Properties of phenolic acid-chitosan composite films and preservative effect on Penaeus vannamei

Novel Electrospun Gelatin Nanofibers Loaded with Purple Potato Anthocyanin and Syringic Acid for Multifunctional Food Packaging

In this study, a series of novel nanofibers based on gelatin (GA) loading with purple potato anthocyanin (PPA) and syringic acid (SA) were obtained by electrospinning technology. The effects of SA on mechanical properties, thermal stability, antioxidant capacity, and antimicrobial activity of the GA/PPA nanofibers were systematically characterized. The scanning electron microscopy observation results revealed a smooth surface on the nanofibers. The incorporation of SA enhanced the viscosity of the electrospun solutions, and it increased the average diameter of nanofibers from 0.17 μm to 0.28 μm. The tensile strength and thermal stability of the obtained nanofibers were enhanced with the addition of a suitable level of SA (1.5%, w/v), which strengthened the intermolecular interaction. The GA/PPA/SA nanofibers presented over 80% antioxidant capacity and strong antibacterial activity against E. coli and S. aureus. Meanwhile, the sensitivity responses of nanofibers to NH3 revealed that GA/PPA/SA II nanofibers (1.5% w/v SA) presented good sensitivity of colorimetric behavior to ammonia. A pork spoilage test was performed to evaluate practical application of the nanofibers, and an obvious color change (dark purple to green) was observed. These results indicated GA/PPA/SA II nanofibers can be utilized as an active and intelligent multipurpose packaging material to preserve and track the freshness of pork.

Food-grade silica-loaded gallic acid nanocomposites: Synthesis and mechanism for enhancing water-based biological activity

As the low water solubility of gallic acid (GA), its biological activities such as water-based antioxidant effect may be greatly reduced. Therefore, GA-loaded nanocomposites (F-SiO2@GA) with high water solubility were synthesized via solvent evaporation using food-grade silica (F-SiO2) as carriers in this work. The assessment of antioxidant capacity revealed that F-SiO2@GA exhibited considerably greater free-radical scavenging ability than free GA and the physical mixture of F-SiO2 and GA. In the photooxidation experiment of food-grade gardenia yellow pigment (GYP), F-SiO2@GA showed a notable antioxidant effect on GYP solution. Additionally, in the storage experiment on chilled whiteleg shrimp (Litopenaeus vannamei) treated with F-SiO2@GA, pH, total volatile basic nitrogen (TVBN), and thiobarbituric acid reactive substance (TBARS) values were effectively inhibited. In conclusion, the internal encapsulation of GA effectively prevented the self-aggregation phenomenon, thereby facilitating the exposure of its active phenolic hydroxyl group and significantly enhancing its water-based biological activity.

Natural Extracts and Their Applications in Polymer-Based Active Packaging: A Review

At a time when food safety awareness is increasing, attention is paid not only to food and additives but also to packaging materials. Most current food packaging is usually made of traditional petroleum-based polymeric materials, which are not biodegradable and have adverse effects on the environment and health. In this context, the development of new non-toxic and biodegradable materials for extending the best-before date of food is receiving increasing attention. In addition, additives in packaging materials may migrate outward, resulting in contact with food. For this reason, additives are also seen as a transition from synthetic additives to natural extracts. Active extracts from animals and plants having good antioxidant and antibacterial properties are also beneficial for human health. It is indisputable that active extracts are ideal substitutes for synthetic additives. Polymer packaging materials combined with active extracts not only maintain their original mechanical and optical properties and thermal stability but also endow polymers with new functions to extend the shelf life of food. This review paper provides an overview of this promising natural extract-containing polymer-based active packaging, with a focus on plant essential oils (containing phenolics, monoterpenes, terpene alcohols, terpene ketones, and aldehydes), pigments (procyanidins), vitamins (vitamin B), and peptides (nisin). In particular, this paper covers the research progress of such active extracts, in single or compound forms, combined with diverse polymers (mostly biopolymers) for food packaging applications with particular focus on the antioxidant and antibacterial properties of packaging materials.

Enhanced mechanical properties and antibacterial activities of chitosan films through incorporating zein-gallic acid conjugate stabilized cinnamon essential oil Pickering emulsion

In this study, zein-gallic acid covalent complex prepared by alkali treatment was utilized as an emulsifier to stabilize cinnamon essential oil (CEO) Pickering emulsion, and the chitosan-based (CZGE) films loaded with CEO Pickering emulsion were prepared by blending. The influences of different contents of CEO Pickering emulsion on the physical properties and biological activities of CZGE films were investigated. The results showed that Pickering emulsion had good compatibility with chitosan matrix and enhanced the interaction between film-forming matrix polymer. In addition, incorporating with CEO Pickering emulsion (15 %, v/v) significantly improved the mechanical and barrier properties of the films, and also enhanced the light transmittance and thermal stability of the films. Furthermore, the loading of emulsion also improved the antioxidant activities of the films and led to the formation of high antimicrobial property against food pathogens, and the slow-release behavior of CEO could effectively extend the biological activity of the films. These results suggested that Pickering emulsion has potential as a loading system and a plasticizer in active packaging, and the feasibility of CZGE film in food packaging.

Antibacterial and antioxidant properties of phenolic acid grafted chitosan and its application in food preservation: A review

Chitosan is a bio-renewable natural polymeric material. The antibacterial and antioxidant activity of chitosan can be enhanced by grafting with phenolic acids to further expand its application in food. Therefore, this paper focuses on reviewing the structure, antimicrobial and antioxidant activities and their mechanisms with phenolic acid-g-CS, evaluating its cytotoxicity, and describing its application in various food preservation. In general, different reaction mechanisms of phenolic acid-g-CS synthesis lead to different product structures. Compared to chitosan, phenolic acid-g-chitosan exhibited enhanced antibacterial and antioxidant activities. The toxicity assessment showed that phenolic acid-g-CS is not cytotoxic. Moreover, phenolic acid-g-CS has been applied to a variety of food products such as fruits, vegetables and meat with good results. Overall, this review provides a certain reference for subsequent researchers to design phenolic acid-g-CS more rationally and for the subsequent development of phenolic acid-g-CS in food preservation.

Efficacy of Chitosan Oligosaccharide Combined with Cold Atmospheric Plasma for Controlling Quality Deterioration and Spoilage Bacterial Growth of Chilled Pacific White Shrimp (Litopenaeus vannamei)

A novel food processing technique based on the combination of cold atmospheric plasma (CAP) and chitosan oligosaccharide treatment (COS) was developed to enhance antibacterial performance and extend the shelf life of Pacific white shrimp (Litopenaeus vannamei). Effects of different treatments on the microbial community composition, physicochemical properties, and post-storage behaviors of Pacific white shrimp were evaluated during chilled storage for up to 10 days. Results showed that the synergistic effects of COS and CAP could be obtained, largely inhibiting the growth of microorganisms. The content of total volatile basic nitrogen (TVB-N), total viable counts (TVC), and pH value in treated groups were lower than in the control group and the loss of moisture content, water activity, and sensory score were observed. Compared to the control group, shrimp was on the verge of spoilage on the 6th day of storage, while the COS-CAP-treated shrimp had a 4-day lag period. Moreover, the COS and CAP could effectively inhibit the growth of Aliivibrio, the predominant microbial group in the ultimate storage period. This study suggests that the combined utilization of COS and CAP could be a high-efficacy technique for extending the shelf-life of shrimp.

The Application of Phenolic Acids in The Obtainment of Packaging Materials Based on Polymers-A Review

This article provides a summarization of present knowledge on the fabrication and characterization of polymeric food packaging materials that can be an alternative to synthetic ones. The review aimed to explore different studies related to the use of phenolic acids as cross-linkers, as well as bioactive additives, to the polymer-based materials upon their application as packaging. This article further discusses additives such as benzoic acid derivatives (sinapic acid, gallic acid, and ellagic acid) and cinnamic acid derivatives (p-coumaric acid, caffeic acid, and ferulic acid). These phenolic acids are mainly used as antibacterial, antifungal, and antioxidant agents. However, their presence also improves the physicochemical properties of materials based on polymers. Future perspectives in polymer food packaging are discussed.

Functionalized cellulose nanocrystal embedded into citrus pectin coating improves its barrier, antioxidant properties and potential application in food

Due to the hydrophilic of the pectin material, the coating has poor barrier properties and a negative preservation effect on fresh fruits. In this study, citrus pectin coating with improved barrier and antioxidant properties was prepared by embedding with functional cellulose nanocrystals (CNC). It was assessed that cellulose nanocrystals grafted with p-coumaric acid (CNC-P) were uniformly dispersed in the pectin matrix to improve coating barrier properties. The addition of 8 % CNC-P to the pectin coating led to a decrease in water vapor and oxygen permeability from the coating by 12.6 % and 22.3 %, respectively. Additionally, the grafted p-coumaric acid (PA) introduced antioxidant properties to the cellulose nanocrystals. The fresh-cut fruits preservation assay showed that the coating containing CNC-P exerted a stronger inhibition effect of the browning process within 8 h than other coatings. This study suggests that pectin coating embedded with CNC-P has the potential to be used in food packaging.

Biodegradable active materials containing phenolic acids for food packaging applications

The development of new materials for food packaging applications is necessary to reduce the excessive use of disposable plastics and their environmental impact. Biodegradable polymers represent an alternative means of mitigating the problem. To add value to biodegradable materials and to enhance food preservation, the incorporation of active compounds into the polymer matrix is an affordable strategy. Phenolic acids are plant metabolites that can be found in multiple plant extracts and exhibit antioxidant and antimicrobial properties. Compared with other natural active compounds, such as essential oils, phenolic acids do not present a high sensorial impact while exhibiting similar minimal inhibitory concentrations against different bacteria. This study summarizes and discusses recent studies about the potential of both phenolic acids/plant extracts and biodegradable polymers as active food packaging materials, their properties, interactions, and the factors that could affect their antimicrobial efficiency. The molecular structure of phenolic acids greatly affects their potential antioxidant and antimicrobial capacity, as well as their specific interactions with polymer matrices and food substrates. These interactions, in turn, can lead to plasticizing or cross-linking effects. In the present study, the antioxidant and antimicrobial properties of different biodegradable films with phenolic acids have been described, as well as the main factors affecting the active properties of these films as useful materials for active packaging development. More studies applying these active materials in real foods are required.

Chitosan based film reinforced with EGCG loaded melanin-like nanocomposite (EGCG@MNPs) for active food packaging

In this study, EGCG loaded melanin-like nanoparticles (EGCG@MNPs) were incorporated into chitosan matrix to prepare an active nanocomposite food packaging film, chitosan-EGCG@MNPs (CH-EM). The influence of EGCG@MNPs on the physical and biological properties of the chitosan film was investigated. The EGCG@MNPs nanoparticles were cross-linked with chitosan through intermolecular hydrogen bonds and uniformly distributed in the matrix. Besides, the incorporation of EGCG@MNPs tremendously improved the solubility, swelling ratio and water vapor barrier properties of the film, and permitted superior ultraviolet rays blocking property. In addition, the mechanical properties, thermal stability and surface hydrophobicity have also been significantly improved. The CH-EM^2.0 nanocomposite films also showed excellent oxidation resistance (58.4 ± 4.4%, DPPH and 92.4 ± 1.3%, ABTS⁺), and strong inhibitory ability against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The experimental results comprehensively showed that the prepared chitosan-EGCG@MNPs nanocomposite film offering excellent potential for eco-friendly active food packaging.

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

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

Effects of ultrasound-assisted chitosan grafted caffeic acid coating on the quality and microbial composition of pompano during ice storage

The effects of ultrasound-assisted chitosan grafted caffeic acid coating on the quality and microbial composition of fresh pompano (Trachinotus ovatus) fillets during ice storage for 24 days were evaluated. Samples were treated by distilled water (CK), ultrasound (US), chitosan grafted caffeic acid coating (G), and chitosan grafted caffeic acid coating with ultrasound-assisted (USG). Results showed that samples treated with USG could inhibit the formation of corrupt substances such as TVB-N, TBA, biogenic amines (BAs), hypoxanthine (Hx), and hypoxanthine riboside (HxR) when compared to the CK group.The results of high-throughput sequencing technology observed that the major bacteria genus of fresh samples was Acinetobacter.The diversity of bacterial communities at the initial stage was more diverse than that at the end of stage. With the extension of storage time, the USG treatment could maintain the microbial diversity. The dominant microbiota was Shewanella and Brochothrix in the CK group after 24 days of storage. In addition, Brochothrix in treated groups was effectively decreased. The microbial communities of samples in all treatments were changed during storage. At the end of storage, there was a significant difference in bacterial composition between the CK and treated samples, indicating that the treatment can effectively inhibit the growth of microorganisms, especially spoilage microorganisms, and reduce the quality deterioration caused by bacteria.

Recent advances in extraction, modification, and application of chitosan in packaging industry

Current environmental concerns fostered a strong interest in extracting polymers from renewable feedstocks. Chitosan, a second most abundant polysaccharide after cellulose, may prove to be a promising green material owing to its renewability, inherent biodegradablity, natural availability, non-toxicity, and ease of modification. This review is intended to comprehensively overview the recent developments on the isolation of chitosan from chitin, its modification and applications as a reinforcing candidate for food packaging materials, emphasizing the scientific underpinnings arising from its physicochemical properties, antimicrobial, antioxidant, and antifungal activities. We review various chitosan-reinforced composites reported in the literature and comprehensively present intriguing mechanical and other functional properties. We highlight the contribution of these mechanically robust and responsive materials to extend the shelf-life and maintain the qualities of a wide range of food commodities. Finally, we assess critical challenges and highlight future opportunities towards understanding the versatile applications of chitosan nanocomposites.

The Physicochemical, Antioxidant, and Color Properties of Thin Films Based on Chitosan Modified by Different Phenolic Acids

Chitosan-based films are promising for consideration as packaging materials. In this study, we modified the chitosan by phenolic acid addition, such as ferulic acid, caffeic acid, tannic acid, and gallic acid. The mechanical and thermal properties were studied, and the water vapor permeability rate was determined. Moreover, the antioxidant activity and film color were considered. The results showed that phenolic acids are effective cross-linkers for chitosan. The addition of phenolic acids improved the mechanical properties and decreased the roughness of surfaces. The enthalpy value was lower for films with phenolic acids than for pure chitosan. Chitosan with ferulic acid showed the highest antioxidant activity and water permeability value. Based on the obtained results, we determined that films obtained from the chitosan/ferulic acid mixture are the most promising for use as packaging material.

Physicochemical properties of films produced using nanoemulsions stabilized by carboxymethyl chitosan-peptide conjugates and application in blueberry preservation

Carboxymethyl chitosan (CMCh)-peptide conjugates were produced by grafting CMCh with peptides from hemp seed, maize and casein. The nanoemulsions stabilized by these conjugates had smaller droplet size and better emulsifying properties. Nanoemulsions stabilized by conjugates were used to develop active films containing Camellia essential oil and the effect of conjugation on physicochemical properties of resulting films was evaluated. Water vapor and oxygen barrier properties, tensile strength, flexibility, and temperature of endothermic peak increased 6.6-19.8% and 6.9-27.2%, 40.1-96.6%, 61.4-83.3% and 7.8-18.5%, respectively when the CMCh-peptide conjugates were used to emulsify the essential oil. The conjugation helped to form compact structure. All of the films containing essential oil emulsions stabilized by conjugates showed the ability to extend the shelf-life of blueberry by maintaining the firmness, reducing the weight loss and slowing down the formation of soluble solids.

Phenolic-Rich Plant Extracts With Antimicrobial Activity: An Alternative to Food Preservatives and Biocides?

In recent years, the search for natural plant-based antimicrobial compounds as alternatives to some synthetic food preservatives or biocides has been stimulated by sanitary, environmental, regulatory, and marketing concerns. In this context, besides their established antioxidant activity, the antimicrobial activity of many plant phenolics deserved increased attention. Indeed, industries processing agricultural plants generate considerable quantities of phenolic-rich products and by-products, which could be valuable natural sources of natural antimicrobial molecules. Plant extracts containing volatile (e.g., essential oils) and non-volatile antimicrobial molecules can be distinguished. Plant essential oils are outside the scope of this review. This review will thus provide an overview of current knowledge regarding the promises and the limits of phenolic-rich plant extracts for food preservation and biofilm control on food-contacting surfaces. After a presentation of the major groups of antimicrobial plant phenolics, of their antimicrobial activity spectrum, and of the diversity of their mechanisms of action, their most promising sources will be reviewed. Since antimicrobial activity reduction often observed when comparing in vitro and in situ activities of plant phenolics has often been reported as a limit for their application, the effects of the composition and the microstructure of the matrices in which unwanted microorganisms are present (e.g., food and/or microbial biofilms) on their activity will be discussed. Then, the different strategies of delivery of antimicrobial phenolics to promote their activity in such matrices, such as their encapsulation or their association with edible coatings or food packaging materials are presented. The possibilities offered by encapsulation or association with polymers of packaging materials or coatings to increase the stability and ease of use of plant phenolics before their application, as well as to get systems for their controlled release are presented and discussed. Finally, the necessity to consider phenolic-rich antimicrobial plant extracts in combination with other factors consistently with hurdle technology principles will be discussed. For instance, several authors recently suggested that natural phenolic-rich extracts could not only extend the shelf-life of foods by controlling bacterial contamination, but could also coexist with probiotic lactic acid bacteria in food systems to provide enhanced health benefits to human.

Improving the functionality of chitosan-based packaging films by crosslinking with nanoencapsulated clove essential oil

The study aimed to obtain chitosan composite films with gratifying physical and functional properties. First, we developed a Pickering emulsion containing clove essential oil (CEO)-loaded nanoparticles with 1:2 (w/w) zein and sodium caseinate (NaCas). We found that in this ratio, the CEO-loaded zein-NaCas (C/ZN) nanoparticles had smaller particle size, proper polydispersity index (PDI) and zeta potential as well as higher encapsulation efficiency. Then, the acquired C/ZN nanoparticles were incorporated into chitosan film at three levels (0.2%, 0.4% and 0.6%), reducing the water vapor permeability to 4.62 × 10^-6 g·s^-1·m^-1·Pa. Also, the tensile strength and break elongation of chitosan films were increased, reaching 38.67 MPa and 1.56%, respectively. The infrared spectroscopy verified that the intermolecular hydrogen bonds exist between chitosan and C/ZN nanoparticles. The chitosan composite films showed a controlled-release property of CEO in 96 h. Finally, the chitosan composite films showed the improved antibacterial property by creating larger inhibition zones against Escherichia coli (3.29 mm) and Staphylococcus aureus (6.15 mm). In general, we improved the water resistance, light blocking, mechanical strength, controlled-release and antibacterial properties of chitosan film with C/ZN nanoparticles. The current edible antibacterial films have great potential on applications for food preservation and food delivery system.

Recent Advances in Biological Activity, New Formulations and Prodrugs of Ferulic Acid

Trans-ferulic acid (FA) is a derivative of 4-hydroxycinnamic acid, which is found in many food products, fruits and beverages. It has scientifically proven antioxidant, anti-inflammatory and antibacterial properties. However, its low ability to permeate through biological barriers (e.g., the blood-brain barrier, BBB), its low bioavailability and its fast elimination from the gastrointestinal tract after oral administration limit its clinical use, e.g., for the treatment of neurodegenerative diseases, such as Alzheimer's disease. Therefore, new nanotechnological approaches are developed in order to regulate intracellular transport of ferulic acid. The objective of this review is to summarize the last decade's research on biological properties of ferulic acid and innovative ways of its delivery, supporting pharmacological therapy.

Synergistic Antimicrobial Activities of Thai Household Essential Oils in Chitosan Film

Foodborne pathogens mostly contaminate ready-to-eat (RTE) meat products by post-process contamination and cause foodborne disease outbreaks. Preventing post-process contamination and controlling microbial growth during storage by packing the RTE meats with active antimicrobial film from chitosan combined with the synergism of Thai household essential oils was investigated. Here, we analyzed antimicrobial activity and mechanical properties of chitosan films incorporated with essential oil of fingerroot (EOF) and holy basil (EOH) based on their fractional inhibitory concentration and isobolograms. We showed that antimicrobial activities of chitosan film and chitosan films formulated with EOF:EOH displayed a dramatical reduction of Listeria monocytogenes Scott A concentration by 7 Log in 12 h. Chitosan film incorporated with EOF:EOH at ratio 0.04:0.04% v/v/w strongly retarded growth of total viable count of L. monocytogenes on vacuum-packed bologna slices during seven days of storage at 4 and 10 °C. Combined EOF and EOH added to chitosan films did not alter thickness, elongation (%) and colors (L*, a* and b*) of the chitosan film, but it increased water vapor transmission rate and decreased film tensile strength. Results suggested that chitosan film had strong antibacterial properties. Its effectiveness in inhibiting foodborne pathogenic bacteria in ready-to-eat meat products was enhanced by adding a combination of EOF:EOH.