Starter cultures as potential inhibitors of Listeria monocytogenes in fermented sausages

Cilj ispitivanja u okviru ove doktorske disertacije odnosio se na mogućnost inaktivacije Listeria monocytogenes u fermentisanim kobasicama. Za potrebe ispitivanja proizvedene su kobasice kontaminirane sa L. monocytogenes, sa i bez dodate starter kulture. Kontrolne grupe kobasica nisu bile kontaminirane. U toku zrenja praćene su promene mikrobiološkog statusa fermentisanih kobasica i fizičko-hemijskih osobina. Za sva ispitivanja korišćene su standardne metode. U fermentisanim kobasicama užeg i šireg dijametra sa i bez dodate starter kulture u toku zrenja broj bakterija L. monocytogenes se smanjivao se posle trećeg dana zrenja. U uzorcima fermentisanih kobasica užeg dijametra, sa i bez dodate starter kulture, na kraju procesa zrenja (18. dan) nije utvrđeno prisustvo bakterija L. monocytogenes. U uzorcima fermentisanih kobasica šireg dijametra sa dodatom starter kulturom, L. monocytogenes nije izolovana 21. dana zrenja, a bez dodate starter kulture od 31. dana zrenja. Prosečan broj enterobakterija u uzorcima fermentisanih kobasica užeg dijametra, sa i bez dodate starter kulture smanjivao se od trećeg dana zrenja, a kod fermentisanih kobasica šireg dijametra od sedmog dana zrenja. Prisustvo enterobakterija nije utvrđeno u uzorcima kobasica užeg dijametra na kraju procesa zrenja (18. dan), a u uzorcima kobasica šireg dijametra 31. dana zrenja. Tokom svih dana ispitivanja broj bakterija mlečne kiseline (BMK) u fermentisanim kobasicama užeg, odnosno šireg dijametra bio je veći od broja u kobasicama bez dodate starter kulture. Broj BMK rastao je kod kobasica užeg dijametra do 14. dana, a zatim je opadao do 18. dana, dok je kod fermentisanih kobasica šireg dijametra rastao do 31. dana, a zatim opadao do 41. dana zrenja. Ukupan broj aerobnih mezofilnih bakterija u fermentisanim kobasicama užeg, odnosno šireg dijametra rastao je do 14., odnosno 31. dana zrenja, a zatim je do kraja zrenja opadao. Između ukupnog broja aerobnih mezofilnih bakterija u uzorcima fermentisanih kobasica oba dijametra tokom svih dana ispitivanja nije utvrđena razlika. Između pH vrednosti fermentisanih kobasica oba dijametra nultog i trećeg dana zrenja nije utvrđena razlika. Od sedmog dana, pa do kraja procesa zrenja u fermentisanim kobasicama oba dijametra pH vrednost kobasica sa dodatom starter kulturom bila je manja od pH vrednosti fermentisanih kobasica bez dodate starter kulture...The aim of the study under this doctoral dissertation was to address the possibility of inactivation of Listeria monocytogenes in fermented sausages. For testing purposes, sausages contaminated with L. monocytogenes were produced, with and without the starter culture added. The sausage control groups were not contaminated. Changes in the microbiological status of fermented sausages and physicochemical properties were monitored during ripening. Standard methods were used for all tests. In fermented sausages of narrower and wider diameter with and without added starter culture during ripening, L. monocytogenes decreased after the third day of ripening. In samples of fermented short-diameter sausages, with and without added starter culture, no L. monocytogenes was detected at the end of the ripening process (day 18). In specimens of broad-diameter fermented sausages with added starter culture, L. monocytogenes was not isolated on day 21 of ripening, and without added starter culture from day 31 of ripening. The average number of enterobacteria in narrower diameter fermented sausage samples, with and without added starter culture, decreased from the third day of ripening, and in fermented sausages of wider diameter from the seventh day of ripening. The presence of enterobacteria was not detected in narrow-diameter sausage specimens at the end of the ripening process (day 18) and in broad-diameter sausage samples on the 31st day of ripening. During all test days, the number of lactic acid bacteria (LAB) in the fermented sausages of narrower or wider diameter was greater than the number in sausages without added starter culture. LAB number increased in narrower diameter sausages by day 14, then decreased by day 18, whereas in fermented sausages of wider diameter, it increased by day 31 and then decreased by day 41. The total number of aerobic mesophilic bacteria in the fermented sausages of narrower or wider diameter increased to the 14th and 31st day of ripening, and then decreased until the end of ripening. No difference was found between the total number of aerobic mesophilic bacteria in fermented sausage samples of both diameters during all test days. No difference was found between the pH values of fermented sausages of both diameters on zero and third day..