PLA films loaded with Achillea millefolium: In vitro antibacterial effects

Abstract

Antimicrobial packaging as active food packaging represents a suitable packaging form for food in products in particular for foods where microbial contamination occurs primarily at the surface. Poly (lactic acid) (PLA) is one of the most frequently used bio-polymers because of its similarities to conventional polymeric materials used in food packaging, however its use is still limited to short-term packaging applications. This research has been focused on preparation of PLA packaging films modified with bioactive compounds from Achillea millefolium (AM) plant extract as possible active packaging solution. Addition of specific natural compounds could give improvements in mechanical, thermal or barrier properties, as well as the antimicrobial effect with significant impact on prolonging the food shelf-life and its quality and safety. Accordingly, the aim of this study was to determine chemical and antimicrobial properties of crude AM ethanolic extract and PLA composite films loaded with two concentrations of AM extract expressed in weight percent (2 wt. % and 5 wt. %). The AM ethanolic extract showed very good antimicrobial activity against E. coli and S. aureus, while PLA films loaded with 5% AM extract showed significant reduction of initial S. aureus after 24 h contact time compared to neat PLA films (up to 90%). PLA films with 2% and 5% AM content did not show any antimicrobial activity against E. coli. Furthermore, the chemical composition of the ethanolic extract was determined considering its phenolic composition. These results indicated promising potential of incorporation of A. millefolium extract in PLA as an antimicrobial agent for food packaging applications.