Carvacrol encapsulation in different carriers for PHBV-based active films: A comparative study of release profiles

Abstract

This study investigated the encapsulation of carvacrol, a natural phenolic compound with antimicrobial properties, into three different carriers: PHBV nanoparticles, β-cyclodextrin, and halloysite nanotubes. The encapsulated carvacrol was then integrated as a coating on PHBV film, and the release of the molecule in the headspace and food simulants was compared to the carvacrol release from the impregnated PHBV film. The results showed a high encapsulation efficiency (66 ± 5 %) but a slow release in the headspace (around 45 % in 30 days) for β-cyclodextrin, a moderate encapsulation efficiency (31 ± 2 %) but a faster release (more than 90 % in 10 days) for PHBV nanoparticles, and a very low encapsulation efficiency (less than 2 %) for halloysite. For all cases, the production of the film generated a 30 % loss of carvacrol, but the remaining concentration was homogeneous in all active films. The carvacrol release from the film in the headspace and food simulant demonstrated a faster release for coated films than impregnated ones, a higher affinity of carvacrol for ethanol than water (food simulant D1 with 50 % ethanol than A with 10 % ethanol), and a higher affinity for β-cyclodextrin than PHBV nanoparticles (coefficient partition higher for PHBV nanoparticles). These results highlighted that coated film with encapsulated carvacrol (PHBV nanoparticles and β-cyclodextrin) could be used for short shelf-life products (one week), while impregnated carvacrol film could be used for longer shelf-life products (a few months), the minimal inhibitory concentration against microorganisms being reached in headspace after this period for all cases.