Grade Level: 5th - 9th; Type: Biology
The goal of this experiment is to evaluate the often outlandish claims regarding health benefits associated with spices. Students will learn to culture bacteria and determine first-hand if the claims about the anti-bacterial properties of curry and cinnamon are true.
- Does cinnamon or current prevent the growth of bacteria?
- What chemicals in cinnamon or curry might be biologically active?
A quick Google search reveals that many people wholeheartedly believe that curry and cinnamon are potent agents in the fight against infectious disease. However, closer examination reveals that almost none of these claims are rooted in experimental studies. In his 2010 paper appearing in Critical Reviews in Food Science and Nutrition, Gruenwald reviewed some of these claims and concludes that additional work needs to be done. This is your chance to contribute to this field. By inoculating Petri dishes with bacteria and exposing them to concentrated oil of curry and cinnamon, you can determine whether some of these claims are true. Unlike other science fair experiments that require boiling the spices, centrifuging them and using the supernatant, this experiment calls for using oil-based essences of the spice. By not limiting the experiment to water-soluble extracts, it is hoped that this will provide a truer picture of any possible anti-bacterial properties.
- Curry oil (available in health food stores)
- Cinnamon oil (available in health food stories.
- Pre-plated Petri dishes
- Individual sterile swabs (available in discount shops or drug stores)
- Label 3 Petri dishes “control.” Label three “cinnamon” and three “curry.”
- Expose all Petri dishes to germs in the environment by removing the lids and touching the agar with your fingers. Make sure that you have not washed your hands recently. Treat each dish identically. Cover the dishes.
- Open a swap and dip it into the cinnamon oil and gently trace the swap over the entire surface of one of the Petri dishes labeled “cinnamon.” If you have to dip the swab again, use a clean swab to avoid contaminating the cinnamon oil. Repeat with the other two Petri dishes labeled “cinnamon.” Cover the dishes and set aside.
- Repeat steps #2 and #3, using the curry oil and the Petri dishes labeled “curry.”
- Store the dishes in an area where they will not be disturbed for several days. Create a data sheet that includes the date (in the left-hand column) and columns for each dish. Twice a day inspect your dishes and count the number of cultures that have grown out in each dish. Record your observations.
- After five days, evaluate your data, comparing the total of cultures grown in the cinnamon and curry dishes with the controls.
Terms/Concepts:Petri dish, Inoculants, Bacteria, Water solubility vs. oil solubility, Plate streaking
Wearing, Judy. Bacteria: Staph, Strep, Clostrium and other Bacteria. Crabtree Publishing Company, 2010
Parker, Steven. Cocci, Spirilla & Other Bacteria. Compass Point, 2009
Cinnamon and Health: Critical Reviews in Food Science and Nutrition