Name: Sara BolandLab: Saturday May 12, 2012

Lab Name: Spices Lab

Purpose: Microorganisms are responsible for the spoilage of food in various ways. Decay microorganisms

change the taste, color, smell and consistency of food making it unpalatable for humans. Throughout history spices have been used medicinally and in food as both a preservative and a camouflage for spoiled food. The purpose of this lab is to illustrate the effect of spices on microorganisms. There are popular spices used traditionally in cooking and the lab looks at three of these spices to see their effect upon common microorganisms. The three spices being observed are black pepper, chili powder and cloves. Black pepper is the most popular spice in the world and was once thought to prevent Black Death. Due to this reputation, it would make sense for this spice to have a bactericidal effect of food or perhaps a bacteriostatic. Chili powder is a combination of chili pepper and various amounts of cumin, oregano, garlic, salt, cloves, allspice and onion. Due to the wide variety of spices included in chili powder it stands to reason that at least one ingredient would have an effect on microorganisms. The final spice included is cloves. Cloves are a very strong spice that has been used as a numbing agent for toothaches as well as a treatment for indigestion. Cloves are very aromatic but because they are more of a soothing agent it seems like the cloves would have very little use in the preventing microorganism growth. It will be very interesting to see whether these common spices have an inhibitory effect on the growth or sporulation of the microbes being sampled.

Materials:-Bottle of Plate Count Agar-Bottle of Plate Count Agar with 2% Black Pepper-Bottle of Plate Count Agar with 2% Chili Powder-Bottle of Plate Count Agar with 2% Cloves-Sterile petri dishes

-Sterile applicator sticks-Hot Plate-Beaker-Disinfectant-Petri dishes

Organisms:-Bacillus cereus-Escherichia coli-Penicillium notatum

-Pseudomonas fluorescens-Saccharomyces cerevisiae

Procedure:

1. Disinfect work surface2. Loosen the caps of the agar and place in the boiling water bath making sure the water level is well above the line of agar in the bottle. Leave the bottles in the boiling water bath until the agar is melted.3. Remove the bottle caps and pass them through a flame to disinfect them before pouring the agar into five petri dishes. Cover the petri dishes immediately following pouring to prevent any contamination.4. Repeat step two with the three other bottles of agar being used and let the agar in petri dishes solidify.5. Each group of students should take one petri dish containing each type of agar as well as one dish containing the material to be cultured.

6. Using an applicator stick which has been carefully removed from packaging to avoid any contamination, pick up some material from the culture dish and spread culture in an even line down the center of the petri dish containing agar. 7. Repeat step six for the other three petri dishes containing agar.8. Clearly label the petri dishes with: type of agar, culture name, group name and date.9. Leave cultured petri dishes at room temperature for five days.10. After five days examine the cultured petri dishes beginning with the culture in the petri dish containing plain agar. Label this petri dish +++. Compare the other samples to this dish and record the growth of the cultures in the other dishes as: marked growth (+++), moderate growth (++), slight growth (+) and no growth (-).11. Record all results in a table.