Release and antibacterial action of phenolic acids incorporated into PHBV films

Ferulic or p-coumaric acids were incorporated (3, 6 or 9%) into PHBV films by melt processing or surface anchoring (3–4% in the film). The release kinetics of phenolics and the films’ antibacterial effect against Escherichia coli and Listeria innocua were analysed. At equilibrium, a near 100% release of phenolics was obtained from melt processed films in a low polar simulant (D1: 50% v/v ethanol in water), whereas it ranged between 10% and 38% in a more polar simulant (A: 10% v/v ethanol in water). The diffusion coefficient of FA or PCA in the matrix also rose by 4–30 times in contact with simulant D1. The limited release of the phenolics in contact with aqueous systems hindered the film’s antibacterial effect in contact with the inoculated culture media. In contrast, surface-loaded films exhibited a complete release of phenolics in aqueous media and a significant (near 2 log CFU) bacterial growth inhibition.