Cleaning Produce Science Fair Projects

Food and Cleanliness

When experimenting with ways to get food clean you have to think about more than just removing bacteria. You also have to think about minimizing the exposure the food has to toxic compounds.

EDU 7080 Detectolab Kit	EDU 8355 Super Chem Kit	EDU 8350 Super Chem Science Kit	Young Scientists Club Set 4
Ages 8 and up	Ages 10 and up	Ages 8 and up	Ages 9 - 12

Objectives/Goals

The purpose of my project was to investigate ways to clean produce with the intention of reducing/eliminating bacteria. I tested bacteria counts on spinach and green onions. I used 4 methods of treatment. My hypothesis was that exposure to ultraviolet light for 120 seconds would have the greatest reduction in bacteria. My goal was to find a method of cleaning vegetables that would decrease bacterial contamination on food.

Methods/Materials

Method for spinach trials;1-Separate unwashed spinach into 5 piles with 15 leaves in each;
2-Fill 15 test tubes with 10ml of distilled water
3-Swab 2cm of the stem and 2 cm of the spinach leaf
4-Cut swab into a test tube
5-Swirl for 30 seconds
6-With pipette, draw 1/10th ml of the solution
7-Drop the 1/10th ml onto agar plate
8-Dip a bent glass rod into methanol alcohol
9-Sterilize glass rod
10- rotate glass rod around the agar plate to even out solution
11-incubate 48 hours 37°C
12- Remove and tape closed
13-Count bacteria colonies, record results
14- repeat 3-13 14 times for a total of 15 trials.

Tap water:
Repeat steps 1-2
Wash 15 spinach leaves in 2 liters of tap water for 60 seconds
Repeat 3-14.

Hydrogen
Peroxide
Repeat steps 1-2
Wash 15 spinach leaves in 2 liters of a 0.3% solution of hydrogen peroxide for 60 seconds
Repeat 3-14.

Repeat steps 1-2
Place 15 spinach leaves 10cm under a germicidal UV light for 60 seconds
Repeat 3-14.

Repeat steps 1-2
Place 15 spinach leaves 10cm under a germicidal UV light for 120 seconds
Repeat 3-14. Green onion trials: Repeat the entire process using green onions in place of spinach.

Results

Spinach; On average the least amount of bacteria was on spinach treated under UV light for 120 seconds with 28 bacteria colonies. Control had 279 colonies. Green onions; On average the least amount of bacteria was on green onions treated under UV light for 60 seconds with 15 bacteria colonies. Control had 116 colonies on average.

Conclusions/Discussion

I correctly predicted that spinach exposed to UV light for 120 seconds would have the least amount of bacteria colonies. Control was not the highest as I had expected. Exposure to UV light for 60 seconds had 5% more colonies than the control. Green onions: 60 second exposure to UV light had the least amount of bacteria (vs. the 120 second exposure I predicted). The control on green onions had the highest bacteria counts as I predicted. 3rd party contributor