Preserving tomatoes in tin cans allows access to the ripe fruit all year round regardless of the climate or growing season. A canned tomato can be either store bought or preserved at home, and can appear in many forms including whole, diced, and seasoned. If high-quality, fresh, ripe tomatoes are not available, a canned tomato preserved at the peak of ripeness can be substituted in many recipes.
Fresh tomatoes can be fickle fruits: home gardens are not always practical or reliable and commercially produced tomatoes are often unripe or bland. While there might be some situations where only a fresh tomato will do, such as a cold slice atop a sandwich or hamburger, a canned tomato can be a steadfast replacement in sauces, soups, chili, or stews. Apart from making tomatoes available in the off seasons or other times of scarcity, canning tomatoes is also useful in preserving excess fruit from a bountiful crop to avoid waste.
A canned tomato can be purchased from most grocery stores, but can also be made by hand at home. Canning at home is actually done in sterilized glass jars with vacuum sealed lids to keep out air and bacteria and preserve the integrity of the tomatoes. The process includes multiple steps and some special equipment, but is a good way for home gardeners to preserve extra produce if they grow significantly more tomatoes than they can eat. Varieties of store bought canned tomatoes are generally found in actual tin cans, as the name suggests. Sturdy, fleshy tomatoes with lower water contents are generally used for canning because they stand up to the process and preservation better than juicier options that are more likely to break down.
In the grocery store, a canned tomato can come in many forms, with popular variations including whole, diced, stewed, and crushed. Whole preparations can be chopped and added to dishes, whereas diced tomatoes come pre-cut and ready to use; the liquid remaining in the tins can be discarded if necessary, but many recipes, especially for sauces and soups, include the canning liquid to take advantage of its tomato flavor. Crushed tomatoes generally refer to a mixture of ground tomatoes and a thin sauce, and stewed tomatoes are cooked before canning. All of these different versions have the skin removed, and can either be packed in tomato juice or tomato puree. Some versions are available pre-seasoned in different flavor profiles, such as “Italian style” tomatoes with herbs and garlic or “Mexican style” with jalapeños.