Controlled release and antibacterial properties of PEO/casein nanofibers loaded with Thymol/β-cyclodextrin inclusion complexes in beef preservation

Formation, stability, and antimicrobial efficacy of eutectic nanoemulsions containing thymol and glycerin monolaurate

In this study, based on the discovery of thymol/glycerol monolaurate (GML) eutectic solvent, we studied the effect of GML as a multi-functional component (ripening inhibitor and antibacterial agent) on the formation, stability and antibacterial activity of eutectic nanoemulsions, and investigated the preservation of nanoemulsion in fresh pork. These results indicated that the formation of eutectic solvent was due to the hydrogen bonding between thymol and GML in the molten state. And eutectic nanoemulsions prepared with medium GML concentrations (20%, 40%, and 60%) of eutectic solvents as oil phases had small droplet diameters (<150 nm), exhibited sustained-release characteristics, and had excellent physicochemical stability. Moreover, the addition of GML enhanced the antibacterial activity of thymol nanoemulsion against S. aureus. as seen by their ability to inhibit affect formation more effectively. Treatment of fresh pork with optimized eutectic nanoemulsions (40% thymol/60% GML) extended its shelf life during refrigeration, which was mainly attributed to the ability of the encapsulated essential oil to inhibit microbial growth and lipid oxidation. These results provide a novel strategy to control Ostwald ripening and maintain the high antibacterial activity of thymol in nanoemulsion-based delivery systems.

Fortification of cassava starch edible films with Litsea cubeba essential oil for chicken meat preservation

Chicken meat is highly perishable and mainly preserved by plastic packaging materials, whereas their widely used have increased environmental burden and threatened human health. Bioactive packaging materials fabricated by biopolymers are promising alternatives for meat preservation. Herein, cassava starch (CS)/sodium carboxymethyl cellulose (CMC) edible films fortified with Litsea cubeba essential oil (LC-EO) were fabricated and characterized. Results showed the textural, mechanical and barrier properties of the CS/CMC edible films were significantly improved after incorporating with LC-EO. Moreover, the composite edible films exhibited potent antibacterial properties, biodegradability, hydrophobicity, and thermal stability. Whereas the water solubility and moisture content was reduced up to 29.68 % and 24.37 %, respectively. The release behavior of LC-EO suggested the suitability of the composite edible films for acidic foods. Comparing with the control group, the pH values of the meat samples packaged with CS/CMC/LCEO-4 mg/mL edible films maintained at around 6.7, and weight loss rate was 15 %. The color and texture changes, and the lipid oxidation of the meat samples with CS/CMC/LCEO-4 mg/mL packaging were also markedly delayed. The microbial growth was retarded at 6.35 log CFU/g after storage for 10 days. These findings suggested the CS/CMC/LCEO-4 mg/mL edible films had great potential for chicken meat preservation.

Rapid-Response Water-Shrink Films with High Output Work Density Based on Polyethylene Oxide and α-Cyclodextrin for Autonomous Wound Closure

Conventional wound closure methods, including sutures and tissue adhesives, present significant challenges for self-care treatment, particularly in the context of bleeding wounds. Existing stimuli-responsive contractile materials designed for autonomous wound closure frequently lack sufficient output work density to generate the force needed to bring the wound edges into proximity or necessitate stimuli that are not compatible with the human body. Here, semi-transparent, flexible, and water-responsive shrinkable films, composed of poly(ethylene oxide) and α-cyclodextrin, are reported. These films exhibit remarkable stability under ambient conditions and demonstrate significant contraction (≈50%) within 6 s upon exposure to water, generating substantial contractile stress (up to 6 MPa) and output work density (≈1028 kJ m-3), which is 100 times larger than that of conventional hydrogel and 25 times larger than that of skeletal muscles. Remarkably, upon hydration, these films are capable of lifting objects 10 000 times their own weight. Leveraging this technology, water-shrink tapes, which, upon contact with water, effectively constrict human skin and autonomously close bleeding wounds in animal models within 10 seconds, are developed further. This work offers a novel approach to skin wound management, showing significant potential for emergency and self-care scenarios.

Recent advances in spoilage mechanisms and preservation technologies in beef quality: A review

Beef is a popular meat product that can spoil and lose quality during postharvest handling and storage. This review examines different preservation methods for beef, from conventional techniques like low-temperature preservation, irradiation, vacuum packing, and chemical preservatives, to novel approaches like bacteriocin, essential oil, and non-thermal technologies. It also discusses how these methods work and affect beef quality. The review shows that beef spoilage is mainly due to enzymatic and microbial activities that impact beef freshness, texture, and quality. Although traditional preservation methods can extend beef shelf life, they have some drawbacks and limitations. Therefore, innovative preservation methods have been created and tested to improve beef quality and safety. These methods have promising results and potential applications in the beef industry. However, more research is needed to overcome the challenges and barriers for their commercialization. This review gives a comprehensive and critical overview of the current and emerging preservation methods for beef and their implications for the beef supply chain.

Design and characterization of tannic acid/ε-polylysine biocomposite packaging films with excellent antibacterial and antioxidant properties for beef preservation

The shelf life of beef is shortened by microbial infection, which limits its supply in the market. Active packaging film is expected to overcome this difficulty. In this study, an antibacterial/antioxidant SS-ε-PL-TA biocomposite film made by soy protein isolate/sodium alginate/ε-polylysine/tannic acid was designed and prepared. Due to the formation of hydrogen bonds and enhanced hydrophobic interactions, the biocomposite film showed enhanced mechanical property. Tensile strength increased from 22.8 ± 2.59 MPa to 64.34 ± 6.22 MPa, and elongation at break increased from 7.70 ± 1.07 % to 13.98 ± 0.22 %. The composite film displayed excellent antibacterial activity owing to the damage to cell membranes and biofilms of bacteria. Furthermore, the antioxidant activity also significantly increased (DPPH ∙ scavenging activity was 78.0 %). The shelf life of beef covered with the SS-ε-PL-TA film was extended by 3 days compared to the control group by decreasing lipid oxidation and inhibiting bacterial growth, showing a good application potential in food packaging.

Study on preservation and monitoring effect of sodium alginate-konjac glucomannan films loaded with tea polyphenols and Lycium ruthenicum anthocyanins

To investigate the efficacy of sodium alginate-konjac glucomannan (SA-KGM) films with anthocyanins (LRA) and tea polyphenols (TP) in meat, beef and grass carp were selected as representative meat products for preservation and freshness monitoring experiments at 4 °C. Concurrently, storage experiments of the films were conducted in this controlled environment. The results of the storage experiment showed that the films delayed meat spoilage by 2-4 days, nearly doubling the preservation time compared to the blank control. Additionally, the film exhibited significant capability to monitor the spoilage process of beef and grass carp. It was revealed by curve fitting analysis that there was a significant correlation between the color change of the film and the spoilage index of the meat. Throughout the storage experiment with the film, it was observed that moisture significantly influenced the microstructure and bonding situation of the films, thereby impacting their mechanical and barrier properties. However, the films were still able to maintain satisfactory physicochemical properties in general. The above findings were crucial in guiding the promotion of the film within the food preservation industry.

Enzyme-responsive controlled-release materials for food preservation and crop protection - A review

The adoption of environmentally friendly and efficient methods to control food spoilage and crop diseases has become a new worldwide trend. In the medical field, various enzyme-responsive controlled-release drug formulations have been developed for precision therapy. Recently, these materials and techniques have also begun to be applied in the fields of food preservation and agricultural protection. This review of contemporary research focuses on applications of enzyme-responsive controlled-release materials in the field of food preservation and crop protection. It covers a variety of composite controlled-release materials triggered by different types of enzymes and describes in detail their composition and structure, controlled-release mechanisms, and practical application effects. The enzyme-responsive materials have been employed to control foodborne pathogens, fungi, and pests. These enzyme-responsive controlled-release materials exhibit excellent capabilities for targeted drug delivery. Upon contact with microorganisms or pests, the polymer shell of the material is degraded by secreted enzymes from these organisms, thereby releasing drugs that kill or inhibit the organisms. In addition, multi-enzyme sensitive carriers have been created to improve the effectiveness and broad spectrum of the delivery system. The increasing trend towards the use of enzyme-responsive controlled-release materials has opened up countless possibilities in food and agriculture.

Preparation, structural and functional characterization of corn peptide-chelated calcium microcapsules using synchronous dual frequency ultrasound

The utilization of peptide-chelated calcium is low due to the influence of factors such as solubility, heat and digestive environmental conditions; therefore, it is crucial to protect, prolong and stabilize this nutrient in order to enhance its efficacy. This study was conducted to prepare corn peptide-chelated calcium microcapsules using β-cyclodextrin (β-CD) as the wall material through an improved ultrasonic-assisted method. The structure, solubility, thermal stability, and in vitro gastrointestinal digestion of these microcapsules were thoroughly investigated and analyzed. The microcapsules were prepared using the following recommended conditions: a chelate concentration of 5 mg/mL, a mass ratio of chelate to β-CD of 1:8 g/g, and a synchronous dual-frequency ultrasound (20/28 kHz) at a power of 75 W, a duty ratio of 20/5 s/s, and a time of 20 min. These specific parameters were carefully selected to ensure the optimal fabrication of the microcapsules. The results showed that the utilization of dual-frequency ultrasound resulted in a significant increase in both the encapsulation rate and yield, which were enhanced by 15.84 % and 15.68 %, respectively, reaching impressive values of 79.17 % and 90.60 %. Moreover, the results of the structure index analysis provided further confirmation that ultrasonic treatment had a significant impact on the structure of the microcapsules, leading to a noticeable reduction in particle size and transformation into nanoparticles. Furthermore, the microcapsules demonstrated excellent solubility within a wide pH range of 2 to 10, with solubility ranging from 93.54 % to 88.68 %. Additionally, these microcapsules exhibited remarkable thermal stability, retaining a minimum of 84.8 % of their stability when exposed to temperatures ranging from 40 to 80 °C. Moreover, during gastric and intestinal digestion, these microcapsules exhibited a high slow-release rate of 44.66 % and 51.6 %, indicating their ability to gradually release calcium contents. The inclusion of dual-frequency ultrasound in the preparation of high calcium microcapsules yielded promising outcomes. Overall, our work presents a novel method for synthesizing corn peptide-chelated calcium microcapsules with desirable properties such as good solubility, excellent thermal stability, and a significant slow-release effect. These microcapsules have the potential to serve as fortified high calcium supplements.

A comprehensive review of intelligent controlled release antimicrobial packaging in food preservation

Intelligent responsive packaging provides informative feedback or control the release of active substances like antimicrobial agents in response to stimuli in food or the environment to ensure food safety. This paper provides an overview of two types of intelligent packaging, information-responsive and intelligent controlled-release, focusing on the recent research progress of intelligent controlled-release antimicrobial packaging with enzyme, pH, relative humidity, temperature, and light as triggering factors. It also summarizes the current status of application in different food categories, as well as the challenges and future prospects. Intelligent controlled-release technology aims to optimize the antimicrobial effect and ensure the quality of food products by synchronizing the release of active substances with food preservation needs through sensing stimuli, which is an innovative and challenging packaging technology. The paper seeks to provide a reference for the research and industrial development of responsive intelligent packaging and controlled-release packaging applications in food.

Inhibition of Cronobacter sakazakii Biofilm Formation and Expression of Virulence Factors by Coenzyme Q0

In this study, we investigated the inhibitory effects of coenzyme Q0 (CoQ0) on biofilm formation and the expression of virulence genes by Cronobacter sakazakii. We found that the minimum inhibitory concentration of CoQ0 against C. sakazakii strains ATCC29544 and ATCC29004 was 100 μg/mL, while growth curve assays showed that subinhibitory concentrations (SICs) of CoQ0 for both strains were 6.4, 3.2, 1.6 and 0.8 μg/mL. Assays exploring the inhibition of specific biofilm formation showed that SICs of CoQ0 inhibited biofilm formation by C. sakazakii in a dose-dependent manner, which was confirmed by scanning electron microscopy and confocal laser scanning microscopy analyses. CoQ0 inhibited the swimming and swarming motility of C. sakazakii and reduced its ability to adhere to and invade HT-29 cells. In addition, CoQ0 impeded the ability of C. sakazakii to survive and replicate within RAW 264.7 cells. Finally, real-time polymerase chain reaction analysis confirmed that nine C. sakazakii genes associated with biofilm formation and virulence were downregulated in response to CoQ0 treatment. Overall, our findings suggest that CoQ0 is a promising antibiofilm agent and provide new insights for the prevention and control of infections caused by C. sakazakii.

Essential oil encapsulation by electrospinning and electrospraying using food proteins: A review

Proteins are excellent polymeric materials for encapsulating essential oils (EOs) by electrospinning and electrospraying to protect these compounds and form nanomaterials with active properties. Proteins can encapsulate bioactive molecules by several mechanisms, including surface activity, absorption and stabilization mechanisms, amphiphilic nature, film-forming capacity, foaming, emulsification, and gelation, due to interactions among their functional groups. However, proteins have some limitations in encapsulating EOs by the electrohydrodynamic process. Their properties can be improved by using auxiliary polymers, increasing their charges by adding ionic salts or polyelectrolytes, denaturing their structure by heat, and exposure to specific pH conditions and ionic strength. This review addresses the main proteins used in electrospinning/electrospraying techniques, production methods, their interactions with EOs, bioactive properties, and applications in food matrices. Multivariate analysis associated with bibliometrics of metadata extracted from studies in Web of Science using the keywords electrospinning and essential oil (EO) were used as the search strategy.

Development of an edible food packaging gelatin/zein based nanofiber film for the shelf-life extension of strawberries

An edible food packaging gelatin/zein nanofiber film co-loaded with cinnamaldehyde (CA)/thymol (THY) was developed, which possessed outstanding features conducive to strawberries preservation. Firstly, the synergistic antibacterial behavior of CA and THY was investigated. Then CA and THY were co-loaded into gelatin/zein nanofiber films by electrospinning technology. The addition of CA and THY increased water contact angle to 85.1° after 10 s and decreased the water vapor transmission rate of 3.1×10^-8 g·mm^-1·h^-1·Pa^-1. The tensile strength was 1.30 MPa and the elongation at break was 185%. The nanofiber films exhibited good shielding effect of ultraviolet-visible light and excellent antioxidant capacity with DPPH free radical scavenging percentage of 99.9% in 4 h. The nanofiber films (12.5 mg/mL) could achieve significant inhibition effects on Escherichia coli ATCC 25922 with the bacteriostatic ratio of 67.5%, Staphylococcus aureus ATCC 6538 and Listeria monocytogenes ATCC 19115 with the antibacterial ratios of 100%. A real-time study on the nanofiber films as fruit packaging materials was carried out on strawberries and the packaged strawberries kept their freshness as long as 7 days at room temperature. Therefore, the GZ/CT nanofiber film prepared in this work has good application potential in the field of fruit packaging.

Inactivation of Salmonella using ultrasound in combination with Litsea cubeba essential oil nanoemulsion and its bactericidal application on cherry tomatoes

The presence of Salmonella in nature poses a significant and unacceptable threat to the human public health domain. In this study, the antibacterial effect and mechanism of ultrasound (US) combined with Litsea cubeba essential oil nanoemulsion (LEON) on Salmonella. LEON + US treatment has a significant bactericidal effect on Salmonella. Reactive oxygen species (ROS), malondialdehyde (MDA) detection, N-phenyl-l-naphthylamine (NPN) uptake and nucleic acid release assays showed that LEON + US exacerbated cell membrane lipid peroxidation and increased the permeability of the cell membrane. The results of field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) showed that LEON + US treatment was able to alter cell morphology. It can be observed by flow cytometry (FCM) that LEON + US treatment can cause cell apoptosis. In addition, bacterial counts of cherry tomatoes treated with LEON (0.08 μL/mL) + US (345 W/cm²) for 9 min were reduced by 6.50 ± 0.20 log CFU/mL. This study demonstrates that LEON + US treatment can be an effective way to improve the safety of fruits and vegetables in the food industry.

Replacement of polyethylene oxide by peach gum to produce an active film using Litsea cubeba essential oil and its application in beef

This study evaluated the effects of adding various concentrations (0 %, 1 %, 2 %, and 3 %) of peach gum (PG) to films made from polyethylene oxide (PEO) combined with Litsea cubeba essential oil (LCEO) to be utilized as active packaging for food in the future. The findings showed that the film containing PG 2 % concentration had the best physic-mechanical properties. In films made with PG, the glass transition temperature was significantly improved. Combining PG and PEO resulted in films that were brighter in color, had lower WVP values, and had the lowest water activity. Furthermore, XRD demonstrated that PG additions were compatible with the film of PEO blended with LCEO. The PG films formulated with PG presented high antioxidant and antibacterial activity against Staphylococcus aureus and E. coli. Wrapping beef with P2G2 film led to maintaining its quality with suitable levels of pH, TBARS, and TVB-N. This also decreased the number of E. coli and S. aureus in beef throughout the storage period. The results indicate that adding PG to PEO films enhances their suitability for food preservation.

Enhancement of water barrier and antimicrobial properties of chitosan/gelatin films by hydrophobic deep eutectic solvent

Biodegradable chitosan/gelatin (CS/GEL) films have attracted attention as food packaging, but the poor water sensitivity and functional limitations of these films should be addressed. In this study, the hydrophobic deep eutectic solvent (DES, 0-15 %) consisting of thymol and octanoic acid was used to improve the water resistance and antibacterial performance of the CS/GEL composite films. FTIR and SEM analyses revealed a strong interaction between the CS/GEL matrix and DES. The films blended with DES showed increased water contact angle values and thermal stability. Furthermore, the addition of DES resulted in a significant increase in the elasticity and decrease water vapor transmission rate (WVTR). The CS/GEL films blended with 9% DES showed a 38.5% decrease in WVTR compared to those without DES. Additionally, the DES-containing film displayed good antibacterial activity against Staphylococcus aureus and Escherichia coli. Overall, the CS/GEL-DES composite films are expected to contribute an improvement to food packaging.

Controlled Release of Thymol by Cyclodextrin Metal-Organic Frameworks for Preservation of Cherry Tomatoes

Thymol is a phenol monoterpene with potential antifungal, antioxidant and antibacterial activities. Due to the low water solubility and high volatility of thymol, encapsulation serves as an effective tool during application. In the present study, cyclodextrin (CD)-based metal-organic-frameworks (MOFs) were synthesized using α-CD, β-CD, and γ-CD as organic building blocks, and further complexed with thymol to produce three CD-MOF-THY inclusion complexes (ICs). The encapsulation content, release kinetics and fruit preservation effect of ICs were analyzed. Results showed that thymol was well embedded in γ-CD-MOFs, with the highest encapsulation content of 286.7 ± 8.4 mg/g. Release kinetics revealed that CD-MOFs exhibited a controlled release effect toward thymol for 35 days. The release kinetics of three ICs fit the Rigter-Peppas model well, with γ-CD-MOF-THY showing the lowest release rate constant of 2.85 at 50 °C, RH 75%. Moreover, γ-CD-MOF-THY exhibited a remarkable preservation performance on cherry tomatoes with the lowest decay index (18.75%) and weight loss (5.17%) after 15 days of storage, suggesting this material as a potential fresh-keeping material for fruit and vegetable preservation.