Inhibition of Listeria monocytogenes by freeze-dried piscicocin CS526 fermentate in food

Abstract

Aims: The effectiveness of freeze-dried powder, fermented with bacteriocin producing Carnobacterium piscicola CS526, was evaluated for the inhibition of Listeria monocytogenes in a food model. Methods and Results: A 10% solution of milk whey powder was fermented with a bacteriocinogenic C. piscicola CS526 Bac+ or its nonbacteriocinogenic mutant strain CS526 Bac- at 30°C for 12 h and freeze-dried. The freeze-dried piscicocin CS526 Bac+ fermentate exhibited strong anti-listerial activity even at a concentration of 1% (w/v) in sterile water (pH 7), but the piscicocin CS526 Bac- fermentate and nonfermented whey powder had no anti-listerial activity. In the presence of 10% piscicocin CS526 Bac+ fermentate, L. monocytogenes in ground meat rapidly decreased from 105 CFU g -1 to less than the detection limit (3.0 × 103 CFU g-1) within 5 and 1 days at 4 and 12°C, and was bacteriostatically inhibited for 25 and 4 days at 4 and 12°C respectively. Furthermore, this inhibitory effect was enhanced at lower temperatures. Conclusions: Piscicocin CS526 Bac+ fermentate was effective for the control of L. monocytogenes in a food model at refrigeration temperatures. Significance and Impact of the Study: A freeze-dried bioactive piscicocin CS526 Bac+ powder can be a powerful tool to ensure food safety against L. monocytogenes contamination in refrigerated foods such as ready-to-eat products. © 2007 The Authors.