Differences between canned and fresh tomatoes I read on the web (including here) that canned tomatoes are usually more suitable for tomato sauces (in particular pizza sauce) than fresh tomatoes.  It is unquestionable that both are really different, but What makes them so different ?  Canned tomatoes aren't supposed to be baked already, or are they ?

I'm thinking it may have to do with the maceration in tomato juice, in which case one should be able to achieve similar results by making jars of fresh tomatoes.  Another possible (partial) cause could be that tomatoes are much more mature than fresh tomatoes a normal human would pick.

Of course I'm assuming we are considering similar tomato varieties (e.g. Roma, I guess).
Canned tomatoes, compared to fresh, are:


Cooked.  As part of the canning process, they are fully cooked.
Peeled.  Most canned tomatoes are peeled
Acidic.  For safety reasons, canned tomatoes often have additional citric acid added to the can (this prevents botulism growth)
Ripe.  The tomatoes to be canned are often vine ripened to a more ideal ripeness than retail tomatoes, and then immediately harvested, processed and canned.


Most of these attributes are actually an advantage in creating a pizza sauce, and so starting with a quality canned tomato may be far more convenient and flavorful than starting with raw tomatoes.