Development and characterization of active bilayer film incorporated with dihydromyricetin encapsulated in hydroxypropyl-β-cyclodextrin for food packaging application

Antimicrobial activities of natural flavonoids against foodborne pathogens and their application in food industry

The application of natural alternatives as food preservatives has gained much attention due to the escalating negative perception of synthetic preservatives among consumers and the spread of drug-resistance foodborne pathogens. Natural flavonoids have the potential to be employed for food safety due to their antimicrobial properties against a wide range of foodborne pathogenic microorganisms. In this perspective, we reviewed the antimicrobial activities of natural flavonoids, the mechanism of action, as well as their application for food safety and quality. Various strategies for the incorporation of flavonoids into food products were highlighted, including direct addition to food formulations, encapsulation as micro or nanocarriers, and incorporation into edible or active films and coatings. Furthermore, we discussed the current challenges of industrial application of flavonoids, and proposed future trends to enhance their potential as natural preservatives. This review provides a theoretical foundation for the further development and application of flavonoids for food safety.

Development and characterization of pectin-based composite film incorporated with cannabidiol/2,6-di-O-methyl-β-cyclodextrin inclusion complex for food packaging

To reduce environmental pollution and improve human health, developing green active food packaging materials is very necessary. In this study, a novel antioxidant and antibacterial composite film was produced by incorporating inclusion complex (CDIC) of cannabidiol (CBD) with 2,6-di-O-methyl-β-cyclodextrin (DM-β-CD) into pectin. The pectin films loaded with CBD and hemp leaf water extract (HLE) were prepared for comparison. Comprehensive characterizations showed CBD was encapsulated by DM-β-CD and CDIC was evenly dispersed into pectin matrix, forming the compact and intact film. The composite films showed good mechanical properties and biodegradability. CDIC film showed the highest transparency and smoothness (Rrms/Rmax: 2.6/16.8 nm). The addition of bioactives reduced the water-binding capacity and CDIC film had the strongest hydrophobicity. Besides, DM-β-CD encapsulation improved the thermal stability of CBD in CDIC film. Benefiting from encapsulation and excellent bioactivities of CBD, CDIC film showed excellent antioxidant capacity and antibacterial activity, effectively inhibiting colony growth and maintaining the strawberry color in strawberry preservation. This work could provide a novel eco-friendly candidate for food packaging material and expand the use of CBD in food industry.

Hydrophobic polyethylene film prepared by film blowing process for preservation of fried shrimp rolls

Hydrophobic coatings have wide applications, but face challenges in food flexible packaging in terms of poor adhesion and inadequate wear resistance. Health hazards and poor adhesion drive the search for novel hydrophobic coatings substitutes. Here, we introduced rationally synthesized carnauba wax-SiO2 microspheres as a component to composite polyethylene (PE) film construction, and created a wear-resistant hydrophobic composite PE film via the blown film technique. The resultant hydrophobic composite film demonstrated an enhanced water contact angle from 86° to above 100°, coupled with favorable mechanical properties such as wear resistance, tensile strength and effective barrier performance against water vapor and oxygen. Upon implementation in the preservation of a Cantonese delicacy, Chaoshan fried shrimp rolls, it was observed that at 25 °C, the carnauba wax-SiO2-PE composite packaging film extended the shelf life of the product by 3 days compared to pure PE film.

An antibacterial film using κ-carrageenan loaded with benzyl isothiocyanate nanoemulsion: Characterization and application in beef preservation

Benzyl isothiocyanate (BITC) is a naturally active bacteriostatic substance and κ-carrageenan (KC) is a good film-forming substrate. In the present study, a nanoemulsion incorporating BITC was fabricated with a particle size of 224.1 nm and an encapsulation efficiency of 69.2 %. Subsequently, the acquired BITC nanoemulsion (BITC-NE) was incorporated into the KC-based film, and the light transmittance of the prepared composite films was lower than that of the pure KC film. Fourier transform infrared spectroscopy and scanning electron microscopy revealed that BITC-NE was compatible with the KC matrix. BITC-NE incorporation enhanced the tensile strength of the KC-based films by 33.7 %, decreased the elongation at break by 33.8 %, decreased the water vapor permeability by 60.1 %, increased the maximum thermal degradation temperature by 48.8 %, and decreased the oxygen permeability by 42 % (p < 0.05). Furthermore, the composite films showed enhanced antimicrobial activity against Staphylococcus aureus, Salmonella typhimurium, and Pseudomonas fluorescens. The developed KC-based composite films were applied to wrap raw beef, which significantly delayed the increase in total viable count, total volatile base nitrogen content, and thiobarbituric acid reactive substances, and prolonged the shelf-life of the raw beef by up to 10 days. These results indicated that the composite films prepared by incorporating BITC nanoemulsions into KC matrices have great antimicrobial application potential.

Development of pectin/chitosan-based electrospun biomimetic nanofiber membranes loaded with dihydromyricetin inclusion complexes for wound healing application

Accidents and surgical procedures inevitably lead to wounds, presenting clinical challenges such as inflammation and microbial infections that impede the wound-healing process. This study aimed to address these challenges by developing a series of novel wound dressings known as electrospun biomimetic nanofiber membranes. These membranes were prepared using electrostatic spinning technique, incorporating hydroxypropyl-β-cyclodextrin/dihydromyricetin inclusion complexes. The prepared electrospun biomimetic nanofiber membranes exhibited randomly arranged fiber morphology with average fiber diameters ranging from 200 to 400 nm, resembling the collagen fibers in the native skin. These membranes demonstrated excellent biocompatibility, hemocompatibility, surface hydrophilicity, and wettability, while also releasing dihydromyricetin in a sustained manner. In vitro testing revealed that these membranes, loaded with hydroxypropyl-β-cyclodextrin/dihydromyricetin inclusion complexes, displayed higher antioxidant potential and inhibitory effects against Staphylococcus aureus and Escherichia coli. Furthermore, these membranes significantly reduced the M1 phenotypic transition in RAW264.7 cells, even when stimulated by lipopolysaccharides, effectively restoring M2 polarization, thereby shortening the inflammatory period. Additionally, the in vivo wound healing effects of these membranes were validated. In conclusion, this study introduces a promising nanofiber membrane with diverse biological properties that holds promise for addressing various crucial aspects of the wound-healing process.

Air-Assisted Electrospinning of Dihydromyricetin-Loaded Dextran/Zein/Xylose Nanofibers and Effects of the Maillard Reaction on Fiber Properties

Dihydromyricetin (DMY) has been encapsulated in delivery systems to address the solubility limitations of DMY in water and improve its bioavailability. Air-assisted electrospinning has been used as a novel technology to load DMY. To evaluate the impact of adding DMY to dextran/zein nanofibers and understand the effects of the Maillard reaction (MR) on the physical and functional properties of DMY-loaded nanofibers, dextran/zein/xylose nanofibers with 0%, 1%, 2%, 3%, and 4% DMY were fabricated, followed by MR crosslinking. Scanning electron microscopy (SEM) observations indicated that the addition of DMY and the MR did not affect the morphology of the nanofibers. X-ray diffraction (XRD) results indicated amorphous dispersion of DMY within the nanofibers and a decreased crystalline structure within the nanofibers following the MR, which might improve their molecular flexibility. The nanofibrous film formed after the MR exhibited both increased tensile strength and elastic modulus due to hydrogen bonding within the nanofibers and increased elongation at break attributed to the increased amorphization of the structure after crosslinking. The nanofibers were also found to exhibit improved heat stability after the MR. The antioxidant activity of the nanofibers indicated a dose-dependent effect of DMY on radical scavenging activity and reducing power. The maintenance of antioxidant activity of the nanofibers after the MR suggested heat stability of DMY during heat treatment. Overall, dextran/zein nanofibers with various DMY contents exhibited tunable physical properties and effective antioxidant activities, indicating that dextran/zein nanofibers offer a successful DMY delivery system, which can be further applied as an active package.

Development of apple pectin/soy protein isolate-based edible films containing punicalagin for strawberry preservation

In this study, we developed punicalagin-loaded antimicrobial films based on soy protein isolate (SPI) and apple pectin (AP). The AP was derived from apple pomace waste while the punicalagin was obtained from pomegranate peel. Punicalagin was identified to exist in both α- and β-isomers, with the β-type being predominant. The composite films were characterized using scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. Our results demonstrated that the incorporation of AP significantly enhanced the mechanical strength, heat resistance, and barrier properties of the films. Moreover, the composite films integrated with punicalagin exhibited excellent antimicrobial activities against Staphylococcus aureus (with a minimum bactericidal concentration value of 0.25 %), Escherichia coli (with a minimum bactericidal concentration value of 0.50 %), and Aspergillus niger. Finally, these antimicrobial film solutions were tested as coatings on strawberries and found to have significantly better effects on reducing weight loss, improving shelf-life, and maintaining the freshness of strawberries compared to coatings without punicalagin. The results indicate that antimicrobial coatings loaded with punicalagin hold great promise as multifunctional active packaging materials for fruit preservation.

Structural and functional characteristics of pectins from three cultivars of apple (Malus pumila Mill.) pomaces

This study aimed to investigate the chemical composition, structural properties, and biological properties of pectin polysaccharides (AP-FS, AP-QG, and AP-HG) isolated from different varieties of apple pomace. Based on the methylation and nuclear magnetic resonance analyses, the structure of AP-FS was determined to be composed of an α-1,4-linked homogalacturonan backbone that exhibited high levels of O-6 methylation. All pectins exhibit potent inhibitory activity against human colon cancer and human liver cancer cells, along with immunostimulatory effects. Among them, AP-FS exhibited the highest activity level. Finally, we further investigated the underlying mechanism behind the effect of AP-FS on RAW 264.7 cells using proteomics analysis. Our findings revealed that AP-FS triggers RAW 264.7 macrophage activation via NOD-like receptor (NLR), NF-κB, and mitogen-activated protein kinase (MAPK) signaling pathways. Therefore, our research contributes to a better understanding of the structure-function relationship among apple pectins, and AP-FS has the potential to be applied to dietary supplements targeting immunomodulation.

Sustainable packaging film based on cellulose nanofibres/pullulan impregnated with zinc-doped carbon dots derived from avocado peel to extend the shelf life of chicken and tofu

A cellulose nanofiber (CNF)/pullulan (PUL) based multifunctional composite film was developed for active packaging applications by incorporating Zn-doped avocado-derived carbon dots (Zn-ACDs). The incorporation of Zn-ACDs improved the interfacial compatibility and produced a dense cross-sectional structure of the composite films. The Zn-ACDs added film showed no significant difference in water vapor permeability and surface hydrophilicity compared to the neat CNF/PUL film, but the tensile strength and elongation at break increased by ~45.4 % and ~64.1 %, respectively. The addition of 5 wt% Zn-ACDs to the CNF/PUL matrix resulted in 100.0 % UV blocking properties, excellent antioxidant activity (100.0 % for ABTS and 68.0 % for DPPH), and complete eradication of foodborne pathogens such as Listeria monocytogenes ATCC 15313 and Escherichia coli O157:H7 after 3 h of exposure. The CNF/PUL composite film with Zn-ACDs applied to the active packaging of chicken and tofu significantly reduced the total growth of aerobic microorganisms without significantly changing the actual color of the packaged chicken and tofu for 9 days at 10°C. This study demonstrates that CNF/PUL composite films with Zn-ACDs are a sustainable and environmentally friendly option for protecting food from microbial contamination.

Dual-function β-cyclodextrin/starch-based intelligent film with reversible responsiveness and sustained bacteriostat-releasing for food preservation and monitoring

The full combination of high sensitivity indication and long-lasting bacteriostatic function is an innovative need to meet the practicality of intelligent film packaging systems for food products. Hence, Blueberry anthocyanins (BA) copigmentated by ferulic acid (FA) was used as an indicator, and cinnamon essential oil (CO) encapsulated by β-cyclodextrin (β-CD) as a bacteriostat, potato starch (PS) as a film-forming substrate to prepared a dual-function starch-based intelligent active packaging film with pH indicator and antibacterial function. FA had the best copigmentation effect with a threefold increase in a value compared to other phenolic acids. The ΔE value increased from 3.24 to 5.13 at pH 2-8, and the change was still prominent in acid-base alternating test, indicating a high response sensitivity. Notably, the yellow gamut of indicating terminus increased its visibility to the naked eye. The release behavior of CO from film was in line with Fick's diffusion. Meanwhile, the release of CO delayed to about 90 h through β-cyclodextrin encapsulation, showing a high growth-inhibition rate in E. coli and S. aureus of almost 100 %. In this study, a dual-function film with indication and bacteriostasis was prepared and enhanced with both, expanding its wide application in intelligent packaging of fresh food.

Role of biotechnology in the advancement of biodegradable polymers and functionalized additives for food packaging systems

Biodegradable polymers have shown enormous potential for application in food packaging systems and offer solutions to mitigate the challenges of single-use plastics. Over the past decade, advances in fermentation technology, metabolic engineering of microorganisms, and synthetic biology have enabled the optimization and functionalization of biodegradable polymers for food packaging application. This article provides an overview of the biotechnological approaches/methods used in advancing the production of biopolymers and summarizes the recent developments in the application of functionalized biopolymers for decision-making and quality control. It discusses the current applications and future perspectives of extracellular biopolymers in food systems. Finally, this review highlights the complexities of public acceptance, safety, and government regulations and legislations.

Multi-functional konjac glucomannan/chitosan bilayer films reinforced with oregano essential oil loaded β-cyclodextrin and anthocyanins for cheese preservation

In this work, a multifunctional bilayer film was prepared by solvent casting method. Elderberry anthocyanins (EA) were incorporated into konjac glucomannan (KGM) film as the inner indicator layer (KEA). β-cyclodextrin (β-CD) loaded with oregano essential oil (OEO) inclusion complexes (β-CD@OEO) was prepared and incorporated into chitosan (CS) film as the outer hydrophobic and antibacterial layer (CS-β-CD@OEO). The impacts of β-CD@OEO on the morphological, mechanical, thermal, water vapor permeability and water resistance properties, pH sensitivity, antioxidant, and antibacterial activities of bilayer films were thoroughly evaluated. The incorporation of β-CD@OEO into bilayer films can significantly improve the mechanical properties (tensile strength (TS): 65.71 MPa and elongation at break (EB): 16.81 %), thermal stability, and water resistance (Water contact angle (WCA): 88.15°, water vapor permeability (WVP): 3.53 g mm/m² day kPa). In addition, the KEA/CS-β-CD@OEO bilayer films showed color variations in acid-base environments, which could be used as pH-responsive indicators. The KEA/CS-β-CD@OEO bilayer films also presented controlled release of OEO, good antioxidant, and antimicrobial activity, which exhibited good potential for the preservation of cheese. To sum up, KEA/CS-β-CD@OEO bilayer films have potential applications in the field of food packaging industry.

Development of chitosan/konjac glucomannan/tragacanth gum tri-layer food packaging films incorporated with tannic acid and ε-polylysine based on mussel-inspired strategy

Constructing biodegradable food packaging with good mechanics, gas barrier and antibacterial properties to maintain food quality is still challenge. In this work, mussel-inspired bio-interface emerged as a tool for constructing functional multilayer films. Konjac glucomannan (KGM) and tragacanth gum (TG) with physical entangled network are introduced in the core layer. Cationic polypeptide ε-polylysine (ε-PLL) and chitosan (CS) producing cationic-π interaction with adjacent aromatic residues in tannic acid (TA) are introduced in the two-sided outer layer. The triple-layer film mimics the mussel adhesive bio-interface, where cationic residues in outer layers interact with negatively charged TG in the core layer. Furthermore, a series of physical tests showed excellent performance of triple-layer film with great mechanical properties (tensile strength (TS): 21.4 MPa, elongation at break (EAB): 7.9 %), UV-shielding (almost 0 % UV transmittance), thermal stability, water, and oxygen barrier (oxygen permeability (OP): 1.14 × 10^-3 g/m s Pa and water vapor permeability (WVP): 2.15 g mm/m² day kPa). In addition, the triple-layer film demonstrated advanced degradability, antimicrobial functions, and presented good moisture-proof performance for crackers, which can be potentially applied as dry food packaging.

Effects of grape seed extract on the properties of pullulan polysaccharide/xanthan gum active films for apple preservation

Grape seed extract (GSE) was added to pullulan polysaccharide (PP)/xanthan gum (XG) as composite film (PP/XG/GSE or PXG). The observed composite morphology indicated their biocompatibility. Sample PXG100 (contain 100 mg/L GSE) demonstrated the best mechanical properties, with tensile strength of 16.62 ± 1.27 MPa, and the elongation at break of (22.60 ± 0.48)%. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging activity of PXG150 were the highest at (81.52 ± 1.57)% and (90.85 ± 1.54)%, respectively. PXG films also demonstrated inhibitory effects on Staphylococcus aureus, Escherichia coli, and Bacillus subtilis. The PXG films could also prolong the shelf life of fresh-cut apples because it could decrease the rate of weight loss and retain more vitamin C and total polyphenol even on the 5th day. The weight loss rate of PXG150 was decreased from (8.58 ± 0.6)% (control) to (4.15 ± 0.19)%. It was able to achieve vitamin C and total polyphenol retention rate of 91 % and 72 %, respectively, which was significantly higher that the control sample. Therefore, GSE had contributed in enhancing the antibacterial, antioxidant properties, mechanical strength, UV protection and water resistance in PXG composite films. This effectively extend the shelf life of fresh-cut apples, which it will be an excellent food packaging material.

Pectin grafted with resorcinol and 4-hexylresorcinol: Preparation, characterization and application in meat preservation

To augment the functional attributes of pectin and expand its prospective utilization in food preservation, this research explored the enzymatic grafting of resorcinol and 4-hexylresorcinol onto pectin. Structural analysis verified the successful grafting of both resorcinol and 4-hexylresorcinol to pectin via esterification, with the 1-OH of resorcinol and 4-hexylresorcinol and the carboxyl group of pectin functioning as grafting sites. The grafting ratios of resorcinol-modified pectin (Re-Pe) and 4-hexylresorcinol-modified pectin (He-Pe) were 17.84 % and 10.98 %, respectively. This grafting modification notably enhanced the antioxidative and antibacterial properties of pectin. Specifically, DPPH clearance and the inhibition ratio in the β-carotene bleaching assay increased from 11.38 % and 20.13 % (native pectin, Na-Pe) to 41.15 % and 36.67 % (Re-Pe), and 74.72 % and 53.40 % (He-Pe). Moreover, the inhibition zone diameter against Escherichia coli and Staphylococcus aureus rose from 10.12 and 10.08 mm (Na-Pe) to 12.36 and 11.52 mm (Re-Pe), and 16.78 and 14.87 mm (He-Pe). Additionally, the application of native and modified pectin coatings effectively impeded pork spoilage, with the modified pectins demonstrating a more potent effect. Among the two modified pectins, He-Pe exhibited the most significant enhancement in pork shelf life.

Functional Chitosan-Based Composite Film Incorporated with 3-(Methylthio) Propyl Isothiocyanate/α-Cyclodextrin Inclusion Complex for Chicken Meat Preservation

The 3-(Methylthio) propyl isothiocyanate (MTPITC)-loaded inclusion complex prepared by α-cyclodextrin (α-CD) was incorporated into chitosan (CS) film to fabricate a packaging material for fresh chicken meat preservation. Scanning electron microscope images indicated homogenous dispersion of the MTPITC-α-CD in CS polymer. Fourier-transform infrared and X-ray diffraction techniques revealed that MTPITC-α-CD was incorporated into the CS film matrix by the physical interactions. The introduction of MTPITC-α-CD improved the UV-vis light-blocking ability, with a slight loss of transparency. Although the water solubility and water vapor barrier capacity were not significantly influenced by the addition of MTPITC-α-CD, the antioxidant attribute was significantly enhanced. The CS-MTPITC-α-CD film displayed obvious and sustained suppressive effects against Salmonella typhimurium, with the inhibition zone diameters of 14.7 mm at 12 h and 7.3 mm at 24 h, respectively. Moreover, the quality index analysis indicated that the CS-MTPITC-α-CD film-wrapped fresh chicken, during refrigerated storage, exhibited better preservative efficacy than the control groups, with the total viable counts of 6.5 Log CFU/g, total volatile base nitrogen of 8.4 mg/100 g, pH of 6.6, thiobarbituric acid-reactive substances of 0.2 mg/kg, and the sensory score of 5 at day 16. Collectively, these results suggest that CS-MTPITC-α-CD film is a prospective packaging candidate for delaying the quality deterioration of chicken meat.