Are canned tomatoes already cooked?

In this article, we will answer the following question: Are canned tomatoes already cooked? We will talk about the benefits and the dangers of using canned tomatoes. We will finish with 5 delicious canned tomato recipes.

Are canned tomatoes already cooked?

Canned tomatoes are not cooked, but sterilized. It is recommended to cook canned tomato sauce, not so much because it is dangerous if you eat it raw, but to combine the flavors of cooked food (such as a steak or pasta) and the sauce.

Most canned tomato products undergo the sterilization process to destroy pathogenic organisms and to ensure an adequate shelf life. Exact processing conditions depend on the product being packed, the size of the can, and the type and brand of retort used. The key is for the internal temperature of the tomatoes to reach at least 88°C (2).

If you want to eat tasty tomatoes out of season, go for canned tomatoes. They were picked when ripe and sealed in a can by induction of heat. They are sometimes peeled or sometimes canned with their skin on. Whether whole, diced, or crushed, these tomatoes can be easily used in a number of ways.

For instance, more than half (57%) of Americans disagree that canned food is as nutritious as unprocessed food and more than one-third (37%) disagree that canned food is as nutritious as frozen varieties (2).

Many canned tomatoes retain most of their nutrients.  Because, according to many studies, they allow a good part of the foods that are sold canned to maintain most of its nutrients. According to which even at higher levels than fresh food cooked at home. The retention of nutrients depends on the processing conditions. Studies showed that vitamin A (as forms of provitamin A) and riboflavin decreased, niacin increased, and thiamin did not change, while minerals (calcium, copper, iron, magnesium, manganese, nickel, potassium, sodium, zinc) showed slightly higher concentrations in juice and significantly higher concentrations in tomato concentrate in tomato juice and concentrate. Thermal processing was found to significantly reduce vitamin C contents in tomato products. Vitamin C is known to be one of most labile vitamins in our food supply and can be significantly lost during thermal processing (2).

Although their great advantage is that they can be stored for a long time and, in case some circumstance prevents leaving the house even to go shopping, they ensure that one can continue to eat.

Long-term storage of all types of food requires three steps: processing, washing, peeling, cutting, cooking; the sealing of the containers so that they are hermetic and avoid that the air spoils them and the heat that is applied to avoid the proliferation of possible bacteria and keep the food in good condition. 

In the case of peeled tomatoes, in the peeling machine the fruit surface is subject to rapid heating by steam, then vacuum is applied to detach the skin partially; then the tomatoes are conveyed over the rotating rollers, which pick up the skin. Then, the tomato solids are mixed with balanced 10° Brix juice in tanks with agitators rotating at low speed. Finally, the mixture is sterilized and filled into the cans and pasteurized (1). Underprocessing of whole peeled tomatoes usually results in spoilage by C. pasteurianum or C. butyricum. Spoilage outbreaks caused by B. coagulans, or flat souring, are fewer in number but of no less importance. At present, the recommended sterilizing value of a process for canned whole peeled tomatoes in juice against spores of butyric acid anaerobes is of 10 min when the pH is above 4.3 or of  5 min when the pH is less than 4.3 (3).

Now, what is the real weak point of canned food? Undoubtedly their repercussions for health, if they are abused. It’s okay to include them on the menu from time to time, but eating only or almost canned products is not the most convenient.

The problem is in the can

One of the main dangers of canned food has to do not exactly with the food itself but with the container that contains it.

A good part of metal cans are coated with a chemical component called Bisphenol A (BPA), which preserves them and prevents oxidation, but is considered harmful to health. It has been shown to be susceptible to heart disease, type 2 diabetes, male sexual dysfunction, among other ailments.

Check the expiration date and do not take them with you either if they are short of time for the limit. 

When you get home, it is convenient to put the cabinets in order, leaving the newly acquired ones at the back and placing the ones already stored in the foreground. Also, try not to keep them too long because they are not eternal nor do they remain in the same conditions from when they are packaged until they expire. Although they do not lose nutritional value, you can change their appearance, texture, and taste.

You should never put the cans in the microwave to heat them, and if it is done in a water bath, always with the can open and covered with a slightly loose aluminum foil so that it breathes. If all the content is not used, always keep the rest in the refrigerator and preferably in another closed plastic or glass container. But never keep it more than 3 or 4 days.

Other FAQs about Tomatoes which you may be interested in.

How do you peel a tomato?

5 canned tomato recipes

Prepare a pasta sauce

1. Sauté finely chopped onions and garlic in olive oil.
2. Add canned diced tomatoes. Season with a pinch of dried basil, oregano, and sweet pepper flakes.
3. Top cooked whole grain pasta with sauce. Sprinkle with grated cheese or a hard cheese like Parmesan.

Make your own salsa

1. Start with canned diced tomatoes.
2. Add green onions, jalapeño peppers, red onions, garlic, and cilantro.
3. Serve with whole-grain tortilla wedges, baked in the oven.

Easily make a pizza sauce

1. In a medium bowl, combine 1 can (398 mL) canned tomato sauce, 1 garlic clove (minced), ½ tsp. (2 mL) dried oregano, ½ tsp. (2 mL) dried basil.
2. Spread the mixture on a whole grain pizza crust.

Quickly prepare a tasty lentil and tomato soup

1. Heat 1 tsp. (15 ml) olive oil in a large skillet or large Dutch oven. Lightly brown 1 finely chopped onion in the oil.
2. Add tomatoes (796 ml can of diced tomatoes), red lentils (1 cup / 250 ml), cumin (½ tsp / 2 ml) and basil (1 tsp / 5 ml) with 1 cup (250 ml) of water.
3. Bring to a boil, reduce the heat to medium-low, then simmer for about 20 minutes or until the lentils are tender.
4. When the lentils are tender, mix the soup.
5. Add Greek yogurt if you like.

Poached eggs in tomato sauce

1. Sauté onion in olive oil until tender (about 5 minutes).
2. Add 1 can (796 mL) canned diced tomatoes, basil (½ tsp / 2 mL), and pepper and bring to a boil.
3. Increase heat to medium-high and cook, stirring frequently, until most of the liquid has evaporated, about 15 minutes.
4. Form 8 wells with a large spoon in the tomato sauce. Carefully break an egg into each well. Season the eggs with salt and pepper.
5. Cover and simmer over low heat until eggs are poached to desired doneness, 6 to 8 minutes. Remove from the heat.
6. Sprinkle ½ cup (125 mL) grated cheese over the eggs. Cover the pan and let sit until the cheese melts, about 1 minute.

For more recipes with canned tomatoes click here.

Final thoughts

It must be recognized that from a practical point of view, canned food is a very good option. And with the current market offer, it is possible to prepare a complete, nutritional and balanced menu, just by opening a few cans or uncovering some glass jars. There are from humble vegetables to authentic delicatessen made by prestigious chefs.

It’s okay to include them on the menu from time to time, but eating only or almost canned products is not the most convenient

No matter how little you know how to cook, it is possible to prepare rich and well-balanced dishes, and if you are a chef, prepare a true gourmet feast. Although make no mistake, they will never be as tasty as those prepared with fresh seasonal produce.

1. Karakaya, Ahmet, and Mustafa Özilgen. Energy utilization and carbon dioxide emission in the fresh, paste, whole-peeled, diced, and juiced tomato production processes. Energy, 2011, 36, 5101-5110. 
2. Wu, Xianli, Liangli Yu, and Pamela R. Pehrsson. Are processed tomato products as nutritious as fresh tomatoes? Scoping review on the effects of industrial processing on nutrients and bioactive compounds in tomatoes. Adv Nutr, 2022, 13, 138-151.  
3. York, G., et al. Thermobacteriology of canned whole peeled tomatoes. J Food Sci, 1971, 40, 764-769.
4. Kendall, Pat, and Kara Barnes. Canning tomatoes and tomato products. Service in action 1989, 9, 341.