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25.4: Materials and Procedures

  • Page ID
    40317
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    Materials

    • One food sample/group, at least 20g
    • Sterile blender container
    • 1 ml pipettes
    • 1-180 ml sterile water blank
    • 1-99 ml sterile water blank
    • Sterile spatula and weigh boats
    • 3 Eugon Agar pours
    • 3 sterile empty petri dishes
    • 1 EMB plate

    Procedures

    1. Using the best aseptic technique possible, weigh out 20g of food and transfer to the sterile blender container.
    2. Add the 180 ml of sterile water to the container and blend the food for 5 minutes.
    3. Use the 99ml water blank for diluting, mix thoroughly, and then plate out the sample to the following dilutions: 1:100, 1:1000, 1:10,000.
    4. Pour the Eugonpours into the plates, gently mix the plates using a slow figure-eight motion on the lab bench. Set aside the plates to harden.
    5. From the food in the blender container, use a sterile loop to streak an EMB plate to look for coliforms.
    6. Incubate plates at 35C for 24h.
    7. After incubation, evaluate plates.
      1. Count the colonies on the appropriate plate and report total #CFUs/ml.
      2. Look for presence of coliforms on the EMB plate.

    Results

    1. Standard Plate Count

    Food that you tested:____________________________________________________________

    Plate Dilution

    1:100

    1:1,000

    1:10,000

    Colonies Counted

    Calculate the SPC, the number of bacteria/g of food for your group:

    1. EMB plate observations:
    clipboard_ef874832e6c04e4945a1f1718c3dc6370.png
    1. Class Results: Place all class results in the table below.

    Group

    Food tested

    SPC

    EMB +/- for coliforms

    1

    2

    3

    4

    5

    6

    Contributors and Attributions


    This page titled 25.4: Materials and Procedures is shared under a CC BY license and was authored, remixed, and/or curated by Kelly C. Burke.

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