Key Ingredients: Tomatoes

Starting with the September 2008 issue of Reader’s Digest, Bonnie Stern—who teaches Canadians how to eat healthfully while still having fun in the kitchen—and Fran Berkoff—a Toronto dietitian/nutritionist—will be bringing you great recipes and nutritional information based around one key ingredient, for healthy home cooking. This month: tomatoes.  

A medium tomato (4 oz/125 grams) has 22 calories, 1.5 grams fibre (nearly as much as a slice of whole wheat bread), and supplies about one quarter of your daily vitamin C as well as other nutrients, including potassium, folate and some B vitamins. Tomatoes are low in sodium and contain almost no fat.

Tomato Facts

Do not refrigerate tomatoes. Cold temperatures interfere with the ripening process, changing the texture, making them mealy and taking away lots of flavour. If they are overripe or it is extremely hot, you can put them in the refrigerator butter compartment. But, to ensure best flavour, let them reach room temperature before serving.

When in season, you can’t beat the taste of fresh tomatoes. But in Canada, where the season is quite short, here are the options:

  • Plum tomatoes are the best to use in cooking because they have more pulp than seeds. When they aren’t in season, use canned.
  • Cherry tomatoes are delicious any time of the year and are wonderful used in cooking or raw in salads.
  • Use field tomatoes only in season.  
  • Heirloom tomatoes, prized for being handed down the generations, come in many shapes, colours and sizes. They are usually available at organic markets, locally, in season.

Choose tomatoes that are firm yet not rock hard, plump and free of surface cracks, bruises or soft spots. Tomatoes are best stored at room temperature, in a single layer, away from direct sunlight to prevent uneven ripening. Once they are ripe, you should use them within a week. Not ripening fast enough? Put them in a brown paper bag with a piece of apple or pear. The fruit releases a natural ethylene gas, which hastens the ripening.


Bonnie Stern has been teaching people to have fun in the kitchen, to eat more healthfully and to nourish their families since she started her cooking school in 1973.


Fran Berkoff is a consulting dietitian/nutritionist in Toronto, as well as a columnist for newspapers and magazines, and co-author of several books.