1. Bacteria on Restaurant Lemon Wedges
What’s On My Water?
Bacteria on Restaurant Lemon Wedges

2. Problem
Are restaurant lemon wedges free from bacteria? If not what is it that humans are ingesting?

3. Background Information
In 2008 Anne LaGrange Loving conducted an experiment with lemon wedges at restaurants to determine what exactly is on them
53 out of 76 lemons that she swabbed were infested with bacteria
Lemon pulp is acidic; it registers with a pH of 4. This could possibly kill bacteria
Coliform bacteria is found in warm-blooded animals
Pathogenic bacteria tags along closely to coliform bacteria
Coliscan Easy Gel plates shows coliform bacteria as either blue or pink colonies

4. Hypothesis
If lemon wedges from restaurants are tested for bacteria and coliforms and are compared to clean lemons, the restaurant lemons will have bacteria present.

5. Materials
15 lemon wedges: 10 from 2 restaurants ; 5 from a control lemon
30 Coliscan Easy Gel plates
30 cotton tipped sterile swabs
Bunsen burner
Gloves, lab coat, protective glasses

6. Procedure Lemons were collected from 2 restaurants
Lemons were swabbed using aseptic technique
Swabs were inserted and swirled in the liquid form of Coliscan Easy Gel
Set dishes were placed in the incubator for 96 hours at 37⁰ Celsius
Colonies were counted by using a grid. 8 sample blocks were counted, and the sum was multiplied by 4
All dishes were disposed by autoclave

7. Variables Control: clean washed lemon Independent: the restaurants
Dependant: the count of bacteria per wedge
Constants: temperature of incubator, amount of time in incubator, area of swabbing

11. T-test between Restaurants and Control Lemon
Restaurant 1 and Control Rind
Restaurant 2 and Control Rind

12. Conclusion
“If lemon wedges from restaurants are tested for bacteria and coliforms and are compared to clean lemons, the restaurant lemons will have bacteria present.”- was supported
No coliforms were found, so half of the hypothesis was rejected.

13. Sources of Error
The incubator may have been opened for long periods of time thus causing a temperature change
Some condensation was found on the plates
In only one plate, spores of mold were found; this plate was discounted

14. Further Research A more comprehensive survey of restaurants
What exactly is on lemon wedges?
What type of soap kills the most bacteria?

15. Works Cited
Growth. (1999). Introduction to Bacteria [Fact Sheet]. Retrieved from University of Missouri- Saint Louis website:
Instructions. (n.d.). Retrieved November 12, 2010, from Micrology Laboratories website: Media/‌Coliscan_Easygel/‌Instructions
Loving, A. L., & Perz, J. (2007, December 1). Microbial flora on restaurant beverage lemon slices. Journal of Enviromental Health. Retrieved from rage+lemon+slices-a
Morton, J. F. (n.d.). Lemon. Retrieved October 6, 2010, from Perdue University website:
pH Panel. (n.d.). The pH Factor. Retrieved October 21, 2010, from Miami Science Museum database.

16. Works Cited Continued
Reynolds, G. (2007, March 21). Bacteria effective against fresh cut fruit contamination. Food Production Daily. Retrieved from Safety/‌Bacteria-effective-against-fresh-cut-fruit- contamination
Stone, A. H. (1966). Chemistry of a Lemon. Englewood Cliffs, New Jersey: Prentice Hall.
Wassenaar, T., Dr. (2009, January 6). Food Safety [Virtual Museum]. Retrieved October 7, 2010, from Safety/‌food-safety.html