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The objective of this study was to develop novel functional stabilizers for Pickering emulsions using phenolic acids-grafted chitin nanofibers (phenolic acids-g-ChNF), which were fabricated by grafting ferulic acid (FA), sinapic acid (SA) and caffeic acid (CA) onto ChNF via free radical-mediated method. The Fourier transform infrared spectrum and Proton nuclear magnetic resonance showed that graft copolymerization occurred between the amino groups of ChNF and the carbonyl of the phenolic acids. Further, it was revealed that CA-g-ChNF and SA-g-ChNF possessed stronger antioxidant and antibacterial properties than the original ChNF and FA-g-ChNF. Additionally, we applied phenolic acids-g-ChNF to develop Pickering emulsions and found that SA-g-ChNF- and CA-g-ChNF-stabilized emulsions displayed reduced droplet sizes compared to FA, the main reason for which was that SA and CA had a rather close bonding relationship with ChNF. Taken together, SA-g-ChNF and CA-g-ChNF as novel multi-functional particles can be employed for facilitating the stability of Pickering emulsions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Resveratrol (RES) is a natural polyphenol with a variety of health beneficial properties, but its application is greatly limited due to low aqueous solubility and poor bioavailability. This study aims to address these issues via gliadin nanoparticles stabilized with oxidized chitin nanocrystals (O-ChNCs) as a delivery system for RES. RES-loaded gliadin nanoparticles (GRNPs) were fabricated by an antisolvent method, and their formation mechanism was elucidated using zeta-potential, FTIR, XRD, and TEM. Furthermore, the effect of O-ChNCs on the colloidal stability and bioactiveness of GRNPs was discussed. The results demonstrate that O-ChNCs are adsorbed onto the surface of GRNPs through hydrogen bonding and electrostatic interactions, leading to the enhanced absolute potential and the improved hydrophobicity of the particles, which in turn facilitates the stability of the GRNPs. Furthermore, the changes in the release profile and antioxidant activity of RES in the simulated gastric and intestinal tracts indicate that the adsorption of O-ChNCs not only delays the release of RES but also has a protective effect on the antioxidant capacity of RES. This study provides significant implications for developing stable gliadin nanoparticles as delivery vehicles for bioactive substances.

An electrospun nanofiber based on pullulan/chitin nanofibers (PCN) containing curcumin (CR) and anthocyanins (ATH) was developed using an electrospinning technique for active-intelligent food packaging. The results of scanning electron microscopy and attenuated total reflection Fourier transform infrared spectroscopy indicated that CR and ATH were successfully immobilized on the film-forming substrate based on PCN. The physical and chemical properties of nanofibers with no colorant, a single colorant, and double colorants were compared. The nanofiber containing ATH and CR (PCN/CR/ATH) had stronger antioxidant and antimicrobial activities than those of nanofibers containing CR (PCN/CR) or ATH (PCN/ATH). With respect to pH sensitivity, the color of the PCN/CR nanofibers did not change obviously, but the color of the PCN/ATH and PCN/CR/ATH nanofibers changed significantly with the change in pH. Furthermore, the PCN/CR/ATH nanofibers clearly changed color with the progressive spoilage of Plectorhynchus cinctus at room temperature. Therefore, the electrospun PCN/CR/ATH nanofiber have great application potential in active-intelligent food packaging., (Copyright © 2021. Published by Elsevier B.V.)

Novel bionanocomposite films were prepared by combining konjac glucomannan/surface deacetylated chitin nanofibers (KGM/S-ChNFs) with different concentrations of citric acid (CA) (10%-25%) via a solution casting method. The effect of CA-induced crosslinking on the rheological behavior of film-forming solutions (FFS) as well as the structural and physicochemical properties of the resulting bionanocomposite films were evaluated. The results revealed that the increased CA loadings increased the shear viscosity of FFS. Fourier transform infrared spectra and scanning electron microscopy results confirmed the successful crosslinking between CA and S-ChNFs. The addition of 20 wt% CA was defined as the optimal condition, resulting in minimum water sensitivity and permeability, while maintaining a good combination of tensile strength and antimicrobial properties. This work supported the conclusion that CA crosslinking was an effective pathway for the preparation of polysaccharide-based bionanocomposite films with improved properties, which may be a promising material for active food packaging applications., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest in the publication of this article., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A novel intelligent film was developed by immobilizing 1%, 3% and 5% black rice bran anthocyanins (BACNs) into oxidized-chitin nanocrystals (O-ChNCs)/ chitosan (CS) matrix. The ultraviolet-visible spectrum of BACNs solutions showed color variations from red to greyish green in a range of pH 2.0-12.0. Fourier transform infrared spectrum and atomic force microscope of the films showed that O-ChNC and BACNs were well dispersed into the CS matrix. Although the incorporation of BACNs decreased the mechanical and barrier properties of the CS/O-ChNCs/BACNs (COB) films, it endowed the COB films with excellent UV-barrier, antioxidant and pH sensitivity character. The results of the application trial showed that the COB films containing 3% of BACNs (COB-3) were able to monitor the spoiling of fish and shrimp by visible color changes. Therefore, the developed COB-3 films could be used as an intelligent food packaging for monitoring animal-based protein food spoilage., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The development of biopolymer-based films for food packaging is increasing owing to their environmental appeal, renewability, and biodegradability. In this study, transparent and biodegradable konjac glucomannan (KGM)/chitosan (CS)/TEMPO-oxidized chitin nanocrystal (TEMPO-ChNCs) bionanocomposite films were prepared. The TEMPO-ChNCs were prepared from chitin using the 2,2,6,6-tetramethylpiperidine-1-oxylradical (TEMPO) oxidation method and were used as a reinforcement nanofiller for the bionanocomposite films. The effect of TEMPO-ChNCs content on both rheological properties of film-forming solutions (FFS) and structural and physical properties of the resultant films was investigated. The rheological results of the FFS revealed that the TEMPO-ChNCs interacted with KGM and CS through electrostatic interaction and the hydrogen bonds in the bionanocomposite matrix, which was in agreement with the Fourier transform infrared spectroscopy and X-ray diffraction results. The microstructure of the films showed that 3% (w/w) TEMPO-ChNCs were homogeneously dispersed within the KGM/CS matrix, reducing the free volume of the biocomposite matrix and improving the final film mechanical and barrier properties (P < 0.05). Furthermore, these bionanocomposite films exhibited good thermal stability. The incorporation of TEMPO-ChNCs in the KGM/CS matrix produced flexible and transparent bionanocomposite films. Thus, this bionanocomposite films has potential use in food packaging applications., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A novel biopreservative was developed by immobilizing phlorotannins into nanochitin (NCh). NCh were selected as a host complex to immobilized phlorotannins and the structural properties and antioxidant activity of the NCh-phlorotannins nanocomplex was investigated. The NCh-phlorotannins showed high antioxidant activity, as evidenced by free radical scavenging activity test. Moreover, the effects of NCh-phlorotannins on physical [color, water holding capacity (WHC), and texture], chemical [thiobarbituric acid (TBA) values, total volatile base nitrogen (TVB-N), and pH], microbiological [total viable count], changes of refrigerated sea bass (Lateolabrax japonicus) fillets were also evaluated. Sea bass fillets add with 1.5 g/kg NCh-phlorotannins had lower bacterial growth, pH, TVB-N and TBA as well as better characteristics of texture, color, and WHC than those of the control group during refrigerated storage. The efficiency of NCh-phlorotannins treatment was also better than that of phlorotannins or NCh treatment alone. Therefore, NCh-phlorotannins may be a potential biopreservative to extend the shelf-life of sea bass fillets quality during refrigerated storage. [Display omitted] • A novel biopreservative was developed by immobilizing phlorotannins into nanochitin (NCh). • NCh were selected as a host complex to immobilized phlorotannins. • The novel biopreservative showed high antioxidant character. • The novel biopreservative can prolong the shelf-life of sea bass fillets. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zwitterionic chitin nanofibers can stabilize pH-responsive Pickering emulsions. • NaCl affects pH-responsive behavior of emulsions by influencing zeta potential. • High levels of zwitterionic chitin nanofibers can enhance emulsion stability. • Zwitterionic chitin nanofibers improve antimicrobial activity of essential oils. In this study, zwitterionic chitin nanofibers (Z-ChNFs) were used to prepare Pickering emulsions containing citrus essential oils (CEO) and their physicochemical properties and antimicrobial activity were investigated. Results show that as-prepared Pickering emulsions exert pH-reversible properties, pH can adjust the charge of Z-ChNFs to influence the stability of the emulsion. As the concentration of Z-ChNFs increase, the droplet size of the emulsion decreases. The high concentration of Z-ChNFs (1.5 wt%) can enhance the viscosity and promote forming nano-network structures within continuous phases, and their amphiphilic nature can strengthen the capacity for adsorption on the oil/water interface, resulting in enhanced physical stability of the encapsulated CEO emulsion. Additionally, Z-ChNFs have positive effects on the improvement of antimicrobial activity of CEO. This study provides valuable implications for the development and application of essential oils as biopreservation in the food field. [ABSTRACT FROM AUTHOR]

Novel smart films for seafood freshness monitoring were developed by incorporating curcumin (Cur) into a chitosan (CS)/oxidized chitin nanocrystal (O-ChNCs) matrix. O-ChNCs (200–400 nm in length) were prepared from chitin by 2,2,6,6-tetramethylpiperidine-1-oxylradical (TEMPO)-oxidation method and used as reinforcement filler for smart films. The effects of O-ChNCs or Cur addition on the structural, mechanical, barrier and optical properties of Cur/CS/O-ChNCs (Cur-CN) films were investigated. It was found that the incorporation of O-ChNCs and Cur could significantly alter the mechanical, barrier and optical properties of the films. The Cur-CN films showed better barrier properties against water vapor and UV-vis light as well as higher mechanical strength than CS film. Among all the films tested, Cur-CN film containing 10 wt % of O-ChNCs (w/w, CS and O-ChNCs basis) presented the best performance. Morphological analysis by scanning electron microscopy and atomic force microscopy showed that an appropriate amount of O-ChNCs and Cur was well dispersed in the CS films. The electrostatic interactions and hydrogen bonds among CS, O-ChNCs and Cur were confirmed by Fourier transform infrared spectroscopy. Moreover, the colour of Cur-CN films varied with the change in pH, and this characteristic was used to monitor the spoilage of hair tail and shrimp during storage. This study demonstrated that the fabricated smart film has a great potential for use in monitoring seafood freshness. Image 1 • Oxidized chitin nanocrystals (O-ChNCs) were successfully obtained. • Curcumin (Cur)/chitosan(CS)/O-ChNCs (Cur-CN) films were developed. • The effect of O-ChNCs and Cur on physical properties of the film was investigated. • Cur-CN films were sensitive to pH changes. • Cur-CN films exhibited colorimetric indicator for seafood freshness monitoring. [ABSTRACT FROM AUTHOR]

A set of chitosan/ε-polylysine (ε-PL) bionanocomposite films were prepared by a simple in situ self-assembly technique using sodium tripolyphosphate (TPP) as cross-linking agent. The physical, mechanical, structural, and antimicrobial properties of these films were investigated. Fourier infrared spectroscopy and X-ray diffraction showed that the introduction of TPP promoted the formation of hydrogen bonds and electrostatic interactions among functional groups of chitosan or ε-PL, which improved the tensile strength and decreased the water solubility, water vapor permeability and surface wettability of films. On the other hand, the incorporation of ε-PL weakened the bionanocomposite film' structure and integrity, resulting in a decrease trend of films' mechanical and barrier properties. More importantly, the bionanocomposite films exhibited excellent antimicrobial efficacy against E. coli and S. aureus by the increasing ratio of ε-PL. And ε-PL presented a sustained release from the films, which was closely related to TPP concentration. Results of this study suggested that chitosan/ε-PL films could be used as antimicrobial bio-material and have great potential in food industry. • Chitosan/ε-polylysine bionanocomposite films were prepared by using sodium tripolyphosphate (TPP) as cross-linking agent. • TPP improved the film's physicochemical properties. • Bionanocomposite films exhibited the extraordinary antimicrobial activity. • Bionanocomposite films presented a sustained release behavior of ε-polylysine. [ABSTRACT FROM AUTHOR]

Konjac glucomannan (KGM) has been widely studied because of its excellent gelling properties. However, the freeze-thaw stability and weak gel strength significantly limit its industrial application. To solve these issues, we innovatively introduced oxidized chitin nanowhiskers (O-ChNWs) under heating and alkaline conditions, thus achieving the improvement of the properties of KGM gels. In this study, rheological measurement and textural analysis were performed to verify the physicochemical properties of the as-prepared KGM/O-ChNWs. Results showed that the KGM/O-ChNWs dispersion exhibited a typical non-Newtonian pseudoplastic fluid behavior and the mechanical property of the gels enhanced with the amount of O-ChNWs increasing. Also, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) was applied to elucidate the interaction between KGM and O-ChNWs. It showed that both strong hydrogen bonding and amide bonds could be formed to stabilize the KGM/O-ChNWs structure. Additionally, morphological images show that O-ChNWs can influence the original KGM structure and then form more uniform pores. Furthermore, thermogravimetric (TGA) analysis and freeze-thaw measurement demonstrated that O-ChNWs could obviously improve the thermal and freeze-thaw stability of the nanocomposite gels. Taken together, this current work can provide new insights into existing KGM gel systems and stimulate the development of additional KGM-based nanocomposite gels with the desired mechanical strength and freeze-thaw stability. [Display omitted] • O-ChNWs acted as nano-filler of KGM and had strong hydrogen bond with KGM. • Microstructure and gel properties of KGM nanocomposite gels depended markedly on O-ChNWs concentration. • The introducing O-ChNWs improved freeze-thaw stability of the KGM-based nanocomposite gels. [ABSTRACT FROM AUTHOR]

In this study, TEMPO-oxidized chitin nanocrystal (TOCN) stabilized oregano essential oil (OEO) Pickering emulsions were incorporated into the Konjac glucomannan (KGM) matrix to prepare an active food packaging film. OEO Pickering emulsions with 2.4% wt TOCN and 2% v/v OEO had a uniform droplet distribution and a particle size of 25.80 μm. The influence of OEO Pickering emulsions on the physical and biological properties of the KGM film was investigated. Scanning electron microscopy results showed that the Pickering emulsion was uniformly distributed in the KGM matrix and formed microstructure-sized holes in the films. The incorporation of OEO Pickering emulsion reduced the mechanical properties of the films, but the water vapor permeability firstly decreased and then increased. Meanwhile, the appropriate emulsion content can improve the film's barrier properties to light. Furthermore, the antioxidant and antimicrobial properties of the films were strengthened by OEO Pickering emulsion incorporation and mainly depended on its concentration. This study suggests the feasibility of KGM-based Pickering emulsion films for active food packaging applications. [Display omitted] • Konjac glucomannan films were prepared by adding oregano essential oil Pickering emulsion. • Pickering emulsions were prepared using TEMPO-oxidized chitin nanocrystal as stabilizer. • Pickering emulsions were evenly distributed due to good compatibility with konjac glucomannan. • Antioxidant and antimicrobial properties were enhanced and depended on Pickering emulsion concentration. [ABSTRACT FROM AUTHOR]

Phosphorylation is a key route to achieve varieties of biological activities for polysaccharides. Here, we report the phosphorylated surface deacetylated chitin nanofibers (PS-ChNFs) using the sodium tripolyphosphate/sodium trimetaphosphate (STPP/STMP) method. Response surface methodology (RSM) was employed to optimize in this study. Under optimal conditions, a maximum degree of substitution (DS) of 0.13 was obtained. In addition, the structures of PS-ChNFs were investigated by Fourier transform infrared spectroscopy (FT-IR), Nuclear Magnetic Resonance spectra (NMR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM) and (Energy Dispersive Spectroscopy-mapping) EDS-mapping. The findings revealed that the FT-IR spectroscopy and XPS analysis confirmed the appearance of phosphate groups in PS-ChNFs. The 31P NMR results indicate that the PS-ChNFs structure has characteristic peaks of P elements. SEM images showed that PS-ChNFs had a rough surface with many cavities, but the P elements on the surface of the EDS-mapping are uniformly distributed throughout the sample without any enrichment. Antioxidant and antibacterial test showed that PS-ChNFs had significant scavenging effect on free radicals and antibacterial effect. The above results indicate that the chemical modification of PS-ChNFs was successful. [Display omitted] • PS-ChNFs was successfully prepared by the STPP/STMP method. • The maximum DS of 0.13 was obtained under the optimal condition using RSM. • P element was evenly distributed throughout the sample without enrichment. • PS-ChNFs possessed stronger antioxidant and antibacterial activities than S-ChNFs. [ABSTRACT FROM AUTHOR]

A new generation of active-intelligent packaging materials is gradually replacing traditional petroleum-based materials due to their anti-bacterial, visual, and eco-friendly properties. In this study, a novel multifunctional nanocomposite film is fabricated to dynamically monitor the food freshness by immobilizing natural red cabbage extracts (RCA) and nisin to a pullulan/chitosan composite matrix reinforced with chitin nanofibers. Fourier transform infrared spectroscopy and XRD spectra results shows that nisin and RCA could interact with pullulan, chitosan and chitin nanofibers through hydrogen bonds. Scanning electron microscopy (SEM) observation reveals the nisin and RCA are uniformly dispersed in the pullulan/chitosan/chitin nanofibers (PC) matrix to form a compatible film. The incorporation of nisin and RCA significantly improve the tensile strength and the thermal stability, and water vapor barrier properties of the resultant nanocomposite films. Additionally, the nanocomposite films show strong antioxidant and strong antibacterial properties. The antioxidant function was mainly attributed to the RCA, and the antibacterial function was attributed to nisin. Moreover, the color of the nanocomposite films changes from red to blue with the increase in pH from 2 to 12, which enables monitoring the freshness of sea bass (Lateolabrax japonicas) during storage. Hence, these results suggest that the PCN-RCA nanocomposites films could be employed as promising potential candidates for active-intelligent food packaging applications. [Display omitted] • Multifunctional films were successfully developed using bioactive ingredients. • Red cabbage extracts enhanced the physical and chemical properties of the films. • The films possessed great UV-blocking, antioxidant and antibacterial activity. • The developed film could be used to dynamic visualization of the product freshness. [ABSTRACT FROM AUTHOR]