Antibacterial and antifungal LDPE films for active packaging

Abstract

Active antimicrobial packaging is a promising form of active packaging that can kill or inhibit microorganism growth in order to maintain product quality and safety. One of the most common approaches is based on the release of volatile antimicrobial agents from the packaging material such as essential oils. Due to their highly volatile nature, the challenge is to preserve the essential oils during the high-temperature melt processing of the polymer, while maintaining high antimicrobial activity for a desired shelf life. This study suggests a new approach in order to achieve this goal. Antimicrobial active films are developed based on low-density polyethylene (LDPE), organo-modified montmorillonite clays (MMT) and carvacrol (used as an essential oil model). In order to minimize carvacrol loss throughout the polymer compounding, a pre-compounding step is developed in which clay/carvacrol hybrids are produced. The hybrids exhibit a significant increase in the d-spacing of clay and enhanced thermal stability. The resulting LDPE/(clay/carvacrol) films exhibit superior and prolonged antibacterial activity against Escherichia coli and Listeria innocua, while polymer compounded with pure carvacrol loses the antibacterial properties within days. The films also present an excellent antifungal activity against Alternaria alternata, used as a model plant pathogenic fungus. Furthermore, infrared spectroscopy analysis of the LDPE/(clay/carvacrol) system displayed significantly higher carvacrol content in the film as well as a slower out-diffusion of the carvacrol molecules in comparison to LDPE/carvacrol films. Thus, these new films have a high potential for antimicrobial food packaging applications due to their longlasting and broad-spectrum antimicrobial efficacy.

Antifungal Poly(lactic acid) Films Containing Thymol and Carvone

“…LDPE/(clay/carvacrol) ¿lms were developed and exhibited superior antibacterial activity against Escherichia coli and Listeria innocua. The ¿lms also presented an excellent antifungal activity against Alternaria alternata [4].…”

Novel LDPE/halloysite nanotube films with sustained carvacrol release for broad-spectrum antimicrobial activity

“…In our recent studies, 29,30 we have demonstrated that organoclays can be used as active carriers for EOs to preserve them during the high-temperature compounding of the polymer, while preserving high antimicrobial properties for a required shelf life. The organo-modication of clay was found as crucial for the EOs intercalation in between the clay galleries and its enhanced thermal stability.…”

“…The organo-modication of clay was found as crucial for the EOs intercalation in between the clay galleries and its enhanced thermal stability. 30 In recent years halloysite nanotubes (HNTs), which are naturally occurring members of the kaolin family of aluminosilicate clay and characterized by a hollow tubular structure, emerge as promising nanoscale containers for the encapsulation of different active molecules. 30 In recent years halloysite nanotubes (HNTs), which are naturally occurring members of the kaolin family of aluminosilicate clay and characterized by a hollow tubular structure, emerge as promising nanoscale containers for the encapsulation of different active molecules.…”

Nanomaterials for products and application in agriculture, feed and food

“…Materials consisting of polyamide layered with silicate barriers have additional properties such as thermal buffering (Johnston, Grindrod, Dodds, & Schimitschek, 2008). In low-density polyethylene films, hybridisation of nanoclays contributed to slow down the out-diffusion and thus maintain higher contents of antibacterial and antifungal essential oils (Shemesh et al, 2015). Nanocomposite films enriched with silicate nanoparticles or nanocrystals exhibiting increased barrier properties can be used for plastic beer bottles (e.g.…”