Some like it cold

Consumers are lapping it up. “Coffee sales always drop in the summer,’’ explained Nathaniel Howell, sales manager of Terroir Coffee in Acton, a supplier of high-end beans to area cafes. “This summer there’s no drop in sales. It’s because of iced coffee.’’ Managers at several Starbucks locations say that about 80 percent of coffee sales this summer are iced. Though many consumers want their icy drink with plenty of milk and sugar, purists around the city drink it black.

Despite the name, the Japanese cold brew is no more common in Japan than Italy’s “Americano’’ (a mix of espresso and water) is in the United States. But it tastes much better. The Japanese method uses drip-brewed coffee with hot water (about 190 degrees), at double strength, which its adherents say allows the best development of the so-called “fruity’’ and “floral’’ high notes of the beans’ taste spectrum. The hot coffee drips directly onto ice cubes for just a few minutes and the glass is served immediately. The delicate flavors have been described as like bubbles in champagne, charming and fleeting.

A competing method has come into vogue called “cold brewing.’’ Here coarse-ground dark roast beans are mixed with cool water and allowed to steep for up to 20 hours. The mixture is then filtered to remove the grounds and sediment. Fans claim that the result is much smoother, and lower in bitter acids, with deep molasses and nut tones. It also packs a wallop; the extra time in the water can raise the caffeine level five-fold. Cold brew keeps in the fridge for hours, and is served over ice. For cafes serving in volume, that is an obvious advantage.

Cold brewing has sparked heated argument. Jaime van Schyndel, general manager at Barismo in Arlington, one of the Hub’s most exacting and perhaps nerdiest roasteries, says that cold brewing “brings out a deep base of caramel and chocolate flavors you can’t get from the bean any other way, with softer citrus and acidic notes.’’