Preventing Introduction, Growth and Cross-Contamination of Listeria monocytogenes ©2006 Department...
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Transcript of Preventing Introduction, Growth and Cross-Contamination of Listeria monocytogenes ©2006 Department...
Preventing Introduction, Growth and
Cross-Contamination of Listeria monocytogenes
©2006 Department of Food Science - College of Agricultural Sciences at Penn State UniversityPenn State is committed to affirmative action, equal opportunity, and the diversity of its workforce.
This publication is available in alternative media on request.
Contamination
Introduction– LM is brought into the facility from an
outside source Growth
– LM present in the facility/food has the ability to multiply
Cross-contamination– LM present in the facility/food is
transferred to another food or surface
Introduction of LM
Employees
Rodents/Pests
Customers
Vendors
Contaminated Food
RetailFacility
Non-food items
Retail establishments are open to the public
Restrictions & controls should be designed to complement normal operations
Introduction of LM
Employees– Sources
Ill employees Unclean hands, clothing
– Prevention Good personal hygiene Restriction of ill employees Training
Introduction of LM
Vendors– Sources
Ill vendors Unclean hands or clothing
– Prevention Restriction from high risk areas Training/vendor agreements
Introduction of LM
Customers– Sources
Ill customer
Unclean hands
– Prevention Facilitate proper handing of food
– Tongs, single use paper
– Instructions for proper handing
Introductions of LM
Rodents/Pests– Sources
Feces Rodents/pest carrying LM on feet and body
– Prevention Pest control program Maintenance of indoor and outdoor facilities
Introduction of LM
Contaminated Food– Sources
Raw products (meat, poultry, fruits, vegetable)
Ready-to-eat foods– Prevention
Vendor assurances (HACCP plan, testing) Vendor audits
Introduction of LM
Non-food Items– Sources
Contaminated packaging, other supplies
– Prevention Receiving standards
Growth of LM
Since it is not possible to eliminate all sources of LM in the retail environment, preventing growth is essential– On Food– On Equipment – In the Environment
Controls to Prevent Growth
1. Adequate time and temperature
controls
2. Proper cleaning and sanitation
3. Good personal hygiene
Time/Temperature Controls
Cold Holding (Refrigeration)41ºF for 7 days
OR
45ºF for 4 days
– LM can grow at refrigeration temperatures, so holding time is important
– Control of LM growth is the basis for 2005 Food Code cold holding temperature/time combinations
Growth of Listeria monocytogenes CFA 433 in chicken broth when
incubated at 47.7. 38.3, 34.7, and 33.4oF. Adapted from S.J. Walker et al. (1990).
4
5
6
7
8
9
0 10 20 30 40 50 60
Time (days)
log
10 c
fu/m
l
47.7F
38.3F
34.7F
33.4F
Time/Temperature Control
Date Marking– Requires active managerial control– Applies to:
Certain high risk foods Foods held for greater than 24 hours
– After prepared by a food establishment– After opened, if a processed food
Estimated Reduction of Cases of Listeriosis from Limits on Refrigeration Temperatures
Maximum Refrigerator Temperature
Cases of Listeriosisa
Median
5th Percentile
95th Percentile
Baselineb 2105 ¾c ¾c
7 °C (45 °F) maximum 656 331 761
5 °C (41 °F) maximum 28 1 126
a Values for the median, upper and lower uncertainty levels.b The baseline uses the full empirical distribution of refrigerator temperatures from the Audits International (1999) survey.c The baseline number of cases of listeriosis is fixed based on CDC surveillance data.
Source: FDA/CFSAN and USDA. 2003. Quantitative Assessment of Relative Risk to Public Healthfrom Foodborne Listeria monocytogenes among Selected Categories of Ready-to-Eat Foods
Time/Temperature Controls
Hot holding– Minimum of 135ºF
No temperature control– Can be held for no longer than 4 hours at
ambient temperatures
Cleaning & Sanitation
Prevention of LM growth requires a sanitation program that is:– Properly designed– Properly carried out
Target areas– Food contact equipment at room temperature– Refrigerated storage & display cases
Controls to Prevent Cross-Contamination
Cleaning & Sanitation
Good Personal Hygiene
Proper Flow of Food & Employees
Cleaning & Sanitation
To prevent cross-contamination– Always clean between working with raw
and ready-to-eat products– Regularly clean to reduce chance that
contaminated product transfers to uncontaminated product
Personal Hygiene
Handwashing stations– Easily accessible to
promote frequent handwashing
– Properly supplied Appropriate training
– Employees should understand concept of cross-contamination
Proper Flow of Food
Facility design– Separation of raw and ready-to-eat
areas– Adequate storage and work space
Refrigeration Preparation tables Display cases
Flow of Employees
Facility design– Location of hand washing facilities– Locations of locker & rest rooms– Separation of raw and ready-to-eat
areas Designated tasks for employees Designated work areas
Flow of Employees
Service Area / Cooler
Prep Table Prep Table
Dry Storage Refrigerated Storage
ReceivingRefuse Storage
Dishwashing Area
Locker / Rest Rooms
Handwashing Sink
Coo
ler
Customer Entrance
Employee Entrance