Antibacterial biopolymeric foams: Structure–property relationship and carvacrol release kinetics

In this work, the feasibility of antibacterial biopolymeric foams containing carvacrol (CRV) for potential food packaging applications was investigated. Sodium bicarbonate (SB) was chosen as foaming agent and a commercial biodegradable polymer, Mater-Bi® (MB), as a matrix. MB/SB and MB/SB/CRV systems were prepared by melt mixing and the foaming process was conducted in a laboratory press. The influence of foaming agent and antibacterial additive content was investigated. The foamed samples were characterized through morphological analysis, mechanical tests and measurements of CRV release kinetics. Moreover, a mathematical model, i.e. power law model, was used to fit the release data in order to investigate the release mechanism. The antibacterial activity of foams containing CRV was tested in vitro against pro-technological, spoilage and pathogenic bacteria applying the disc diffusion method. The results showed that by using 3% of SB it is possible obtain foams with a porosity of about 40%. The presence of carvacrol, strongly influenced the properties of the biopolymeric foams but at the higher content ensured antibacterial activity of the samples.