Poly(Lactic Acid) Composite with Chitosan: Synergistic Effects of Physical Hurdles and Kinetics of Bacterial Inactivation

Due to the increasing need to develop sustainable options for food packaging, a composite material (PLA-CHI) produced by blending poly(lactic acid), maleic anhydride-grafted polypropylene, oxidized polypropylene, and chitosan was challenged against Escherichia coli and Listeria innocua in apple juice, alone or in the combination with two physical hurdles: ultraviolet light (UV-A light) or mild heat (50 °C). PLA-CHI was more effective against L. innocua, being able to reduce its population by up to > 99.998% under UV-A exposure or mild heat. In contrast, E. coli exhibited more resistance against PLA-CHI and either hurdle, with its population declining by up to 99.8% under UV-A light exposure and by up to 99.99% under mild heat. Surface analyses, including infrared spectroscopy and atomic force microscopy, confirmed the overall physical and chemical stability of PLA-CHI after exposure to the physical hurdles. This study confirms the effectiveness and synergy between antimicrobial packaging and hurdle technology.