Cooking questions
Cooking questions
Here are the questions that come up most often for people who cook with tomatoes: where to keep them, why a sauce turns out sour, whether green tomatoes are safe to eat and how to get preserving right. The answers are short; for more detail, see the sections we link to.
If you have doubts about a jar of preserves, don't taste it. It's the one kitchen question where caution matters more than flavour.
How this section works: a question is included if home cooks ask it often and it can be answered briefly on the basis of tested guidance.
Choosing and storing
Should tomatoes be kept in the fridge?
Ripe tomatoes that you'll eat in the next few days are best kept at room temperature, out of the sun: chilling dulls their aroma. Refrigerate cut tomatoes and use them quickly.
How can I tell if a tomato is ripe?
It's evenly coloured, gives slightly when pressed, feels heavy for its size and smells fragrant at the stem.
Will unripe tomatoes ripen at home?
Tomatoes that have already started to turn red or brownish usually ripen at room temperature. Fully green ones ripen less well — they are often used for preserves.
Which tomatoes are best for sauce?
Meaty plum tomatoes: they have less juice, so the sauce reduces faster. Out of season, canned tomatoes will do.
Cooking
Why does my sauce taste sour?
The acidity of tomatoes depends on the variety and ripeness. Add a pinch of sugar, heat through and taste; sometimes simply cooking the sauce down for longer helps.
Do I have to peel tomatoes?
Not for a salad. For smooth sauces, soups and preserves, it's better to peel them by blanching: score a cross, 20–60 seconds in boiling water, then iced water.
Can you eat green tomatoes?
They contain the glycoalkaloid tomatine. In cooking, green tomatoes are usually eaten pickled, fried or braised rather than raw in large amounts.
Are cooked tomatoes healthier than raw ones?
We don't give nutrition advice. All we can say is that lycopene is better absorbed from heat-treated tomatoes, and in the presence of fat, than from raw ones.
Preserving and safety
Why add acid to tomatoes when canning?
Their acidity is borderline. The National Center for Home Food Preservation advises adding 1 tbsp of bottled lemon juice or ¼ tsp of citric acid per pint (≈ 0.47 L), and twice as much per quart (≈ 0.95 L).
Can I can jars using my own recipe?
It's safer to use tested recipes that give processing times. Improvising with preserves increases the risk of botulism.
The lid has bulged — what should I do?
Don't open the jar to taste it and don't eat the contents. The same applies if there is foam inside or an unpleasant smell.
How long can a cooked dish sit out?
Refrigerate cooked food within 2 hours — this is the USDA's recommendation.
Related sections
- Ingredients
Types of tomatoes and what goes with them: how to choose, how to store, how to use.
- Cooking techniques
Blanching, roasting, oven-drying, sauce, homemade tomato paste, freezing and safe home canning.
- Korean-style green tomato salad (in Russian)
A new home recipe for Korean-style green tomato salad with carrot, pepper and garlic.
- Cooking tips
Short cooking tips about tomatoes, plus the article catalogue.
Sources
- National Center for Home Food Preservation (USDA)
- USDA Food Safety and Inspection Service
- PNAS (2016) — study on storing tomatoes at low temperature
Times and temperatures in these recipes are a guide: a lot depends on your hob, oven, pans and the tomatoes themselves. For home preserving, use tested recipes that give processing times.