sanitary control of listeria monocytogenes in the poultry processing environment

Sanitary Control of Listeria monocytogenesin the Poultry Processing Environment

Leslie Thompson, Ph.D.Department of Animal and Food SciencesTexas Tech University

Why the Concern over Listeriosis?

• Rare but serious foodborne disease

• 20 to 30% mortality

• Opportunistic pathogen for at-risk-populations

• Immunosuppressed

• Pregnant women

• Unborn or newly born

• Elderly

Listeriosis Characteristics

• 1980s foods recognized as primary route of transmission for human listeriosis

• Clinically two categories of disease• Non-invasive – febrile gastroenteritis

– Onset a few hours to 2 to 3 days

• Invasive – septicemia, encephalitis, meningitis, spontaneous abortion, death

– Onset 3 days to 3 months


• First observed in industrialized nations

• Mostly associated with ready-to-eat foods (RTE)

• Many foods associated with outbreaks have 103 CFU of LM/g or greater


• Implicated foods: Raw or inadequately pasteurized milk, chocolate milk,

ice cream, Cheese (queso fresco in particular) Raw vegetables Raw and smoked fish Raw poultry and meat Deli meats and hot dogs

WHO and FAO, 2004

Survival and Growth Characteristics of Listeria monocytogenes

• Extremely hardy

• Facultative anaerobe (grows with or without oxygen)

• Salt-tolerant (Survives salt challenge of 25.5%)

• Attaches to surfaces to form difficult-to-remove biofilms

• More resistant to sanitizers when in a biofilm

Listeria monocytogenes Characteristics

• Habitat: Ubiquitous, found in soil, moist environments, decaying vegetation, silage, fecal material, air, dust

• Psychrophilic – grows well under refrigeration

• Grows well in cool, damp environments


• More heat resistant than most foodborne pathogens

• Survives freezing and drying

• Resists nitrates, high salt levels and acid

• Can grow in vacuum package

• Known for it’s persistence in food manufacturing environments

Growth Limits for Listeria monocytogenes

Characteristic Minimum Optimal Maximum

Temperature (°C)

-1.5 37 50

pH 4.3 7.0 9.6Water activity 0.92 NA NA

USDA-FSIS, 2012, and Donnelly, 2001


• Can establishes niche or harborage site

• LM can be spread from harborage site to food contact surfaces and product

• Cornerstone of control is a well-designed sanitation program

Foods of Greatest Concern

• Ready-to-eat (RTE) foods with characteristics of: Support the growth of LM Have a long refrigerated shelf-life Consumed without further listericidal treatment

FAO/WHO, 2004a, b

http://www.foodsafetymagazine.com/magazine-archive1/octobernovember-2010/listeria-monocytogenes-controlling-the-hazard-in-rte-meat-and-poultry-processing-environments/

Potential Contamination Sources

• Employees (gloves, boots, aprons)

• Incoming air

• Raw materials (Raw chicken)

• Soil

• Water

• Processing environment

Potential Contamination Sources

• LM persistence in processing niches• Floors

• Drains

• Standing water

• Hollow rollers

• Hollow equipment frames

Improved Public Health Can Be Achieved Relative to LM

Reducing the occurrence of LM in manufacturing and retailing of foods that

don’t support it’s growth

FAO/WHO, 2004a, b

Improved Public Health Can be Achieved Related to LM

• In foods that support LM growth Control measures

• Better temperature control

• Limiting length of storage period

• Managing the post-lethality treatment environment Reformulation of foods so they don’t support the growth

of LM Use of a combination of interventions in post-lethality

exposed foodsWHO and FAO, 2004 and FSIS, 2012

Controlling LM in Ready-to-Eat Foods

• Focus is on RTE meat and poultry products

• USDA - Food Safety Inspection Service Compliance Guideline – 2012

“Controlling Listeria monocytogenes in post-lethality exposed RTE Meat and Poultry

Products” FSIS, 2012

Controlling LM in RTEs

• “Zero tolerance” of LM in ready-to-eat meat and poultry products (USDA-FSIS 9 CFR Part 430, the Listeria Rule)

• RTE products are considered adulterated if they come in contact with LM or a food contact surface (FCS) that is contaminated with LM

FSIS, 2012

Incorporation of One of Three Strategies to Control LM in RTEs

• Alternative 1 Employ both:

• post-lethality treatment that reduces or eliminates LM, and

• use of an antimicrobial agent (i.e. sodium diacetate or potassium lactate) or a process (i.e. freezing) to suppress or limit the growth of LM that functions during the shelf-life of the product.

Verification focus is on post-lethality treatment. Sanitation is important still however.

FSIS, 2012


• Alternative 2 Employ a post-lethality treatment or an antimicrobial

agent or process. Sanitation program must include testing of post-lethality

food contact surfaces. Establishments are subject to more frequent verification activities compared to Alternative 1.

FSIS, 2012


• Alternative 3 No post-process lethality treatment, no antimicrobial or

no antimicrobial process. Relies only on sanitation program.• Specific focus on measures which can be

incorporated into the HACCP plan. SSOP’s and other prerequisite programs control LM.

• Sanitation program must include testing of food contact surfaces. Establishments are targeted for the most verification activities compared to Alternative 1 and 2. FSIS, 2012

Listeria Control Guideline

1. Determine if product is RTE

Is there a standard identity that product is fully cooked? Deli meats and hotdog products, salads, spreads, fully cooked sausages

FSIS, 2012


2. Determine if product is post-lethality exposed? Is product exposed to environment post cooking during

further processing as in slicing, peeling, freezing, packaging?

Is product removed from cook bag to slice or repackage?

Fermented or acidified, salt cured or dried and smoked product that is packaged after application of process.

FSIS, 2012


3. Determine if product is covered by Listeria Rule If product is RTE and post-lethality exposed, then

subject to Listeria Rule If product is RTE but doesn’t have post-lethality

exposure then not subject to Listeria Rule If not RTE then not subject to Listeria Rule

FSIS, 2012

Control of LM in the Processing Environment

• Alternative 3 is a higher risk environment

FSIS, 2012

Critical Components of an Effective LM Sanitation Program

Four key components

• Pre-operational cleaning and sanitizingthat are effective in preventing LM from forming niche sites in processing environment

• Operational sanitation to prevent cross-contamination in the RTE processing environment

FSIS, 2012

Critical Components of an Effective LM Sanitation Program

• Intensified cleaning and sanitizing procedures when LM-positive sampling results occur

• Documentation and verification of cleaning and sanitizing procedures

FSIS, 2012

LM Niche or Harborage

• An area where Listeria has grown to high numbers within the plant

• LM can be distributed from harborage to food contact surface or product surface

FSIS, 2012

Factors Affecting Niche Formation

• Equipment design

• Construction activities

• Operational conditions that move product to difficult to clean areas

• Mid-shift cleaning and sanitizing

• Poor use of high pressure during cleaning

• Product characteristics that require excessive rinsing FSIS, 2012

Niche Sites in Processing Environment

• Drains, floors

• Hollow rollers on conveyors

• Valves

• Worn and cracked rubber seals

• Vacuum or air pressure pumps

• Air Filters

• Cleaning tools

• Boots

• Ice makers

• Trash cans

• Cracked hoses

• Wet insulation

• Fork lifts

• Pallets

• Hollow frame work

• Maintenance toolsFSIS, 2012

Niche Sites in Processing Environment

• Chiller shelves

• Roller guards

• Passage ways

• Standing water

• Pallet jacks

• Equipment lubricants

• Space between close fitting plastic-to-metal parts or metal-to-metal

• Packing equipment

• Packaging film or wrappers

• Chilling solutions including brines

• Peelers, slicers, shredders, blenders, scales, casing removal equipment

• Bins, tubs, totes

FSIS, 2012

Cleaning and Sanitizing

Cleaning – Removal of visible soil

• Dry and wet

• Cleaning agents

• Tools – Separate for food contact surfaces and non-food contact surfaces

• Temperature, contact times, match soil types with cleaning agent

Sanitizing – Reduction of harmful microorganisms to

safe levels

• Surface must be clean first

• Use heat or chemicals

• Follow manufacturer’s directions

• Time, temperature, concentration and pH are critical

Pre-Operational Cleaning and Sanitizing

Nine Steps1. Dry cleaning – Remove solid materials,

disassemble equipment such as slicers and dicers – floors, conveyor belts and tables

2. Wash and rinse floor

3. Pre-rinse equipment (in same direction as product flow) warm or cool water ≤60°C. Temps above 60°C can bake soils on the surface making them more difficult to remove.

FSIS, 2012

Pre-operational Cleaning and Sanitizing

4. Clean, foam and scrub equipment with minimum recommended contact time (5 to 25 min)

5. Rinse equipment (in same direction as product flow)

6. Visually inspect equipment to identify residues, re-clean areas as needed

FSIS, 2012


7. Sanitize floor, then equipment Avoid contaminating equipment with aerosols from floor Caution with high pressure hoses Use hot water ≥ 82.2°C for 10 sec Acidic quaternary ammonia Steam not very effective on LM

8. Rotate sanitizers periodically. Alternate between alkaline and acid-based detergents.For example: Alternate between neutral and acid quaternary ammonia FSIS, 2012


9. Dry Air drying Reduce relative humidity if possible Squeegees Avoid cross-contamination from splash from non-food

contact to food-contact surfaces

FSIS, 2012

Sanitizer Considerations for Inactivating LM Biofilms

• Chlorine and iodophors not effective on LM biofilms

• Most effective sanitizers on LM biofilms are acid quaternary ammonia, peracetic acid, chlorine dioxide

• Neutral quaternary ammonia compounds not very effective

FSIS, 2012

Operational Sanitation Procedures

1. Control air temperature and air handling units Maintain cold temp in packaging room ≤10°C Monitor temps Use positive air pressure out of the RTE room into the

raw room Clean air handlers and cooling units periodically Immediately correct condensation or standing water

problems in RTE rooms. Stop production during repair. Clean and sanitize after repair.

FSIS, 2012


2. Equipment Design and Maintenance• Maintain equipment properly and routinely

• Use lubricants that have listericidal additives such as sodium benzoate

• Clean maintenance tools on a regular basis. If possible have separate tools for raw and RTE rooms and equipment

FSIS, 2012

American Meat Institute Principles for Sanitary Design of Facilities and Equipment

• Ten Principles of Sanitary Design

Cleanable to a microbiological level Made of compatible materials Accessible for inspection, maintenance,

cleaning and sanitation No product or liquid collection Hollow areas hermetically sealed


Ten Principles of Sanitary Design, continued No niches Sanitary operational performance Hygienic design of maintenance enclosures Hygienic compatibility with other plant systems Validated cleaning and sanitizing protocols


3. Traffic Control• Imperative to control movement of personnel

and raw product to prevent cross-contamination of RTE products and food contact surfaces in post-lethality areas.

• Create traffic patterns that prohibit the movement of product, equipment and personnel between raw and RTE areas.

FSIS, 2012


3. Traffic Control, continuedEmployees should not work in both raw and RTE areas!

If they must:

• Change outer clothing (aprons, coats, hard hats and soiled clothes)

• Wash and sanitize hands

• Clean and sanitize bootsFSIS, 2012


3. Traffic Control, continued• Use airlocks or vestibules between raw and RTE

areas

• Use foam sanitizing sprays on either side of RTE doors

• Foot baths are not the best option, but if used change frequently, use 400 to 800 ppm quats, minimum 5-cm depth, chlorine is not effective.

FSIS, 2012


4. Employee Hygiene• Handwashing for a minimum of 20 sec: After restroom use Before entering work area When leaving the work area Before handling product

FSIS, 2012


4. Employee Hygiene, continued• Gloves Wash hands before applying gloves RTE gloves should be disposable Dispose of glove after touching non-food contact surface Dispose of gloves upon leaving processing line

FSIS, 2012


4. Employee Hygiene, continued• Remove coats, gloves, sleeves, and outer clothing when

leaving RTE areas

• Coats, gloves, sleeves, and outer clothing should never be worn in restrooms, eating areas, or left in lockers

• Do not eat in locker rooms or store food in lockers

• Do not store tools, knives or other equipment in personal lockers

FSIS, 2012


4. Employee Hygiene, continued• Have separate cleaning crews for raw and RTE

areas

• Train, monitor and verify employees in proper hygiene practices

• Maintenance employees and tools pose a special risk

FSIS, 2012


5. Controlling Cross-Contamination• Rodent and insect control

• Eliminate standing water

• Discard product that touches non-food contact surfaces

• Use separate pallets for raw and RTE areas, color coded

• Avoid condensationFSIS, 2012


5. Controlling Cross-contamination, continued• Do not use high pressure sprays near exposed

RTE product

• Drains from raw or “dirty” side should not be connected to drains on cooked or “clean” side of plant

FSIS, 2012


• Three broad themes:

Provide zones of control Keep it cold and moisture control Equipment and facility design to facilitate

sanitation

FSIS, 2012

Environmental Sampling Plan

• Four zones of focus. Zones are based on level of risk to product contamination: Zone 1 – Food product contact surfaces such as belts,

conveyors, etc. Zone 2 – Equipment surfaces close to the food contact

surfaces such as control buttons, equipment framework, mechanic’s tools

FSIS, 2012


• Four zones of focus, continued: Zone 3 – Surfaces not in direct contact with food or

surfaces that are close to food contact surfaces (floors, walls, ceilings, floor mats, pallets, forklifts, pallet jacks)

Zone 4 – Areas distant from production areas (restrooms, loading dock, hallways, warehouses, coolers, break rooms, locker rooms)

FSIS, 2012


• For a processing environment not in control of LM focus on Zone 1 first.

• Once Zone one compliance is demonstrated expand focus to Zones 2, 3 and 4.

FSIS, 2012

Hold and Release Program

• Need a “Hold and Release Program” in the event a positive test occurs

• Need a plan for corrective actions

FSIS, 2012

Conclusions

• Current technology is not possible to totally eliminate LM

• Raw product is likely the source of LM in a plant (USDA, 2010)

• Focus on preventing post-lethality environment

• Sanitation practices are keyFSIS, 2012

Thank you for your time and attention!

References

Berrang, M.E., R.J. Meinersmann, J.F. Frank, D.P. Smith and L.L. Genzlinger. 2005. Distribution of Listeria monocytogenes subtypes within a poultry further processing plant. J. Food Prot. 68(5):980-985.

Donnelly, C.W. 2001. Listeria monocytogenes: A continuing challenge. Nutrition Reviews 59(6):183-194.

FAO/WHO. 2004a. Risk assessment of Listeria monocytogenes in ready-to-eat foods. Microbiological Risk Assessment Series 4. Technical Report. Food and Agriculture Organization and the World Health Organization. Geneva, Switzerland.

FAO/WHO. 2004b. Risk assessment of Listeria monocytogenes in ready-to-eat foods. Microbiological Risk Assessment Series 5. Food and Agriculture Organization and the World Health Organization. Geneva, Switzerland.

FDA. 2012. Bad bug book. Foodborne pathogenic microorganisms and natural toxins handbook, 2nd Ed. Center for Food Safety and Applied Nutrition (CFSAN) of the Food and Drug Administration, U.S. Department of Health and Human Services

Lianou, A., and J.N. Sofos. 2007. A review of the incidence and transmission of Listeria monocytogenes in ready-to-eat products in retail and food service environments. J. Food Prot. 70(9):2172-2198.

References

USDA-FSIS. 2012. FSIS compliance guideline. Controlling Listeria monocytogenes in post-lethality exposed ready-to-eat meat and poultry products. United States Department of Agriculture, Food Safety and Inspection Service.

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