This study evaluated food handling practices and potential sources of cross contamination in four types of foodservice operations. Researchers observed practices, tested mitigation strategies, and measured temperatures and sanitizer concentrations over time. Key findings included sources of cross contamination during receiving, preparing, and serving foods. Educational strategies focused on handwashing, cleaning/sanitizing, and cold temperature maintenance. Food safety practice scores improved for all sectors after the interventions.

1. Mitigating Cross Contamination
in the Food Flow
Jeannie Sneed, PhD, RD, CP-FS, SNS
Catherine Strohbehn, PhD, RD, CP-FS
Janell Meyer, MBA
Paola Paez, MS
Project funded by the United States
Department of Agriculture Cooperative State
Research, Education, and Extension Service
Project Number 2005-51110-03282

2. Purposes in the Study
• Evaluate food handling practices that were
potential sources of cross contamination in
the flow of food.
• Test the effectiveness of mitigation
strategies to minimize cross
contamination.

3. Study Sample
• 4 Assisted-Living Facilities
• 4 Child Care Centers
• 4 Restaurants
• 4 Schools

4. Methods
• 4-hour observation period
– Start of project
– After 6 months
– After 2 years
• Flow of Food Form
• Validated Food Handling Practices
Observation Form

5. Methods, cont.
• Measurements
– Time/temperatures
– Sanitizing concentrations
• Used data logger to follow temperature
of cold cuts
– Storage
– Preparation
– Service

6. Logged Temperature From Storage to Service

7. Results
• Sources of cross contamination in flow of
food
• Cold chain management
• Food Safety Practice Scores

8. Cross Contamination

9. Sources of Cross
Contamination—
Receiving/Storing
Delivery person placed products in storage 4
Storage accessible to non-foodservice staff 5
Food stored on floor 2
Food stored where it could be contaminated 2

10. Sources of Cross
Contamination--Preparing
• Packages on food contact surfaces 12
• Touching other surfaces 12
• Multiple items on same cutting board 9
• No sanitizing of food contact surfaces 6
• F&V not washed in preparation 5
• Sinks used for multiple purposes 5
• Towels used for wiping multiple surfaces 2

11. Sources of Cross
Contamination--Serving
Self service 7
Inadequate sanitizing of surfaces 7
Boxes on food contact surfaces 5
RTE foods served with bare hands 4
Gloves not changed when needed 4

12. Sources of Cross Contamination,
Cleaning and Sanitizing
• Inadequate cleaning and sanitizing of
food contact surfaces 8
• No handwashing between handling dirty
and clean dishes 8
• Sanitizer concentration not checked 7
• Sanitizing concentrations too low 3
• Hot water not hot enough 2
• Limited corrective actions taken 2

13. Cold Chain Management

14. Cold Meat/Sandwich Temps

15. Some Supporting Data
• Cold food held at 41 ⁰F or below in 7 of the
16 operations at 1st visit; 12 of 16 at 2nd
visit
• Hot food held at 140 ⁰F or higher in 11 of 16
operations at 1st visit; 12 of 16 at 2nd visit
As educators, we seem to have gotten
the word out about hot food!

16. Key Educational Messages
Based on Research
• Handwashing—frequency and technique
• Cleaning and sanitizing techniques
• Avoiding cross contamination
• Maintaining cold temperatures
• Cleaning produce
• Keeping facility secure

17. Educational Strategies
• Initial Site Visit
– Installed soap dispensers with audible
– Demonstrated SpotCheck
• At 6 months
– Trained foodservice manager on use of
revealing powder and black light
– Face-to-face training
– Showed video, “Do It in Your Sleeve”

18. SpotCheck
Clean vs. Soiled

19. Educational Strategies
• Reports of observations after each site
visit
• Provided sector specific standard
operating procedures

20. Educational Strategies, cont.
• Ongoing educational messages based on
results of research
– Calendar with monthly picture and message
based on observations
– “Yuck” photos
– Newsletters
• Food Code
• Handwashing
• Cross contamination
• Sandwich making

22. Microorganisms found on the
bottom of the lettuce box
Microorganisms from fingers that
have touched the lettuce box

23. Microorganisms found on Microorganisms from
the celery bag fingers after touching the
celery bag
Microorganisms found on
the counter after the
celery bag sat on it

24. Sample of microorganisms found Growth of microorganisms from
on a food film box in a production fingers that have touched a
kitchen well-used food film box

25. A clean and sanitized cutting board shows
no sign of microorganisms

26. Food Safety Practice
Scores
Sector Mean Pre Score Mean Post Score
Assisted Living 76.8 + 14.0 82.5 + 10.7
Child Care 68.0 + 11.4 72.2 + 9.9
Restaurants 63.7 + 5.7 70.7 + 7.7
Schools 84.1 + 1.8 90.0 + 4.9
Post intervention scores increased for all sectors
(p < 0.05)

27. Improvements
• Thermometer use
• Cold holding temperatures
• Sanitizing solution concentrations
• More frequent changing of sanitizing
solutions
• Fewer packages on countertops
• More cutting board/countertop sanitizing

28. Conclusions
• Cross contamination potential at all steps
in the flow of food
• Organization of work needed to reduce
potential for cross contamination and
need for handwashing

29. •Organize work
•Use multiple employees
•Use barriers