Antimicrobial and Antioxidant Effects of Kappa-Carrageenan Coatings Enriched with Cinnamon Essential Oil in Pork Meat

Behavior of Spoilage Bacterial Communities in Different Cuts of Enshi Black Pork under Refrigerated Storage (4 °C)

The Enshi black pig is a Chinese native breed known for its rich nutrition content and high quality, which has notable traction in the consumer market. In this study, the potential impact of the main commercial cuts from Enshi black pork carcasses (ham, loin, and belly) on the bacteria community of spoiled meat under refrigerated storage (4 °C) was assessed by using a high-throughput sequencing method. Moreover, the spoilage potential of isolated strains from spoiled pork was investigated. The results demonstrated significant differences (p < 0.05) in bacterial community diversity and composition among spoiled ham, loin, and belly samples. Linear discriminant analysis effect size (LEfSe) analysis revealed a total of 20 significantly different potential bacterial biomarkers, with the dominant genera of Pseudomonas, Psychrobacter, Shewanella and Carnobacterium. Additionally, C. divergens THT1-5, isolated from spoiled ham samples, displayed cold adaptation and higher spoilage potential in Enshi black pork. These findings are helpful for identifying key factors contributing to spoilage in Enshi black pork and developing strategies to inhibit bacterial growth during preservation.

Techniques, applications and prospects of polysaccharide and protein based biopolymer coatings: A review

The growing relevance of sustainable materials has recently led to the exploration of naturally derived biopolymeric hydrogels as coating materials due to their biodegradability, biocompatibility, ease of fabrication and modification. Although many review articles exist on biopolymeric coatings, they mainly focus on a specific polysaccharide, protein biopolymer, or a particular application- biomedical engineering or food preservation. The current review first summarizes the commonly used polysaccharide and protein-based biopolymers like chitosan, alginate, carrageenan, pectin, cellulose, starch, pullulan, agarose and silk fibroin, gelatin, respectively, with a systematic description of the techniques widely used for physical coating on substrates. Then, broad applications of these biopolymeric coatings on various substrates in biomedical engineering- 3D scaffolds, biomedical implants, and nanoparticles are described in detail. It also entails the application of biopolymeric coatings for food preservation in the form of food packaging and edible coatings. A brief discussion on the newly discovered interest in exploring biopolymers for anticorrosive coating applications is also included. Finally, concluding remarks on the role of biopolymer microstructures in forming homogeneous coatings, prospective alternatives to the currently used biopolymers as coating material and the advent of computer-aided technologies to expedite experimental findings are presented.

Investigating the effects of chitosan/ tragacanth gum/ polyvinyl alcohol composite coating incorporated with cinnamon essential oil nanoemulsion on safety and quality features of chicken breast fillets during storage in the refrigerator

The present study investigated the effects of composite coatings made of chitosan (CS), tragacanth gum (TG), and polyvinyl alcohol (PVA) containing cinnamon essential oil (CEO) on the shelf-life of refrigerated chicken breast fillets. The samples were treated with different coating dispersions, and coded as: T1 (distilled water as control), T2 (blank composite coating), and T3 (composite coating containing CEO). Results showed that incorporating CEO into CS/TG/PVA coatings could significantly increase the quality of chicken fillets. The obtained results showed that after 21 days, the total microbial population of lactic acid bacteria (LAB), psychrotrophic and mesophilic bacteria in T3 samples was less than T1 and T2 samples. In addition, the highest antioxidant activity (48.04 %) and total phenolic content (TPC) values (2.458 mg gallic acid /g), the best sensory characteristics and the lowest pH (5.73), total volatile basic nitrogen (TVB-N) (21.89 mg N/100 g), thiobarbituric acid reactive substances (TBARS) (1.678 mg malondialdehyde equivalent/kg) and percentage of cooking loss (30 %) were related to T3. Results disclosed that this composite coating is a promising technology to improve the shelf life of chicken fillets during storage.

Development of functional, sustainable pullulan-sodium alginate-based films by incorporating essential oil microemulsion for chilled pork preservation

Developing safe, eco-friendly, and functionally edible packaging materials has attracted global attention. Essential oils, can be incorporated into packaging materials as antioxidant and antibacterial agents. However, their high volatility and discontinuous film matrix issues may cause a rough film surface, limiting the application in food packaging. In this study, thyme essential oil microemulsion (TEO-M) was prepared and incorporated into a pullulan-sodium alginate (PS) film. The TEO-M incorporation endowed the PS film with antioxidant and UV protection properties. The antioxidant activities of the TEO-M-incorporated PS film were significantly better than those of the TEO-C (thyme essential oil coarse emulsion)-incorporated PS film. In comparison to TEO-C, the distribution of TEO-M in the film is more uniform. Lipid oxidation and the growth of microorganisms in chilled pork were inhibited by incorporating TEO-M at a concentration of 50 mg/mL in the PS film (PS-50M). After 10 days of storage at 4 °C, the total viable count (TVC) of chilled pork preserved in the PS-50M material was significantly reduced compared to the control group (P < 0.05). This study shows that incorporating TEO-M in the PS film provides a method for applying essential oils in food packaging, which may have great potential in the food industry.

Current and emerging applications of carrageenan in the food industry

Carrageenan, a polysaccharide derived from red algae, has a long history of use as a food additive in food. Carrageenan comes in three classes, κ-, ι-, and λ-carrageenan, with different properties attributed to their organosulfate substitution levels, and their interactions with other food components give rise to properties such as water holding, thickening, gelling, and stabilizing. Over the years, carrageenan has been used in wide variety of food products such as meat, dairy, and flour-based products, and their mechanisms and functions in these matrices have also been studied. With the emergence of novel food technologies, carrageenan's potential applications have been extensively explored alongside, including encapsulation, edible films/coatings, plant-based analogs, and 3D/4D printing. As the food technology evolves, the required functions of food ingredients have changed, and carrageenan is being investigated for its role in these new areas. However, there are many similarities in the use of carrageenan in both classic and emerging applications, and understanding the underlying principles of carrageenan will lead to a proper use of carrageenan in emerging food products. This review focuses on the potential of carrageenan as a food ingredient in these emerging technologies mainly based on papers published within the past five years, highlighting its functions and applications to better understand its role in food products.

Antibacterial Activity of Zinc Oxide Nanoparticles Loaded with Essential Oils

One major problem with the overuse of antibiotics is that the microorganisms acquire resistance; thus the dose must be increased unsustainably. To overcome this problem, researchers from around the world are actively investigating new types of antimicrobials. Zinc oxide (ZnO) nanoparticles (NPs) have been proven to exhibit strong antimicrobial effects; moreover, the Food and Drugs Administration (FDA) considers ZnO as GRAS (generally recognized as safe). Many essential oils have antimicrobial activity and their components do not generate resistance over time. One of the drawbacks is the high volatility of some components, which diminishes the antimicrobial action as they are eliminated. The combination of ZnO NPs and essential oils can synergistically produce a stronger antimicrobial effect, and some of the volatile compounds can be retained on the nanoparticles' surface, ensuring a better-lasting antimicrobial effect. The samples were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), and thermal analysis (TG-DSC) coupled with analysis of evolved gases using FTIR. The ZnO NPs, with a size of ~35 nm, exhibited a loading between 1.44% and 15.62%-the lower values were specific for limonene-containing oils (e.g., orange, grapefruit, bergamot, or limette), while high values were obtained from cinnamon, minzol, thyme, citronella, and lavender oils-highlighting differences among non-polar terpenes and alcohol or aldehyde derivatives. The antibacterial assay indicated the existence of a synergic action among components and a high dependency on the percentage of loaded oil. Loaded nanoparticles offer immense potential for the development of materials with specific applications, such as wound dressings or food packaging. These nanoparticles can be utilized in scenarios where burst delivery is desired or when prolonged antibacterial activity is sought.

Plant Antimicrobials for Food Quality and Safety: Recent Views and Future Challenges

The increasing demand for natural, safe, and sustainable food preservation methods drove research towards the use of plant antimicrobials as an alternative to synthetic preservatives. This review article comprehensively discussed the potential applications of plant extracts, essential oils, and their compounds as antimicrobial agents in the food industry. The antimicrobial properties of several plant-derived substances against foodborne pathogens and spoilage microorganisms, along with their modes of action, factors affecting their efficacy, and potential negative sensory impacts, were presented. The review highlighted the synergistic or additive effects displayed by combinations of plant antimicrobials, as well as the successful integration of plant extracts with food technologies ensuring an improved hurdle effect, which can enhance food safety and shelf life. The review likewise emphasized the need for further research in fields such as mode of action, optimized formulations, sensory properties, safety assessment, regulatory aspects, eco-friendly production methods, and consumer education. By addressing these gaps, plant antimicrobials can pave the way for more effective, safe, and sustainable food preservation strategies in the future.

Chitosan-based packaging films with an integrated antimicrobial peptide: Characterization, in vitro release and application to fresh pork preservation

Chitosan (CS) films were developed incorporating peptide HX-12C. The films were studied to determine their microstructures, physical properties, release properties of peptide HX-12C and functional properties. The results indicated that there may be hydrogen bonding interactions between CS and peptide HX-12C, thereby creating a homogeneous internal microstructure and lower crystallinity (10.8-12.8 %). Compared with CS film, CS-HX-12C films displayed lower light transmission, MC (20.8-19.9 %), WVP (8.82-8.59 × 10^-11·g·m^-1·s^-1·Pa^-1), OTR (0.015-0.037 cc/(m².day)) and higher WS (15.7-32.4 %) values. Moreover, controlled-release experiments showed that pH, ionic strength and temperature could all significantly affect the release of peptide HX-12C from the films. Finally, the increase of pH value and TVC and lipid oxidation of fresh pork were delayed due to the treatment with CS-2%HX-12C film. However, incorporating peptide HX-12C into CS films did not improve the mechanical properties of the films and their effects against protein oxidation. Our results suggest that the CS-based antimicrobial packaging films integrated with peptide HX-12C exhibit the potential for fresh pork preservation.

Development and Application of Edible Coatings with Malva sylvestris L. Extract to Extend Shelf-Life of Small Loaf

Edible coatings that have a recognized ecological effect are an alternative to retard the processes of moisture evaporation and mold growth in bakery products. The aim of the present research was to study the influence of Malva sylvestris L. (mallow) flowers' extract on the antimicrobial activity of edible coatings of three types of polysaccharides, pectin/P/, xanthan/X/ and carboxymethylcellulose/C/, as well as to analyze their effect on the freshness and microbiological status of coated small loaves during storage. It was found that the presence of a mallow extract had a positive effect on the fungicidal and yeasticidal activities of the X and C coatings. The loaves were evaluated for their physical (moisture, color), textural (firmness and crumb firming kinetics) and microbiological characteristics. The coatings (P, X and C) with mallow extract had the strongest moisture-retaining effect on the loaves' crumb. The coatings with X and with P (with/without mallow extract) significantly slowed down the crumb firming process, and the value of the rate constant for the crumb firming (k) is the lowest for the X coating-0.1815 day^-1. The smallest changes in the crust color were reported when mallow-based coatings were used. They have also been proven to have the lowest microbial load when they are stored for up to three days. This study shows that polysaccharide edible coatings with an active mallow component have significant potential to extend the shelf life of bakery products.