Making tomatoes ripe for the cooking

It’s hard to imagine a meal in San Antonio without fresh tomatoes playing at least a supporting role, be it in a batch of pico de gallo, scattered over a puffy taco or tucked into a bun along with a juicy burger patty. Unfortunately, preparing those meals can be a challenge when the only tomatoes in the store are hard, unripe specimens with the barest blush of red hue.

The good news is you can take control of that ripening process with tomatoes since they’re among the family of fruits that naturally release ethylene, a gas that can be harnessed to help speed their ripening.

The first place to start is storage. Tomatoes that are less than perfectly ripe will develop and retain their best flavor and aroma when held at room temperature. Refrigeration will halt their ripening, damage the way they taste and smell, and give them a mealy texture. Temperature is the key here — anything below 55 degrees will stop ripening. Temperatures between 70 and 80 degrees work best, with more sugars and less acid developing in the tomatoes on the higher end of that range.

If you have a few days before you’ll need to use your tomatoes, help them ripen by placing them stem side down — this is mainly to keep them from rolling around — in a windowsill. The sunlight will help the tomatoes develop a little more color and gently coax them into ripeness. This can take up to six or seven days depending on how underripe the tomatoes are.

To speed the process, place the tomatoes in a paper bag, cardboard box or other breathable container. Avoid plastic bags or tubs; the humidity trapped inside those containers will encourage mold growth and rot. Tomatoes can spoil in that kind of environment in just a few days.

Once closed, the breathable container will trap some of the ethylene gas and hasten the ripening process. You can speed this even more by adding a banana to the box, which will produce even more ethylene.

If you’re a gardener with tomato plants full of underripe fruits, there’s one tip the Farmers’ Almanac recommends should the weather forecast indicate a coming frost. Pull up the whole plant, roots and all, and hang it indoors upside down in an area with indirect sunlight and temperatures that don’t top 80 degrees.

If you have tomatoes that are perfectly ripe but you aren’t ready to use them, you have a couple of options.

The refrigerator is colder than ideal to hold tomatoes, but it can buy you a couple days if need be. Noted food scientist Harold McGee says 55 degrees is the perfect temperature to both halt ripening and prevent the flavor loss that occurs as enzymatic activity inside the fruit decreases in the roughly 35 degree temperatures inside a refrigerator.

Fortunately, McGee notes, some of that flavor can be recovered if you let the tomatoes sit at room temperature for a day or two after refrigerating before using them. Alternatively, if the tomatoes are destined for a sauce or other application where texture isn’t a concern, they can be washed, cut, packed into bags and frozen for longer storage without damaging their flavor.

There are several ways to hasten the ripening of tomatoes — just keep them out of the fridge.