Effect of temperature on the release of carvacrol and cinnamaldehyde incorporated into polymeric systems to control growth and biofilms of Escherichia coli and Staphylococcus aureus

This study assessed the effect of temperature on the release of essential oil components incorporated by melt compounding into polymeric films. Specifically, polyethylene-co-vinylacetate (EVA) films containing carvacrol (CAR) and cinnamaldehyde (ALD), alone and in combination, were prepared and their surface and mechanical properties and antibacterial and anti-biofilm activity against Escherichia coli and Staphylococcus aureus were evaluated. The addition of ALD and CAR did not provoke variation in the surface morphology of EVA and allowed their delivery. At 37°C, films containing CAR, ALD or their combination (25+75%) were found to have the strongest bactericidal effect, whereas at lower temperatures a lower killing rate was observed. There was no clear evidence of the influence of temperature on the anti-biofilm activity of the essential oil component-based polymeric films. The biomass formed on EVA containing ALD, CAR or their combination (25+75) was significantly lower (60–80% reduction) than that formed on the EVA control at both 37° and 22°C.