Aim: Study of the effectiveness of in situ bacteriocin production by lactic acid bacteria (LAB) to control Listeria monocytogenes in dry-fermented sausages. Methods and Results: Two bacteriocin-producing strains: Lactococcus lactis subsp. lactis LMG21206 and Lactobacillus curvatus LBPE were grown in a pilot scale fermentor and lyophilized to be directly used in dry sausage fermentation. A commercial starter culture (Bel'meat TM SL-25) not inhibitory to L. monocytogenes (Bac ) starter) was mixed (1 : 1) with each of the two lyophilized bacteriocin-producing strains to obtain starters active against the pathogen (Bac + starter). Anti-Listeria effectiveness of the Bac + starters was studied in dry-fermented sausages. The meat batter was experimentally contaminated with a mixture of four different strains of L. monocytogenes (10 2 -10 3 CFU g )1 ). The results showed that L. monocytogenes did not grow in any of the contaminated batches, but no significant decrease (P > 0AE05) was observed either in the positive control (no added starter culture) or in samples fermented with the Bac ) starter culture during the fermentation period and up to 15 days of drying. When the Bac + starter contained Lb. curvatus LBPE, cell counts of L. monocytogenes decreased to below the detectable limit (<10 CFU g )1 ) after 4 h of fermentation and no survivors could be recovered by enrichment beyond day 8 of drying. When the Bac + starter culture containing Lc. lactis LMG21206 was used, a decrease in Listeria counts to below the detectable limit was achieved after 15 days of drying. Conclusions: The bacteriocin-producing strains studied may be used as adjunct cultures for sausage fermentations to control the occurrence and survival of L. monocytogenes. Significance and Impact of the Study: Addition of the Bac + strains, especially the Lb. curvatus strain would provide an additional hurdle to enhance the control of L. monocytogenes in fermented meat products.

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The objectives of this study were to evaluate the effectiveness of a bacteriocin-producing Lactobacillus curvatus CWBI-B28 to inhibit the growth of Listeria monocytogenes in de Man, Rogosa and Sharp (MRS) broth and in bacon meat. A co-culture of L. monocytogenes with the Bac strain in MRS broth, resulted in a reduction of the pathogen counts by 4.2 log cycles after 24h of incubation at 37°C. In bacon, the counts of L. monocytogenes was reduced to below the detectable limit (<10cfu/g) in samples inoculated with the Bac strain within 1 or 2 weeks in absence or presence of nitrites (210mg/kg), respectively. However, a week later, a re-growth of the pathogen has occurred. In contrast, no such reduction in Listeria cfus was observed in samples treated with the Bac derivative of Lb. curvatusCWBI-B28. Nonetheless, the extent of inhibitory effect of the Bac strain against L. monocytogenes in bacon was somewhat reduced in the presence of nitrites. A separate study on the influence of nitrites and fats on growth and bacteriocin production by Lb. curvatus CWBI-B28 revealed that the curing agent affects the growth of the Bac strain and, thereby bacteriocin production and activity only at concentrations (>5%) far beyond those allowed in the meat industry. Fat content did not affect the bacterial growth even at the highest concentration used (i.e. 50%), however, it interfered significantly with the detection of AUs and the antilisterial activity. Use of the Bac Lb. curvatus CWBI-B28 has proven efficient in controlling L. monocytogenes in bacon despite the slight antagonistic effect of nitrites, however the efficacy was dramatically reduced upon extended period of storage at 4°C.

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Sensory, physicochemical and microbiological changes in Moroccan cooked kosher sausages stored at 6°C and 25°C were monitored over 35 days. Kosher sausages were very prone to changes in microbial status, as a result of high pH and water activity-values (aw-values) after processing. After 3 days of storage at 25°C and 1 week at 6°C the microbial colonies increased distinctively. Sensory changes were only detectable after the seventh day at 25°C. At 6°C, these sausages kept their sensorial characteristics. Levels of total volatile basic nitrogen were lower in the kosher sausages at 6°C than in those kept at 25°C. Changes at 25°C affected the quality of kosher sausage and limited the shelf life. From these results it can be concluded that storage at 25°C (ambient temperature) for 3 days or at 6°C (chilling) for 7 days without sensory changes is possible.