Growth and Case Studies Roy Biggs Tegel Research and Case Studies Research on growth of Listeria in products; chicken roll, chicken bacon and pre-cooked sausages Tegel experience – case studies

Background - NZ Tegel is the largest producer of cooked chicken products in NZ – over 150 tonnes per week, up to one third of this is chilled, long shelf life products Last Tegel recall for micro contamination was in January 2000

The Research - 1 Objective – to test our assumptions (models) on consequences if contamination occurred. 3 products –Sliced chicken roll –Chicken bacon –Pre-cooked sausages

The Research - 2 Innoculate them with <100 per g of Listeria Incubate at 2 o C & 10 o C and test fortnightly Plot the growth Be scared, be very, very scared!

The Results – Chicken Roll

The Results - Bacon

The Results - Sausages

The Research - Conclusions If we have a low level of contamination it is serious Need to concentrate our efforts on prevention and monitoring Be scared, be very, very scared!

The Incidents - 1 Product – chicken tenders Dedicated cook plant with excellent separation & facilities Isolation 1 – shift changeover – repair Isolation 2 – shift changeover – wash Isolations 3 & 4 – intermediate washes Conclusions – conveyor, mandated wash

The Incidents - 2 Product – shredded chicken Dedicated cook plant with excellent separation but poor entry facilities Isolation 1 – product produced on nightshift Isolation 2 – 6 days later on same shift Isolation 3 – over next 7 days 37/160 Conclusion – shaft seal on dicer

The Incidents - 3 Dedicated cook plant with excellent separation & entry facilities Poor maintenance led to Lm isolations from floors over a period of months, shutdown planned in 3 months No product isolations and product testing increased to 5 per line per day NZFSA instruction to cease processing

The incidents – 3 - continued Negotiated continuation of processing for most products with increased sampling and supervision by Tegel technical staff Maintenance shutdown 2 weeks later Sporadic incidents over the next few months followed by “deep” cleans DNA typing No isolations for the following 2 years

The Current Monitoring Regime Pre-start physical check daily & ATP monitoring First product off the line for all sliced and shredded products Product samples and PC swabs at start up, 25%, 50% and 75% of the production run and during the last hour. Non PC swabs (up to 20 locations) during last 2 hours of production Any Intermediate cleans followed by product samples, PC and non-PC swabs Escalation response

Guidance Control of Listeria monocytogenes in the Food Processing Environment – R. B. Tompkin (2002)Journal of Food Protection, vol 65 No4, pages Listeria Guidelines MAF