title: Raman spectroscopy, electronic microscopy and SPME-GC-MS to elucidate the mode of action of a new antimicrobial food packaging material.
abstract: One critical challenge when developing a new antimicrobial packaging material is to demonstrate the mode of action of the antimicrobials incorporated into the packaging. For this task, several analytical techniques as well as microbiology are required. In this work, the antimicrobial properties of benzyl isothiocyanate, allyl isothiocyanate and essential oils of cinnamon and oregano against several moulds and bacteria have been evaluated. Benzyl isothiocyanate showed the highest antimicrobial activity and it was selected for developing the new active packaging material. Scanning electron microscopy and Raman spectroscopy were successfully used to demonstrate the mode of action of benzyl isothiocyanate on Escherichia coli. Bacteria exhibited external modifications such as oval shape and the presence of septum surface, but they did not show any disruption or membrane damage. To provide data on the in vitro action of benzyl isothiocyanate and the presence of inhibition halos, the transfer mechanism to the cells was assessed using solid-phase microextraction-gas chromatography-mass spectrometry. Based on the transfer system, action mechanism and its stronger antimicrobial activity, benzyl isothiocyanate was incorporated to two kinds of antimicrobial labels. The labels were stable and active for 140 days against two mould producers of ochratoxin A; Penicillium verrucosum is more sensitive than Aspergillus ochraceus. Details about the analytical techniques and the results obtained are shown and discussed. Graphical Abstract Antimicrobial evaluation of pure compounds, incorporation in the packaging and study for mode of action on S. coli by Raman, SEM and SPME-GC-MS.
authors: Aragón Institute of Engineering Research (I3A), EINA, Department of Analytical Chemistry, University of Zaragoza, María de Luna 3 Torres Quevedo Bldg., 50018, Zaragoza, Spain.
authors: Isabel
authors: I
authors: Clemente
authors: Aragón Institute of Engineering Research (I3A), EINA, Department of Analytical Chemistry, University of Zaragoza, María de Luna 3 Torres Quevedo Bldg., 50018, Zaragoza, Spain.
authors: Margarita
authors: M
authors: Aznar
authors: Aragón Institute of Engineering Research (I3A), EINA, Department of Analytical Chemistry, University of Zaragoza, María de Luna 3 Torres Quevedo Bldg., 50018, Zaragoza, Spain.
authors: Jesús
authors: J
authors: Salafranca
authors: Aragón Institute of Engineering Research (I3A), EINA, Department of Analytical Chemistry, University of Zaragoza, María de Luna 3 Torres Quevedo Bldg., 50018, Zaragoza, Spain. cnerin@unizar.es.
authors: Cristina
authors: C
authors: Nerín
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D004926:Escherichia coli / Q000648:ultrastructure; D018857:Food Packaging; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D008853:Microscopy / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D052617:Solid Phase Microextraction / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D000890:Anti-Infective Agents
keywords: Antimicrobial active packaging; Benzyl isothiocyanate; Essential oil; Raman spectroscopy; SPME-GC-MS; Scanning electron microscopy