Agua fresca de jamaica, using a hibiscus.[Photo/The New York Times]

The hot-brew argument sounded convincing to me, and I'd be happy not to need any special kit or forethought. But when I compared a 12-hour cold brew of freshly roasted Ethiopian coffee side by side with double-strength pour-overs brewed onto ice, each was good, and it was the cold brew that consistently tasted fruitier and more refreshing. That experiment made me a fan of cold-brewed coffee. It's certainly worth trying. Both are an improvement over simply brewing hot coffee and chilling it for hours in the refrigerator, which gives a cloudy, less flavorful drink on its own, one that benefits from mixing with milk or cream and sugar.

When it comes to tea, there's less controversy and more flexibility. The standard proportions for American iced tea are about 4 teaspoons or 2-gram bags per quart, with a brewing time of 8 to 12 hours. In Taiwan, where cold-brewed tea has become increasingly popular in recent years and spurred studies of its chemistry, about twice that ratio of tea to water is used for a similarly long infusion. And one purveyor of fine Japanese teas in Kyoto recommends making small cups of cold sencha with 5 times that ratio, infusing first for 15 minutes, then for briefer times. The first couple of infusions are like no other version of green tea I've had, intensely grassy and bitter, with subsequent brews progressively milder and more refreshing.

Since cold infusion is a relatively slow and gentle process, proportions and times aren't critical. There's plenty of leeway for both. As a general rule, the more fragile the tea leaves, or the smaller the particles, the less tea and time you need to get a strong brew. If a cold brew infuses too slowly, just add more tea.

Two of my favorite cold-brewed teas come from Maricel Presilla, who serves a number of them at her Latin restaurant Zafra in Hoboken, N.J. One perennial on her list is a mojito iced tea, in which oolong tea scented with osmanthus flowers, or with a sliced peach and its pit, suggests the sweet aroma of white rum.

Ms. Presilla also makes an unadorned agua fresca de jamaica, the tart, deep-red sepals that surround the flower of a particular species of hibiscus.

"Nothing compares to the bright color and flavor of the cold-infused drink," she wrote in an e-mail. "It can steep for as little as two hours and needs nothing but some sugar, though you can include spices like cinnamon, allspice or star anise for a subtle but nice flavor."

I like to use allspice and then muddle some fresh basil in the infusion just before serving.

Jamaica (pronounced ha-MY-ka) is especially rich in antioxidant polyphenolic compounds, including its anthocyanin pigments, and food chemists are investigating its potential as a nonalcoholic alternative to red wine. They have found that a two-hour cold infusion extracts as much of the pigments as a standard hot infusion, and that the flavor is fruitier and less marked by green-leaf, clove and cooked aromas.

Less heat may mean less flavor in coffees and teas, but not necessarily less pleasure.