Molecular characterisation of a bio-based active packaging containing Origanum vulgare L. essential oil using pyrolysis gas chromatography-mass spectrometry.

BACKGROUND Environmental, economic and safety challenges motivate shift towards safer materials for food packaging. New bioactive packaging techniques, i.e. addition of essential plant oils ( EOs), are gaining attention by creating barriers to protect products from spoilage. Analytical pyrolysis gas chromatography-mass spectrometry (Py- GC-MS) was used to fingerprint a bioactive polylactic acid ( PLA) with polybutylene succinate ( PBS) (950 g kg⁻¹:50 g kg⁻¹) film extruded with variable quantities (0, 20, 50 and 100 g kg⁻¹) of Origanum vulgare EO. RESULTS Main PLA: PBS pyrolysis products were lactide enantiomers and monomer units from the major PLA fraction and succinic acid anhydride from the PBS fraction. Oregano EO pyrolysis released cymene, terpinene and thymol/carvacrol peaks as diagnostic peaks for EO. In fact, linear correlation coefficients better than 0.950 R² value ( P < 0.001) were found between the chromatographic area of the diagnostic peaks and the amount of oregano EO in the bioplastic. CONCLUSION The pyrolytic behaviour of a bio-based active package polymer including EO is studied in detail. Identified diagnostic compounds provide a tool to monitor the quantity of EO incorporated into the PLA:PBS polymeric matrix. Analytical pyrolysis is proposed as a rapid technique for the identification and quantification of additives within bio-based plastic matrices. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]