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The purpose of this study was to compare the effects of different concentrations of the amine-functionalized isoreticular metal-organic framework-3 loaded with carvacrol (IRMOF-3/CA) on the properties of sodium alginate (SA) composite films, thus determining the optimal addition amount and further preparing bioactive packaging film with antibacterial and antioxidant activities. The morphology, structure, physical properties, antioxidant and antibacterial activities of the films were characterized and analyzed. The results showed that the thermal stability and light barrier property of the films were improved by the addition of IRMOF-3/CA. When the additional concentration was 0.4 wt%, the tensile, water vapor barrier and hydrophobic properties of the films were increased by 30.13%, 9.06% and 46.43% respectively compared with those of pure SA film. Moreover, the film added with IRMOF-3/CA had sustained antioxidant and antibacterial activities, and had an apparent fresh-keeping effect on pork, suggesting its application potential in food packaging. [Display omitted] • SA-based composite active films added with IRMOF-3/CA have been successfully developed. • The tensile, water vapor barrier and hydrophobic properties of the composite film with 0.4 wt% IRMOF-3/CA have been improved. • The composite film added with IRMOF-3/CA showed excellent UV barrier performance. • The composite active film SMC 2 had significant antioxidant and antibacterial activity and showed good preservation effect. [ABSTRACT FROM AUTHOR]

In this work, a novel grafted film with both antimicrobial and antioxidant properties was developed. ε-polylysine (EPL) and caffeic acid (CA) were used as raw materials, and EPL-CA was synthesized by grafting CA onto EPL by the carbodiimide coupling method. Using dicumyl peroxide (DCP) as a radical initiator, EPL-CA was crosslinked with low-density polyethylene (LDPE) by reactive co-extrusion to produce grafted films with both antimicrobial and antioxidant properties. Compared with pure LDPE film, all graft films show antimicrobial and antioxidant properties. Specifically, when the EPL-CA concentration is >3%, the inhibition rates against Escherichia coli (>91%) and Staphylococcus aureus (>97%) significantly increase, and the DPPH free radical scavenging rate (>60%) also significantly increases. Compared with the control film, the grafted film exhibits increased tensile strength and decreased elongation at break. In addition, the migration levels of all graft films in food simulants are below the migration standards set by the European Union. Overall, immobilizing EPL-CA on the LDPE matrix improves antimicrobial, antioxidant, and mechanical properties. Among them, the film exhibits the best comprehensive performance when the EPL-CA content is 3%. Therefore, the development of antimicrobial and antioxidant active LDPE film is proposed. These results indicate that active packaging films can be prepared through reactive extrusion, a promising and industrializable technology, and have broad prospects in improving food safety and other aspects. [Display omitted] • ε-polylysine is functionalized with caffeic acid by carbodiimide coupling. • Low density polyethylene is grafted with caffeic acid functionalized ε-polylysine. • The composite film was prepared by reaction co-extrusion technology. • The prepared films exhibits antibacterial and antioxidant functions. [ABSTRACT FROM AUTHOR]

A practical prediction method for the Total volatile basic nitrogen (TVB-N) content evaluation of beef covered by the packaging films was proposed by using visible-near infrared hyperspectral imaging (HSI). Hyperspectral image under three conditions: beef without films, beef covered by appressed films, and beef covered by non-touch films was obtained. The results indicated that the influence on prediction accuracy of TVB-N content with the presence of films could be properly eliminated by spectral preprocessing methods and modeling methods. Moreover, the successive projections algorithm (SPA) combined with least squares support vector machines (SPA-LSSVM) was the best predictive model for beef without film, beef covered by non-touch polypropylene and polyethylene, and determination coefficient in prediction (R P 2) were 0.9167, 0.9157, and 0.9423 respectively, and root mean square errors in prediction (RMSEP) was 1.7808, 1.8758, and 1.4304 respectively. The competitive adaptive reweighted sampling (CARS) combined with LSSVM (CARS-LSSVM) was more effective for beef covered by appressed films of polypropylene and polyethylene, and R P 2 were 0.9046 and 0.9533 respectively, and RMSEP was 2.0444 and 1.2858 respectively. This study demonstrated that it is feasible to predict the TVB-N content of packaged beef using visible-near infrared hyperspectral technology. • Hyperspectral technology was used to predict the TVB-N content of packaged beef. • Three conditions were designed to investigate the influence of packaging films on the predicted results. • The reflectance spectrum of beef with film was affected by the dual effects of films scattering and transmission. • CARS-LSSVM was suitable for the condition of beef covered by appressed films, while SPA-LSSVM was better for non-touch films. [ABSTRACT FROM AUTHOR]

The chitosan (CS)-based bioactive packaging film with good antibacterial and antioxidant activities was developed using AHNT (modified halloysite nanotube) loaded with carvacrol (AHNT-Car) as the nanofiller. The zeta potential, Fourier transform infrared, and rheology analysis indicated that hydrogen bonding and electrostatic interactions were formed between AHNT-Car and CS film substrate, and scanning electron microscope images exhibited that the cross-sections of the bioactive film were denser. The mechanical and barrier properties (water vapor, oxygen, and light barrier properties) of the bioactive film were enhanced by adding AHNT-Car due to the hydrogen bonding, electrostatic interactions, and compact structure. Specifically, when the additional amount of AHNT-Car was 10 wt%, the film's tensile, oxygen barrier, and water vapor barrier properties were improved by 49.7%, 36.78%, and 11.92%, respectively. Moreover, compared to CS-Car film (adding Car into the CS film directly), the CS-10% film (AHNT-Car added at 10 wt%) had a slow-release effect on Car and could effectively protect the Car from external high temperature and UV light. In addition, the prepared bioactive film had sustained antioxidant and antibacterial properties and could significantly slow down the spoilage of pork during storage, proving the promising application of the bioactive film as food packaging. [Display omitted] • The CS-based bioactive film incorporated with AHNT-Car was successfully developed. • CS film connected AHNT-Car via electrostatic interaction and hydrogen bonding. • Physical property and functional activity were improved of the bioactive film. • The prepared bioactive film had a significant preservation effect on pork. [ABSTRACT FROM AUTHOR]

• LBL technique was successfully implemented to formulate active packaging films. • CS and ALG were employed to modify the surface of PP films grafted with PAA. • The CS/ALG layers on the films improved the chelation ability for transition metal ions. • The PP-g-PAA/(CS/ALG) n films showed potentiality in antioxidant packaging application. In order to remove the trace transition metal ions which catalyze the oxidation in food, chitosan (CS) and sodium alginate (ALG) multilayers were assembled on the polypropylene (PP) surface grafted with polyacrylic acid (PAA) to obtain PP-g-PAA/(CS/ALG) n films. The morphology of the active films was observed, and the thickness of each single assembled layer was about 7 nm. The chelation ability of the films improved with increasing number of (CS/ALG) n multilayers, and Cu2+ chelating quantity of PP-g-PAA/(CS/ALG) 15.5 films was about 3.4 umol/cm2 for 72 h at pH about 5, improved by about 9.92 % as compared with PP-g-PAA films. In addition, the PP-g-PAA/(CS/ALG) n films had chelation activity for both Cu2+ and Fe2+, suggesting the potentiality in antioxidant food package application. [ABSTRACT FROM AUTHOR]