Novel, eco-friendly α-tocopherol/layered double hydroxides/poly(3-hydroxyoctanoate)-based active packaging materials with enhanced antimicrobial, barrier and antioxidant activities

Abstract

Among various climate actions taken as a response to environmental concerns, important and highly influential are ones related to the packaging industry being still one of the largest plastic sectors responsible for the majority of post-consumer wastes. Therefore, in this manuscript, for the first time assessment of the potential application of biodegradable bacterially derived poly(3-hydroxyoctanoate) (P(3HO)) doped with functional 2D nanoparticles as a more sustainable active packaging material has been investigated. In particular, P(3HO) combined with two types of layered double hydroxide (LDHs) modified with α-tocopherol (type of vitamin E) was applied for the fabrication of polymeric nanocomposite films and a comprehensive investigation of their structure and relevant properties (mechanical, barrier, bactericidal, and antioxidative) was performed. Permeation study revealed that P(3HO)-based films with 4 wt% tocopherol-modified nanoparticles meet the barrier requirements for storing fruits and vegetables, whereas antibacterial assay indicated inhibited growth of Gram-positive bacteria (particularly S. Aureus). Monitoring of polyphenols (PPH) content in strawberries after 6 days of storage at room conditions showed a slightly higher level of PPH with reference to fresh fruits, which indicates the preserved freshness of strawberries kept in P(3HO) containing 4 wt% Zn-based LDHs modified with tocopherol contrary to fruits kept in commercial polypropylene packaging which led to significant drop in PPH content. Thus, the application-focused experiments indicated that investigated P(3HO)-based nanocomposites are promising candidates for more sustainable active packaging that may extend the shelf-life of fruits and protect consumers from food-borne pathogenic bacteria.