Lemon essential oil/vermiculite encapsulated in electrospun konjac glucomannan-grafted-poly (acrylic acid)/polyvinyl alcohol bacteriostatic pad: Sustained control release and its application in food preservation

Lemon essential oils (LEO), as natural bacteriostatic agents, show significant loss in the preparation processes of food packaging materials, therefore, an effective encapsulation of LEO is urgent for realizing the protection. In this study, LEO was absorbed by thermally stable and porous vermiculite (VML) to form LEO/VML complex, which is further coupled with konjac glucomannan-grafted-poly (acrylic acid)/polyvinyl alcohol (KGM-g-PAA/PVA) composite. KGM-g-PAA/PVA bacteriostatic water-absorbing pad was prepared via electrospinning technique, which can minimize the loss of LEO. The VML (1 g) can significantly reduce LEO loss and achieve sustained control LEO release from the pad, which follows the predominant mechanism of Fick diffusion law. The sustained control LEO release from the pad can effectively inhibit the growth of E. coli during storage, thus prolonging shelf life of chilled pork for 3 day. This study suggests that KGM-g-PAA/PVA pad may have a great potential in the field of intelligent packaging.

Synthesis, characterization, and anti-microbial activity of superabsorbents based on agar–poly(methacrylic acid-glycine)

In this study, poly(methacrylic acid-glycine)-grafted agar-based hydrogels with optimized process parameters were synthesized via a two-step green-radiation induced grafting process using microwave heating. Poly(methacrylic acid) chains were graft copolymerized onto an agar backbone using ammonium persulfate as a free radical initiator and N,N′-methylene-bis-acrylamide as a cross-linking means using microwave heating. The influence of different reaction parameters was investigated on the percentage swelling behavior of the cross-linked hydrogel networks. The prepared hydrogel networks with optimum percentage swelling were characterized by Fourier transform infrared spectroscopy, time-of-flight secondary ion mass spectrometry, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis, using agar as a reference. The anti-bacterial activities of the prepared hydrogels against Gram-positive Staphylococcus aureus bacteria and Gram-negative Escherichia coli bacteria were investigated. Staphylococcus aureus was found to be more susceptible to the compounds compared to Escherichia coli. These results indicate that the prepared hydrogels have the potential to be applied as anti-bacterial agents.