Tomatoes, like potatoes, carrots and all the other good stuff in
your soup contains a lot of water. That water holds a lot of heat.
So why is the tomato sometimes hotter than the rest of the broth
(which is also mostly water)? Well, the water in the soup broth is
moving around a lot, and when it passes close to the air or touches the
bowl, it loses heat. but the water in the tomato is mostly trapped - it
doesn't swirl around with the rest of the broth when you scoop up a
spoonful. So the water in the tomato doesn't come close to the air or
the bowl as much and doesn't cool down as quickly.
Further, when you eat the soup, you probably drink the broth by
small spoonfulls - even smaller spoonfuls if the soup is really hot.
But unless you feel like eating your soup with a knife and fork, the
tomatoes probably come in pretty big chunks. So you get a big bite of
hot stuff instead of just a little sip.
So why do the tomatoes sometimes seem hotter than the other good
stuff - like the potatoes? We've gone around quite a bit on this one,
and we're really not sure, but here's a possibility:
Tomatoes hold a lot of water, but unlike potatoes, they're also
really squishy, and the water is held in large-ish pockets. When you
bite into a tomato, a whole lot of that hot water comes squishing onto
your tongue all in one big gush. With a potato, it takes a little
longer, since you have to chew it up.
(republished on 07/27/06)