Hypothesis: Organic carrots should exhibit a higher quantity of microbial growth than their conventional counterparts, even after the application of various sanitizers.

1. By: Crystal Hamelburg and Tomasz Perlinski

2. Organic carrots should exhibit a higher quantity of
microbial growth than their conventional counterparts,
even after the application of various sanitizers.

3. • There were two main objectives of this study:
• The first objective involved testing the efficacy
of three different sanitizers used to clean cutting
boards purposely contaminated with
Escherichia coli.
• The second objective was to compare the
quantity of E.Coli contamination present on
organic and conventionally grown carrots
prepared on the cutting boards after the
application of the disinfectants.

4. Media Preparation
• 40 g of Tryptic Soy Agar was weighed out on a
balance and slowly added to 1.0 L of distilled
water, while the flask was stirred with a stir bar
(directions obtained directly from the bottle)
• The media was placed into the autoclave on a
Liquid 9 setting for 45 minutes at 121°C
• 56 plates were poured for the two trials conducted

5. Sample Preparation
Carrots were washed with warm
tap water and dawn dish soap
A borer, forceps, and scissors
were autoclaved and used to
obtain the carrot cores
Carrot cores were obtained
under a sterile hood and
placed into sterile weigh boats

6. Cutting Board Preparation
A used cutting board was obtained from Texas
Roadhouse, cut into four roughly equal
boards, and sterilized under UV light for 2 hours.
Each board was divided into 6 sections and
labeled the “control, bleach, Eco-San, and lime.”

7. Disinfectants
Control: Sterile
Distilled Water
1% Bleach Solution 50% Diluted Eco-San Lime Essential Oil
(1 mL Lime + 2 mL dH2O)(10 mL dH2O+10 mL Eco San)

8. Pre and Post experiment procedures and testing
• Four separate sterile cotton swabs were used to test each cutting board prior to the application
of any E.coli to ensure that they were free from contamination that would skew the results.
• Four Additional samples were collected after the application of each disinfectant.

9. Application of Escherichia coli and Disinfectants
A McFarland standard was used to prepare the E.Coli cells
0.5 mL of E.coli was transferred using a sterile pipette to each section of
the four cutting boards
The bacteria was spread all over each section of the cutting board using
a sterile cotton swab
The bacteria were given 10 minutes to dry before 0.5 mL of each
respective sanitizer was applied to each respective section

10. Incorporation of carrot core samples and
consequent plating on TSA plates
Giant Organic
Shoprite
Organic
Weis Organic
Giant
Conventional
Shoprite
Conventional
Weis
Conventional
• Carrot cores were spread around about an inch
forward and then back again with forceps.
• The Bunsen burner was used to sterilize the forceps
after each carrot core application.

11. Colony Quantification
Control Bleach Eco-San Lime Essential Oil

12. Gram Stains
Gram stains were performed on the E.coli
Bacteria after they were given a 24 hour incubation
period.
The TSA plates that showed growth were tested using
the standard gram stain procedure.
This allowed the quantification of any sort of
contamination.

13. Figure 5: Sample gram stains from colony forming carrot samples.
Photographs of gram stains, showing E. coli (gram negative) colonies
that formed from carrot core swabs. A – Sample gram stain of carrot
swab used on control (dH2O) cutting board; B - Bleach treated cutting
board, C – Eco-San treated cutting board, and D – Lime treated cutting
board.
Gram Stains

14. Table 1: Colony Quantification of Experiment I. The number of colonies
that formed from the carrot swabs after the 24 hour incubation period
(standard conditions).
*Using a streak plate method and counted using naked eye.
Table 2: Colony Quantification of Experiment II. The number of colonies
that formed from the carrot swabs after the 24 hour incubation period
(standard conditions).
*Using a streak plate method and counted using naked eye.
Colony Counts
Experiment I
Carrots Control (dH2O) Bleach Eco-San Lime
Giant Organic TNTC 0 0 5
Giant Conventional TNTC 0 0 TNTC
Shoprite Organic 16 0 0 TNTC
Shoprite Conventional TNTC 0 0 TNTC
Weis Organic 0 0 0 TNTC
Weis Conventional 2 0 0 TNTC
Experiment II
Carrots Control (dH2O) Bleach Eco-San Lime
Giant Organic TNTC 2 0 0
Giant Conventional TNTC 0 0 0
Shoprite Organic 83 6 0 0
Shoprite Conventional TNTC 0 0 0
Weis Organic 28 0 0 42
Weis Conventional TNTC 0 1 0

15. Sanitizer Effectiveness
0
5 5
2
0
1
2
3
4
5
Control Bleach EcoSan Lime
ScaleofEffectiveness
Figure 1: Sanitizer Effectiveness Scale. The effectiveness of sanitizers used
compared to the control, using a 1-5 scale. (0 = Not effective, 5 = Very effective)
*Effectiveness refers to the number of colonies formed, 0-20 CFU’s is considered very effective.
The most effective
sanitizers were
Bleach and Eco-
San.
The lime’s effectiveness
varied between
experiments, but was
not very effective in
either case.

16. Pre and Post Experiment Testing
1
0 0 0
Control Bleach EcoSan Lime
Figure 2: Cutting Board Cleanliness Before the start of the experiment. A sample
of each cutting board was plated on TSA to evaluate the effectiveness of cutting board
sterilization under the UV light in a laminar flow biological hood for approximately 2
hours. Any colony growth after a 24 incubation period was noted.
+330
4
0 11
Control Bleach EcoSan Lime
Figure 3: Cutting Board Cleanliness 10 minutes after applying Sanitizers. A
sample of each cutting board was plated on TSA to evaluate the effectiveness of the
sanitizers before applying the carrot samples. Any colony growth after a 24 incubation
period was noted.

17. Organic vs. Conventionally Grown Carrot Cores
Figure 4: Microbial Growth Comparison between
Organic and Conventional Carrots. The number of
each carrot category that had colony formation was
summed together to determine the total number of
organic carrot growth to conventional carrot growth out
of a possible 24 samples. For example, every time there
was growth on a TSA plate it was counted as “1”.

18. Eco-San was found
to be the most
effective.
Bleach was also
found to be the
most effective.
Lime essential oil
was found to be
the least effective.
Effectiveness of Sanitizers The results of this experiment have shown that plastic cutting
boards can be effectively cleaned with the use of various
sanitizers that may help to prevent cross contamination.

19. Overall, it was observed that organic carrots exhibited more microbial growth.
Conventional carrots are often associated with the application of chemical
fertilizers, genetic modification, hormones, pesticides, and residues in food.
Microbial growth comparison between organic and conventional produce

20. Typically, the use of the external portion of the carrots were utilized for
experimental procedures in the literature that was explored.
However, our experiment used aseptic carrot cores, but was still consistent
with theories that stated organic microbial growth would be higher than
conventional carrot growth, despite the differences in methods.
Literature Comparison