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Fat and frying

  1. Mar 12, 2008 #1
    So, you have steak which you toss on a hot pan. The heat eventually break apart the molecules, making oxygen and hydrogen evaporate and you are left with just carbon, a burnt crust on your steak.

    My question is, why does this change when you use oil or fat?

    I have two possible solutions that I can think of. The oil might work as an insulator of sorts, since the steak "floats on top of it" and thus it gets less direct contact with the pan. The other is that it might be a chemical reaction where atoms from the oil takes the position of evaporating atoms.

    I consider the first explanation the most likely.

    So, anyone care to enlighten me?

  2. jcsd
  3. Mar 12, 2008 #2

    Andy Resnick

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    You are forgetting about the water content: as long as there is water present, the temperature cannot exceed 100 C.

    Frying, or using oil, allows the temperature to exceed 100C at the surface of the meat. This, in turn, allows the temperature of the surface of the meat to get high enough so that the various components undergo browing reactions (Maillard reactions), which is responsible for the developed flavor.

    The same concept holds for roasting in an oven- searing the surface with high heat allows the skin to dry out and brown.

    McGee's book "On Food and Cooking" has more information about this.
  4. Mar 12, 2008 #3


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    Andy, did you notice he was asking why the steak doesn't brown if you use oil or fat?
  5. Mar 12, 2008 #4

    Andy Resnick

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    The OP's question, taken literally, makes no sense. The question seems to inquire about the role of fat and frying in creating a tasty steak.

    My answer is correct- in order to brown meat, the temperature must rise about 100C, and this can only happen by drying. Boiling meat will never brown.

    If (s)he is truely asking "why the steak doesn't brown if you oil or fat to cook the meat", the correct answer is "Because the heat is too low".
  6. Mar 12, 2008 #5
    The OP's question is just fine.

    As someone with lots of experience cooking steak, the only answer I can give is that the oil is not as hot as a grill or pan surface that has been heated with flame. When I cook a steak over charcoal, we're talking about 1000 degrees or more at the surface of the grill. When you fry something in oil, you don't reach those kinds of temperatures. I believe your insulation idea is right. The oil requires far more energy to reach the heat necessary to char the steak than the metal surface does. Whether the crust is formed depends entirely on how hot the meat gets. If the meat only touches the oil (which burns above 450 degrees or so, which is NOT hot enough to char the steak), it will never char.
    Last edited: Mar 12, 2008
  7. Mar 13, 2008 #6
    Peter that makes perfect sense, thank you.
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