Listeria Guidance – Part 1

Sally Hasell

Purpose of Guide 1

1. Gives an overview of the issues – why controls are needed and why this need is becoming greater than ever

2. Identifies how Listeria gets into food via the environment, contaminated surfaces, ingredients and equipment

3. Explains why there must be a focus on RTE foods that support the growth of Listeria

4. Discusses microbiological limits and how they are applied5. Describes how to setup, document and implement a

Listeria Management Programme

What makes Listeria special?

1. Grows at low temperatures i.e. during refrigerated storage of food and in chillers

2. Grows in most types of packaging – vacuum packing does not inhibit it

3. Is everywhere in the environment, so can potentially be re-introduced into clean areas at any time

4. Is able to invade the cells of people with poor immune systems and cause very severe often fatal illness

Why Listeria needs to be controlled

1. Cases are few (20 a year) but high mortality rate (25%) and includes babies

2. If a large quantity of highly contaminated food got into the market, many could be hospitalised and die

3. Vulnerable consumers such as the elderly and those with poor immune systems are an increasing group

4. Food preferences are increasing the volume and types of RTE foods that Listeria can survive and grow in

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

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

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

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

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

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

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

Microbiological targets

Product risk group

Characteristics of the food and processing

L. monocytogenes level targets

At the end of processing

At the end of shelf life

High Processed RTE foods in which growth can occur (during storage in final packaging) and the food stored refrigerated for > 3 days

Absent in 25g Absent in 25g

Medium Processed RTE foods in which growth will not occur

Absent in 25g Not more than 100cfu/g

Low Products where the occurrence and/or survival is highly unlikely

L. monocytogenes not a pathogen of concern

Testing not usually required. Not more than 100cfu/g

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

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

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

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