Bacteriocin Production by Protective Cultures

Bacteriocinogenic Lactococcus Lactis CSCC 146 and pediococcus ATCC 43200 can be used to improve the safety of extended shelf-life cook-chill foods, however, the information on their growth and bacteriocin production rate at refrigeration temperatures was lacking. These cultures were inoculated at 10(5)-10(8) cfu/mL in TPGY broth an grown at 10 degrees celsius. Their populations were enumerated and bacteriocin titre was measured using well diffusion assay. The bacteriocins' identity produced by L.Lactis and P. Pentosaceus was confirmed as nisin and pediocin A, respectively by their enzyme sensitivity pattern. Nisn (>100IU/mL) was detected between the third and fifth day of storage when the populations of L. lactis reached 10(8) cfu/mL. Pediocin A (35 AU/mL) was detected on the fourth day when the population of P. pentosaceus reached 10(9) cfu/mL. Freeze-drying of the cultures did not reduce the speed of the production of bacteriocins. Colour, mouth-feel, texture, flavour and the overall acceptabilty of commercial sous vide meals was not affeted by the presence of the cutures.