Anti-listerial activity of chitosan and Enterocin 416K1 in artificially contaminated RTE products

We investigated the anti-listerial activity of chitosan and Enterocin 416K1 alone or in association by threedifferent experiments performed (i) in agar well diffusion, (ii) in buffer suspensions assay, (iii) in RTEvegetables and fruit artificially contaminated with Listeria monocytogenes NCTC 10888. All testsdemonstrated the anti-listerial activity of the natural bioactives and the best action obtained by their usein combination. In the artificially contaminated vegetables (trial 1 zucchini, corn, radishes; trial 2 mixedsalad, carrots, zucchini) the inhibition of listeria was almost comparable, with the greatest killing activityobserved in samples added with both antibacterial substances. In the artificially contaminated fruits(trial 3 apples, grapes; trial 4 pineapple, melon) a more evident anti-listerial activity in samples treatedwith chitosaneenterocin in association also emerged. In particular, in trial 3 we obtained a total killing oflisteria within 72 h, while in trial 4 there was only a minimal inhibition, difference attributable to thecomposition of the two samples. Considering the results obtained, we can conclude that the use ofchitosan and Enterocin 416K1, alone or in combination, could be a feasible solution to extend the shelflife and to obtain the microbiological safety of ready-to-eat vegetable and fruits.