3. Results and discussion
3.1. Biocides antimicrobial activity In order to guarantee biocides antimicrobial effectiveness on the microorganisms selected, the Kirby–Bauer test was firstly carried out on their pure or 10 vol.% aqueous solution samples. As previously mentioned, if bacteria are susceptible to a particular antimicrobial, an area of clearing called ‘‘inhibition zone’’ (where bacteria are not capable of growing) surrounding the paper disc soaked in the biocide arises. As an example, Fig. 1a illustrates the effect of oregano essential oil, pure and diluted, on B. cereus. Table 1 presents the inhibition zone diameters corresponding to the different microorganisms studied for the two types of active agents.