Juiced-up fruit: unbelievably flavorful.

Food scientists have harnessed natural enzymes to make fruits taste almost too good to be true. Ralf G. Berger and his colleagues at the University of Hanover (Germany) developed a technique for storing apples, pears and bananas in airtight containers along with different kinds of alcohols. The alcohols serve as building blocks, or precursors, for molecules called carboxylic esters, which impart fruity flavors. When the alcohols seep into the fruit, they cause the enzymes inside to increase their ester production by as much as 30-fold, Berger reports. His team tested the technique by measuring alcohol concentrations outside the fruit and ester concentrations inside the treated fruit at 32-hour intervals.

Taste tests verified the transfer and transformation of the precursors, Berger says. For example, six of nine people who sipped juices made from treated or untreated apples could distinguish between the two. However, a few tasters said they preferred the juice from untreated apples because they believed that only an artificial flavoring could make the other juice so fruity. "You can have too much," Berger admits. "The [treated fruits] are like perfume, they have so much flavor."

The technique also works well with bananas and pears, he reports, although it doesn't do much to enhance the taste of citrus fruits. And there's nothing artificial about it. "We use natural precursor substrates, and we're making use of the natural biosynthetic pathways," Berger says.

Treated fruits stay firmer longer, he adds, because the excess precursors slow down natural degradation. But it's important to use the right kind of alcohol for each fruit, or the treatment may impart a funny taste. "I can flavor you a banana that tastes like strawberries," he says. "But I don't think that would be really well received."