Teixeira et al. (2014) were only able to detect inhibition of Listeria
monocytogenes in fish protein films containing garlic essential
oil by the agar diffusion method, whereas the dilution method
revealed inhibition of most of the microorganisms assayed. These
findings could be due to the larger film sample used in the latter
method in comparison with the diffusion assay. In this regard, Pires
et al. (2013) also observed higher inhibition rates in the dilution
method than in the agar diffusion method in fish protein films
containing citronella, coriander, tarragon or thyme oils. They reported
that the limited diffusion of the essential oil active agents
through agar medium could explain these results. Therefore, in our
opinion, complementary studies to the diffusion assay should be
carried out to confirm antimicrobial activity.