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Keeping Listeria at Bay: The battle that ready-to-eat processors can’t afford to lose. Host: Bill Kinross, Publisher, Meatingplace Moderator: Lisa Keefe, Editor, Meatinglace. Presenter. Harshavardhan Thippareddi,
Host: Bill Kinross, Publisher, Meatingplace
Moderator: Lisa Keefe, Editor, Meatinglace
Associate Professor of Food Science, Department of Food Science and Technology, University of Nebraska, Lincoln
Harshavardhan Thippareddi, Ph. D.
Sept 9, 2009
Prepared by: Martin Wiedmann, Ph. D., Cornell University, Ithaca, NY
Human listeriosis can occur as an epidemic or as sporadic cases
L. monocytogenes common in certain/many environments
L. monocytogenes grows at refrigeration temperatures
Infectious dose is high
Growth in foods is usually needed to reach levels likely to cause human disease
Martin Wiedman, Cornell University
Most human listeriosis cases in US appear to be caused be contaminated deli meats
RTE deli meats – 1,598 cases
Pasteurized milk – 90 cases
High fat and other dairy products – 56 cases
Not-reheated frankfurters – 31 cases
Cooked ready-to-eat crustaceans – 2.8 cases
Smoked seafoods 1.3 cases
Fruits and vegetables – 1.1 cases
*FSIS results of ready-to-eat products analyzed for Listeria monocytogenes
LM is common throughout the food chain
A single magic bullet will not work
Focusing on one product (RTE deli meats) at one point (processing) does not seem to work
Establishments producing post-lethality exposed RTE product must comply with requirements included in one of the following alternatives (§430.4)
Alternative 1:Use post-lethality treatment AND an antimicrobial agent or process
Alternative 2: Use post-lethality treatment OR an antimicrobial agent or process
Alternative 3: Use sanitation measures ONLY
Submersion in hot water
Radiant oven heating
High Pressure Processing
Meat product type and composition
Whole muscle vs. restructured product - product surface characteristics
Packaged vs. non-packaged
Film thickness and material
Product orientation & package design
Single vs. double layer – hot dogs
Sliced product – deli type products
Hot water-based systems
Condensing saturated steam
Flash steam system
Muriana et al., 2002
Non-thermal intervention technology
Minimal quality changes
Can be combined with other treatments such as heat
Pressures in the range of 250 MPa (36,260 PSI) to 600 MPa (87,023 PSI)
100 MPa=14,504 PSI
Product type and composition
Processing time and temperature
Types of microorganisms to be inactivated
Acidic calcium sulfate
Acidified sodium chlorite
Liquid smoke fractions
Ozone (ozonated water)
Luchansky et al. 2006
Geornaras et al., 2005
Gedela et al. 2007
Approved for meat product use
Sodium or Potassium salts of lactic acid
Sodium acetate or diacetate
Sodium citrate buffered with citric acid to pH 5.6
Live bacteria – Canbiocin
Levulinate (not commercialized yet)
This Project was funded through a grant from the National Integrated Food Safety Initiative (Special emphasis grant No. 2005-51110-03278) of the Cooperative State Research, Education and Extension Service, U. S. Dept. of Agriculture
John N. Butts,
Vice President of Research,
Land O’ Frost
“Follow the data trail to the source but always be alert and aware to the organism’s ubiquitous presence and pervasive nature.”
Land O’ Frost
Resistant – don’t believe it has value
Accepting – why not
“Buy-in” – we will do it
Engagement – involved in solution
Commitment – hold self and others accountable for achieving results
Transferred from Zone 4 area outside of the High-Risk RTE area
Homeless, but looking for a harborage location
Typically found with a transfer point monitoring positive
Growth niches within High-Risk RTE area
This means they are established, and have found a protective home in equipment or facility.
They may exist in a transient home such as rework pans, trash containers or other difficult to clean mobile container / environment.
Many positive sites found during monitoring are not growth niches. They are transfer points (i.e., a product handler’s gloved hands, floor sample in high traffic pathway).
Transfer points are not growth niches because the organism is eliminated during the cleaning and sanitizing process.
Locations harboring the organism after the routine sanitation process for that area has been completed.
Hollow roller with solid stainless steel shaft in center (almost press fit).
When center shaft removed organic matter is evident.
Must either be designed out of the system or managed as a part of the process.
Equipment is redesigned to eliminate or seal hollow areas
Hollow areas of equipment (e.g., frames, rollers) must be eliminated where possible or permanently sealed (caulking not acceptable). Bolts, studs, mounting plates, brackets, junction boxes, name plates, end caps, sleeves and other such items must be continuously welded to the surface of the equipment and not attached via drilled and tapped holes.
AMI Equipment Design Task Force
Minimize with process control techniques
The potential to support growth still exists within the machine, part or area
Whenever this becomes the chosen path remember to implement methods that will hold the gains with turnover in both hourly and management ranks.
Examples of how to minimize with process control techniques
Disassemble clean and sanitize
Cook in oven or smokehouse
Cover with tarp and inject steam
Place in COP tank
Normal cleaning and
Are all parts and
Observe Post assembly sanitizer
Observe normal setup and
start up activities
Stop operation before product
is placed on the line
Disassemble to normal daily
Disassemble any remaining
Inspect and swab
any suspect areas
Clean and flood or heat sanitize all
disassembled line components
Is degree of
If APC growth is supported then
If area is Ls positive then it
the suspect area is a potential
is a growth niche
Locating a Transfer Vector
The Time Study typically starts during setup and assembly . Samples will be taken as workers and product come to the line, repeated after line is running then every 2 hrs thereafter
A Time Study consists of sampling the line components and every thing that comes to the line over a period of time
Sample during an idle period after sanitation, before production i.e. Saturday when no production is running
Sample large areas using sponges or gauze.
Sample areas not typically sampled during routine sampling
We found a transient growth niche using this method – COP basket handle
Vice President of Food Safety,
West Liberty Foods
There is no one magic bullet.
There is no one department responsible.
Attitude must start from the top one down.
For every one dollar spent up front, multiple dollars are saved later.
No one is immune.
Building Design/Physical Barriers
Each product slicing cell has separate positive pressure, air handling system.
HEPA air filtering systems keep with our clean room focus.
Separate slicing cells prevent cross contamination.
Encapsulated suits to prevent cross contamination from employees.
Separate drain system in each slicing cell with capability of back flooding each drain system.
Ceilings, floors and walls are designed for easy cleaning and sanitizing.
Exposed product production areas are targeted to <38°F.
Design eliminates cardboard and wood from entering exposed product areas.
Sanitizer challenge studies
Choosing the correct cleaners and sanitizers for your equipment, your environment and the organism.
Deep cleaning programs (see next 2 slides for examples)
Use of indicator organisms to identify potential niches
Maintenance Tool Cleaning
When removed this cover exposed the spindle to allow for cleaning. This cover is removed and cleaned with a Solvaxx solution once a week.
These cabinets are opened up and inspected weekly. These areas can be carefully cleaned with a Wypall lightly saturated with isopropyl alcohol by a qualified member of the maintenance department.
Modified Atmosphere Packaging
Shelf Life Determination
Temperature Control (cold chain management)
Partnered with Iowa State
Use of Visual Aids
Food Safety Certification as a pre-hire concept
GAP Training (Getting Acquainted Period) successive classes throughout the first 90 days
Strong Listeria program
>3500 Listeria species swabs per month company wide
Zone 1 (conveyors, slicers, product beds)
Zone 2 – indirect contact (on off buttons, framework, etc.)
Zone 3 environmental (floors, ceilings walls)
Zone 4 adjacent to RTE areas (employee welfare areas, hallways, dry storage)
Every line, every week
Random product sampling
Rapid detection methods
The listeria control system is a never ending process.
Constant changes due to continuous education, extensive training and monitoring processes.
Watching for new technology.
Utilize Trade organizations as valuable resource for latest topics and technical expertise.
Utilize your chemical representatives and equipment representatives.
Growing concept that Food Safety is not proprietary.
When one company stumbles we are all affected in the eyes of the consumer.
WLF and IA State teamed up to sponsor a food safety conference to share our training program with everyone.
Harshavardhan Thippareddi: email@example.com
John N. Butts: John.Butts@landofrost.com
Mike DeSmet: Mike.DeSmet@wlfoods.com
Bill Kinross: firstname.lastname@example.org
Lisa M. Keefe: email@example.com
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