quality, offering valuable insights to both customers and retailers, and playing a pivotal role in advancing the food industry.

Biopolymeric Insulin Membranes for Antimicrobial, Antioxidant, and Wound Healing Applications

Delayed wound healing increases the wound's vulnerability to possible infections, which may have lethal outcomes. The treatments available can be effective, but the urgency is not fully encompassed. The drug repositioning strategy proposes effective alternatives for enhancing medical therapies for chronic diseases. Likewise, applying wound dressings as biodegradable membranes is extremely attractive due to their ease of application, therapeutic effectiveness, and feasibility in industrial manufacturing. This article aims to demonstrate the pleiotropic effects during insulin repositioning in wound closure by employing a biopolymeric membrane-type formulation with insulin. We prepared biopolymeric membranes with sodium alginate cross-linked with calcium chloride, supported in a mixture of xanthan gum and guar gum, and plasticized with glycerol and sorbitol. Human insulin was combined with poloxamer 188 as a protein stabilizing agent. Our investigation encompassed physicochemical and mechanical characterization, antioxidant and biological activity through antibacterial tests, cell viability assessments, and scratch assays as an in vitro and in vivo wound model. We demonstrated that our biopolymeric insulin membranes exhibited adequate manipulation and suitable mechanical resistance, transparency, high swelling capability (1100%), and 30% antioxidant activity. Furthermore, they exhibited antibacterial activity (growth inhibition of S. aureus at 85% and P. aeruginosa at 75%, respectively), and insulin promoted wound closure in vitro with a 5.5-fold increase and 72% closure at 24 h. Also, insulin promoted in vivo wound closure with a 3.2-fold increase and 92% closure at 10 days compared with the groups without insulin, and this is the first report that demonstrates this therapeutic effect with two administrations of 0.7 IU. In conclusion, we developed a multifunctional insulin-loaded biopolymeric membrane in this study, with the main activity derived from insulin's role in wound closure and antioxidant activity, augmented by the antimicrobial effect attributed to the polymer poloxamer 188. The synergistic combination of excipients enhances its usefulness and highlights our innovation as a promising material in wound healing materials.

Excellent Antibacterial Properties of Silver/Silica-Chitosan/Polyvinyl Alcohol Transparent Film

Transparent films with excellent antibacterial properties and strong mechanical properties are highly sought after in packaging applications. In this study, Ag/SiO2 nanoparticles were introduced into a mixed solution of chitosan (CS) and polyvinyl alcohol (PVA) and a Ag/SiO2-CS-PVA transparent film was developed. The excellent properties of the film were confirmed by light transmittance, water contact angle tests and tensile tests. In addition, for the antibacterial test, the antibacterial properties of the sample against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) were explored, and the average size of the bacteriostatic circle was measured by the cross method. The final results show that Ag/SiO2-CS-PVA transparent film has the advantages of good antibacterial properties, high transparency and high mechanical strength.

Natural Pigments Recovery from Food By-Products: Health Benefits towards the Food Industry

Given the health risks associated with synthetic colorants, natural pigments have emerged as a promising alternative. These renewable choices not only provide health benefits but also offer valuable technical and sensory properties to food systems. The effective application of natural colorants, however, requires the optimization of processing conditions, exploration of new sources, and development of novel formulations to ensure stability and maintain their inherent qualities. Several natural pigment sources have been explored to achieve the broad color range desired by consumers. The purpose of this review is to explore the current advances in the obtention and utilization of natural pigments derived from by-products, which possess health-enhancing properties and are extracted through environmentally friendly methods. Moreover, this review provides new insights into the extraction processes, applications, and bioactivities of different types of pigments.

An Overview of Advanced Antimicrobial Food Packaging: Emphasizing Antimicrobial Agents and Polymer-Based Films

The food industry is increasingly focused on maintaining the quality and safety of food products as consumers are becoming more health conscious and seeking fresh, minimally processed foods. However, deterioration and spoilage caused by foodborne pathogens continue to pose significant challenges, leading to decreased shelf life and quality. To overcome this issue, the food industry and researchers are exploring new approaches to prevent microbial growth in food, while preserving its nutritional value and safety. Active packaging, including antimicrobial packaging, has gained considerable attention among current food packaging methods owing to the wide range of materials used, application methods, and their ability to protect various food products. Both direct and indirect methods can be used to improve food safety and quality by incorporating antimicrobial compounds into the food packaging materials. This comprehensive review focuses on natural and synthetic antimicrobial substances and polymer-based films, and their mechanisms and applications in packaging systems. The properties of these materials are compared, and the persistent challenges in the field of active packaging are emphasized. Specifically, there is a need to achieve the controlled release of antimicrobial agents and develop active packaging materials that possess the necessary mechanical and barrier properties, as well as other characteristics essential for ensuring food protection and safety, particularly bio-based packaging materials.

Toxicity of water-soluble polymers polyethylene glycol and polyvinyl alcohol for fish and frog embryos

Personal Care Products (PCPs) have been one of the most studied chemicals in the last twenty years since they were identified as pseudo-persistent pollutants by the European Union in the early 2000s. The accumulation of PCPs in the aquatic environment and their effects on non-target species make it necessary to find new, less harmful, substances. Polyethylene glycol (PEGs) and polyvinyl alcohol (PVAs) are two polymers that have increased their presence in the composition of PCPs in recent years, but little is known about the effect of their accumulation in the environment on non-target species. Through embryotoxicity tests on two common models of aquatic organisms (Danio rerio and Xenopus laevis), this work aims to increase the knowledge of PEGs and PVAs' effects on non-target species. Animals were exposed to the pollutant for 96 h. The main embryotoxicity endpoint (mortality, hatching, malformations, heartbeat rate) was recorded every 24 h. The most significant results were hatching delay in Danio rerio exposed to both chemicals, in malformations (oedema, body malformations, changes in pigmentation and deformations of spine and tail) in D. rerio and X. laevis and significant change in the heartbeat rate (decrease or increase in the rate) in both animals for all chemicals tested.

The Effect of Irradiation on Meat Products

The effects of irradiation on meat constituents including water, proteins, and lipids are multifaceted. Irradiation leads to the decomposition of water molecules, resulting in the formation of free radicals that can have both positive and negative effects on meat quality and storage. Although irradiation reduces the number of microorganisms and extends the shelf life of meat by damaging microbial DNA and cell membranes, it can also accelerate the oxidation of lipids and proteins, particularly sulfur-containing amino acids and unsaturated fatty acids. With regard to proteins, irradiation affects both myofibrillar and sarcoplasmic proteins. Myofibrillar proteins, such as actin and myosin, can undergo depolymerization and fragmentation, thereby altering protein solubility and structure. Sarcoplasmic proteins, including myoglobin, undergo structural changes that can alter meat color. Collagen, which is crucial for meat toughness, can undergo an increase in solubility owing to irradiation-induced degradation. The lipid content and composition are also influenced by irradiation, with unsaturated fatty acids being particularly vulnerable to oxidation. This process can lead to changes in the lipid quality and the production of off-odors. However, the effects of irradiation on lipid oxidation may vary depending on factors such as irradiation dose and packaging method. In summary, while irradiation can have beneficial effects, such as microbial reduction and shelf-life extension, it can also lead to changes in meat properties that need to be carefully managed to maintain quality and consumer acceptability.

Plant betalains-mixed active/intelligent films for meat freshness monitoring: A review of the fabrication parameters

The plant pigments called betalains are nutritionally safe polar compounds. They are subdivided into betaxanthins (having orange to yellow hues) and betacyanins (purple to red violet hues). Betacyanins change color with a change in pH, particularly in the range 6-8 and 9-11. Perishable foods like fish, chicken, beef, pork, and others tend to release total volatile base-nitrogen (TVB-N) during storage or deterioration, which leads to a change in the pH of pH-sensitive materials in the vicinity. pH-sensitive pigment-incorporated polymeric films with inherent active properties (or active/intelligent films) are increasingly being studied as an alternative to synthetic pH indicators to detect the accumulation of TVB-N by changing its color to indicate the stage of perishable food spoilage. There are many methods of developing such films under different conditions using different bio-based biodegradable polymer(s) and biocompatible plasticizer combinations. Among the reported methods, solution casting method has been the preferred one in most studies covered in this review. This method can be carried out under mild conditions. As such, betacyanins-incorporated polymeric films essentially require mild processing conditions because of their heat sensitivity, which will invariably affect the performance in food freshness monitoring. In this review, film fabrication parameters like temperature and duration of dissolution of polymers, plasticizer concentration, pH of the film-forming solution, film drying, and conditioning/aging, have been critically appraised based on the available literature. The lack of studies on the safety of active/intelligent films has been systematically highlighted in this review to focus future studies on this area.

Graphical abstract

Smart colorimetric indicator films prepared from chitosan and polyvinyl alcohol with high mechanical strength and hydrophobic properties for monitoring shrimp freshness

This work aimed to develop and characterize a colorimetric indicator films based on chitosan (CS), polyvinyl alcohol (PVA), and shikonin (SKN) from radix Lithospermi by casting method. The prepared films can serve as smart packaging for monitoring shrimp freshness which having excellent antimicrobial and antioxidant activity. The shikonin containing films have better hydrophobicity, barrier properties, and tensile strength. The release kinetics analysis shows that the loading amount causes a prolonged release of SKN from the prepared films. Increasing SKN in the CS/PVA film from 1 wt% to 2 wt% improved antibacterial effect for 24 h. Additionally, pH-sensitive color shifts from reddish (pH 2) to purple-bluish (pH 13) were visually seen in shikonin based solutions as well as films. The CS/PVA/SKN film detected shrimp deterioration at three temperatures (25, -20, and 4 °C) through color change. This study introduces a favorable approach for smart packaging in the food industry using multifunctional films.

Exploring the impact of irradiation on the sensory quality of pork based on a metabolomics approach

The effects of irradiation on pork quality characteristics were investigated by combining sensory experiments, pork color, TBARS, volatile components, and differential metabolites. Pork irradiated at a dose of 1 kGy received the highest sensory scores, whereas pork irradiated at doses of 3 and 5 kGy obtained lower sensory scores, particularly with regard to odor. Irradiation makes pork more ruddy and promotes fat oxidation, leading to increased a* and TBARS values. The main volatile substances in irradiated pork were hydrocarbons, aldehydes, and alcohols, and hexanal, heptanal, and valeric acid were considered as important substances responsible for the generation of radiation-induced off-flavors. 65 differential metabolites were identified. l-pyroglutamic acid, l-glutamate, l-proline, fumarate acids, betaine, and l-anserine were considered as the main substances contributing to the differences in pork quality. In addition, metabolic pathways such as arginine biosynthesis, alanine, aspartate and glutamate metabolism were found to be considerably affected by irradiation.

Pomegranate Peel and Olive Leaf Extracts to Optimize the Preservation of Fresh Meat: Natural Food Additives to Extend Shelf-Life

Quality and safety are one of the main concerns of the European Union in food preservation. Using chemical additives extends the shelf-life of fresh foods but raises consumer's concerns about the potential long-term carcinogenic effects. Using natural substances derived from agro-industrial by-products, which have significant antimicrobial and antioxidant activities, could extend the shelf-life of fresh foods such as meat. Furthermore, they can provide nutritional improvements without modifying organoleptic properties. This study analyzes the antimicrobial activity of pomegranate peel extract (PPE) and the antioxidant activity of olive leaf extract (OLE), added at concentrations of 10 mg g-1 and 0.25 mg g-1, respectively, to minced poultry and rabbit meat. PPE exhibited in vitro antimicrobial activity against foodborne pathogens starting at 10 mg/well. PPE and OLE determined a reduction in colony count over a storage period of 6 days at 4 °C. Additionally, the combination of PPE and OLE showed antioxidant effects, preserving lipid oxidation and maintaining pH levels. The obtained results demonstrate that PPE and OLE can be recommended as food additives to preserve the quality and extend the shelf-life of meat products.

Advances in sustainable food packaging applications of chitosan/polyvinyl alcohol blend films

Researchers are addressing environmental concerns related to petroleum-based plastic packaging by exploring biopolymers from natural sources, chemical synthesis, and microbial fermentation. Despite the potential of individual biopolymers, they often exhibit limitations like low water resistance and poor mechanical properties. Blending polymers emerges as a promising strategy to overcome these challenges, creating films with enhanced performance. This review focuses on recent advancements in chitosan/polyvinyl alcohol (PVA) blend food packaging films. It covers molecular structure, properties, strategies for performance improvement, and applications in food preservation. The blend's excellent compatibility and intermolecular interactions make it a promising candidate for biodegradable films. Future research should explore large-scale thermoplastic technologies and investigate the incorporation of additives like natural extracts and nanoparticles to enhance film properties. Chitosan/PVA blend films offer a sustainable alternative to petroleum-based plastic packaging, with potential applications in practical food preservation.