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Peanut smoke?

  1. Dec 11, 2003 #1
    Hi all,
    maybe this is not the proper forum to post this. Because it rather belongs into a section 'strange effects in everyday life', or whatever. Well.

    Yesterday I opened a bag of peanuts. The ones that have the closed shells which contain two nuts each. I found the best way to crack them was this:

    - Grab the shell between right thumb and index finger, and also between left thumb and index finger, so that the shell is held by these 4 fingers.
    - Hold it so that one nut is left, and the other is right.
    - Find the line of symmetry (where the shell will crack), and align that with the horizontal.
    - Now, use both hands like pincers, cracking the shell in the middle between the two nuts. The shell will crack cleanly into an upper and lower half.

    I observed the following (which each single shell in the bag!):

    - As the shell cracks, a 'whisp of smoke' rises from it, curling for a second or two in the air, much like you flicked a lighter or blew at a candle.

    Of course, this is not smoke but probably a very fine dust or aerosol (like in oranges), but still here's my questions:

    1) Can anybody reproduce the effect?
    2) What is the physical nature of this, and can it be explained from the peanut's structure?
    3) Why does this substance move up as if it was hot?
    4) Is there any biological/evolutional sense in this?
    5) Are there related phenomena?

  2. jcsd
  3. Dec 11, 2003 #2


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    I have observed the same in the past, I just thought that it must be dried shell material due to the roasting process. It probably moves up because the micro air current that is created when it breaks open..

    I have another interesting observation for you:

    Did you ever look at the structure of the peanut when you take the two parts apart? You can actually see the peanut embryo inside!! A tiny little plant, the leaves are outlined an the sack from which it would have grown
  4. Dec 11, 2003 #3
    No, I don't think the breaking causes an upward current. Not so strong, at least. The altitude I'm talking about is 15 cm or so. However, could be the warm air heated by the eater's body...
    Interesting. I'll have a look next time I eat them. Is there one or two embryos in a two-nut shell?
  5. Dec 11, 2003 #4


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    Every peanut has one embryo. Maybe the upward motion of the 'smoke' is because the material is very fine/light and IS thus influenced by the microvortex created by breaking open the shell. This smoke won't appear when you open it in a non-forcefull way, would it?
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