Antimicrobial polypropylene with ε-poly(lysine): Effectiveness under UV-A light and for food storage applications

Publication date: Available online 17 December 2018Source: LWTAuthor(s): Luis J. BastarracheaAbstractPolypropylene (PP) was mixed with polypropylene-graft-maleic anhydride (PP-g-MA) to obtain a reactive blend (PP/PP-g-MA) and render it antimicrobial by the application of ε-poly(lysine) and styrene maleic anhydride copolymer (SMA) onto its surface through reactive blending. Infrared spectroscopy confirmed covalent attachment through imide ring coupling between ε-poly(lysine), SMA, and PP/PP-g-MA. The resulting antimicrobial plastic (PP-SMA-PL) was effective in aqueous suspensions against Escherichia coli K12 ATCC 47009 with or without UV-A light irradiation providing > 99.99% reduction, and against the same bacterium in apple juice providing ∼ 90% reduction under UV-A light. Fluorometric assays suggested that this enhanced effect may be caused by reactive oxygen species (ROS) generation. In addition, PP-SMA-PL showed effectiveness against Listeria innocua L2 inoculated in milk in a storage study under refrigeration for 21 days, providing ∼90% reduction as compared to the starting level of inoculum and 99.99%–99.999% lower microbial load as compared to the control inoculated milk at the end of the storage study. Scanning electron microscopy, energy dispersive X-Ray spectroscopy, infrared spectroscopy, and colorimetric analyses confirmed no deposition of bacteria or organic matter onto PP-SMA-PL during the storage period with milk, as well as no release of ε-pol...
Source: LWT Food Science and Technology - Category: Food Science Source Type: research