Growth of pathogen bacteria Listeria monocytogenes in salads with addition of sweet basil

Abstract

Listeria monocytogenes are well known as one of the pathogen bacteria which cause listeriosis human disease. Fresh or no processed food is more often the vector in carrying these bacteria. Since vegetables and salads are most often consumed in fresh, no processed form, they present the possible risk for consumers health. In order to reach suitable organoleptic properties of salads, different spices can be used, and due to their constituents they can react as antimicrobial agents, which can decrease possible pathogenic microorganisms. By examing the growth of L.monocytogenes in cabbage and radish salads, during 48h, at 4 i 20°C, we determined that cabbage presents very convenient base for the growth of these bacteria. At 20°C, sweet basil added in 1%, 2,5% and 5% concentrations, were not so effective in preventing the growth of L.monocytogenes in cabbage salad. At the other hand, it was determined that radish doesn't present a convenient media for L.monocytogenes growth, because of the presence of phitoncide, sulphuric compounds and spicy ingredients in the vegetables. Adding sweet basil causes decreasing the initial amount of L.monocytogenes which are at the highest concentration of 5% more than 1 log cycle for both examined temperatures. The influence of basil can be explained by the influence of essential oils and aromatic compounds which are present in spice.

Listeria monocytogenes je poznata kao jedna od patogenih bakterija koja kod ljudi izaziva oboljenje listeriozu. Najčešće se kao vektor u prenosu ove bakterije javlja sirova ili neprerađena hrana. Pošto se povrće i salate najčešće konzumiraju u svežem, neprerađenom obliku, oni predstavljaju potencijalni rizik za zdravlje potrošača. Za postizanje odgovarajućih organoleptičkih osobina salate, mogu se koristiti različite začinske biljke koje sa svojim sastojcima mogu delovati kao antimikrobni agens koji će smanjiti eventualno prisutne patogene mikroorganizme. Ispitivanjem rasta Listeria monocytogenes u salatama od kupusa i rotkve, u toku 48h, na temperaturi od 4 i 20°C, utvrđeno je da kupus predstavlja veoma pogodnu sredinu za razvoj ove bakterije. Na temperaturi od 20°C se dodatak bosiljka u koncentracijama od 1%; 2,5% i 5%, u kupus salati pokazao potpuno neefikasan u sprečavanju rasta Listeria monocytogenes. Sa druge strane, utvrđeno je da rotkva ne predstavlja pogodnu sredinu za razvoj Listeria monocytogenes, što se može pripisati prisustvu fitoncida, sumpornih jedinjenja i ljutih materija u ovom povrću. Dodatak bosiljka, dovodi do smanjenja početnog broja Listeria monocytogenes, koje za najveću koncentraciju od 5% iznosi više od 1 log ciklusa, za obe ispitivane temperature. Ovakav uticaj se može objasniti delovanjem etarskih ulja i aromatičnih jedinjenja koja su prisutna u začinu.