Biodegradable Active Packaging Enriched with Essential Oils for Enhancing the Shelf Life of Strawberries

The strawberry (Fragaria ananassa) is a nutrient-rich fruit with high content of health-beneficial compounds. However, strawberries are susceptible to mechanical damage and microbiological contamination which can cause changes in fruit sensory properties. These changes consequently effect on ripening and shelf life of the strawberry. In recent years, essential oils (EOs) have been famous for their antimicrobial and antioxidant properties and are promising ecological alternatives to chemical antimicrobial substances. Nowadays, active packaging is one of several techniques developed for slowing down the metabolic processes of fresh fruits. Poly(lactic acid) (PLA) is one of the several polymers suitable for encapsulation EOs, whereas at the same time represent non-toxic, biodegradable, and compostable polymer derived from renewable resources. Suitable packaging prolongs the shelf life of fruit, keeps the products at the highest possible nutrition level, improves quality, and attracts customer attention. In the current study, we encapsulated EOs (lemongrass and oregano) into a PLA and poly(3-hydroxybutyrate) (PHB) packaging film and explored their antimicrobial and antioxidant properties. Moreover, biochemical and quality parameters for strawberry preservation and shelf-life extension were also assessed. Our tested active packaging film with EOs was proven to be useful for postharvest quality maintenance and shelf-life extension of strawberries, with PLA/PHB/ATBC + 5% lemongrass EO being slightly better than PLA/PHB/ATBC + 5% oregano EO.

Characterization of Optimized Ternary PLA/PHB/Organoclay Composites Processed through Fused Filament Fabrication and Injection Molding

The aim of this study was to investigate the structure-properties relationship of ternary blends of polylactide/polyhydroxybutyrate (PLA/PHB)/organo-modified layered silicate (OMLS). Morphological, thermal, rheological, and mechanical characterizations were performed to understand the influence of OMLS on PLA/PHB (70/30 wt%) formulations optimized through modifications with an epoxy-based chain extender, the use of a plasticizer, as well as the influence of the type of processing route: injection molding or fused filament fabrication. The addition of OMLS allowed the blend compatibility to be improved, with the appearance of a single melting peak on DSC thermograms at 146 °C, as well as the reduction in the size of the nodules for the injected molded specimens. Concerning the printed samples, AFM analysis revealed a coalescence of the PHB minor phase due to its degradation. This phenomenon was dramatically enhanced in the presence of OMLS and has been ascribed to the degradation of both the organo-modifier and the PHB minor phase in the blend. Rheological and mechanical tests (17% decrease in Young's modulus and 13% decrease in elongation at break) confirmed this degradation that would have occurred during the manufacturing of the filaments and the printing of specimens due to additional thermal and cooling steps.