A study of the effect of Iysozyme, pediocin and heat treatment on the survival of pathogenic bacteria in fermented meat products.

A method for the isolation of listeria from meat products based on the use of primary enrichment with LEB, secondary enrichment with UVM-II, followed by plating on PALCAM agar was developed. The method yielded a higher number of better isolated colonies, with a lower rate of mould contamination than other methods examined. Retail samples of sausage (27), salami (16) and pate (9) were tested for listeria; 21 samples were positive of which 7 were confirmed as Listeria monocytogenes. Lysozyme (3000 units/ml) in combination with heat (4, 8, 37, 47, 52 and 57°C for 1 and 4 hours) in a broth medium showed an enhanced rate of death and injury compared with heating alone against Listeria monocytogenes, particularly at higher temperatures. Under similar conditions the death and injury rate for Staphylococcus aureus was unaltered in the presence of lysozyme. The fate of added pathogens (salmonella, Listeria monocytogenes and Staphylococcus aureus at the approximate concentration of 2 x 10 to the power of 4 cfu/g) in salami prepared using combinations of heat treatment (57°C/30min), lysozyme addition (6000 units/g) and smoking (22-24°C/4 hours) was investigated. Fermentation and heat treatment alone reduced salmonella to below the minimum detection level of 100 cfu/g within 1-2 weeks. Fermentation, heat treatment and smoke application reduced Staphylococcus aureus numbers to below the limit of detection (100 cfu/g) within 56 days. This was not rapid enough to be commercially effective. Effects on Listeria monocytogenes were only sustained for a short period as the organism could be recovered by enrichment after the tenth week of storage. Lysozyme was noted to be less effective in salami than in the broth medium previously used. The use of pediocin prepared from a culture of Pediococcus acidilactici for the control of Listeria monocytogenes and Staphylococcus aureus was investigated, initially in a model salami system (MSS), then in a salami formulation. A combination of pediocin and smoke controlled listeria within 4 days in an acidic MSS and within 14 days in salami, a similar rate of control (6 and 14 days respectively) was observed for Staphylococcus aureus. No recovery of either organism was observed within a 14 week storage period.

Grantor dc:publisher.institution

Robert Gordon University

Year dc:date.issued

1997

Author dc:creator

• Gunasinghe, Chandaka P.G.L.

Advisor dc:contributor.advisor

• A. Rutter, C. Henderson and D. Fenlon

• Iysozyme
• Pediocin
• Heat treatment
• Fermentation
• Pathogenic bacteria
• Meat products
• Listeria monocytogenes
• Staphylococcus aureus

Language dc:language

en

Identifier

oai:rgu-repository.worktribe.com:2807401
https://doi.org/10.48526/rgu-wt-2807401

OAI identifier oai:identifier

oai:rgu-repository.worktribe.com:2807401