Microbial biofilm formation represents a serious problem for both food industry and
households. Natural biofilms are formed mostly by multiple species, and show resistance
against most of the usual sanitizers. In this study, the effects of cinnamon ( Cinnamomum
zeylanicum), marjoram ( Origanum majorana) and thyme ( Thymus vulgaris) essential
oils (EOs) and their main components (cinnamaldehyde, terpinene-4-ol, and thymol)
were investigated on four-species biofilms of Escherichia coli, Listeria monocytogenes,
Pseudomonas putida and Staphylococcus aureus. Minimum bactericide concentration (MBC)
and killing time were determined by means of the microdilution method. MBC of the
investigated EOs and components was between 0.5 mg/mL (cinnamaldehyde) to 25 mg/mL
(terpinene-4-ol). Killing times for the four-species suspension were 5 or 10 min,
time spans usable in the food industry. For eradication of the mixed-population biofilm
from stainless steel (SS), polypropylene (PP), tile and wood surfaces, EO- or EO component-based
disinfectant solutions were developed, and their effects were compared to a peracetic
acid-based industrial sanitizer (HC-DPE). Total eradication of biofilms (99.9%) was
achieved, with solutions containing cinnamon and thyme EO and EO components, from
SS and PP, but not from tile or wood surfaces. Apparently, cinnamon EO, terpinene-4-ol
and thymol have better disinfectant activity than HC-DPE.
