THE EFFECT OF LACTOBACILLUS SAKEI ON THE BEHAVIOR OF LISTERIA MONOCYTOGENES ON SLICED BOLOGNA-TYPE SAUSAGES

This study was conducted to determine the effects of Lactobacillus sakei Lb 706 (bacteriocin positive) and L. sakei Lb 706-B (bacteriocin negative) on the growth of Listeria monocytogenes on sliced bologna-type sausage under vacuum or modified-atmosphere packaging (MAP) (50%CO2/50%N-2) stored at 4C up to 6 weeks. L. monocytogenes multiplied on bologna slices under vacuum or modified atmosphere by approximately 3 log cfu/g at the end of storage. However, in samples under MAP with or without L. sakei, the number of L. monocytogenes during the storage remained generally at the inoculated level. In vacuum-packaged samples containing L. sakei Lb 706-B, the number of L. monocytogenes increased 1 log cfu/g after 3 weeks, while the pathogen did not grow in the samples with L. sakei Lb 706. The pH value of samples with L. sakei did not drop below 5.5. The results indicate that CO2 (in modified atmosphere) and the use of L. sakei (Bacteriocin negative or positive) have a synergistic inhibitory effect on the growth of L. monocytogenes in sliced beef bologna-type sausages.