Abstract
Plant-derived essential oils (EOs) represent a green alternative to conventional antimicrobial agents in food preservation. Due to their volatility and instability, their application is dependent on the development of efficient encapsulation strategies allowing their protection and release control. Encapsulation in Polyhydroxyalkanoate (PHA)-based nanoparticles (NPs) addresses this challenge, providing a biodegradable and biobased material whose delivery properties can be tuned by varying polymer composition. In this work, EO from Mexican oregano was efficiently encapsulated in Polyhydroxybutyrate (PHB) and Poly-3-hydroxybutyrate-co-hydroxyhexanoate (PHB-HHx)-based NPs by solvent evaporation technique achieving high encapsulation efficiency, (>60%) and loading capacity, (about 50%). The obtained NPs displayed a regular distribution with a size range of 150–210 nm. In vitro release studies in food simulant media were fitted with the Korsmeyer–Peppas model, indicating diffusion as the main factor controlling the release. The cumulative release was affected by the polymer composition, possibly related to the more amorphous nature of the copolymer, as confirmed by WAXS and DSC analyses. Both the EO-loaded nanosystems displayed antimicrobial activity against Micrococcus luteus, with PHB-HHx-based NPs being even more effective than the pure EO. The results open the way to the effective exploitation of the developed nanosystems in active packaging.
Highlights
The growing people awareness for the green consumerism has oriented the food industry towards the use of plant-derived products such as natural and eco-friendly food preservatives [1]
essential oils (EOs) derived from Origanum and Thymus species, commonly applied in traditional medicine since ancient times, have been shown to exhibit significant antimicrobial activity towards food-borne pathogens, this being property ascribable to their major components, namely the phenolic monoterpene carvacrol and its isomeric form thymol [3,4,5]
PHA-based nanoparticles were prepared by the solvent evaporation method, by dispersing a polymer solution in the aqueous phase containing a proper surfactant
Summary
The growing people awareness for the green consumerism has oriented the food industry towards the use of plant-derived products such as natural and eco-friendly food preservatives [1]. Today, controlling bacterial contamination in fresh or processed foods is a critical issue, especially considering the challenges related to the use of synthetic preservatives, i.e., the possibility of promoting bacterial resistance and their adverse impact on the health and environment In this scenario, plant essential oils (EOs) are characterized by intrinsic antimicrobial activity against food-borne pathogens and could represent a green and safe alternative to the use of chemical additives. EO derived from Origanum and Thymus species, commonly applied in traditional medicine since ancient times, have been shown to exhibit significant antimicrobial activity towards food-borne pathogens, this being property ascribable to their major components, namely the phenolic monoterpene carvacrol and its isomeric form thymol [3,4,5] This action is less effective towards the beneficial probiotic bacteria Lactobacillus [3]. Synergism of such major components with minor ones, including monoterpene hydrocarbons, has been found to modulate the antimicrobial performance of different populations of Origanum vulgare subsp. hirtum [7]
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