Canned tomatoes are available in various forms including peeled, whole, crushed, and those with herbs such as oregano and/or basil added. Canned tomato purée consists of tomatoes that have been cooked briefly and strained, resulting in a thick liquid. Tomato sauce is a slightly thinner tomato purée, often with seasonings and other flavorings added so that it is ready to use in various dishes or as a base for other sauces. Tomato paste, which is available in cans and tubes, consists of tomatoes that have been cooked for several hours, strained and reduced to a deep red, richly flavored concentrate. Tomatoes are rich in vitamin C and contain appreciable amounts of vitamins A and B, potassium, iron and phosphorus.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.