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An antibacterial film based on Chinese yam starch (D-sorbitol as plasticizer) incorporated with eugenol (YDE) was prepared for pork preservation. The structure of films was characterized and the evaluation of two plasticizers (glycerol and D-sorbitol) on their mechanical and barrier properties was performed to determine the vehicle of eugenol. The release behavior and antimicrobial activity of YDE were investigated and the application of the films for pork preservation was evaluated. The mechanical and barrier properties of films were dependent on plasticizer. The release of eugenol from films was well-controlled by two release mechanisms of diffusion and erosion. YDE displayed good eugenol dose-dependent antibacterial activity which was higher against E. coli than against L. monocytogenes and S. aureus. The film with 3% eugenol can extend the shelf-life of pork beyond 50%, suggesting that the film may have great potential in active packaging for extending the shelf-life of foodstuffs.

This study was to design a novel wide pH–sensing colorimetric film of κ-carrageenan incorporated with extract from Lycium ruthenicum Murr. (Car-LRM) for food freshness monitoring. The structure, basic properties (thermal stability, mechanical, barrier and antioxidant activity), and release kinetics of LRM from the films were investigated. Attentions were centered on colorimetric response of films and their applications for freshness monitoring of milk and shrimps. A low incorporation of LRM (no more than 2.5%) led to an enhancement in thermal stability and water vapor barrier of films to a certain extent. At above level of incorporation, LRM could be well-distributed in Car matrix by the interactions of hydrogen bonds. In addition to good antioxidant activity, the film displayed colorimetric response at a wide range of pH (2−10) and the color change was reversible. The release of LRM from films followed Fickian's law which was controlled by diffusion mechanism rather than swelling mechanism. The successful applications of Car-LRM2.5 for the freshness monitoring of milk and shrimps indicate that Car-LRM2.5 may have great potential for monitoring the freshness of milk and aquatic products.

The aim of the present study was to evaluate the release kinetics and antibacterial activities of curcumin (CUR) loaded in zein (zein-CUR) electrospun fibers towards Escherichia coli ( E. coli , 8099) and Staphylococcus aureus ( S. aureus , ATCC 6538). CUR was successfully loaded in zein fibers by electrospinning technique, and the encapsulation efficiency was close to 100% and the encapsulated CUR still retained its antioxidant capacity. The morphology and size of fibers strongly depended on CUR contents. The interaction between CUR and zein matrix was confirmed to be hydrogen bonding, and the addition of CUR caused a slight increase in the T g of zein matrix. The electrode process of CUR electrooxidation was diffusion-controlled and could be preceded by chemical reaction. The predominant release of CUR from fibers was Fickian diffusion, and First-order model and Hixson-Crowell model could well describe this diffusion behavior. The zein-CUR fibers showed good antibacterial activity towards S. aureus and E. coli , and the inhibition efficiency increased with the increase of CUR contents. However, the antibacterial activity towards S. aureus was better than that towards E. coli . The study displayed that the zein-CUR fibers might have potential as a promising material for antimicrobial applications to inhibit bacterial growth and propagation in active food packaging.

Resveratrol (R) has received growing attentions in therapeutic potential, however less focus is paid to its antibacterial or antioxidant nature for food preservation. In this work, R was efficiently encapsulated in electrospun gelatin/zein (GA/ZN) fibers for developing antibacterial mats to extend pork shelf life. The fiber morphology, thermal stability and hydrophobicity of the mats were associated with the ratios of GA/ZN. The secondary structure changes of protein were dependent on the intermolecular hydrogen bonds formed in the fiber matrix. The presence of R endowed the mats with antibacterial and antioxidant activity and the release of R followed Fickian diffusion mechanism in 10% ethanol and the coexistence of diffusion and erosion mechanisms in 3% acetic acid, respectively. The target fiber mats could extend the pork shelf life by 3 d at 4 °C, indicating the good application prospect in food preservation.

Recently, colorimetric films with antibacterial or antioxidant activity have received growing attentions. In this work, novel intelligent double-layer fiber mats were developed via electrospinning technique for pork freshness monitoring and preservation. The mats are composed of a layer of pullulan-purple sweet potato extract (PL-PSPE) and a layer of zein-glycerol-carvacrol (ZN-GL-CA). The colorimetric response and antibacterial activity were respectively dependent on the mats of PL-PSPE and ZN-GL-CA, while the antioxidant activity was ascribed to both of them. The distinguishable color changes of PSPE at pH 2–12 endowed the mats with a wide pH–sensing range. Each component of PL-PSPE and ZN-GL-CA were hydrogen bonded. An appropriate presence of GL (no more than 20%) could improve the thermal stability of the fibers. The releases of PSPE and CA from fiber matrix were controlled and followed Fickian diffusion mechanism. In addition to the reversible and high sensitive color change, the mats showed good antibacterial and antioxidant activities, which could extend the shelf life of pork by 24 h at 25 °C. This study demonstrated the great potential of PL-PSPE@ZN-GL-CA in food freshness monitoring and preservation.