Listeria Guidance – Part 1

1. Listeria Guidance – Part 1 Sally Hasell

2. Purpose of Guide 1 • Gives an overview of the issues – why controls are needed and why this need is becoming greater than ever • Identifies how Listeria gets into food via the environment, contaminated surfaces, ingredients and equipment • Explains why there must be a focus on RTE foods that support the growth of Listeria • Discusses microbiological limits and how they are applied • Describes how to setup, document and implement a Listeria Management Programme

3. What makes Listeria special? • Grows at low temperatures i.e. during refrigerated storage of food and in chillers • Grows in most types of packaging – vacuum packing does not inhibit it • Is everywhere in the environment, so can potentially be re-introduced into clean areas at any time • Is able to invade the cells of people with poor immune systems and cause very severe often fatal illness

4. Why Listeria needs to be controlled • Cases are few (20 a year) but high mortality rate (25%) and includes babies • If a large quantity of highly contaminated food got into the market, many could be hospitalised and die • Vulnerable consumers such as the elderly and those with poor immune systems are an increasing group • Food preferences are increasing the volume and types of RTE foods that Listeria can survive and grow in

5. Listeria sp. • Only Listeria monocytogenes is a significant human pathogen • Other members e.g. L.innocua are rarely harmful but share other characteristics with L.monocytogenes • This means finding any type of Listeria in food or somewhere it should not be, means that control is needed or has failed

6. Growth in food as a critical factor • Small numbers of Listeria are unlikely to be a problem for healthy adults but as numbers increase, the potential for illness increases • When number get really high, even healthy adults can become ill. • If Listeria can grow in a food, over time a small number can quickly become a large number, especially if temperature control not good • HIGHEST RISK FOOD ARE THOSE THAT SUPPORT THE GROWTH OF LISTERIA AND ARE STORED CHILLED FOR MORE THAN 3 DAYS

7. Control strategies • Listeria present are destroyed or removed - apply a listericidal step, wash, incoming ingredient specs • Limit the potential for growth in the food e.g. low pH (<4.4), water activity <0.92, combinations of pH and water activity and other hurdles, freeze, some packaging • Prevent/protect from recontamination, especially after a listericidal step

8. Preventing recontamination • A major problem is when food gets contaminated after a listericidal step e.g. cook the ham and then slice and package • Need to make sure that cannot get contaminated – slicers, conveyor belts, aerosols, condensation drips, work flow, people • Focus cleaning and sanitation on this part of the process i.e create a high care hygiene area and monitor effectiveness

9. How many is too many? • Healthy consumers can tolerate small numbers of Listeria in their food but vulnerable consumers may not. • Thus important that Listeria should not be detected in food intended for these consumers e.g. infants. • Foods that are consumed regularly by all consumers should also be Listeria free e.g. spreads, butter, milk • Foods like salads need to make sure fresh and washed to keep numbers as low as possible

10. How many Listeria is too many? • Food should never have more than 100cfu/g of Listeria monocytogenes present. • When counts are >100cfu/g it is obvious that Listeria controls have failed - • Incoming ingredients • Processing control steps failed • Contamination from equipment, environment

11. Listeria limits and Regulators • Zero limits typically set to support strategies to reduce the incidence of listeriosis and for foods known to be problematic Std 1.6.1 for example • Now international agreement that the focus is on not letting numbers get above 100cfu/g and this most often is because of contamination during processing and then growth during chilled storage

12. Microbiological targets

13. Microbiological limits • Regulatory limits that may apply to a product • Food Standards Code Std 1.6.1 • Product safety limits for dairy products (DPC1) • Operator defined limits • Customers • Countries to which exporting food

14. Listeria Management Programmes • A record of how a business manages Listeria - • What controls are in place e.g. specifications, cleaning/ sanitation, training, monitoring, responding to failures, new products and processes reviewed • How they are done e.g. new staff get trained, pasteurisation failures responded to, out of spec ingredients rejected, lab results acted on, new equipment checked

15. Listeria Management Programmes • Provides an overview of the Listeria control system so that everyone (management, auditor, regulator, customer) knows what is being done, their role and how to see and know when it is failing

16. Critical aspects of a LMP • It is written down • Everyone who needs to be involved is • It truly reflects what is happening in the processing environment • Observations made are responded to • It is a living document • It is focussed on the key factors that could be the source of contamination