1. The POISON Drink

2. Problem  What type of fruit drink permits the least amount of bacterial growth if left open to the environment?

3. How?  Need to make sure all samples have same bacteria to begin with E. coli  Need to find accurate way to measure Colorimeter

4. Escherichia coli  Common bacteria found in raw meats and unwashed vegetables  Live in lining of large intestines of humans within 40 hours of birth  Can cause gastrointestinal and urinary tract infections  One of the main worries when people hear of food poisoning

5. Colorimeter  Shines a light through a cuvette filled with liquid of choice  Measures the amount of that light that enters a sensor on the opposite side of the cuvette  Records this as a percentage transmission  Can use green, red, or blue light

6. Hypothesis  Lemonade will allow the least growth E. coli grows best in a relatively neutral pH ○ Lemonade has the lowest, around 2.5 ○ The others have pH around 3 or 3.5 All bacteria needs something to feed on ○ Lemonade has least amount of sugar  Fruit punch or apple will be worst Have highest pH Second only to grape in sugar

7. Procedure  Take three 15 ml samples of each juice Place in 20 ml test tubes  Inoculate each sample with E. coli Heat a wire loop over flame, allow to cool, touch loop to E. coli colony, dip loop in sample, repeat with each  Leave samples open to air Placed samples in incubator on day 4 due to lack of growth, depends on “room temperature”

8. Continued  Take 3 ml sample of each in cuvette Used 1 ml pipette  Place cuvette in colorimeter  Record data  Pour juice back into original test tube  Repeat this test, recording time of test

9.  Experimental Variable Type of juice  Experimental Groups apple, cran-rasberry, lemonade, white grape, fruit punch, and powerade  Control Group Bottled mineral water

10. Control Variables  Same equipment Colorimeter Laptop Sterile test tubes  Sterile pipette and cuvette for each test  Same batch of E. coli  Samples kept at same temp. and light Placed in incubator at same time

11. Cuvette Control  Noticed that not all cuvettes were same condition  Might affect results Filled cuvettes with water Placed in colorimeter  Had a plus or minus 1% effect on samples, consider this while testing

12. Sample Raw Data

13. Choosing a Color  Three colors of light Not all decrease equally  Research uses of colorimeter Chose blue for all except powerade because it is blue Showed greatest change for all juices Used both red and blue for control to compare both

14. Averages Over Time  Divided average of each day by starting average  Still hard to understand

16. Percent Change of Averages

17. Conclusion  Incorrect hypothesis Lemonade was visibly worst on day 1  Fruit punch ended worst, off chart  Water and powerade ended slightly above grape and apple  Cranberry? Somehow kept increasing Cranberry juice helps fight urinary tract infection, often caused by E. coli

18. Further Testing  Other types of bacteria or juice  Specific parts of juice that have the greatest effect pH, sugar, vitamins and minerals  Amount and type of preservatives