I am doing a science project on food decomposition. I
would like to know why food -- especially meat--smells bad when it goes
bad. Also Why does bread grow mold and why is it green and blue? Thank you.
When food is being eaten by bacteria, they produce
byproducts just like we do. The compounds they produce
cause the smell of rotten meat. There is a reason we
don't like that smell: it warns us that that food is
probably unsafe to eat. So biology has built in a
safety rule: you would not normally eat something that
you don't like the smell of.
The molds on bread are a special kind that like bread.
Their spores are everywhere but only when we leave our
bread long enough can they grow to sufficient numbers
so that we can see them. Again, you can smell the
bread is off, you can see it, and if you hadn't
noticed you will taste it. However you should not eat
bread with molds on: they produce toxic substances. I
don't think there is a reason for them to be green and
blue, at least I don't know it.
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Update: June 2012