Listeria Intervention and Control

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Listeria Intervention and Control

• Animal Sciences 550
• Lynn Knipe

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Listeria Control

• sanitation
• product formulation
• post-packaging re-heating
• sampling for process control

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Sanitation

• Purpose 1
• Prevent the establishment of L. monocytogenes
  growth in a niche or other sites that can lead
  to contamination of ready-to-eat (RTE) products.

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Sanitary Design

• applies to the entire manufacturing unit etc.)
  
• focusses on the entire life cycle of the
  manufacturing unit (next 20-30 yrs.)
• insures proper efficient cleaning at 3
  levels phys., chem. bio.

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Listeria Control

• Controlled traffic patterns (to prevent
  cross-contamination from raw product, public
  areas, outside)
• GMPs (e.g., no raw or inedible product/trash
  in room)
• Clean, dry, uncracked floors
• Equipment/building design
• Effective SSOPs

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Sanitary Design Principles

• Separate raw from RTE
• physical, personnel traffic, air handling
• Must be cleanable
• equipment, walls, floors, ceilings, etc.
• Made of compatible materials
• inert, nonporous nonabsorbent
• Need smooth accessible surfaces

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• Must be self-draining
• no pooling, or dripping onto product zone areas
• Framework must not be penetrated
• bolts, studs, etc. must be welded to surface, no
  drilled or tapped holes
• Proper ventilation
• filtered, to prevent condensation, odors, mold,
  etc.

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Sanitary Zones

• Zone 1 product contact surfaces
• Zone 2 non-product contact areas, adjacent to
  product
• ext. of equipment, chill units, etc.
• Zone 3 More remote non- contact areas
• phones, forklifts, walls, drains

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Sanitary Zones (Contd)

• Zone 4 remote areas, outside the processing
  room
• bathroom doors, cafeteria, halls, etc.

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Construction Site GMPs

• Associated with gt30 recalls
• Traffic pattern controls
• Use of doors
• Maintain negative pressure
• Entry into sensitive area
• Aerosol prevention
• Temporary partitions

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Four Step Cleaning

• Dry clean-up
• Rough rinse (90 of visible soil, 140-160F
  water)
• Soap (proper concentration, type and
  application)
• mechanical action?
• Rinse, top down
• before soap dries (prevent biofilm)

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Fat/Grease Film

• Hanging water
• greasy (white)
• Caused by
• water temperature lt130F
• improper cleaner concentration
• Alkaline detergent recommended

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Cleaning

• Control condensation
• Focus on cleaning the room, not just the
  equipment
• e.g., clean floor before equipment

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Use of Sanitizers for RTE

• Apply by flood method
• Use cold water to sanitize
• Double sanitize
• rotate between 200 ppm chlorine or 25 ppm
  iodine
• 200 ppm Quats. (residual effect)

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Sanitizers

• Floors 800 ppm quats
• doorway foamers, rather than flood, for visual
  verification
• Hands alcohol based sprays
• Fog with 200 ppm quats weekly.
• Verify concentration with test tape.

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Heat as a Sanitizer

• Flood equip. with 180F water.
• Steam sanitize
• 180F sprays on conveyors
• Oven heating for peelers, slicers, etc.
• 170F steam for 1 ¾ hrs.
• 120F dry for 15 mins.

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Drain Cleaning

• Designated brushes
• Designated sanitation employee do at end of
  their shift (leave room).
• Use chlorinated alkaline cleaner.
• Weekly clean all surfaces.
• Sanitize with bucket of 75 ppm iodine.

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Overhead Cleaning

• Do monthly (min.)
• All overheads
• lights, conduit, pipes, etc.)
• Use 4 step method
• Use chlorinated alkaline cleaner
• Clean ref. Units using non- chlorinated alkaline
  cleaner
• Sanitize by foaming 800 ppm quats (do not
  rinse).

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RTE Cooler Cleanup

• Clean from top down, using 4 step method (min.
  once a qtr.)
• Use chlorinated alkaline cleaner on all, except
  ref. units
• Clean racks thoroughly, watching for hidden
  areas (wheels, etc.)
• Clean drains
• Sanitize with 800 ppm quats

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Cross Traffic Ovens

• pick up heavy soil
• Flood sanitize floor w/800 ppm quats
• Squeegee away pools
• Employees must change frocks, gloves, sleeves,
  and aprons before handling hot racks or
  (cooked) product.

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RTE Employee Practices

• Clean RTE clothing daily
• Maintain sanitary lockers
• Hairnets required by all.
• Clean rubber footwear
• street/tennis shoes a problem
• Leave RTE garments in RTE area.
• Stay within the designated traffic patterns.

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Disposable Gloves

• Hands must be clean before applying gloves
  inside glove is a great growth environment.
• Change gloves as needed
• holes
• touching inedible items
• Sanitize gloves often

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Product Formulations

• Some products will not support growth of L.
  monocytogenes
• High acid content (lt pH4.5)
• Low water activity
• High salt levels
• Fermented products (lactics)

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Product Formulations

• Acids
• Smoke liquid or natural
• Spices natural resins, oleoresins
• preservatives
• bacteriocins

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Organic Acids

• 2-4 acetic, lactic and citric inhibit L. mono.
  in products
• 0.2-0.8 diacetate controls L. monocytogenes in
  products
• Organic acids more effective at lower pHs.
• Can affect the flavor cost.

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Smoked Products

• Both natural liquid effective.
• Phenols and acetic acid most antilisterial.

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Preservatives

• High levels of sodium benzoate, propyl paraben,
  potassium sorbate.
• More effective at lower pH and temperatures
• BHA, BHT, TBHQ effective.
• Limited approval for use in meat products.

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Bacteriocins

• Natural polypeptides from bacteria that inhibit
  other bacteria.
• Nisin pediocin (lactics) inhibit L. mono.)
• Only Nisin approved and commercially available
  on large scale.

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Post-Packaging Heat/Pasteurization

• Heat re-applied to package surfaces to destroy
  any surface cross contamn.
• Immerse pkg. in hot water
• Surface steam (205F, 15 sec)
• Hot air or infrared.

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Post-Packaging Heat Disadvantages

• Difficult to heat all surfaces
• May adversely affect package.
• Product changes with heat (color, texture,
  purge, etc.)
• Expensive
• Apply heat/moisture in ref. room (condensation,
  etc.)