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If I buy a loaf of freshly-made bread and leave it out at room temperature for a day or two, when I reach into the bag the air inside is much warmer than the rest of the room. Why?

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Hi sparkleshy, I don't really think it is a chemical process. I tried migrating to our Physics brother site, but they don't think the question is appropriate for their site. Sorry! –  F'x Oct 10 '12 at 8:51
    
Maybe there is some crystallization of organic molecules going on while the bread turns hard. This might be a chemical question after all. –  Spießbürger Oct 11 '12 at 8:10
    
After reading some more stuff I actually think that crystallization of starch might be the answer to this question. There is a lot of literature about this and it might very well be that it can be sufficiently exothermic to warm the small volume of air in a bag. –  Spießbürger Oct 11 '12 at 18:53
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To the above point i also want to include possible exothermic enzymatic reactions by microorganisms also –  Eka Oct 18 '12 at 15:31

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After reading some more stuff I actually think that crystallization of starch might be the answer to this question. There is a lot of literature about this and it might very well be that it can be sufficiently exothermic to warm the small volume of air in a bag.

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I call for an experiment. Bread, digital thermometer with recording device... –  Spießbürger Oct 14 '12 at 17:16

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