Effect of enterocin 4231 in Slovak fermented salami Púchov after its experimental inoculation with Listeria innocua Li1.

BACKGROUND

Enteroccocci occur and may compete well in fermented sausages and Enterococcus faecium represents that species of the lactic acid bacteria which can be found in the fermented sausages. The representatives of this species can produce bacteriocins with predominant anti-listerial effect. Therefore, the effect of enterocin (Ent) 4231 produced by Enterococcus faecium CCM 4231 strain with probiotic properties was tested in a dry fermented salami Púchov (Slovak product) experimentally inoculated with L. innocua Li1 strain (10(7) cfu/ml).

MATERIAL AND METHODS

The bulk salami mixture was prepared in the pilot plant and 2.5 kg for each of three trials were transferred to the laboratory for the experiments. Three independent trials were conducted, each comprising then five salami samples (0.500 g). Trial A (reference control) involved only untreated salami mixture. Trial B represented salami mixture inoculated with Listeria innocua Li1 (10(7) cfu/ml). For trial C, Ent 4231 possessing activity 6400 AU/ml was added into the salami mixture inoculated with L. innocua Li1 (Li/Ent). The mixtures were stuffed into collagen casings and the flat shape salamis were transferred back to the pilot plant and treated according to conditions typical for this product and stored for 4 weeks.

RESULTS

The initial number of L. innocua Li1 in the inoculated salami mixture was 10(4) cfu/ml.After Ent 4231 addition, the count of Listeria detected in the salami samples inoculated with Li1 and treated with Ent 4231 was 3.64±0.14 cfu/ml; difference 0.40 logarithmic cycles was noted between Li samples and Li/Ent samples. On day 2, the difference 1.86 log cycles was noted between Li1 and Li/Ent samples. Although, in weeks 3 and 4, slight increase in Li1 cells was determined in Li salamis, the difference in the detection of Li1 cells in Li salamis and Li/Ent samples was even higher than that immedially after Ent addition (difference 2.30; 2.48 log cycles). Bacteriocin activity itself was not recovered from Li/Ent salamis. The pH of the all salamis was almost at the same level. Water activity and water content were not influenced.

CONCLUSION

Addition of Ent 4231 during processing of salami Púchov experimentally inoculated with L. innocua Li1 has lead to decrease of Li1 cell growth, although the bacteriocin activity of Ent itself was not possible to detect in salami samples. The pH value, water activity, as well as sensory character of the final products were not negatively influenced.