Testing the Interior Sterility of Meat

Starting materials

One slab of meat (e.g.: a piece of chicken white meat is excellent)
Sterile cotton swabs
sterilized single-edged razor blade wrapped in paper
3 nutrient agar petri plates
Directable flame source (e.g.: plumber's propane torch)
A drinking glass (made of glass!)

Methods

1 You will find out how to make the nutrient agar plates on its special page. These must be ready to use before continuing. Click to learn how to make beginner's nutrient agar plates.
2 Your three plates are for three replicates. Label each of the bottoms of the plates as shown with these three letters: "B" (before cooking), "A" (after cooking", and "X" (experimental incision). These indicate lanes into which you will swab your test materials.
3 Set the drinking glass upside down on a table.
4 Setting up your sterilizing "table."
Balance the piece of meat upon the inverted drinking glass.
Imagine a line that runs crosswise in the center of the piece of meat.
Aseptically remove a sterile swab from its wrapper. Do this by tearing off or peeling back the enclosing paper from the handle end of the swab. Withdraw the swab from the wrapper. Do not touch the cotton with your fingers unless you have cooked your fingers in a flame for several minutes. Do not allow the cotton end to touch anything.
To soak up microbes, if any, that may be on the surface of the meat, draw the sterile cotton along that imaginary line, and then use it to rub around onto lanes "B" of each plate's agar surface.

5 To sterilize the surface of the meat.
Hold the burner somewhat upside down and use the flame to cook the center section of the surface of the slab of meat. Cook to the sides of the slab - not to the ends of the elongated piece. It is IMPORTANT to cook only the surface of the meat and not all the way through!
Get a NEW sterile swab swab from its container and wipe it down the now cooked imaginary line you had swabbed before you cooked the meat.
Rub that swab onto the center lanes ("A") of the three plates.

6 To gain access to the inside of the meat, carefully unwrap the sterilized razor blade. Touch it only on the non-sharp edge. On your imaginary line, make a slice about half-way through the meat. Thou shalt not cut all the way through!
7 To swab the inside of the meat:
With your fingers, pick up the piece of meat ONLY by its slimy ends, and bend it so that your incision opens up.
Using yet another NEW swab, wiggle it around inside of the incision.
Rub that swab onto the rightside lanes ("X") of the three plates.

8 Now consider what results you might get after allowing the plates to grow for a day or so at room temperature.
If the meat were sterile inside, which of these two plates would you get, or
If the meat were not sterile on the inside.

Note: it is imperative that lanes "A" do not grow. If they do, you have not cooked the exterior of the meat sufficiently. Thus bacteria can be transferred to the inside as the blade slices into the meat.
9 CLEAN UP! Do not allow your plates to sit around and stink up the place! To dispose of the putrid, disgusting stuff, dribble a little household bleach directly onto the surfaces of the agar and tilt the plates to get the bleach to cover the whole surface. Instantaneous death to the microbes! Make sure that you splash the bleach onto your skin and clothes. Imagine the increasing pain as the bleach attacks you, and the racing stripes you will get on your clothes!
If you are using disposable plates, drain the excess bleach into a sink with running water, and trash the plates and their disgusting agar. If you are using non-disposable plates, allow the bleach to sit overnight, drain liquid into a sink, and then using a stick or spatula dig the agar out and flip into a trash can. Then wash the plates thoroughly.

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1	You will find out how to make the nutrient agar plates on its special page. These must be ready to use before continuing.	Click to learn how to make beginner's nutrient agar plates.
2	Your three plates are for three replicates. Label each of the bottoms of the plates as shown with these three letters: "B" (before cooking), "A" (after cooking", and "X" (experimental incision). These indicate lanes into which you will swab your test materials.
3	Set the drinking glass upside down on a table.
4	Setting up your sterilizing "table." Balance the piece of meat upon the inverted drinking glass. Imagine a line that runs crosswise in the center of the piece of meat. Aseptically remove a sterile swab from its wrapper. Do this by tearing off or peeling back the enclosing paper from the handle end of the swab. Withdraw the swab from the wrapper. Do not touch the cotton with your fingers unless you have cooked your fingers in a flame for several minutes. Do not allow the cotton end to touch anything. To soak up microbes, if any, that may be on the surface of the meat, draw the sterile cotton along that imaginary line, and then use it to rub around onto lanes "B" of each plate's agar surface.
5	To sterilize the surface of the meat. Hold the burner somewhat upside down and use the flame to cook the center section of the surface of the slab of meat. Cook to the sides of the slab - not to the ends of the elongated piece. It is IMPORTANT to cook only the surface of the meat and not all the way through! Get a NEW sterile swab swab from its container and wipe it down the now cooked imaginary line you had swabbed before you cooked the meat. Rub that swab onto the center lanes ("A") of the three plates.
6	To gain access to the inside of the meat, carefully unwrap the sterilized razor blade. Touch it only on the non-sharp edge. On your imaginary line, make a slice about half-way through the meat. Thou shalt not cut all the way through!
7	To swab the inside of the meat: With your fingers, pick up the piece of meat ONLY by its slimy ends, and bend it so that your incision opens up. Using yet another NEW swab, wiggle it around inside of the incision. Rub that swab onto the rightside lanes ("X") of the three plates.
8	Now consider what results you might get after allowing the plates to grow for a day or so at room temperature. If the meat were sterile inside, which of these two plates would you get, or If the meat were not sterile on the inside. Note: it is imperative that lanes "A" do not grow. If they do, you have not cooked the exterior of the meat sufficiently. Thus bacteria can be transferred to the inside as the blade slices into the meat.
9	CLEAN UP! Do not allow your plates to sit around and stink up the place! To dispose of the putrid, disgusting stuff, dribble a little household bleach directly onto the surfaces of the agar and tilt the plates to get the bleach to cover the whole surface. Instantaneous death to the microbes! Make sure that you splash the bleach onto your skin and clothes. Imagine the increasing pain as the bleach attacks you, and the racing stripes you will get on your clothes! If you are using disposable plates, drain the excess bleach into a sink with running water, and trash the plates and their disgusting agar. If you are using non-disposable plates, allow the bleach to sit overnight, drain liquid into a sink, and then using a stick or spatula dig the agar out and flip into a trash can. Then wash the plates thoroughly.