By Harold McGee
Iced tea is the most popular form of tea in the United States; it first caught on at the 1904 World’s Fair in steamy St. Louis. It’s made by brewing tea with about half-again as much dry tea per cup, to compensate for the later dilution by melting ice. The addition of ice to normally brewed tea tends to make the tea cloudy, due to the formation of particles of a complex between caffeine and theaflavin. The way to avoid this is to brew the initial tea at room or refrigerator temperature, over several hours. This technique extracts less caffeine and theaflavin than brewing in hot water, so the caffeine-theaflavin complexes don’t form in sufficient quantities to become visible in the chilled tea.