Development of novel antimicrobial films based on poly(lactic acid) and essential oils

Novel biocomposite films based on poly (lactic acid) (PLA) were prepared by incorporating essential oils as active additive with different concentrations (0.5, 1.5, 2 and 5%). Different types of essential oils from Rosemary, Myrtle and Thyme were used. The optical, thermal, mechanical, water vapour permeability and antifungal properties of all films was carried out. The analysis of essential oils by GC-MS showed the presence of terpene and phenolic compounds that are the most important compounds in essential oils. The addition of different essential oils does not affect the colour change of the films significantly. Thermal degradation of studied films showed a small decrease in the initial degradation temperature when the concentration of essential oil increased, however maximum degradation temperature was similar. Thermal analysis by differential scanning calorimetric (DSC) showed that PLA films containing 5% of commercial essential oils of myrtle and thyme could reduce the polymer chain to crystallize. The mechanical properties are improved by the incorporation of essential oils in the PLA matrix. The effect of commercial essential oil of myrtle in the transfer of humidity from the atmosphere to food is low compared with those containing the commercial essential oils of rosemary and thyme. Finally, the addition of 1.5% commercial thyme and 5% natural myrtle increase significantly the antifungal activity against Aspergillus.niger sp.